Anatomical variation of habitat-related changes in scapular morphology.

The mammalian forelimb is adapted to different functions including postural, locomotor, feeding, exploratory, grooming and defence. Comparative studies on morphology of the mammalian scapula have been performed in an attempt to establish the functional differences in the use of the forelimb. In this study, a total of 102 scapulae collected from 66 species of animals, representatives of all major taxa from rodents, sirenians, marsupials, pilosa, cetaceans, carnivores, ungulates, primates and apes, were analysed. Parameters measured included scapular length, width, position, thickness, area, angles and index. Structures included supraspinous and infraspinous fossae, scapular spine, glenoid cavity, acromium and coracoid processes. Images were taken using computed tomographic (CT) scanning technology (CT-Aquarium, Toshiba and micro CT-LaTheta, Hotachi, Japan), and measurement values were acquired and processed using Avizo computer software and CanvasTM 11 ACD systems. Statistical analysis was performed using Microsoft Excel 2013. Results obtained showed that there were differences in morphological characteristics of scapula between mammals with arboreal locomotion and living in forest and mountainous areas and those with leaping and terrestrial locomotion living in open habitat or savannah. Differences were seen in the ratio of maximum length and maximum width, the orientation of scapular spine and the horizontal length of acromion and coracoid processes. The cause for the statistical grouping of the animals and the way the scapular shape covaries with habitat and to the type of locomotion and speed are discussed in detail.

Alleviating effects of artificial tear instillation on S-1-induced ocular toxicity in dogs.

S-1 is an anticancer agent that consists of tegafur, gimeracil, and oteracil potassium at a molar ratio of 1:0.4:1. S-1 is used to treat metastatic and resectable gastric cancer. However, the extensive use of S-1 in clinical practice results in watery eyes, a serious clinical problem, which worsens patients' quality of life. Although repeated instillation of artificial tears is recommended, therapy or prophylaxis against S-1-induced ocular toxicity has not been established. In the present study, we evaluated the alleviating effects of repeated artificial tear instillation on S-1-induced ocular toxicity in dogs. Ten beagle dogs (5 males and 5 females) were orally administered 3 mg/kg/day of S-1 for up to 21 days. Five drops of artificial tears were instilled to the left eye, eight times daily, within 6 hr after S-1 administration. The mean cornea staining score tended to be low in the left eye with repeated artificial tear instillation. In 4 out of 10 dogs, the corneal staining score of the left eye was more than 2-fold lower than that of the right eye. The incidence of dogs indicating normal tear drainage increased and stenosed tear drainage decreased by repeated artificial tear instillation. In conclusion, we demonstrated that artificial tear instillation can alleviate corneal surface damage induced by S-1 in dogs.

Sensitivity of the meiotic stage to hyperthermia during in vitro maturation of porcine oocytes.

The present study was conducted to clarify whether the meiotic stage of porcine oocytes has the highest sensitivity to hyperthermia during in vitro maturation by evaluating meiotic competence and DNA damage. Oocytes were exposed to 41 °C for 12 h at various intervals during 48 h of maturation culture. When the oocytes were exposed to 41 °C from 12 to 24 h of the maturation culture, the proportion of oocytes reaching metaphase II (MII) decreased as compared to the control oocytes cultured at 38.5 °C (P < 0.05). Moreover, the proportions of DNA fragmentation in all oocytes exposed to 41 °C in each culture period after 12 h from the start of maturation culture were significantly higher (P < 0.05) than for the control oocytes. When the meiotic stage of oocytes cultured at 38.5 °C between 12 and 24 h was examined, the majority of oocytes remained at the germinal vesicle (GV) stage at 12 h and approximately half of the oocytes reached metaphase I (MI) at 24 h. These results indicate that the meiotic stage of porcine oocytes having the highest sensitivity to hyperthermia during in vitro maturation is a transition period from the GV stage to the MI stage.

Different responses to 5-fluoraouracil in mutagenicity and gene expression between two human lymphoblastoid cell lines with or without TP53 mutation.

Human lymphoblastoid TK6 and WTK-1 cells are widely used to detect mutagens in vitro. TK6 cells have wild-type TP53 alleles, while WTK-1 cells have one allele of mutated TP53. Both cells were treated with 5-fluorouracil (5-FU), and gene mutation assay and micronucleus assay were performed to clarify the differential response related to the TP53 gene status. The effects of 5-FU on gene expression were assessed by microarray and quantitative RT-PCR analyses. In WTK-1 cells, 5-FU increased the frequency of cells with micronucleus and mutation. In TK6 cells, frequency of cells with micronucleus was increased but the mutation frequency was not. The cytotoxicity induced by 5-FU was more prominent in TK6 cells than in WTK-1 cells. Analysis of gene expression showed that the genes involved in the TP53 pathway were up-regulated in TK6 cells but not in WTK-1 cells. The differential responses to 5-FU between these cell lines appeared to be due to the difference in the TP53 gene status, thus providing a molecular basis for the bioassays using these cell lines in the toxicology field. Our results indicate that the clinical efficacy of 5-FU chemotherapy may depend on the TP53 genotype.

Hoffmann reflex in a rat bipedal walking model.

The rat bipedal walking model (RBWM) refers to rats that acquired anatomical and functional characteristics for bipedal walking after the completion of a long-term motor training program. We recorded the Hoffmann reflex (H-reflex) of the forelimb and hindlimb in RBWM and control (not trained, normal) rats to evaluate the effects of bipedal walking on central nervous system (CNS) activity. The H-reflex recorded from the hindlimbs of the RBWM was significantly inhibited compared with that in the control. Furthermore, the inhibition of the H-reflex recorded from both forelimbs and hindlimbs by paired pulse stimulation tended to be enhanced in RBWM. These results indicate that bipedal walking or bipedal walking training cause functional changes in spinal reflex pathways in the CNS.

Investigation and characterization of rat bipedal walking models established by a training program.

The purpose of the present study was to establish a rat bipedal walking model to examine the effects of bipedal walking on the central nervous system by training rats to perform bipedal walking over a period of 3 months. The characteristics of bipedal walking were investigated using kinematic and electromyographic methods in established bipedal walking models. Stable bipedal walking was achieved in rats by training them to stand with an upright posture and to walk with the hindlimbs using bipedal-walking training equipment to obtain a water reward. A stable head position in the rat bipedal walking model was attained primarily by closing the swing-phase period with a large angular change in the hip, knee, and ankle joints. The EMG burst pattern of the knee extensor (m. rectus femoris) and the erector muscle of the spine (m. longissimus) during bipedal walking was similar to that during quadrupedal walking in rats. We established two bipedal walking models using normal and forelimb-amputated rats. Comparative studies of these two bipedal walking models are expected to provide the information about the influence of forelimb movements on neuronal control of bipedal walking.