Immunohistochemical Detection of Carcinogen-DNA Adducts and DNA Repair in Mouse Skin

4-Hydroxyaminoquinoline 1-oxide (4HAQO) and (±)-trans-7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydroben-zo[a]pyrene (BP-DE)-DNA adducts were immunohisto-chcmically demonstrated in the nuclei of mouse skin using antibodies directed against carcinogen (4HAQO or BP) modified DNA. The specificity of the immunostaining was confirmed by several tests, including preincubation of the antibody with carcinogen modified DNA or related molecules, and digestion of the sections with DNase.Subcutaneous injection of 4HAQO dissolved in isotonic solution into an isolated portion of the mouse skin clamped off with ring-shaped forceps resulted in dose-dependent generation of DNA adducts in the nuclei of epithelial cells, fibroblasts, and panniculus carnosus cells. BP-DNA adducts could also be similarly detected dose-dependently in the nuclei of skin cells after local application of BP-DE. Nuclear staining was absent in animals injected with isotonic solution alone, and the intensity of staining correlated well with the level of unscheduled DNA synthesis (UDS) demonstrated autoradiographically after treatment with 4HAQO. Killing of mice at different time points after a single injection of 4HAQO revealed a gradual decrease in the intensity of the staining. Thus the postulated generation and repair of DNA adducts can be followed at the cellular level using the presently described method. J Invest Dermatol 92:275S–279S, 198

ARCHITECTURAL DIFFERENCES OF LOWER LIMB MUSCLE-TENDON FOR MONOZYGOTIC TWINS WITH DIFFERENT SPORT EXPERIENCES

The purpose of this study was to examine architectural differences of lower limb muscle-tendon for monozygotic twins with different sport experiences and for monozygotic twins with same sport experiences. 50 monozygotic twins (MZT) participated in this study, consisting of 16 MZT with different sport experiences, 34 MZT with same sport experiences. Musculoskeletal ultrasonography is applied to measure the muscle fascicle length of gastrocnemius medialis (GM) muscle as well as Achilles and patella tendon cross-sectional area (CSA) and length. Achilles tendon was separately measured from the AT insertion point on the calcaneus to the distal end of soleus muscle (ATSOL) and to the AT junction between medial and lateral gastrocnemii muscles (ATGML), respectively. The measured intraclass correlation coefficient (ICC) clearly showed poor concordances in the ATSOL length of MZT with different sport experiences (ICC of 0.74), and good concordance in the MG fascicle length of MZT with different sport experiences (ICC of 0.83). Other parameters in all intra-pears showed excellent concordances (ICC\u3e0.9). Thus, different concordances of AT length between GM and SOL parts can indicate the different plasticity by the structural and functional mechanics and different concordances between groups indicate that ATSOL and GM fascicle length are affected not only by genetic factors but also by acquired environmental factors

Lower complexity of motor primitives ensures robust control of high-speed human locomotion

Walking and running are mechanically and energetically different locomotion modes. For selecting one or another, speed is a parameter of paramount importance. Yet, both are likely controlled by similar low-dimensional neuronal networks that reflect in patterned muscle activations called muscle synergies. Here, we challenged human locomotion by having our participants walk and run at a very broad spectrum of submaximal and maximal speeds. The synergistic activations of lower limb locomotor muscles were obtained through decomposition of electromyographic data via non-negative matrix factorization. We analyzed the duration and complexity (via fractal analysis) over time of motor primitives, the temporal components of muscle synergies. We found that the motor control of high-speed locomotion was so challenging that the neuromotor system was forced to produce wider and less complex muscle activation patterns. The motor modules, or time-independent coefficients, were redistributed as locomotion speed changed. These outcomes show that humans cope with the challenges of high-speed locomotion by adapting the neuromotor dynamics through a set of strategies that allow for efficient creation and control of locomotion.Peer Reviewe

Morphological Markers of Chromosomal Instability

Cancer is characterized by genomic complexity and chromosomal instability (CIN). Atypical mitosis and nuclear atypia such as micronuclei have been reported as morphological characteristics of chromosomal instability. An atypical mitotic figure is defined as anything other than the typical form of normal mitosis, including multipolar, ring, dispersed, asymmetrical, and lag-type mitoses. A micronucleus is defined as the small nucleus that forms whenever a chromosome or its fragment is not incorporated into one of the daughter nuclei during cell division. A telomere plays a key role in chromosomal instability. Telomere dysfunction induces fusion of chromatids and chromosome missegregation and this phenomenon can be observed as abnormal mitotic figures and micronuclei. Detection of morphological markers of chromosomal instability using pathological specimens, even small biopsy or cytological specimens, may provide valuable information concerning the prognosis of cancers. Here, we discuss morphological assessment of chromosomal instability using routine pathological specimens

Effects of mask fitness and worker education on the prevention of occupational dust exposure

To decrease the incidence of pneumoconiosis, we examined dust protective mask performance and its relation to pulmonary function as well as the effects of worker education on the proper wearing of masks. One hundred and seventy-eight workers from 15 factories subject to dust exposure participated in this study. All participants were interviewed to obtain relevant personal information and underwent both a mask leakage and a pulmonary function test. The mask leakage was expressed as a percentage, with under 10% leakage indicating that the dust protective mask worked efficiently. In addition, 23 workers from 2 factories were educated on how to wear masks properly. The average mask leakage was 24.3%, and 58% of workers wore ineffective masks. Though pulmonary function was almost normal, the percent vital capacity (%VC) tended to be lower depending on the mask leakage. Mask education, which was very easy and took only a short time, dramatically decreased average mask leakage from 32.1% to 10.5% (p0.001). Educating workers to wear masks properly might prevent the worsening of pulmonary function in response to dust exposure. Appropriate mask fitness by education could be useful in preventing the development of pneumoconiosis.</p

α- and β-Tubulin Lattice of the Axonemal Microtubule Doublet and Binding Proteins Revealed by Single Particle Cryo-Electron Microscopy and Tomography

SummaryMicrotubule doublet (MTD) is the main skeleton of cilia/flagella. Many proteins, such as dyneins and radial spokes, bind to MTD, and generate or regulate force. While the structure of the reconstituted microtubule has been solved at atomic resolution, nature of the axonemal MTD is still unclear. There are a few hypotheses of the lattice arrangement of its α- and β-tubulins, but it has not been described how dyneins and radial spokes bind to MTD. In this study, we analyzed the three-dimensional structure of Tetrahymena MTD at ∼19 Å resolution by single particle cryo-electron microscopy. To identify α- and β-tubulins, we combined image analysis of MTD with specific kinesin decoration. This work reveals that α- and β-tubulins form a B-lattice arrangement in the entire MTD with a seam at the outer junction. We revealed the unique way in which inner arm dyneins, radial spokes, and proteins inside MTD bind and bridge protofilaments

Gene Suppression of Mouse Testis In Vivo Using Small Interfering RNA Derived from Plasmid Vectors

We evaluated whether inhibiting gene expression by small interfering RNA (siRNA) can be used for an in vivo model using a germ cell-specific gene (Tex101) as a model target in mouse testis. We generated plasmid-based expression vectors of siRNA targeting the Tex101 gene and transfected them into postnatal day 10 mouse testes by in vivo electroporation. After optimizing the electroporation conditions using a vector transfected into the mouse testis, a combination of high- and low-voltage pulses showed excellent transfection efficiency for the vectors with minimal tissue damage, but gene suppression was transient. Gene suppression by in vivo electroporation may be helpful as an alternative approach when designing experiments to unravel the basic role of testicular molecules