In-vivo measurement of radio frequency electric fields in mice brain.

With the development of novel technologies, radio frequency (RF) energy exposure is expanding at various wavelengths and power levels. These developments necessitate updated approaches of RF measurements in complex environments, particularly in live biological tissue. Accurate dosimetry of the absorbed RF electric fields (E-Fields) by the live tissue is the keystone of environmental health considerations for this type of ever-growing non-ionizing radiation energy. In this study, we introduce a technique for direct in-vivo measurement of electric fields in living tissue. Proof of principle in-vivo electric field measurements were conducted in rodent brains using Bismuth Silicon Oxide (BSO) crystals exposed to varying levels of RF energy. Electric field measurements were calibrated and verified using in-vivo temperature measurements using optical temperature fibers alongside electromagnetic field simulations of a transverse electromagnetic (TEM) cell.

Left Atrial Size; a Missing Component in Scoring Systems for Predicting Atrial Fibrillation Following Coronary Artery Bypass Surgery.

BACKGROUND: Several risk factors have been associated with the development of postoperative atrial fibrillation (AF). However, some important factors that may play substantial roles have been neglected in the final suggested risk models. In this study, we aimed to derive a new clinical risk index to predict AF in coronary artery bypass graft (CABG) patients. METHODS: In this retrospective cohort study we enrolled 3047 isolated CABG patients. A random sample of 2032 patients was used to derive a risk index for the prediction of post-CABG AF. A multivariate logistic regression model identified the independent preoperative predictors of post-CABG AF, and a simple risk index to predict AF was constructed. This risk index was cross-validated in a validation set of 1015 patients with isolated CABG. RESULTS: Post-CABG AF occurred in 15.9% and 15.7% of the patients in the prediction and validation sets, respectively. Using multivariate stepwise analysis, four preoperative variables including advanced age, left atrial (LA) enlargement, hypertension and cerebrovascular accident contributed to the prediction model (area under the receiver operating characteristic curve curve = 0.66). The effect of advanced age appeared to be dominant [age ≥ 75 years; odds ratio: 4.134, 95% confidence interval (CI): 2.791-6.121, p < 0.001]. Moderate to severe LA enlargement had an odds ratio of 2.176 (95% CI: 1.240-3.820, p = 0.013) for developing AF in our risk index. CONCLUSIONS: LA size was an important factor in risk stratification of post-CABG AF, which remained significant in the final model. Future scoring system studies might benefit from the use of this variable to obtain a more robust predictive value.

Incidence and predictors of chronic thromboembolic pulmonary hypertension following first episode of acute pulmonary embolism.

INTRODUCTION: Late obstructive pulmonary artery remodeling presented as CTEPH portends adverse sequelae and therapeutic challenges. Although progressive dyspnea on exertion beyond three-month period of treatment with anticoagulants is a diagnostic cornerstone, uncertainty still surrounds early identification and risk factors. MATERIAL AND METHODS: We have conducted a prospective study among survivors of acute pulmonary embolism (PE) who were treated by anticoagulants for at least 3 months. Patients with preexisting pulmonary hypertension (PH), severe chronic obstructive pulmonary disease (COPD), and low ejection fraction (EF) in baseline echocardiography (EF < 30%) were excluded. Complete follow-up for 290 subjects were performed. According to a predetermined stepwise diagnostic protocol, patients with exertional Dyspnea and PH probable features in echocardiography underwent lung perfusion scan. RESULTS: Cumulative two-year incidence of CTEPH was 8.6% (n = 25). There was no patient with normal baseline right ventricular (RV) function in CTEPH group. In the same way, none of these patients had only segmental involvement in baseline CT angiography (CTA) in CTEPH group. Greater proportion of CTEPH group received fibrinolytic therapy, however the difference was not significant (2.6% vs 8 %, P = 0.16). Multivariate logistic regression demonstrated significant association of RV diameter, and PAP in baseline echocardiography as well as RV strain in CTA with development of CTEPH. Corresponding odds ratios were 1.147 (1.063-1.584) P < 0.0001) , 1.062 (1.019-1.106, P = 0.004), and 2.537 (1.041-6.674), P = 0.027), respectively. CONCLUSIONS: We found that incidence of CTEPH was relatively high in the present investigation. RV diameter, baseline PAP and RV dysfunction were independent predictors of CTEPH.

Tramadol state-dependent memory: involvement of dorsal hippocampal muscarinic acetylcholine receptors.

The effects on tramadol state-dependent memory of bilateral intradorsal hippocampal (intra-CA1) injections of physostigmine, an acetylcholinesterase inhibitor, and atropine, a muscarinic acetylcholine receptor antagonist, were examined in adult male NMRI mice. A single-trial step-down passive avoidance task was used for the assessment of memory retention. Post-training intra-CA1 administration of an atypical µ-opioid receptor agonist, tramadol (0.5 and 1 µg/mouse), dose dependently impaired memory retention. Pretest injection of tramadol (0.5 and 1 µg/mouse, intra-CA1) induced state-dependent retrieval of the memory acquired under the influence of post-training tramadol (1 µg/mouse, intra-CA1). A pretest intra-CA1 injection of physostigmine (1 µg/mouse) reversed the memory impairment induced by post-training administration of tramadol (1 µg/mouse, intra-CA1). Moreover, pretest administration of physostigmine (0.5 and 1 µg/mouse, intra-CA1) with an ineffective dose of tramadol (0.25 µg/mouse, intra-CA1) also significantly restored retrieval. Pretest administration of physostigmine (0.25, 0.5, and 1 µg/mouse, intra-CA1) by itself did not affect memory retention. A pretest intra-CA1 injection of the atropine (1 and 2 µg/mouse) 5 min before the administration of tramadol (1 µg/mouse, intra-CA1) dose dependently inhibited tramadol state-dependent memory. Pretest administration of atropine (0.5, 1, and 2 µg/mouse, intra-CA1) by itself did not affect memory retention. It can be concluded that dorsal hippocampal muscarinic acetylcholine receptor mechanisms play an important role in the modulation of tramadol state-dependent memory.

Giant aneurysmal fistula of the left main coronary artery to the right atrium.

A 42-year-old woman presented to our outpatient department with complaints of atypical chest pain and palpitation. On physical examination, the patient's blood pressure was 140/95 mm Hg, and there was a systolic cardiac murmur on the left sternal border. A transthoracic echocardiography examination was performed, and a left-to-right shunt ratio (Qp/Qs) of approximately 1.5 was detected. Computed tomography angiography and coronary angiography examinations confirmed the presence of a large fistula between the left main coronary artery and the right atrium, with giant aneurysm formation and an intact right coronary artery. Surgical closure of the shunt was performed with a good final result.