Evaluation of compressed lung CT image quality using quantitative analysis

The goals of this study were (1) to evaluate the quality of compressed lung CT images obtained using high resolution CT (HRCT: 2 mm slice thickness) for degree of compression and conventional CT (10 mm slice thickness) images by using physical and subjective evaluations, and (2) to analyze the distortion of density distribution on lung CT images using histogram analysis for each compression ratio. The coding method was performed according to the Joint Photographic Experts Group (JPEG). We physically evaluated the quality of compressed lung CT images using the peak signal-to-noise ratio (PSNR) as given by the square root of the ratio of the peak value of the gray level squared to the mean square error (dB) and subjectively evaluated the CT images using the mean opinion score (MOS). The acceptable compression ratio for diagnosis was about 1:6 to 1:7 for conventional CT images and about 1:4 to 1:5 for HRCT images as determined by MOS. The PSNR corresponding to acceptable compression ratios was about 50 dB. The difference in density distribution between HRCT and conventional CT was statistically significant (Friedman test: p<0.02) in histogram analysis. Results suggested that, in comparison with conventional CT, a high compression ratio was not suitable for HRCT.     

Pathophysiological role of endothelin-1 in the vascular remodeling process

Endothelin (ET)-1, which had been discovered as the most potent vasoconstrictive peptide, plays active roles in the various biological responses. However, it is controversial how is ET-1 involved in the vascular remodeling process. Therefore, present experiments were performed to investigate the role of ET-1 for the initiation/progression of intimal hyperplasia. Intimal hyperplasia was caused with the time to peak of 4 to 6 weeks after endothelial removal of the rabbit carotid artery and accompanied by increased ET-1 content as well as ET receptor density within the hyperplastic vessel wall. ET-1 receptors could be classified into three subtypes of ETA, ETB and tentative nonETA/nonETB. TUNEL- and Ki-67-positive cells were detectable with the time to peak of 1 to 2 weeks, whereas all positive cells disappeared within 6 weeks. ATZ1993 as a mixed type antagonist for ET-A, ET-B and nonETA/nonETB receptor subtypes inhibited the intimal hyperplasia, of which inhibition was accompanied by increased TUNEL- and p53-positive cells and decreased Bcl-2-positive cells. ET-1 accelerated the [3H]-thymidine incorporation by cultured vascular smooth muscle cells and, on the other hand, reduced TUNEL-positive cells, which was caused by the serum deprivation. The reduction of TUNEL-positive cells with ET-1 was blocked by ATZ1993 or BQ123 as an antagonist for ETA receptor, but unaffected by BQ788 as an antagonist for ETB receptor. These results strongly suggest that ET-1 plays crucial roles as a mitogen and an inhibitory factor of apoptosis in the vascular remodeling process after endothelial removal.     

Biological and pathophysiological roles of endogenous methylarginines as inhibitors of nitric oxide synthase

Protein arginine N-methyltransferases (PRMTs) catalyse the methylation of guanidinonitrogen(s) of arginine to produce NG-monomethyl-L-arginine (L-NMMA), asymmetric NG,NG-dimethyl-L-arginine (ADMA) and symmetric NG,NG-dimethyl-L-arginine (SDMA), which are subsequently released into the cytoplasm following proteolysis. Free intracellular L-NMMA and ADMA, but not SDMA, are inhibitors of all three isoforms of nitric oxide synthases (nNOS, eNOS and iNOS). L-NMMA and ADMA, but not SDMA, are actively metabolized by dimethylarginine dimethylaminohydrolase (DDAH) to L-citrulline and methylamine (and dimethylamine). Free methylarginines are detectable in cell cytosol, plasma and tissues. Elevated ADMA has been detected in the plasma of patients or experimental animals with hypercholesterolemia, renal failure, atherosclerosis, hypertension, thrombotic microangiopathy, peripheral arterial occlusive disease and in the regenerated endothelial cells after angioplasty. Moreover, in the non-cardiovascular field, ADMA was increased in the urethral tissue following ischemia and in the plasma of patients with schizophrenia and multiple sclerosis. Altered biosynthesis of NO has been implicated in the pathogenesis of these diseases, and it is possible to consider that the accumulation of endogenous L-NMMA and ADMA underlies the impaired NO generation and increased O2- production. We described herein the biosynthesis, transmembrane transport, metabolic pathway and possible pathophysiological roles of endogenous methylarginines.     

Lectin histochemistry of glycoconjugates in the feline hair follicle and hair

The distribution of glycoconjugate in the feline hair follicle and hair was studied by light and electron microscopic histochemical methods. The hair apparatus was found to contain considerable amounts of complex carbohydrates with different saccharide residues (alpha-D-mannose, beta-D-glucose, alpha-L-fucose, beta-N-acetyl-D-glucosamine). Variations of those were detected in the plasma membrane of the hair follicle cells during the course of their differentiation and keratinization, namely, alph-D-glucose, alpha-L-fucose and beta-N-acetyl-D-glucosamine in the suprabulbar and bulbar regions. The reaction level of sialic acid residues in the plasma membrane decreased in some cell layers during the course of differentiation. The results obtained from the present study indicated that interaction between saccharide residues of neutral carbohydrates and sialyl groups during the anagen phase might contribute to cell keratinization in hair follicles and hairs. It is discussed whether the existence of glycogen in outer root sheath cells might enable these cells to provide other hair apparatus cells with energy when necessary. Moreover, it became obvious from variations in sialyl residue distribution that cell differentiation processes terminate first of all in Huxley's and Henle's layers within the suprabulbar region of the hair follicle, as followed by the hair cortex.     

Assessment of styrene oligomers eluted from polystyrene-made food containers for estrogenic effects in in vitro assays

Recently, several substances from among the huge numbers of chemicals used by mankind have been implicated as instigators of disrupted endocrine function and related human health problems. Polystyrene (PS) is one of the most frequently used resins in the world, and the styrene oligomer dissolved out from PS has been designated as a potential trigger of estrogen-like activity in the Wingspread Declaration and the Japan Environment Agency's SPEED98 [JEA (Japan Environment Agency) Strategic Problem on Environmental Endocrine Disruptors '98 (SPEED) '98), http://www.env.go.jp/en/pol/speed98/sp98.html]. In order to assess the endocrine disrupting effect of styrene oligomers, we tested one styrene monomer (SM), three styrene dimers (SDs) and seven styrene trimers (STs), newly isolated from optical isomers, known to dissolve in small amounts from cup noodle containers made of polystyrene by the estrogen receptor binding assay, luciferase reporter gene assay, and human breast cancer cell MCF-7 proliferation assay. In all three tests, none of the SM, SDs and STs showed any significant activity. Accordingly, we concluded that these substances have no estrogenic activity.     

A patient with type I CD36 deficiency whose myocardium accumulated123I-BMIPP after 4 years

A 73-year-old man with aortic regurgitation was examined by 123I-alpha-methyl-p-iodophenylpentadecanoic acid (BMIPP) myocardial single photon emission computed tomography (SPECT) in 1995. Myocardial accumulation was not evident on either the early or the delayed image obtained 15 minutes and 3 hours, respectively, after injecting 123I-BMIPP. Flow cytometric analysis of CD36 expression in monocytes and platelets identified a type I CD36 deficiency. The patient was hospitalized for severe heart failure in 1999. Upon admission, the cardiothoracic ratio on chest X-rays was 73%, and the left ventricular end-diastolic diameter on echocardiograms was enlarged to 77 mm. On the second day, we performed 123I-BMIPP myocardial SPECT. Myocardial accumulation was evident in the delayed, but not in the early image. We repeated 123I-BMIPP myocardial SPECT on the 10th day after admission. Myocardial accumulation was evident on both early and delayed images. 99mTc-tetrofosmin myocardial SPECT was immediately performed after 123I-BMIPP myocardial SPECT to distinguish myocardial from pooling images in the left ventricle, but, because the images from both 99Tc-tetrofosmin and 123I-BMIPP myocardial SPECT were idential, we considered that the 123I-BMIPP myocardial SPECT images reflected the actual myocardial condition. The CD36 molecule transports long-chain fatty acid (LCFA) on the myocardial membrane, but 123I-BMIPP scintigraphy does not show any myocardial accumulation in patients with type I CD36 deficiency, indicating that myocardial LCFA uptake occurs through CD36 on the human myocardial membrane. Even though our patient had type I CD36 deficiency, BMIPP was uptaken by the myocardium during heart failure, suggesting a variant pathway on the human myocardial membrane for LCFA uptake.     

Ductal carcinoma in situ: correlation between FDG-PET/CT and histopathology

Purpose  The aim of this study was to determine if any correlation exists between tumor cell density and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET)/CT) for pure or predominant ductal carcinoma in situ (DCIS). Materials and methods  Subjects in this retrospective review comprised 11 patients who underwent FDG-PET/CT for DCIS. Pathological tumor cell density and FDG-PET/CT images were compared. A tumor background count density ratio of >1.5 was defined as the detectable range for DCIS. Results  Pathological density of disease was high in eight patients, intermediate in one, and low in two. In all eight patients with a detectable intraductal component on PET/CT, the density of disease was classified as high. In three patients undetected by PET/CT, the density of disease was classified as intermediate or low. On statistical analysis, the correlation between the density of disease and tumor background count density ratio (TBCDR) on PET/CT was significant (<0.05), whereas the nuclear grade and Van Nuys grade were not significant. In the eight patients detected by PET/CT, the discrepancy between histopathological mapping and FDG-PET/CT mapping was >20 mm in four patients and represented underestimation in four patients who showed low density of disease in the peripheral area. Conclusions  Tumor cell density of intraductal carcinoma appears strongly correlated to detection by FDG-PET/CT.