Time-frequency analysis reveals an association between the specific nuclear magnetic resonance (NMR) signal properties of serum samples and arteriosclerotic lesion progression in a diabetes mouse model.

Diabetes causes arteriosclerosis, primarily due to persistent hyperglycemia, subsequently leading to various cardiovascular events. No method has been established for directly detecting and evaluating arteriosclerotic lesions from blood samples of diabetic patients, as the mechanism of arteriosclerotic lesion formation, which involves complex molecular biological processes, has not been elucidated. "NMR modal analysis" is a technology that enables visualization of specific nuclear magnetic resonance (NMR) signal properties of blood samples. We hypothesized that this technique could be used to identify changes in blood status associated with the progression of arteriosclerotic lesions in the context of diabetes. The study aimed to assess the possibility of early detection and evaluation of arteriosclerotic lesions by NMR modal analysis of serum samples from diabetes model mice. Diabetes model mice (BKS.Cg db/db) were bred in a clean room and fed a normal diet. Blood samples were collected and centrifuged. Carotid arteries were collected for histological examination by hematoxylin and eosin staining on weeks 10, 14, 18, 22, and 26. The serum was separated and subjected to NMR modal analysis and biochemical examination. Mice typically show hyperglycemia at an early stage (8 weeks old), and pathological findings of a previous study showed that more than half of mice had atheromatous plaques at 18 weeks old, and severe arteriosclerotic lesions were observed in almost all mice after 22 weeks. Partial least squares regression analysis was performed, which showed that the mice were clearly classified into two groups with positive and negative score values within 18 weeks of age. The findings of this study revealed that NMR modal properties of serum are associated with arteriosclerotic lesions. Thus, it may be worth exploring the possibility that the risk of cardiovascular events in diabetic patients could be assessed using serum samples.

Safety of Copolyamide Filler Injection for Breast Augmentation.

Although injections with copolyamide fillers (Aquafilling/Los Deline and Aqualift/Activegel) are currently used widely for breast augmentation, many complications have been reported. A recent position statement by a Korean aesthetic/reconstructive breast surgery society indicated these fillers are the same as polyacrylamide gel (PAAG), which is widely prohibited due to complications. To test this statement, this retrospective cohort study examined the clinical complications after breast augmentation with copolyamide fillers. Nuclear magnetic resonance (NMR) analysis of copolymer and PAAG fillers was also conducted. METHODS: All consecutive patients with concerns about or sequelae from copolyamide fillers who visited our hospital in 2018-2020 were identified. The injected formulation, complications, and intraoperative findings were recorded. Copolyamide fillers were compared with PAAG and 2 PAAG fillers (Amazingel and Aquamid) by NMR. RESULTS: Of the 29 patients (all women; average age, 42 years), 17 complained of breast deformity. Eight had puncture site infections and mammary gland inflammation. Five exhibited induration (single large/small lumps). In 4 cases, the filler had migrated outside of the breast, including to the back and vulva; these cases had severe symptoms. NMR showed that the copolyamide and PAAG fillers bore all of the characteristic peaks of PAAG. CONCLUSIONS: Our clinical/intraoperative and NMR findings showed, respectively, that copolyamide fillers cause the same complications as PAAG fillers and have the same composition. Thus, the risks of copolyamide fillers for breast augmentation are equivalent to those for PAAG fillers. It is strongly recommended not to use copolyamide fillers until their long-term safety is established.

Time-frequency analysis of serum with proton nuclear magnetic resonance for diagnosis of pancreatic cancer.

Although serum markers such as carcinoembryonic antigen (CEA) and carbohydrate antigen (CA19-9) have been widely used in screening for pancreatic cancer (PC), their sensitivity and specificity are unsatisfactory. Recently, a novel tool of analyzing serum using the short-time Fourier transform (STFT) of free induction decays (FIDs) obtained by 1H-NMR has been introduced. We for the first time evaluated the utility of this technology as a diagnostic tool for PC. Serum was obtained from PC patients before starting any treatments. Samples taken from individuals with benign diseases or donors for liver transplantation were obtained as controls. Serum samples from both groups underwent 1H-NMR and STFT of FIDs. STFT data were analyzed by partial least squares discriminant analysis (PLS-DA) to clarify whether differences were apparent between groups. As a result, PLS-DA score plots indicated that STFT of FIDs enabled effective classification of groups with and without PC. Additionally, in a subgroup of PC, long-term survivors (≥ 2 years) could be discriminated from short-term survivors (< 2 years), regardless of pathologic stage or CEA or CA19-9 levels. In conclusion, STFT of FIDs obtained from 1H-NMR have a potential to be a diagnostic and prognostic tool of PC.

Short-time Fourier Transform of Free Induction Decays for the Analysis of Serum Using Proton Nuclear Magnetic Resonance.

Proton nuclear magnetic resonance (NMR) is useful for the analysis of biological samples such as serum. Free induction decays (FIDs) are NMR signals that follow a radio-frequency pulse applied at the resonance frequency. Short-time Fourier transform (STFT) is a basic method for time-frequency analyses. The purpose of this study was to ascertain whether the STFT of FIDs enables the sensitive detection of changes and differences in serum properties. FIDs were obtained from serum collected from young, healthy, male volunteers ≤ 40 years of age and seniors ≥ 65 years of age. Temporal changes in the instantaneous amplitudes for the time-domain analysis, fast Fourier transform for frequency-domain analysis, and STFT were applied to the FIDs. The STFT-based spectrogram represented the complex frequency components that changed dynamically over time, indicating that the spectrogram enabled the visualization of the features of an FID. Furthermore, the results of a partial least-squares discriminant analysis demonstrated that the STFT was superior to the other two methods for discriminating between serum from younger and older subjects. In conclusion, the STFT of FIDs obtained from proton NMR measurements was useful for evaluating similarities and dissimilarities in the FIDs obtained from serum samples.

Pattern recognition analysis of proton nuclear magnetic resonance spectra of postmortem cerebrospinal fluid from rats with drug-induced seizure or coma.

Cerebrospinal fluid (CSF) is routinely subjected to gross evaluation in postmortem investigations; however, its use in chemical evaluations has not been fully realized. Analysis of nuclear magnetic resonance (NMR) spectra with pattern recognition methods was applied to CSF samples. Rats were treated with pentylenetetrazol (PTZ) to induce seizure or pentobarbital (PB) to induce coma, and postmortem CSF was collected after CO2 gas euthanization. Pattern recognition analysis of the NMR data was performed on individual postmortem CSF samples. The aim of this study was to determine if pattern recognition analysis of NMR data could be used to classify the rats according to their drug treatment. The applicability of NMR data with pattern recognition analysis using postmortem CSF was also assessed. Partial Least Squares-Discriminant Analysis (PLS-DA) score plots indicated that the PTZ, PB, and NS (control) groups were clustered and clearly separated. PLS-DA correlation loading plots showed respective spectral and category variances of 41% and 42% for factor 1, and 17% and 27% for factor 2. Thus, factors 1 and 2 together described 58% (41%+17%) and 69% (42%+27%) of the variation, respectively. NMR study of postmortem CSF has the potential to be utilized as both a novel forensic neurochemistry method and in the clinical setting.

Visualization of different characteristics of cerebrospinal fluid with acute encephalopathy and febrile seizures using pattern recognition analysis of 1H NMR.

BACKGROUND: In acute encephalopathy, deterioration of the condition can be rapid, and early intervention is essential to prevent progression of the disease. However, in the acute period, differentiating acute encephalopathy from febrile seizures is difficult. Thus, an early diagnostic marker has been sought to enable early intervention. Proton nuclear magnetic resonance ((1)H NMR) spectroscopy is used to study the chemical characteristics of biological fluids such as cerebrospinal fluid (CSF). The purpose of this study was to ascertain if pattern recognition of (1)H NMR spectra could differentiate CSF obtained from patients with acute encephalopathy and febrile seizures. METHODS: CSF was obtained from patients with acute encephalopathy (n = 4), complex febrile seizures (n = 9), and simple febrile seizures (n = 9). RESULTS: NMR spectra of CSF did not visually differ across the three groups. Spectral data were analyzed by partial least squares discriminant analysis and visualized by plotting the partial least squares scores of each sample. The three patient groups clustered separately on the plots. CONCLUSION: In this preliminary study, we were able to visualize different characteristics of CSF obtained from patients with acute encephalopathy and simple and complex febrile seizures using pattern recognition analysis of (1)H NMR data.

Pattern recognition analysis of proton nuclear magnetic resonance spectra of extracts of intestinal epithelial cells under oxidative stress.

BACKGROUND: Mesenteric ischemia-reperfusion induces gut mucosal damage. Intestinal mucosal wounds are repaired by epithelial restitution. Although many different molecular mechanisms have been shown to affect cell metabolism under oxidative conditions, these molecular mechanisms and metabolic phenotypes are not well understood. Nuclear magnetic resonance (NMR) spectroscopic data can be used to study metabolic phenotypes in biological systems. Pattern recognition with multivariate analysis is one chemometric technique. The purpose of this study was to visualize, using a chemometric technique to interpret NMR data, different degrees of oxidant injury in rat small intestine (IEC-6) cells exposed to H2O2. METHODS: Oxidant stress was induced by H2O2 in IEC-6 cells. Cell restitution and viability were assessed at different H2O2 concentrations and time points. Cells were harvested for pattern recognition analysis of (1)H-NMR data. RESULTS: Cell viability and restitution were significantly suppressed by H2O2 in a dose-dependent manner compared with control. Each class was clearly separated into clusters by partial least squares discriminant analysis, and class variance was greater than 90% from 2 factors. CONCLUSION: Pattern recognition of NMR spectral data using a chemometric technique clearly visualized the differences of oxidant injury in IEC-6 cells under oxidant stress.

High-resolution 3D-MRI of postmortem brain specimens fixed by formalin and gadoteridol.

PURPOSE: The purpose of this investigation was to compare magnetization-prepared rapid gradient echo (MP-RAGE) images with T1-weighted images (T1WI) and T2-weighted images (T1W2) of postmortem brain tissue fixed by admixtures of formalin and gadoteridol. We additionally sought to explore the feasibility of using fixed brain magnetic resonance imaging (MRIs) in forensic practices. METHODS: Specimens included in the study were eight whole brains that had been removed during forensic autopsy. Brain specimens were randomly divided into three groups and MRIs were performed either (A) the day of autopsy (n=2) on unfixed tissue, (B) after immersion fixation in 20% formalin (n=3), or (C) after immersion fixation in 20% formalin mixed with 4 mL/L ProHance® (gadoteridol) (n=3). T1WI, T2WI, and MP-RAGE images of all group samples were acquired with a 3T clinical MR scanner. Gray and white matter contrasts of the cortex and basal nucleus in every fixation group and image sequence were then visually compared. RESULTS: Gray/white matter contrasts of the cortex were good in all images obtained by MP-RAGE, and T1WIs of specimens fixed by formalin and gadoteridol-mixed formalin. Additionally, gray/white matter contrast in the basal nucleus was sufficient in the MP-RAGE sequence of specimens fixed by gadoteridol-mixed formalin. CONCLUSIONS: MRI of brains immersion-fixed in formalin and gadolinium could serve as a promising tool for neuropathological assessment in forensic practices.

Team-based learning using an audience response system: a possible new strategy for interactive medical education.

Following the "Guidelines for reporting TBL" by Haidet et al, we report on a team-based learning (TBL) course we adopted for our 4th-year students in 2011. Our TBL course is a modified version of the one suggested in the guidelines, but its structure generally follows the core elements described therein. Using an audience response system (ARS), we were able to obtain individual and group readiness assurance test scores immediately and give instant feedback to the students. Instructors were thus able to monitor students' understanding in real time and so appreciated the system, which supports interactive classes even in large classrooms. However, TBL is teacher-oriented, and students were less appreciative of ARS, because they recognized that it could be easily used for grading. Nevertheless, we believe that a combination of TBL, and problem-based learning in a mature design can improve both motivation and understanding among learners.

Proton nuclear magnetic resonance and pattern recognition analysis of liver extracts from rats under different anesthetics.

BACKGROUND: Although general anesthesia is widely used in the surgical arena, the mechanisms by which general anesthetics act remain unclear. We previously described alterations in gene expression ratios in hepatic tissue taken from rats treated with anesthetics. Consequently, it is considered that anesthetics influence liver metabolism. Thus, the goal of this study was to use pattern recognition analysis of proton nuclear magnetic resonance spectra to visualize changes in liver metabolic phenotypes in response to widely used intravenous anesthetics (propofol and dexmedetomidine) and inhalational anesthetics (sevoflurane and isoflurane). METHODS: Rats were randomized into 13 groups (n = 6 in each group), and each group received one of following agents: propofol, dexmedetomidine, sevoflurane, isoflurane, or no anesthetic (control group). The liver was directly removed from rats immediately after or 24 h or 48 h after a 6-h period of anesthesia. Hydrophilic compounds were extracted from the liver and were analyzed with proton nuclear magnetic resonance spectroscopy. All spectral data were processed and analyzed by principal component analysis for comparison of metabolite profiles. RESULTS: Data were visualized by plotting principal component (PC) scores. In the plots, each point represents an individual sample. Each group was clustered separately on the plots, and the PC scores of the propofol group were clearly distinct from those of the control group and other anesthetic groups. The difference in PC scores was more pronounced immediately after completion of anesthesia when compared with 24 or 48 h after completion of anesthesia. Although the effect of intravenous anesthetics on the liver dissipated over time, the effect of inhalational anesthetics persisted. CONCLUSIONS: Propofol, dexmedetomidine, sevoflurane and isoflurane exert different effects on liver metabolism. In particular, liver metabolism was markedly altered after exposure to propofol. The effect of anesthesia on the liver under propofol or dexmedetomidine resolved rapidly when compared with the effect under sevoflurane or isoflurane.

Measurement of temperature changes in cooling dead rats using magnetic resonance thermometry.

Magnetic resonance imaging thermometry has been introduced as a technique for measurement of temperature changes in cooling dead rats. Rat pelvic magnetic resonance images were acquired sequentially more than 2h after euthanasia by halothane overdose. A series of temperature difference maps in cooling dead rats was obtained with calculating imaging phase changes induced by the water proton frequency shift caused by temperature changes. Different cooling processes were monitored by the temperature difference maps in the rats. Magnetic resonance imaging thermometry applied in the study of laboratory animals could theoretically reproduce a variety of causes of death with different environmental conditions. Outcomes from experimental animal studies could be translated into a temperature-based time of death estimation in forensics.

Pattern recognition analysis of proton nuclear magnetic resonance spectra of brain tissue extracts from rats anesthetized with propofol or isoflurane.

BACKGROUND: General anesthesia is routinely used as a surgical procedure and its safety has been endorsed by clinical outcomes; however, its effects at the molecular level have not been elucidated. General anesthetics influence glucose metabolism in the brain. However, the effects of anesthetics on brain metabolites other than those related to glucose have not been well characterized. We used a pattern recognition analysis of proton nuclear magnetic resonance spectra to visualize the changes in holistic brain metabolic phenotypes in response to the widely used intravenous anesthetic propofol and the volatile anesthetic isoflurane. METHODOLOGY/PRINCIPAL FINDINGS: Rats were randomized into five groups (n = 7 each group). Propofol and isoflurane were administered to two groups each, for 2 or 6 h. The control group received no anesthesia. Brains were removed directly after anesthesia. Hydrophilic compounds were extracted from excised whole brains and measured by proton nuclear magnetic resonance spectroscopy. All spectral data were processed and analyzed by principal component analysis for comparison of the metabolite profiles. Data were visualized by plotting principal component (PC) scores. In the plots, each point represents an individual sample. The propofol and isoflurane groups were clustered separately on the plots, and this separation was especially pronounced when comparing the 6-h groups. The PC scores of the propofol group were clearly distinct from those of the control group, particularly in the 6-h group, whereas the difference in PC scores was more subtle in the isoflurane group and control groups. CONCLUSIONS/SIGNIFICANCE: The results of the present study showed that propofol and isoflurane exerted differential effects on holistic brain metabolism under anesthesia.

Experimental analysis of silicone leakage.

We analyzed whether gel bleed, the leakage of silicone gel from breast implants, occurs in the human body. We simulated the phenomenon with olive oil. Silicone breast implants were submerged in olive oil, and the concentration of silicone polymers in the olive oil was measured periodically with nuclear magnetic resonance spectroscopy. We found no increase in the silicone concentration. However, clinical conditions might not be adequately simulated because of the shortness of the experimental period and the lack of external stress. However, when clinical experiences and our data are considered, we think that silicone implant durability is an important factor to prevent leakage or gel bleeding.

Experimental estimation of postmortem interval using multivariate analysis of proton NMR metabolomic data.

Nuclear magnetic resonance (NMR) spectroscopy has recently been applied to metabolic studies. In particular, metabolic profiles of tissues or of the whole body can easily be acquired through multivariate analysis of NMR spectra. The present study investigates metabolic changes after death in rat femoral muscles using pattern recognition of proton NMR spectra. Rats were killed by suffocation, cocaine overdose and induced respiratory failure, and then low molecular weight metabolites extracted using perchlorate from excised tissues were measured using proton NMR. All spectral data were processed and assessed by multivariate analysis to obtain metabolic profiles of the tissues. The results of principal component analysis (PCA) score plots soon after death showed that the metabolic profiles of the tissues differed according to the mode of death. The principal component (PC) scores of the data varied hourly and correlated with postmortem interval. The present results showed that NMR-based metabolic profiling could provide useful information with which to estimate postmortem intervals and causes of death.

Complications after autologous fat injection to the breast.

BACKGROUND: Although autologous fat injection (fat grafting) to the breast was performed widely throughout the twentieth century, the authors at their hospital have recently had to repair the damage suffered by a number of patients subjected to this procedure. The authors are concerned that this procedure is being performed incorrectly by untrained and untutored individuals, especially in Japan. The authors report several cases of complications after this procedure. Several related issues are discussed. METHODS: The authors retrospectively reviewed 12 patients who had received autologous fat grafts to the breast and required breast surgery and/or reconstruction to repair the damage presenting between 2001 and 2007. The symptoms are described and the fat grafting procedures that were used are analyzed. RESULTS: All 12 patients (mean age, 39.3 years) had received fat injections to the breast for augmentation mammaplasty for cosmetic purposes. They presented with palpable indurations, three with pain, one with infection, one with abnormal breast discharge, and one with lymphadenopathy. Four cases had abnormalities on breast cancer screening. All patients underwent mammography, computed tomography, and magnetic resonance imaging to evaluate the injected fats. CONCLUSIONS: Autologous fat grafting to the breast is not a simple procedure and should be performed by well-trained and skilled surgeons. Patients should be informed that it is associated with a risk of calcification, multiple cyst formation, and indurations, and that breast cancer screens will always detect abnormalities. Patients should also be followed up over the long-term and imaging analyses (e.g., mammography, echography, computed tomography, and magnetic resonance imaging) should be performed.

Clinical imaging diagnosis of implant materials for breast augmentation.

BACKGROUND: The ingredients of substances implanted for breast augmentation sometimes remain unknown due to lack of information from patients. Significant clinical problems sometimes necessitate removal and reconstruction. Thus, preoperative diagnostic imaging to identify the ingredients of implants may improve the treatment decision-making process. In this report, we created a clinical imaging index. PURPOSE: Here, we summarize computed tomography (CT) and magnetic resonance imaging (MRI) imaging of implant materials to predict the ingredients of implant substances preoperatively. METHODS: A total of 104 patients with late complications after receiving breast augmentations between 1971 and 2002 were examined using CT and MRI. In addition, further examinations were conducted, including postoperative chemical analysis using Nuclear magnetic resonance (NMR) spectroscopy and MRI imaging of various implanted substances using an experimental magnetic resonance system. RESULTS: We identified the ingredients of implant materials used for breast augmentation by imaging diagnostics as follows: silicone: radiopaque-low/high (CT-MRI T1/T2); hydrogel: radiolucent-low approximately iso/high; hydrocarbon: radiolucent-high approximately iso/low approximately iso; saline: radiolucent-low/high. CONCLUSION: We have identified by imaging diagnosis the ingredients of implant materials.