Utility of spectrum and wavelet analysis of heart rate variability as a tool to assess orthostatic intolerance

Three studies were performed to test the hypotheses: (1) lower body negative pressure (LBNP) tolerance, autonomic, and cardiovascular responses to the LBNP are reproducible, (2) women have a lower LBNP tolerance and less ability to maintain homeostasis in cardiovascular system against orthostatic stress, and (3) wavelet analysis technique is a unique tool to study the autonomic nervous activities during LBNP test. College-age men and women underwent graded LBNP to either presyncope or -100 mmHg in increments of 10 mmHg negative pressure every 6 minutes;The LBNP tolerance were highly reproducible (cumulative stress index: 1698 +/- 171 vs 1938 +/- 139, trial 1 vs trial 2, respectively; Cronbach alpha coefficient = 0.87). Changes of the autonomic and cardiovascular responses in the two trials were similar. Autonomic and cardiovascular responses to LBNP at most level were reproducible (alpha coefficient ≥ 0.41);The females showed 44% less tolerance to the orthostatic stress induced by LBNP than the male. Heart rate increased above rest at ≥-40 mmHg (P \u3c 0.05) in both groups and mean arterial pressure was maintained in males while it fell below rest at ≥-30 mmHg (P \u3c 0.05) in females. Based on spectral analysis, sympathetic nervous system activity as quantified by the LF/HF ratio increased above rest at ≥-40 mmHg in males but it increased only at presyncope in females (P \u3c 0.05);The wavelet analysis technique is a valuable-unique tool to study autonomic responses to LBNP over spectral analysis since: (1) this method provides a dynamic autonomic response to LBNP by showing both time- and frequency-description simultaneously and (2) this method yield the additional valuable information from transient and nonstationary part of heart rate signal which normally discarded to satisfy the underlying condition of spectral analysis;These results suggest that (1) LBNP tolerance, autonomic, and cardiovascular responses to LBNP are reproducible, (2) women have a lower orthostatic tolerance than men and this gender difference in orthostatic tolerance may be due to differences in the autonomic activity responses to this stress, and (3) wavelet analysis is a unique tool over spectral analysis to access autonomic responses to LBNP

Sympathetic withdrawal is associated with hypotension after hepatic reperfusion

Objective: Post-reperfusion syndrome (PRS), severe hypotension after graft reperfusion during liver transplantation, is an adverse clinical event associated with poorer patient outcomes. The purpose of this study was to determine whether alterations in autonomic control in liver transplant recipients prior to graft reperfusion are associated with the subsequent development of PRS. Methods: Heart rate variability (HRV), systolic arterial blood pressure (SBP) variability, and baroreflex sensitivity of 218 liver transplant recipients were evaluated using 5 min of ECG and arterial blood pressure signals 10 min before graft reperfusion along with other clinical parameters. Logistic regression analyses were performed to assess predictors of PRS occurrence. Results: Seventy-seven patients (35 %) developed PRS while 141 did not. There were significant differences in SBP (110 ± 16 vs. 119 ± 16 mmHg, P < 0.001) and the ratio of low frequency power to high frequency power (LF/HF) of HRV (1.0 ± 1.4 vs. 2.1 ± 3.7, P = 0.003) between the PRS group and No-PRS group. In multivariate logistic regression analysis, predictors were LF/HF (odds ratio 0.817, P = 0.028) and SBP (odds ratio 0.966, P < 0.001). Interpretation: Low LF/HF and SBP measured before hepatic graft reperfusion were significantly correlated with subsequent PRS occurrence, suggesting that sympathovagal imbalance and depressed SBP may be key factors predisposing to reperfusion-related severe hypotension in liver transplant recipients

Estimation of changes in instantaneous aortic blood flow by the analysis of arterial blood pressure

The purpose of this study was to introduce and validate a new algorithm to estimate instantaneous aortic blood flow (ABF) by mathematical analysis of arterial blood pressure (ABP) waveforms. The algorithm is based on an autoregressive with exogenous input (ARX) model. We applied this algorithm to diastolic ABP waveforms to estimate the autoregressive model coefficients by requiring the estimated diastolic flow to be zero. The algorithm incorporating the coefficients was then applied to the entire ABP signal to estimate ABF. The algorithm was applied to six Yorkshire swine data sets over a wide range of physiological conditions for validation. Quantitative measures of waveform shape (standard deviation, skewness, and kurtosis), as well as stroke volume and cardiac output from the estimated ABF, were computed. Values of these measures were compared with those obtained from ABF waveforms recorded using a Transonic aortic flow probe placed around the aortic root. The estimation errors were compared with those obtained using a windkessel model. The ARX model algorithm achieved significantly lower errors in the waveform measures, stroke volume, and cardiac output than those obtained using the windkessel model (P < 0.05)

Dose-Dependent Changes of Chemical Attributes in Irradiated Sausages

To determine the effects of irradiation on the chemical attributes of sausages, TBARS values, volatile compounds, gas compounds, and hydrocarbons of vacuum-packaged sausages were analyzed during 60 d of refrigerated storage. A sulfur-containing volatile compound (dimethyl disulfide), a gas compound (methane), and radiation-induced hydrocarbons (1-tetradecene, pentadecane, heptadecane, 8-heptadecene, eicosane, 1, 7-hexadecadiene, hexadecane) were mainly detected in irradiated sausages, and the concentrations of the compounds were irradiation dosedependent. Especially methane and a few hydrocarbons were detected only in irradiated sausages and their amounts were dose-dependent. On the other hand, TBARS values, other off-odor volatiles (carbon disulfide, hexanal), and gas compounds (carbon monoxide, carbon dioxide) were found both in irradiated and nonirradiated sausages. Therefore, it is suggested that irradiation-induced hydrocarbons (1-tetradecene, pentadecane, heptadecane, 8-heptadecene, eicosane, 1, 7-hexadecadiene, hexadecane), dimethyl disulfide, and methane can be used as markers for irradiated sausages

Evaluation of Radiation-induced Compounds in Irradiated Raw or Cooked Chicken Meat during Storage

The concentrations of hydrocarbons, 2-alkylcyclobutanones, and sulfur volatiles in irradiated (0, 5 kGy) chicken meats (raw, pre-cooked, and irradiatedcooked) were analyzed after 0 and 6 months of frozen storage (-40°C) under oxygen permeable packaging conditions. Two hydrocarbons [8-heptadecene (C17:1) and 6,9-heptadecadiene (C17:2)], two 2-alkylcyclobutanones [2-dodecylcyclobutanone (DCB) and 2-tetradecylcyclobutanone (TCB)], and dimethyl disulfide were determined as radiation-induced detection markers in the irradiated raw and cooked chicken meats. Although, irradiated-cooked samples produced less hydrocarbons and 2-alkylcyclobutanones than pre-cooked irradiated ones, the amount of individual hydrocarbons or 2-alkylcyclobutanones was still sufficient enough to detectradiation treatment even after 6 months of storage at -40°C. Among sulfur volatiles, only dimethyl disulfide were found in meat after 6 months of storage indicating it has potential to be used an irradiation detection marker for frozen-stored meats under oxygen permeable packaging conditions

A deep learning model for automated kidney calculi detection on non-contrast computed tomography scans in dogs

Nephrolithiasis is one of the most common urinary disorders in dogs. Although a majority of kidney calculi are non-obstructive and are likely to be asymptomatic, they can lead to parenchymal loss and obstruction as they progress. Thus, early diagnosis of kidney calculi is important for patient monitoring and better prognosis. However, detecting kidney calculi and monitoring changes in the sizes of the calculi from computed tomography (CT) images is time-consuming for clinicians. This study, in a first of its kind, aims to develop a deep learning model for automatic kidney calculi detection using pre-contrast CT images of dogs. A total of 34,655 transverseimage slices obtained from 76 dogs with kidney calculi were used to develop the deep learning model. Because of the differences in kidney location and calculi sizes in dogs compared to humans, several processing methods were used. The first stage of the models, based on the Attention U-Net (AttUNet), was designed to detect the kidney for the coarse feature map. Five different models–AttUNet, UTNet, TransUNet, SwinUNet, and RBCANet–were used in the second stage to detect the calculi in the kidneys, and the performance of the models was evaluated. Compared with a previously developed model, all the models developed in this study yielded better dice similarity coefficients (DSCs) for the automatic segmentation of the kidney. To detect kidney calculi, RBCANet and SwinUNet yielded the best DSC, which was 0.74. In conclusion, the deep learning model developed in this study can be useful for the automated detection of kidney calculi

FDG-PET for evaluating the antitumor effect of intraarterial 3-bromopyruvate administration in a rabbit VX2 liver tumor model

OBJECTIVE: We wanted to investigate the feasibility of using FDG-PET for evaluating the antitumor effect of intraarterial administration of a hexokinase II inhibitor, 3-bromopyruvate (3-BrPA), in a rabbit VX2 liver tumor model. MATERIALS AND METHODS: VX2 carcinoma was grown in the livers of ten rabbits. Two weeks later, liver CT was performed to confirm appropriate tumor growth for the experiment. After tumor volume-matched grouping of the rabbits, transcatheter intraarterial administration of 3-BrPA was performed (1 mM and 5 mM in five animals each, respectively). FDG-PET scan was performed the day before, immediately after and a week after 3-BrPA administration. FDG uptake was semiquantified by measuring the standardized uptake value (SUV). A week after treatment, the experimental animals were sacrificed and the necrosis rates of the tumors were calculated based on the histopathology. RESULTS: The SUV of the VX2 tumors before treatment (3.87+/-1.51 [mean+/-SD]) was significantly higher than that of nontumorous liver parenchyma (1.72+/-0.34) (p < 0.0001, Mann-Whitney U test). The SUV was significantly decreased immediately after 3-BrPA administration (2.05+/-1.21) (p = 0.002, Wilcoxon signed rank test). On the one-week follow up PET scan, the FDG uptake remained significantly lower (SUV 1.41+/-0.73) than that before treatment (p = 0.002), although three out of ten animals showed a slightly increasing tendency for the FDG uptake. The tumor necrosis rate ranged from 50.00% to 99.90% (85.48%+/-15.87). There was no significant correlation between the SUV or the SUV decrease rate and the tumor necrosis rate in that range. CONCLUSION: Even though FDG-PET cannot exactly reflect the tumor necrosis rate, FDG-PET is a useful modality for the early assessment of the antitumor effect of intraarterial administration of 3-BrPA in VX2 liver tumor

Utility of spectrum and wavelet analysis of heart rate variability as a tool to assess orthostatic intolerance

Three studies were performed to test the hypotheses: (1) lower body negative pressure (LBNP) tolerance, autonomic, and cardiovascular responses to the LBNP are reproducible, (2) women have a lower LBNP tolerance and less ability to maintain homeostasis in cardiovascular system against orthostatic stress, and (3) wavelet analysis technique is a unique tool to study the autonomic nervous activities during LBNP test. College-age men and women underwent graded LBNP to either presyncope or -100 mmHg in increments of 10 mmHg negative pressure every 6 minutes;The LBNP tolerance were highly reproducible (cumulative stress index: 1698 +/- 171 vs 1938 +/- 139, trial 1 vs trial 2, respectively; Cronbach alpha coefficient = 0.87). Changes of the autonomic and cardiovascular responses in the two trials were similar. Autonomic and cardiovascular responses to LBNP at most level were reproducible (alpha coefficient ≥ 0.41);The females showed 44% less tolerance to the orthostatic stress induced by LBNP than the male. Heart rate increased above rest at ≥-40 mmHg (P < 0.05) in both groups and mean arterial pressure was maintained in males while it fell below rest at ≥-30 mmHg (P < 0.05) in females. Based on spectral analysis, sympathetic nervous system activity as quantified by the LF/HF ratio increased above rest at ≥-40 mmHg in males but it increased only at presyncope in females (P < 0.05);The wavelet analysis technique is a valuable-unique tool to study autonomic responses to LBNP over spectral analysis since: (1) this method provides a dynamic autonomic response to LBNP by showing both time- and frequency-description simultaneously and (2) this method yield the additional valuable information from transient and nonstationary part of heart rate signal which normally discarded to satisfy the underlying condition of spectral analysis;These results suggest that (1) LBNP tolerance, autonomic, and cardiovascular responses to LBNP are reproducible, (2) women have a lower orthostatic tolerance than men and this gender difference in orthostatic tolerance may be due to differences in the autonomic activity responses to this stress, and (3) wavelet analysis is a unique tool over spectral analysis to access autonomic responses to LBNP.</p