Plasma brain natriuretic peptide as a surrogate marker for cardioembolic stroke

<p>Abstract</p> <p>Background</p> <p>Cardioembolic stroke generally results in more severe disability, since it typically has a larger ischemic area than the other types of ischemic stroke. However, it is difficult to differentiate cardioembolic stroke from non-cardioembolic stroke (atherothrombotic stroke and lacunar stroke). In this study, we evaluated the levels of plasma brain natriuretic peptide in acute ischemic stroke patients with cardioembolic stroke or non-cardioembolic stroke, and assessed the prediction factors of plasma brain natriuretic peptide and whether we could differentiate between stroke subtypes on the basis of plasma brain natriuretic peptide concentrations in addition to patient's clinical variables.</p> <p>Methods</p> <p>Our patient cohort consisted of 131 consecutive patients with acute cerebral infarction who were admitted to Kagawa University School of Medicine Hospital from January 1, 2005 to December 31, 2007. The mean age of patients (43 females, 88 males) was 69.6 ± 10.1 years. Sixty-two patients had cardioembolic stroke; the remaining 69 patients had non-cardioembolic stroke (including atherothrombotic stroke, lacunar stroke, or the other). Clinical variables and the plasma brain natriuretic peptide were evaluated in all patients.</p> <p>Results</p> <p>Plasma brain natriuretic peptide was linearly associated with atrial fibrillation, heart failure, chronic renal failure, and left atrial diameter, independently (F_4,126= 27.6, p < 0.0001; adjusted R²= 0.45). Furthermore, atrial fibrillation, mitral regurgitation, plasma brain natriuretic peptide (> 77 pg/ml), and left atrial diameter (> 36 mm) were statistically significant independent predictors of cardioembolic stroke in the multivariable setting (Χ²= 127.5, p < 0.001).</p> <p>Conclusion</p> <p>It was suggested that cardioembolic stroke was strongly predicted with atrial fibrillation and plasma brain natriuretic peptide. Plasma brain natriuretic peptide can be a surrogate marker for cardioembolic stroke.</p

Simulation for position determination of distal and proximal edges for SOBP irradiation in hadron therapy by using the maximum likelihood estimation method

In radiation therapy with hadron beams, conformal irradiation to a tumour can be achieved by using the properties of incident ions such as the high dose concentration around the Bragg peak. For the effective utilization of such properties, it is necessary to evaluate the volume irradiated with hadron beams and the deposited dose distribution in a patient\u27s body. Several methods have been proposed for this purpose, one of which uses the positron emitters generated through fragmentation reactions between incident ions and target nuclei. In the previous papaer, we showed that the maximum likelihood estimation (MLE) method could be applicable to the estimation of beam end-point from the measured positron emitting activity distribution for mono-energetic beam irradiations. In a practical treatment, a spread-out Bragg peak (SOBP) beam is used to achieve a uniform biological dose distribution in the whole target volume. Therefore, in the present paper, we proposed to extend the MLE method to estimations of the position of the distal and proximal edges of the SOBP from the detected annihilation gamma ray distribution. We confirmed the effectiveness of the method by means of simulations. Although polyethylene was adopted as a substitute for a soft tissue target in validating the method, the proposed method is equally applicable to general cases, provided that the reaction cross sections between the incident ions and the target nuclei are known. The relative advantage of incident beam species to determine the position of the distal and the proximal edges was compared. Furthermore, we ascertained the validity of applying the MLE mehtod to determinations of the position of the distal and the proximal edges of an SOBP by simulations and we gave a physical explanation of the distal and the proximal information

Quantitative comparison of suitability of various beams for range monitoring with induced Beta^+^ activity in hadron therapy

In radiation therapy with hadron beams, it is important to evaluate the range of incident ions and the deposited dose distribution in a patient body for the effective utilization of such properties as the dose concentration and the biological effect around the Bragg peak. However, there is some ambiguity in determining this range because of a conversion error from the x-ray CT number to the charged particle range. This is because the CT number is related to x-ray absorption coefficients, while the ion range is determined by the electron density of the substance. Using positron emitters produced in the patient body through fragmentation reactions during the irradiation has been proposed to overcome this problem. The activity distribution in the patient body can be deduced by detecting pairs of annihilation gamma rays emitted from the positron emitters, and information about the range of incident ions can be obtained. In this paper, we propose a quantitative comparison method to evaluate the mean range of incident ions and monitor the activity distribution related to the deposited dose distribution. The effectiveness of the method was demonstrated by evaluating the range of incident ions using the maximum likelihood estimation (MLE) method and Fisher\u27s information was calculated under realistic conditions for irradiations with several kinds of ions. From the calculated Fisher\u27s information, we compared the ralative advatages of initial beams to determine the range of incident ions. The 16O irradiation gave the most information among the stable heavy ions when we measured the induced activity for 500s and 60s just after the irradiation. Therefore under these conditions, we concluded that the 16O beam was the optimum beam to monitor the activity distribution and to evaluate the range. On the other hand, if the positron emitters were injected directly as a therapeutic beam, the 15O irradiation gave the most information. Although the relative advantages of initial beams as well as the measured activity distributions slightly varied accorging to the measurement conditions, comparisons could be made for different conditions by using Fisher\u27s information

Monitoring the irradiation field of 12C and 16O SOBP beams using positron emitters produced through projectile fragmentation reactions

In order to effectively utilize the prominent properties of heavy ions in radiotherapy, it is important to evaluate both the position of the field irradiatedwith incident ions and the absorbed dose distribution in a patient\u27s body. One ofthe methods for this purpose is the utilization of the positron emitters producedthrough the projectile fragmentation reactions of stable heavy ions with targetnuclei. In heavy-ion therapy, spread-out Bragg peak (SOBP) beams are used to achieve uniform biological dose distributions in the whole tumor volume.Therefore, in this study, we designed SOBP beams of 30 and 50 mm waterequivalentlength (mmWEL)in width for 12Cand 16O, and carried out irradiation experiments using them. Water, polyethylene and polymethyl methacrylate were selected as targets to simulate a human body. Pairs of annihilation gamma rays were detected by means of a limited-angle positron camera for 500 s, and annihilation gamma-ray distributions were obtained. The maximum likelihood estimation (MLE) method was applied to the detected distributions for evaluating the positions of the distal and proximal edges of the SOBP in a target. The differences between the positions evaluated with the MLE method and those derived from the measured dose distributions were less than 1.7 mm and 2.5 mm for the distal and the proximal edge, respectively, in all irradiation conditions. When the positions of both edges are determined with the MLE method, the most probable shape of the dose distribution in a target can be estimated simultaneously. The close agreement between the estimated and the measured distributions implied that the shape of the dose distribution in an irradiated target could be evaluated from the detected annihilation gamma-ray distribution

Analysis of Morphology and Infectivity of Measles Virus Particles

The measles virus (MeV) shows polymorphisms in morphology and viral particle size, however, the localization of viral proteins and infectivity in viral particles of different sizes have not been well characterized. To determine the localization of viral proteins and the infectivity of viral particles of different sizes, MeV-infected cells and their culture supernatant were analyzed by electron microscopy and membrane filter fractionation. The sizes of MeV-like particles were distributed between 50 and 1000 nm and the major distribution peak was found for particles with diameters of 350-400 nm. The MeV M protein was lined under the envelope of all MeV-like particles and membrane-filter-fractionated MeVs of all sizes showed infectivity. These findings suggest that MeV particles, particularly large particles, can be used as a vaccine by designing a chimera virus containing antigens or genome of other virus species

RNA-dependent DNA Polymerase (RT) Activity of Bacterial DNA polymerases

RNA-dependent DNA polymerase (RT) is an enzyme that synthesizes DNA from an RNA template in retroviruses. The Klenow fragment (KF), part of E. coli DNA polymerase I (Pol I), is similar to RT molecule and exhibits RT activity. The HIV-1 RT inhibitor, AZT, has been reported to be bactericidal against some species of bacteria. This finding indicates that AZT targets bacterial polymerase which possesses RT activity. In this study, we analyzed the RT activities of E. coli, Shigella sonnei I, Vibrio cholerae non-O1, Pseudomonas aeruginosa and Staphylococcus aureus. Except in Staphylococcus aureus, AZT-TP inhibited bacterial RT activities. Expect in P. aeruginosa, these results corresponded to the effect of AZT against these bacterial species. We further determined the similarity of bacterial DNA polymerases by examination using inhibitory antibodies obtained from a rabbit immunized with E. coli KF (anti-KF). Anti-KF inhibited the RT activities of E. coli and S. sonnei I. Our findings indicate that the bacterial DNA polymerases which possess RT activities may be targets of antibiotic therapy