Iterative Tomographic Image Reconstruction Algorithm Based on Extended Power Divergence by Dynamic Parameter Tuning.

Computed tomography (CT) imaging plays a crucial role in various medical applications, but noise in projection data can significantly degrade image quality and hinder diagnosis accuracy. Iterative algorithms for tomographic image reconstruction outperform transform methods, especially in scenarios with severe noise in projections. In this paper, we propose a method to dynamically adjust two parameters included in the iterative rules during the reconstruction process. The algorithm, named the parameter-extended expectation-maximization based on power divergence (PXEM), aims to minimize the weighted extended power divergence between the measured and forward projections at each iteration. Our numerical and physical experiments showed that PXEM surpassed conventional methods such as maximum-likelihood expectation-maximization (MLEM), particularly in noisy scenarios. PXEM combines the noise suppression capabilities of power divergence-based expectation-maximization with static parameters at every iteration and the edge preservation properties of MLEM. The experimental results demonstrated significant improvements in image quality in metrics such as the structural similarity index measure and peak signal-to-noise ratio. PXEM improves CT image reconstruction quality under high noise conditions through enhanced optimization techniques.

Natural and Synthetic Pyrethrins Act as Feeding Deterrents against the Black Blowfly, Phormia regina (Meigen).

Pyrethrum is a botanical insecticide derived from pyrethrum flowers. Feeding deterrence caused by pyrethrum has been reported in several sucking insects; however, there is no account of the cause of deterrence-whether from a single component or the combination of six active ingredients, called pyrethrins. We determined the feeding deterrence of natural pyrethrins, their two main components (pyrethrins I and II), and pyrethroid insecticides on the blowfly, Phormia regina. In a dual-choice feeding assay that minimized tarsal contact with food sources but allowed feeding through proboscises, natural pyrethrins, synthetic pyrethrins I/II, and allethrin were observed to induce deterrence at a concentration 16 times lower than the lowest concentration at which the knockdown rate increased. Feeding bouts were interrupted by intensive grooming of the proboscis at the deterring concentration, but no such grooming was observed to occur while feeding on the unpalatable tastants-NaCl, quinine, and tartaric acid. The underlying mode of action for the feeding deterrence of pyrethrins at sub-lethal concentrations probably occurs on the fly oral gustatory system, while differing from that of unpalatable tastants. The potent feeding deterrence of pyrethrins may provide effective protection for pyrethrum plants by rapidly deterring insects from feeding, before insecticidal activities occur.

Block-Iterative Reconstruction from Dynamically Selected Sparse Projection Views Using Extended Power-Divergence Measure.

Iterative reconstruction of density pixel images from measured projections in computed tomography has attracted considerable attention. The ordered-subsets algorithm is an acceleration scheme that uses subsets of projections in a previously decided order. Several methods have been proposed to improve the convergence rate by permuting the order of the projections. However, they do not incorporate object information, such as shape, into the selection process. We propose a block-iterative reconstruction from sparse projection views with the dynamic selection of subsets based on an estimating function constructed by an extended power-divergence measure for decreasing the objective function as much as possible. We give a unified proposition for the inequality related to the difference between objective functions caused by one iteration as the theoretical basis of the proposed optimization strategy. Through the theory and numerical experiments, we show that nonuniform and sparse use of projection views leads to a reconstruction of higher-quality images and that an ordered subset is not the most effective for block-iterative reconstruction. The two-parameter class of extended power-divergence measures is the key to estimating an effective decrease in the objective function and plays a significant role in constructing a robust algorithm against noise.

Noise-Robust Image Reconstruction Based on Minimizing Extended Class of Power-Divergence Measures.

The problem of tomographic image reconstruction can be reduced to an optimization problem of finding unknown pixel values subject to minimizing the difference between the measured and forward projections. Iterative image reconstruction algorithms provide significant improvements over transform methods in computed tomography. In this paper, we present an extended class of power-divergence measures (PDMs), which includes a large set of distance and relative entropy measures, and propose an iterative reconstruction algorithm based on the extended PDM (EPDM) as an objective function for the optimization strategy. For this purpose, we introduce a system of nonlinear differential equations whose Lyapunov function is equivalent to the EPDM. Then, we derive an iterative formula by multiplicative discretization of the continuous-time system. Since the parameterized EPDM family includes the Kullback-Leibler divergence, the resulting iterative algorithm is a natural extension of the maximum-likelihood expectation-maximization (MLEM) method. We conducted image reconstruction experiments using noisy projection data and found that the proposed algorithm outperformed MLEM and could reconstruct high-quality images that were robust to measured noise by properly selecting parameters.

Natural history of upper and lower gastrointestinal bleeding in hemodialysis patients: A dual-center long-term cohort study.

BACKGROUND AND AIM: Knowledge on the risk of gastrointestinal (GI) bleeding in hemodialysis patients is limited. We evaluated the risk of GI bleeding in hemodialysis patients compared with non-hemodialysis patients. METHODS: We performed a retrospective cohort study from 1996 to 2017 at the Graduate School of Medicine, University of Tokyo, and Horinouchi Hospital. We analyzed patients on hemodialysis for chronic renal failure and controls not on hemodialysis. The primary endpoint was GI bleeding. A survival analysis was performed to estimate the cumulative incidence and hazard ratio of GI bleeding. RESULTS: A total of 14 451 patients were analyzed (417 hemodialysis and 14 034 non-hemodialysis patients). In total, 524 GI bleeding events occurred. Upper and lower GI bleeding occurred in 432 and 92 patients in the hemodialysis and non-hemodialysis groups, respectively. The most frequent source of upper and lower GI bleeding was gastric ulcer and colonic diverticular bleeding, respectively. The cumulative incidence of GI bleeding was 4.44% at 1 year, 7.15% at 3 years, and 10.40% at 5 years in hemodialysis patients; the respective rates were 2.35%, 2.98%, and 3.79% in non-hemodialysis patients during a mean follow-up period of 3.5 years. Hemodialysis was significantly associated with an increased risk of GI bleeding after adjustment (hazard ratio 1.67, P = 0.01, 95% confidence interval 1.13-2.50). CONCLUSIONS: Hemodialysis patients had a GI bleeding rate of 10% over 5 years, and hemodialysis was a risk factor for GI bleeding.

A novel intestinal rotation method for digestive reconstruction after combined pancreaticoduodenectomy and extended right hemicolectomy: A case report and surgical technique.

INTRODUCTION: Pancreaticoduodenectomy (PD) combined with extended right hemicolectomy (RH) is a challenging procedure for locally advanced malignancies. However, information concerning the reconstruction method of the digestive system is limited. Here, we present a case and surgical technique of a novel intestinal rotation method for digestive reconstruction after PD combined with RH. PRESENTATION OF CASE: A 62-year-old man with locally advanced pancreatic cancer received conversion surgery combined with PD and RH after preoperative chemotherapy. With respect to the reconstruction of the digestive system, the entire intestinal mesentery was rotated 180° forward counterclockwise around the axis of the superior mesenteric artery, and then the reconstruction, according to Child's method, was performed. The patient recovered without problems in gastroenterological functions after the operation. DISCUSSION: With respect to the reconstruction of the digestive system in patients undergoing combined PD and RH, practitioners should pay close attention to twisting of the intestinal mesentery when bringing up the proximal jejunum for pancreatojejunostomy and hepatojejunostomy and the distal ileum for ileocolic anastomosis. This intestinal rotation method enables a smooth and uneventful reconstruction of the digestive system. CONCLUSION: This is the first detailed description of an intestinal rotation method for digestive reconstruction after combined PD and extended RH. The intestinal rotation method can be an alternative and helpful technical option for digestive reconstruction in patients with combined PD and RH.

Amplitude spectral area: predicting the success of electric shock delivered by defibrillators with different waveforms.

OBJECTIVES: Prolonged ventricular fibrillation (VF) is associated with a low rate of return of spontaneous circulation (ROSC) following electric shock. Moreover, electric shock that does not reestablish spontaneous circulation causes myocardial dysfunction even if ROSC is subsequently achieved. Amplitude spectral area (AMSA), calculated by analysis of VF waveforms immediately before electric shock, is considered to predict the outcome of electric shock. This study aimed to evaluate the prognostic value of AMSA in relation to waveforms of defibrillators in prehospital settings. METHODS: The AMSA values of 81 patients with VF confirmed by ambulance crews were compared according to the type of defibrillators with different waveforms and between those with and without ROSC. RESULTS: With a biphasic defibrillator, the mean AMSA was significantly different between the 14 patients who achieved ROSC (25.3 ± 9.5 mV-Hz) and the 43 subjects who did not achieve ROSC (15.4 ± 8.1 mV-Hz; p = 0.0006). No significant difference was seen in the corresponding values when a monophasic defibrillator was used, at 19.1 ± 2.4 mV-Hz for 3 ROSC patients and 16.1 ± 7.5mV-Hz for 21 non-ROSC patients. CONCLUSION: AMSA may serve as a predictive measure for ROSC following electric shock delivered by a biphasic defibrillator.

Photo-orientation regulates seasonal habitat selection in the two-spotted spider mite, Tetranychus urticae.

Non-diapausing spider mites (Tetranychus urticae) live on the undersurface of host leaves during summer, but diapausing mites overwinter in dark hibernacula. The light environments of these habitats differ: visible radiation (VIS) but not ultraviolet radiation (UV) reaches the undersurface of leaves, but neither enters dark hibernacula. Thus, mites of either seasonal form could locate their preferred habitat by photo-orientation responses to UV and VIS. To investigate this possibility, we analysed the mites' locomotion behaviour on a virtual field with a programmed chequered pattern of light and dark patches in a micro-locomotion compensator. Both non-diapausing and diapausing mites moved away from UV-illuminated patches into dark patches. Non-diapausing mites moved towards VIS-illuminated patches, whereas diapausing mites did not show a preference. Our results show that non-diapausing mites avoid UV and are attracted to VIS, suggesting that this can guide them beneath a leaf. Diapausing mites simply avoid UV. The lack of a preference for VIS during diapause could be due to changes in carotenoid metabolism, which also involve orange pigmentation of diapausing mites. We consider that a diapause-mediated switch of the response to VIS, together with regular avoidance of UV, plays a key role in the seasonal change of habitat selection in this species. This seasonal polyphenism involves alterations in not only reproductive state and pigmentation, but also in photo-spectral responses.

Electrical defibrillation outcome prediction by waveform analysis of ventricular fibrillation in cardiac arrest out of hospital patients.

OBJECTIVE: Indexes such as amplitude spectrum area (AMSA) and power spectrum area (PSA) obtained from electrocardiogram waveform analysis are possible predictors of outcome after electrical defibrillation for ventricular fibrillation (VF). In this study, we examined AMSA and PSA to determine whether these parameters can predict defibrillation outcome. MATERIALS AND METHODS: A total of 83 out-of-hospital VF victims were classified into four groups according to type of cardiac rhythm after shock: return of spontaneous circulation (ROSC), VF, pulseless electrical activity (PEA), and asystole. AMSA and PSA were calculated from electrocardiograms prior to shock and compared between groups. RESULTS: The mean AMSA (4.0-48 Hz) in the ROSC group was 24.2 ± 8.5 mV-Hz, which was significantly higher than that in the VF and asystole groups. CONCLUSION: It is possible by analyzing the AMSA of VF to predict cases where electrical defibrillation is more likely to return cardiac rhythm. Furthermore, unnecessary electrical shocks with a low possibility of ROSC can be avoided, and chest compression should be continued to prevent myocardial damage and consequently improve prognosis.

[Yersinia psuedotuberculosis septicemia in a healthy young woman].

We report a case of Yersinia pseudotuberculosis (Y. pseudotuberculosis) septicemia in a healthy 22-year-old woman with clinical manifestations including high fever and general fatigue. The patient's ferer sudden elevation of her fever, and, liver damage and elevated inflammatory markers were indicated. General fatigue and appetite loss were noted on hospitalization. Exanthema was recognized, and all oral medications, including antibiotics, was stopped. The fever continued and high inflammatory parameters developed. After chemotherapy with imipenem, subjective symptoms ameliorated. Membranous desquamation without itching appeared between the fingers of both hands but improved naturally. Y. psuedotuberculosis septicemia was diagnosed as Y. psuedotuberculosis isolated from blood and elevated serum antibody titer against Y. psuedotuberculosis 4b detected at 1:160.

[A case of Legionella pneumonia complicated with acute respiratory distress syndrome treated with methylprednisolone and sivelestat sodium in combination with intravenous erythromycin and ciprofloxacin].

A 64-year-old man was referred to us because of pneumonia refractory to panipenem/betamipron. His chest radiography showed patchy consolidations in the lower lobe of the right lung and in the middle field of the left lung, and severe hypoxia was present. He was diagnosed as having acute respiratory distress syndrome due to severe pneumonia, and was treated with pulse methylprednisolone and sivelestat sodium in combination with intravenous erythromycin and ciprofloxacin. The patient recovered with this treatment. Serological examination using blood samples collected on the 12th and 28th hospital days revealed elevation of anti-L. pneumophila serogroup I antibody. It is suggested that administration of methylprednisolone and sivelestat sodium in combination with intravenous erythromycin and ciprofloxacin in a case of severe Legionella pneumonia complicated with acute respiratory distress syndrome is effective, and may be of use in similar cases.

Changes in focal macular electroretinograms and foveal thickness after vitrectomy for diabetic macular edema.

PURPOSE: To evaluate the changes in the focal macular electroretinogram (FMERG) and foveal retinal thickness after vitrectomy for diabetic macular edema (DME). METHODS: FMERGs were elicited from 25 eyes of 21 patients (ages 29-75 years) who underwent vitrectomy for DME by a 15 degrees stimulus. A posterior vitreous detachment (PVD) was created during surgery in 19 eyes (group 1), and 4 eyes had a PVD before surgery (group 2). In the remaining 2 eyes, a PVD could not be created (group 3). FMERGs were recorded before and 3, 6, and 12 months after vitrectomy. The foveal thickness, determined by optical coherence tomography (OCT), and visual acuity were measured on the same day as the FMERG recordings. RESULTS: The postoperative visual acuity (logarithm of the minimum angle of resolution [logMAR]) improved gradually after the surgery and was significantly better at 12 months in eyes in group 1 (P = 0.0393). The postoperative mean foveal thickness was significantly less at 3 months after surgery in group 1 eyes (P = 0.0006), and there was a further decrease thereafter. In the 2 eyes in group 3, the decreased foveal thickness 3 and 6 months after surgery became thicker at 12 months. The mean b-wave amplitude of the FMERGs increased significantly at 12 months in group 1 eyes (P = 0.0297). The mean implicit time of a- and b-waves was more delayed at 3 months, and the change in a-wave was statistically significant in group 1 eyes (P = 0.0474). There was a wide range of changes in the b-wave amplitude at 12 months, however, the increase in the b-wave was correlated with the decrease in foveal thickness (r =.49, P = 0.012). CONCLUSIONS: A disparity in the time course and degree of recovery of the foveal thickness and macular retinal function was found in eyes with DME after vitrectomy. Part of the functional recovery could be attributed to decreased retinal thickness and the absorption of the subretinal fluid.

Vitrectomy for diabetic macular edema: effect of glycemic control (HbA(1c)), renal function (creatinine) and other local factors.

AIMS: To determine the effect of preoperative factors on the foveal thickness following vitrectomy for diabetic macular edema. METHODS: Fifty-eight eyes of 47 patients underwent vitrectomy for diabetic macular edema. In all eyes, no clear, visible vitreomacular traction was present. Twelve eyes were pseudophakic before vitrectomy, and 31 eyes underwent concurrent phacoemulsification and intraocular lens (IOL) implantation. Multiple logistic regression analysis was used to assess the independent effect of age, history of photocoagulation, diabetic retinopathy status, preoperative posterior vitreous detachment, HbA(1c) and serum creatinine levels within 2 weeks before surgery, lens status after surgery and follow-up period on the foveal thickness determined by optical coherence tomography. RESULTS: The median preoperative visual acuity was 20/100 (range from 20/500 to 20/20), and the median postoperative visual acuity was 20/70 (range from 20/500 to 20/13). The preoperative visual acuity (logarithm of minimal angle of resolution; logMAR) was 0.73 +/- 0.36 (mean +/- SD; 20/107 Snellen acuity), and the mean postoperative logMAR visual acuity was 0.60 +/- 0.39 (20/80), which was significantly better than the mean preoperative value (Wilcoxon signed rank test, p = 0.011). The mean +/- SD of preoperative foveal thickness was 475.9 +/- 172.5 micrometer, and the mean postoperative foveal thickness was 277.3 +/- 171.9 micrometer. The mean postoperative foveal thickness was significantly thinner than the preoperative thickness (Student's paired t test, p < 0.0001). Multiple logistic regression analysis showed that a preoperative low HbA(1c) and postoperative pseudophakia were independently associated with the decrease in foveal thickness (p = 0.01, p = 0.04, respectively). CONCLUSIONS: The greater reduction in foveal thickness in eyes with an IOL probably resulted from a relatively larger amount of vitreous being removed during the vitrectomy. Because the decrease in foveal thickness may be related to the preoperative glycemic control and the amount of vitreous, these factors should be considered in the planning for vitrectomy.

Mapping posterior vitreous detachment by optical coherence tomography in eyes with idiopathic macular hole.

PURPOSE: To determine the relationship between posterior vitreous detachment and idiopathic macular hole. DESIGN: Observational case series. METHODS: In a prospective study, the posterior hyaloid face was scanned from the posterior pole to the far periphery by optical coherence tomography in 25 eyes (22 patients) with an idiopathic macular hole (stage 1 = 1, stage 2 = 7, stage 3 = 10, and stage 4 = 7), and a map of the posterior vitreous detachment was constructed. RESULTS: One eye with a stage 1 macular hole had a posterior vitreous detachment confined to the vascular arcade, but attached to the fovea. In all seven eyes at stage 2, the detached posterior hyaloid enlarged upward beyond the superior vascular arcade, but stopped at the margin of inferior vascular arcade. In two cases, the posterior vitreous detachment also extended temporally and superonasally. In all cases, the vitreous face remained attached to the fovea. Six of the 10 eyes at stage 3 had larger partial posterior vitreous detachment that extended not only upward, but also beyond the inferior vascular arcade, while in the other four eyes, the size and position of the posterior vitreous detachment was similar to stage 2 macular holes. However, unlike stage 2, the posterior vitreous detachment included the fovea in all eyes. All seven eyes with a stage 4 macular hole had complete posterior vitreous detachment that extended to the far periphery in all directions. CONCLUSION: There is a close correlation between the stage of the macular hole and the degree of posterior vitreous detachment. This close correlation suggests that progression of idiopathic macular hole is related to enlargement of the posterior vitreous detachment.

Molecular bases for human complement C7 polymorphisms, C7*3 and C7*4.

Complement C7 is one of the components of membrane attack complex (MAC) generated by the terminal complement cascade. C7 protein is polymorphic and most of its polymorphisms have been identified using isoelectric focusing (IEF), which detects protein charge differences. To date, the molecular bases of the polymorphisms detected by IEF have not been determined. In this paper, we describe the structural bases of two C7 IEF-detected polymorphisms, C7*3 and C7*4, both of which are common in Asian populations. C7*3 resulted from substitution of cysteine (Cys) at amino acid residue 106 by charged arginine (Arg; C106R), while charged lysine (Lys) at amino acid residue 398 was replaced by neutral glutamine (Gln; K398Q) in C7*4. As C7*3 is hypomorphic, it is important to study its possible associations with diseases such as immunological disorders and infections. We present genetic bases for this C7 polymorphism, which we determined using polymerase chain reaction (PCR)-based genotyping, a simple and accurate method suitable for large-scale studies.

Loss of stereopsis with optic chiasmal lesions and stereoscopic tests as a differential test.

OBJECTIVE: To identify and characterize the loss of stereopsis observed in patients with lesions of the optic chiasm. STUDY DESIGN: Cross-sectional study. PARTICIPANTS: Forty-three patients who had good visual acuity with orthophoria and without strabismologic histories were divided into two groups. Group 1 consisted of 13 patients with lesions involving the optic chiasm (regardless of their visual field loss) diagnosed by magnetic resonance imaging findings. Group 2 (control group) consisted of 30 patients who had large absolute visual field defects as a result of other causes, including 11 intracranial disorders other than optic chiasmal lesions, 11 cases of open-angle glaucoma, and 8 patients with lesions of the retina. METHODS: The stereoacuity and visual field in each case in group 1 (before and after surgery) and group 2 were assessed, and the results were compared. MAIN OUTCOME MEASURES: Stereoacuity was assessed by the Titmus stereo test (normal value for circle, 6/9; 80 seconds of arc) and by Lang-stereotest (normal value for circle, 3/3; 350 seconds of arc). Visual field was evaluated by Goldmann and Humphrey perimetry (conventional perimetry), the starlight test (binocular visual field test), and scanning laser ophthalmoscopic microperimetry (microperimetry). RESULTS: Before surgery, 11 of 13 cases (85%) in group 1 failed stereo tests, and after surgery, 5 of 13 cases (38%) in group 1 failed stereo tests. Before surgery, four patients who failed stereo tests showed no absolute scotoma by Humphrey or Goldmann analysis; after surgery, one patient who failed stereo tests showed no absolute scotoma by Humphrey or Goldmann analysis. However, starlight testing showed complete bitemporal hemianopsia only under binocular conditions, and microperimetry demonstrated a relative bitemporal hemianopsia at the fixating point. No patient failed in the Titmus circle test, but one patient in group 2 failed the Lang test (3%). The patients with chiasmal lesions significantly lost the ability of stereopsis compared with other diseases (group 1 [before or after surgery] vs. group 2, P < 0.001, Fisher's exact test). Conventional perimetry was unable to measure scotomas within 3 degrees of the fixation point, which is the key area for acute foveal stereopsis, because of an attached observational mirror. CONCLUSIONS: The difficulty with stereopsis in patients with lesions of the optic chiasm is most likely caused by the compression of the decussating optic nerve fibers resulting in the loss of an overlapping visual field at the fixation point. Stereo tests were demonstrated to be simple and effective adjunctive tests for suspected chiasmal compression.