Free radicals, hydroxyperoxides and H(2)O(2) are all known to damage cell components. This study was designed to compare the concentrations of hydroxyperoxide and free radical scavengers in the ...cardiac muscles of old rats in the hyper- or hypothyroid condition, to determine whether rates of peroxidation would differ with age, thyroid status, or both. Rats were rendered hyper- or hypothyroid by administration of l-thyroxine or methimazole for 4 weeks. Among the old rats, the lipid peroxide (LPO) concentrations, measured as thiobarbituric acid (TBA) reactants, were significantly greater in the hyperthyroid than in the euthyroid state and the LPO concentrations measured as TBA+Fe(3+) reactants, which may be precursors of LPO, were significantly greater in the hyperthyroid state, whereas in young rats, the LPO concentrations measured by TBA or TBA+Fe(3+) methods did not differ significantly in the hyperthyroid state. In the euthyroid state, the concentration of LPO measured as TBA+Fe(3+) reactants was significantly reduced with age. Xanthine oxidase (XOD) activity also was markedly increased with age, being more pronounced in the hyperthyroid than in the euthyroid state. The Mn and Cu/Zn superoxide dismutase activities were greater in the hyperthyroid than in the euthyroid state. Glutathione peroxidase activity decreased with age in the euthyroid and, particularly, in the hyperthyroid state. Catalase activity was not affected in the old rats. Concentrations of alpha-tocopherol in the old rats were high in the hyperthyroid state and low in the hypothyroid state, whereas the levels of beta- and gamma-tocopherols in these rats were unchanged in both conditions as compared with the euthyroid state findings. Data suggest that the site of free radical generation differs in older rats, with additional shifts in the location of intracellular lipid peroxidation being noted during hyperthyroidism. Thus, as rats age, the reduction of the free radical scavenger system and the increase in LPO and XOD activities might induce myocardial dysfunction.
Purpose:
The exposure index (EI) proposed by the International Electrotechnical Commission (IEC) 62494‐1 is expected to be utilized as a standard dose index by every manufacturer. The IEC recommended ...the usage of RQA5 for the EI. However, X‐ray beam qualities, particularly in clinical practices, vary depending on the examination objects and exposure conditions, including usage of anti‐scatter grids. We investigated the effects of the X‐ray beam qualities other than RQA5 on the EI.
Methods:
The Xray beam qualities of RQA3, 5, 7, and 9 in IEC 61267 Ed. 1.0 were adopted in a computed radiography system. A uniform exposure without objects was performed to measure the exposure indicators (S values) and air kerma (K). The relational equations between the S values and K were derived for the determination of the EI values. The EI values for RQA3, 7, and 9 were compared to those for RQA5 at the fixed S values of 100, 200, 400, and 600. Finally, the half‐value layers (HVLs) using four grids (ratio 6:1, 8:1, 10:1, and 12:1) for the RQA5 X‐ray were compared to those with RQA3–9.
Results:
The EI values for RQA3, 7, and 9 were up to 35.3%, 11.8%, and 38.7% higher, respectively, than that for RQA5 at the S value of 600. The HVLs without grids and with various grids for RQA5 were 6.85 mm Al. and in the range of 6.94–7.29 mm Al. (ΔHVL: up to 0.44 mm Al.), respectively. This variation in the HVLs with grids was smaller than that observed for RQA3–9 (ΔHVL: 2.0–7.5 mm Al.).
Conclusion:
Although the usage of grids may not greatly affect the EI, the X‐ray beam quality for the determination of the EI cannot be ignored in the clinical evaluation of the dose index.
The effects of notch root radius on fracture toughness and crack initiation sites have been investigated in this paper using three different classes of materials. Data on alumina which represent ...ceramics, mild steel from the metals ffeily and polycarbonate representing plastics were obtained and analysed. The locations of crack initiation sites have been pinpointed by scanning electron microscopy. These identified sites more or less are located within the critical process zone or the theoretical plastic zone. The critical process zone size (Dc ) or the theoretical plastic zone size (RYF ) are independent of the notch root radius unlike the plain‐strain fracture toughness of notched specimens KIC (ρ). The authors emphasize why the parameters Dc and RYF are useful for a quantitative evaluation of the reliability of structural materials.
The novel 1-(2-fluorovinyl)-4-quinolone-3-carboxylic acid derivatives Z-15a − c, E-15a − c, Z-16a − c, and E-16a − c, conformationally restricted analogues of fleroxacin (5), were synthesized, and ...their in vitro antibacterial activity was evaluated. A dehydrosulfenylation of a 2-fluoro-2-(4-methoxyphenyl)sulfinylethyl group was employed as a key step for the construction of a 2-fluorovinyl group at the N-1 position. It appeared evident that the Z-isomers Z-15a − c and Z-16a − c exhibited 2- to 32-fold more potent in vitro antibacterial activity than the corresponding E-isomers E-15a − c and E- 16a − c. Furthermore, since Z-15b showed in vitro antibacterial activity and DNA gyrase inhibition comparable to that of 5, it was hypothesized that the conformation of Z-15b would be equivalent to the active conformer of 5. The results revealed that the antibacterial Z-1-(2-fluorovinyl)quinolone derivatives carry the novel N-1 substituent of the fluoroquinolones.
Purpose:
We are trying to develop an image‐searching technique to identify misfiled images in a picture archiving and communication system (PACS) server by using five biological fingerprints: the ...whole lung field, cardiac shadow, superior mediastinum, lung apex, and right lower lung. Each biological fingerprint in a chest radiograph includes distinctive anatomical structures to identify misfiled images. The whole lung field was less effective for evaluating the similarity between two images than the other biological fingerprints. This was mainly due to the variation in the positioning for chest radiographs. The purpose of this study is to develop new biological fingerprints that could reduce influence of differences in the positioning for chest radiography.
Methods:
Two hundred patients were selected randomly from our database (36,212 patients). These patients had two images each (current and previous images). Current images were used as the misfiled images in this study. A circumscribed rectangular area of the lung and the upper half of the rectangle were selected automatically as new biological fingerprints. These biological fingerprints were matched to all previous images in the database. The degrees of similarity between the two images were calculated for the same and different patients. The usefulness of new the biological fingerprints for automated patient recognition was examined in terms of receiver operating characteristic (ROC) analysis.
Results:
Area under the ROC curves (AUCs) for the circumscribed rectangle of the lung, upper half of the rectangle, and whole lung field were 0.980, 0.994, and 0.950, respectively. The new biological fingerprints showed better performance in identifying the patients correctly than the whole lung field.
Conclusion:
We have developed new biological fingerprints: circumscribed rectangle of the lung and upper half of the rectangle. These new biological fingerprints would be useful for automated patient identification system because they are less affected by positioning differences during imaging.
Purpose:
A receiver operating characteristics analysis is one of the most useful methods for evaluating diagnostic accuracy. However, methods to evaluate the visibility of images displayed on a ...liquid‐crystal display (LCD) are not well established. The detection time of signals can be used to evaluate visibility. However, detection time depends on the characteristics each observer's eye‐brain system. This study aimed to evaluate the visibility of static images with a normalized‐rank approach of detection times.
Methods:
Sixty images with 2–6 bright or dark signals against background luminance on an LCD were observed by 10 observers. We measured the time required for the observer to determine whether signals existed just after the image was displayed on the LCD. This study assumed that images with short detectability times would be superior to those with longer times. The detection times of the 60 images were sorted for each observer for additional analyses of visibility. A normalized‐rank approach was applied to the ranked data in order to evaluate the visibility of bright and dark signals. In addition, we calculated the positive predictive value (PPV) and the negative predictive value (NPV) for all observers.
Results:
In the normalized‐rank approach, the visibility of dark signals against background luminance was statistically superior to that of bright signals (p = 0.0393). The PPV/NPV values for the bright and dark signals were 98%/96% and 97%/97%, respectively.
Conclusion:
This novel normalized‐rank approach for analyzing detection time can be used to evaluate the visibility of simple signals on an LCD and compare them with PPV and NPV.
Thyroid hormones affect reactions in almost all pathways of lipid metabolism. It has been reported that plasma free fatty acid (FFA) concentration in hypothyroidism is generally within the normal ...range. In this study, however, we show that plasma FFA concentration in some hypothyroid patients is higher than the normal range. Symptoms of thyroid dysfunction in these individuals were less severe than those of patients with lower plasma FFA concentrations. From these findings we hypothesized that the change in FFA concentration must correlate with thyroid function. Using an animal model, we then examined the effect of highly purified eicosapentaenoic acid ethyl ester (EPA-E), a n-3 polyunsaturated fatty acid derived from fish oil, on thyroid function in 1-methyl-2-imidazolethiol (MMI)-induced hypothyroid rats. Oral administration of EPA-E inhibited reduction of thyroid hormone levels and the change of thyroid follicles in MMI-induced hypothyroid rats. These findings suggest that FFA may affect thyroid functions and EPA-E may prevent MMI-induced hypothyroidism.
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