Quantitative Analysis of Torso FDG-PET Scans by Using Anatomical Standardization of Normal Cases from Thorough Physical Examinations

Understanding of standardized uptake value (SUV) of 2-deoxy-2-[18F]fluoro-d-glucose positron emission tomography (FDG-PET) depends on the background accumulations of glucose because the SUV often varies the status of patients. The purpose of this study was to develop a new method for quantitative analysis of SUV of FDG-PET scan images. The method included an anatomical standardization and a statistical comparison with normal cases by using Z-score that are often used in SPM or 3D-SSP approach for brain function analysis. Our scheme consisted of two approaches, which included the construction of a normal model and the determination of the SUV scores as Z-score index for measuring the abnormality of an FDG-PET scan image. To construct the normal torso model, all of the normal images were registered into one shape, which indicated the normal range of SUV at all voxels. The image deformation process consisted of a whole body rigid registration of shoulder to bladder region and liver registration and a non-linear registration of body surface by using the thin-plate spline technique. In order to validate usefulness of our method, we segment suspicious regions on FDG-PET images manually, and obtained the Z-scores of the regions based on the corresponding voxels that stores the mean and the standard deviations from the normal model. We collected 243 (143 males and 100 females) normal cases to construct the normal model. We also extracted 432 abnormal spots from 63 abnormal cases (73 cancer lesions) to validate the Z-scores. The Z-scores of 417 out of 432 abnormal spots were higher than 2.0, which statistically indicated the severity of the spots. In conclusions, the Z-scores obtained by our computerized scheme with anatomical standardization of torso region would be useful for visualization and detection of subtle lesions on FDG-PET scan images even when the SUV may not clearly show an abnormality.     

EML4 promotes the loading of NUDC to the spindle for mitotic progression

Echinoderm microtubule-associated protein (EMAP)-like (EML) family proteins are microtubule-associated proteins that have a conserved hydrophobic EMAP-like protein (HELP) domain and multiple WD40 domains. In this study, we examined the role of EML4, which is a member of the EML family, in cell division. Time-lapse microscopy analysis demonstrated that EML4 depletion induced chromosome misalignment during metaphase and delayed anaphase initiation. Further analysis by immunofluorescence showed that EML4 was required for the organization of the mitotic spindle and for the proper attachment of kinetochores to microtubules. We searched for EML4-associating proteins by mass spectrometry analysis and found that the nuclear distribution gene C (NUDC) protein, which is a critical factor for the progression of mitosis, was associated with EML4. This interaction was mediated by the WD40 repeat of EML4 and by the C-terminus of NUDC. In the absence of EML4, NUDC was no longer able to localize to the mitotic spindle, whereas NUDC was dispensable for EML4 localization. Our results show that EML4 is critical for the loading of NUDC onto the mitotic spindle for mitotic progression.     

Determination of 9α,11β-prostaglandin F2 by stereospecific antibody in various rat tissues

In view of the recent finding that prostaglandin D₂ is stereospecifically converted to 9α,11β-prostaglandin F₂, an isomer of prostaglandin F₂α, a highly specific and sensitive radioimmunoassay for 9α,11β-prostaglandin F₂ was developed and applied to determine the content of this prostaglandin in various rat tissues. Antisera against 9α-11β-prostaglandin F₂ were raised in rabbits immunized with the bovine serum albumin conjugate, and [³H]9α,11β-prostaglandin F₂ was enzymatically prepared from [³H]prostaglandin D₂. The assay detected 9α,11β-prostaglandin F₂ over the range of 20 pg to 1 ng, and the antiserum showed less than 0.04% cross-section with prostaglandin F₂α, prostaglandin F₂β and 9β,11β-prostaglandin F₂. To avoid postmortem changes, tissues were frozen in liquid nitrogen immediately after removal. The basal level of 9α,11β-prostaglandin F₂ was hardly detectable in various tissues of the rat examined, including spleen, lung, liver and brain; although it was found to be 0.31 ± 0.06 ng/g wet weight in the small intestine. During convulsion induced by pentylenetetrazole, enormous amounts of prostaglandin D₂ (ca. 180 ng/g wet weight) and prostaglandin F₂α (ca. 70 ng/g) were produced in the brain; however, 9α,11β-prostaglandin F₂ was detected neither there nor in the blood. This result demonstrates that the conversion to 9α,11β-prostaglandin F₂ is a minor pathway, if one at all, of prostaglandin D₂ metabolism in the rat brain.     

Single amino acid substitutions in procollagen VII affect early stages of assembly of anchoring fibrils

Procollagen VII is a homotrimer of 350-kDa pro-alpha1(VII) chains, each consisting of a central collagenous domain flanked by the noncollagenous N-terminal NC1 domain and the C-terminal NC2 domain. After secretion from cells, procollagen VII molecules form anti-parallel dimers with a C-terminal 60-nm overlap. Characteristic alignment of procollagen VII monomers forming a dimer depends on site-specific binding between the NC2 domain and the triple-helical region adjacent to Cys-2634 of the interacting procollagen VII molecules. Formation of the intermolecular disulfide bonds between Cys-2634 and either Cys-2802 or Cys-2804 is promoted by the cleavage of the NC2 domain by procollagen C-proteinase. By employing recombinant procollagen VII variants harboring G2575R, R2622Q, or G2623C substitutions previously disclosed in patients with dystrophic epidermolysis bullosa, we studied how these amino acid substitutions affect intermolecular interactions. Binding assays utilizing an optical biosensor demonstrated that the G2575R substitution increased affinity between mutant molecules. In contrast, homotypic binding between the R2622Q or G2623C molecules was not detected. In addition, kinetics of heterotypic binding of all analyzed mutants to wild type collagen VII were different from those for binding between wild type molecules. Moreover, solid-state binding assays demonstrated that R2622Q and G2623C substitutions prevent formation of stable assemblies of procollagen C-proteinase-processed mutants. These results indicate that single amino acid substitutions in procollagen VII alter its self-assembly and provide a basis for understanding the pathomechanisms leading from mutations in the COL7A1 gene to fragility of the dermal-epidermal junction seen in patients with dystrophic forms of epidermolysis bullosa.     

Preparative fractionation of protein, RNA, and plasmid DNA using centrifugal precipitation chromatography with tubular dialysis membrane inside a convoluted tubing as separation channel

Fractionation of clarified E. coli lysate components in bench-scale and preparative-scale centrifugal precipitation chromatography (CPC), using a solution of cationic surfactant cetyltrimethylammonium bromide (CTAB) containing 0.5 M NaCl as precipitant, are compared here. Step gradient of CTAB from 0.50% to 0.16% (w/v) gave a successful fractionation in bench-scale CPC; however, a linear gradient of lower CTAB concentration, 0.20-0% (w/v), was used in the preparative scale and resulted in similar fractionation. The preparative-scale CPC has a superior sample loading capacity by the use of tubular dialysis membrane inside convoluted tubing as the separation channel. In this study, the quantity of the sample loaded into the preparative CPC was about 15 times more than that in the bench scale, and in a single run the preparative CPC could prepare approximately 3 mg of plasmid DNA with about 96% of RNA removed. The higher surface area per length of the separation channel in the preparative CPC was believed to benefit mass transfer of CTAB across the membrane, leading to less CTAB being required in the process.     

Human tyrosinase is able to oxidize both enantiomers of rhododendrol

Racemic RS‐4‐(4‐hydroxyphenyl)‐2‐butanol (rhododendrol, RD) was used as a topical skin‐whitening agent until it was recently reported to induce leukoderma. We then showed that oxidation of RD with mushroom tyrosinase rapidly produces RD‐quinone, which is quickly converted to RD‐cyclic quinone and RD‐hydroxy‐p‐quinone. In this study, we examined whether either or both of the enantiomers of RD can be oxidized by human tyrosinase. Using a chiral HPLC column, racemic RD was resolved optically to R(?)‐RD and S(+)‐RD enantiomers. In the presence of a catalytic amount of l ‐dopa, human tyrosinase, which can oxidize l ‐tyrosine but not d ‐tyrosine, was found to oxidize both R(?)‐ and S(+)‐RD to give RD‐catechol and its oxidation products. S(+)‐RD was more effectively oxidized than l ‐tyrosine, while R(?)‐RD was less effective. These results support the notion that the melanocyte toxicity of RD depends on its tyrosinase‐catalyzed conversion to toxic quinones and the concomitant production of reactive oxygen species.     

Mutant vasopressin precursors that cause autosomal dominant neurohypophyseal diabetes insipidus retain dimerization and impair the secretion of wild-type proteins

Autosomal dominant familial neurohypophyseal diabetes insipidus is caused by mutations in the arginine vasopressin (AVP) gene. We demonstrated recently that mutant AVP precursors accumulate within the endoplasmic reticulum of neuronal cells, leading to cellular toxicity. In this study, the possibility that mutant AVP precursors interact with wild-type (WT) proteins to alter their processing and function was explored. WT and mutant precursors were epitope-tagged to allow them to be distinguished in transfected cells. An in vivo cross-linking reaction revealed homo- and heterodimer formation between WT and mutant precursors. Mutant precursors were also shown to impair intracellular trafficking of WT precursors from the endoplasmic reticulum to the Golgi apparatus. In addition to the cytotoxicity caused by mutant AVP precursors, the interaction between the WT and mutant precursors suggests that a dominant-negative mechanism may also contribute to the pathogenesis of familial neurohypophyseal diabetes insipidus.