Hydration status and running performance during cool and hot training sessions in rugby union forwards and backs.

BACKGROUND: Rugby showed a high incidence of exertional heatstroke. Different physiques and running performances between the forward and back players (FW and BK) may result in different heatstroke risks. This study aimed to compare the hydration status, running performance, and perceived heatstroke symptoms (PHS) between cool and hot environment training (HT and CT) in university rugby union FW and BK. METHODS: Thirteen university rugby players (seven forwards and six backs) participated in this study. During both conditions, players were allowed to drink water and sports drink, and the amount of fluid intake was recorded. Body mass was measured pre- and post-training, and weight loss was calculated. Sweat loss was calculated based on body mass and fluid intake. During training, running performance was measured using GPS. The presence of PHS was assessed using a questionnaire administered after training. RESULTS: Fluid intake and sweat loss were higher in the HT as opposed to the CT, and FW showed higher fluid intake and dehydration than BK. However, there were no significant differences in weight loss observed during data collection. Running distance per minute and maximum speed were higher in BK than in FW, but there was no significant difference between conditions. Although a significant weight loss was not observed between conditions, the number of PHS was higher in the HT. CONCLUSIONS: Although BK had a higher running distance and maximum speed than FW during training, a higher cycle of fluid intake and sweat loss was observed in the FW than that in the BK.

Elite Rugby Players have Unique Morphological Characteristics of the Hamstrings and Quadriceps Femoris Muscles According to their Playing Positions.

Rugby is a popular sport requiring high-intensity and maximal speed actions. Numerous studies have demonstrated that physical performance variables, such as strength, sprinting, and jumping, are different between the forwards and backs. However, there is little information about muscle morphological characteristics specific for each rugby playing position. This study aimed to clarify the morphological characteristics of the thigh muscles in forwards and backs. Ultrasound images were obtained from the proximal, middle, and distal regions of the thigh. Then, the anatomical cross-sectional areas of particular muscles in the hamstrings and quadriceps femoris were calculated for seven forwards, seven backs, and ten non-athletes. The anatomical cross-sectional areas were normalised by the two-third power of lean body mass, and the normalised values of the three regions were averaged as that of the individual muscle. In the hamstrings, the normalised anatomical cross-sectional areas of the biceps femoris long head were significantly greater in forwards than in non-athletes, whereas those of the semitendinosus were significantly greater in backs than in non-athletes. Furthermore, in the quadriceps femoris, the normalised anatomical cross-sectional areas of the rectus femoris and vastus intermedius were significantly greater in forwards than in backs and non-athletes. These results suggest that forwards have great muscularity of the biceps femoris long head and vastus intermedius which can generate large force, whereas backs possess great muscularity of the semitendinosus which can generate high contraction velocity. These findings allow coaches to design more effective training programs according to particular rugby playing positions.

Sub-elite sprinters and rugby players possess different morphological characteristics of the individual hamstrings and quadriceps muscles.

Numerous studies have clarified that sprinters possess unique morphological characteristics of the thigh muscles compared with non-athletes. However, little evidence is available regarding the morphological differences between sprinters and rugby players. This study aimed to examine the morphological differences in the individual hamstrings and quadriceps femoris muscles between sub-elite sprinters and rugby players. Ultrasound images were acquired from the proximal, middle, and distal regions of the thigh. From the images, the anatomical cross-sectional areas were calculated for 14 sub-elite sprinters, 14 rugby players, and 14 non-athletes. The calculated anatomical cross-sectional areas were normalized to two-thirds power of the body mass, and the normalized values of all regions were averaged as those of the individual muscles. In the hamstrings, the sizes of the biceps femoris short head and semitendinosus were greater in the sprinters than in the rugby players and/or non-athletes (all p < 0.05). In contrast, in the quadriceps femoris, the sizes of the rectus femoris, vastus lateralis, and vastus intermedius were the greatest in the rugby players (all p < 0.05). In the middle region of the biceps femoris short head and the proximal-middle regions of the semitendinosus, the muscle sizes were greater in the sprinters than in the rugby players (all p < 0.05), and vice versa in the middle-distal regions of the rectus femoris (all p < 0.05). These results suggest that 1) sub-elite sprinters possess larger sizes of the biceps femoris short head and semitendinosus, whereas rugby players have larger sizes of the rectus femoris, vastus lateralis, and vastus intermedius, and 2) each of the athletes has different size distributions, especially along the lengths of BFsh, ST, and RF. The findings of the present study would be helpful for rugby players in designing training regimens aimed at enhancing sprint performance.

RAD18 mediates DNA double-strand break-induced ubiquitination of chromatin protein.

The E3 ubiquitin ligase RAD18 mono-ubiquitinates PCNA to promote bypass of replication fork-stalling DNA lesions. On the other hand, RAD18 also contributes to DNA double-strand break (DSB) repair. RAD18 is recruited to ionizing radiation (IR)-induced DSB and colocalizes with ubiquitinated chromatin proteins. RAD18 interacts with the ubiquitinated chromatin proteins via its ubiquitin-binding Zinc finger (UBZ) domain and is proposed to propagate DNA DSB signalling and recruit DNA repair proteins. We found that purified human RAD18 protein complexed with RAD6B (RAD6B-RAD18) catalyzes mono- and poly-ubiquitination of histone H2A in vitro while UBZ domain-mutated RAD18 complexed with RAD6B protein catalyzes mono- but not poly-ubiquitination of histone H2A. Human RAD18-/-cells synchronized at the G1 phase show a reduced signal of ubiquitinated protein in chromatin after IR when compared to that of wild-type control cells. The reduced signal of ubiquitinated protein in RAD18-/-cells is rescued by the introduction of RAD18 cDNA but to a lesser extent by the introduction of cDNA coding RAD18 lacking UBZ domain. Taken together, these results indicate that RAD18 mediates DSB-induced ubiquitination of chromatin protein during the G1 phase.

p53 dysfunction precedes the activation of nuclear factor-κB during disease progression in mice expressing Tax, a human T-cell leukemia virus type 1 oncoprotein.

Transgenic (Tg) mice expressing Tax, a human T-cell leukemia virus type 1 (HTLV-1) oncoprotein, develop mature T-cell leukemia/lymphoma. The leukemic cells in Tg mice expressing Tax show p53 dysfunction and nuclear factor-κB (NF-κB) activation, similar to that seen in adult T-cell leukemia/lymphoma (ATLL) cells from patients infected with HTLV-1. However, it is unclear when these effects occur in HTLV-1 carriers during the development of ATLL. Here, we examined p53 function and NF-κB activity before the onset of leukemia in Tax-expressing Tg (Tax-Tg) mice between 4 and 25 months of age. At 4-10 months of age, 71% of mice showed p53 inactivation, without evidence for NF-κB activation, even though tax expression was consistent from 4 to 25 months of age. The decline in p53 function resulted from decreased p53 accumulation after DNA damage. From 11 months of age onward, 75% of mice showed p53 dysfunction and 37.5% showed constitutive NF-κB activation with the components of p50 and RelB. An NF-κB inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), reduced NF-κB activity (i.e. p50/RelB) but did not restore p53 function. In vivo, treatment with DHMEQ until 24 months of age prevented the onset of T-cell leukemia in Tax-Tg mice. These results suggest that the Tax-induced decline in p53 function, which is independent of NF-κB activation in the early stage, might be the first stage in the onset of ATLL. NF-κB activity is involved in the later stages of ATLL onset.

Therapeutic effects of γ-irradiation in a primary effusion lymphoma mouse model.

Primary effusion lymphoma (PEL) is a unique and recently identified non-Hodgkin's lymphoma in immunocompromised individuals. PEL is caused by the Kaposi sarcoma-associated herpes virus/human herpes virus 8 (KSHV/HHV-8) and has a peculiar presentation involving liquid growth in the serous body cavity, chemotherapy resistance and poor prognosis. In search of a new therapeutic modality for PEL, we examined the effect of γ-irradiation on PEL-derived cell lines (BCBL-1, BC-1, and BC-3) in vitro and in vivo. An MTT assay and trypan blue exclusion assay revealed that irradiation significantly suppressed cell proliferation in the PEL cell lines in a dose-dependent manner, and induced apoptosis. The PEL cell lines were relatively radiosensitive compared with other hematological tumor cell lines (Raji, Jurkat, and K562 cells). Inoculation of the BC-3 cell line into the peritoneal cavity of Rag2/Jak3 double-deficient mice led to massive ascites formation, and subcutaneous injection of BCBL-1 led to solid lymphoma formation. Total body irradiation (4 Gy × 2) with bone marrow transplantation resulted in the complete recovery of both types of PEL-inoculated mice. These results suggest that total body irradiation with bone marrow transplantation can be successfully applied for the treatment of chemotherapy-resistant PEL.

Cholangiocarcinomas associated with long-term inflammation express the activation-induced cytidine deaminase and germinal center-associated nuclear protein involved in immunoglobulin V-region diversification.

Cholangiocarcinoma (CCA) represents a model of tumor development after long-term inflammation which causes DNA damage or impairs DNA repair mechanism. AID and GANP, both appearing in antigen-driven B cells, are involved in affinity maturation of the immunoglobulin V-region with increased somatic mutation. A normal cholangiocyte line showed the induction of AID transcripts after stimulation with TNF-alpha, whereas ganp transcripts appeared constitutively in this cell line. Next, we examined the expression of AID and GANP in clinical CCA specimens to obtain information whether their expression levels are associated with the malignant grade of CCA. AID expression was similarly detected in the clinical cases of both well-differentiated and poorly-differentiated CCAs. On the contrary, GANP expression was detected in CCA cells at a higher level in the nucleus of poorly-differentiated CCAs with shorter survivals than in that of well-differentiated CCAs. The high and low cases of nuclear GANP expression showed no change in the frequency of the TP53 mutations, however, further investigation by in vitro experiment demonstrated that the high GANP expression caused the increased number of gammaH2AX foci after DNA damage by ionizing-irradiation. These results suggest that GANP is involved in regulation of DNA repair mechanism and the abnormal over-expression of GANP together with AID might be associated with rigorous DNA damage, potentially causing the malignant development of CCAs during long-term inflammation.

GANP suppresses DNA recombination, measured by direct-repeat beta-galactosidase gene construct, but does not suppress the type of recombination applying to immunoglobulin genes in mammalian cells.

Immunoglobulin V-region somatic hypermutation and C-region class-switch recombination are initiated by activation-induced cytidine deaminase (AID) in B-cells. AID-induced DNA damage at the immunoglobulin S-region is known to be repaired by non-homologous end-joining, but repair mechanisms at the V-region remain to be elucidated. In Saccharomyces cerevisiae, DNA homologous recombination is regulated by the expression of Sac3, involved in actin assembly, cell cycle transition and mRNA metabolism. Here, we demonstrate that the Sac3-homologue GANP suppresses DNA recombination in a direct-repeat beta-galactosidase gene construct in mammalian cells. Homozygous ganp gene knockout is embryonic lethal in mice. Embryonic fibroblasts immortalized from hetero-deficient ganp(+/-) mice showed more DNA recombination than wild-type. In contrast, over-expression of GANP suppressed either spontaneous DNA recombination or that caused by the introduction of aid cDNA into NIH3T3 cells (susceptible to I-sceI restriction enzyme cleavage but not to RAG-mediated immunoglobulin gene recombination). GANP suppresses the DNA recombination not only on the extrachromosomal DNA construct but also on the integrated DNA. The Sac3-homology portion is necessary for the suppressive activity, but the truncated carboxyl terminal MCM3-binding/acetylating region adversely augmented DNA recombination, acting as a dominant negative form. Expression of full-length GANP is critical for suppression of DNA hyper-recombination in mammalian cells.

Vitamins K1 and K2 potentiate hyperthermia by down-regulating Hsp72 expression in vitro and in vivo.

Hyperthermia is used to treat various malignancies, including esophageal, stomach and rectal cancer. Since hyperthermia alone has produced limited results, much attention has been focused on combining hyperthermia with chemotherapy and on searching for substances able to sensitize tumor cells to hyperthermia-induced damage. Here, we show that vitamins K1 and K2 (VK1, VK2) inhibited the expression of heat-shock protein 72 (Hsp72) but did not affect the constitutive expression of Hsc70 or calnexin in vitro and in vivo. VK1 and VK2 sensitized A549 cells to heat-shock induced cell death, while the compounds alone had no effect on cell viability. The suppression of Hsp72 was apparently at the protein level because the mRNA expression of Hsp72 was unchanged. Moreover, the chaperone activity of Hsp72 was compromised after heat-shock when cells were pre-treated with VK2. The effect of VK2 on Hsp72 suppression, however, was also observed in normal mouse tissue after the mice were subjected to whole-body hyperthermia. To eliminate this side effect, local hyperthermia was performed on tumors in mice. The pre-treatment with VK2 potentiated the effect of local hyperthermia on tumor growth suppression. The findings here that VK1 and VK2 inhibit heat-shock-induced Hsp72 suggest their possible use as an adjuvant for hyperthermia in cancer therapy.

Measurement of the whole-body 137Cs in residents around the Chernobyl nuclear power plant.

To understand the current situation of internal radiation exposure in the population around the Chernobyl Nuclear Power Plant (CNPP), we examined the 137Cs body burden in six residents of Belarus, Ukraine and Russia in 2002 and 2004 using the whole-body counter (WBC) at Nagasaki University (Japan). The data were compared with those of our previous study performed in 1993-1994 using the same method. In 2002 and 2004, peaks of 137Cs were detected in two residents from Gomel, which was heavily contaminated by the CNPP accident, one from Minsk (Belarus) and one from Kiev (Ukraine), but another resident from Minsk showed no 137Cs peaks. The results of the present study suggests that residents around the CNPP are still exposed to chronic 137Cs internal irradiation, probably due to the daily consumption of contaminated domestic foods, but the risk of any disease by the irradiation is quite low. Long-term follow-up of WBC around the CNPP is useful and may contribute to radiation safety regulation together with a reduction of unnecessary radiophobia for the residents.

The Sac3 homologue shd1 is involved in mitotic progression in mammalian cells.

Saccharomyces Sac3 required for actin assembly was shown to be involved in DNA replication. Here, we studied the function of a mammalian homologue SHD1 in cell cycle progression. SHD1 is localized on centrosomes at interphase and at spindle poles and mitotic spindles, similar to alpha-tubulin, at M phase. RNA interference suppression of endogenous shd1 caused defects in centrosome duplication and spindle formation displaying cells with a single apparent centrosome and down-regulated Mad2 expression, generating increased micronuclei. Conversely, increased expression of SHD1 by DNA transfection with shd1-green fluorescent protein (gfp) vector for a fusion protein of SHD1 and GFP caused abnormalities in centrosome duplication displaying cells with multiple centrosomes and deregulated spindle assembly with up-regulated Mad2 expression until anaphase, generating polyploidy cells. These results demonstrated that shd1 is involved in cell cycle progression, in particular centrosome duplication and a spindle assembly checkpoint function.