A new causative heat supply for exertional heat stroke on runners in cold air.

The dysregulation in heat balance, the main cause of exertional heat stroke, occurs not only in midsummer but also in the cold season. Possible causes of this are a reduction in convection and evaporation due to tailwinds and an acceleration of radiant heat inflow. Although the amount of radiant heat that reaches the surface can be estimated, the actual amount of heat that flows into the body cannot be specified yet. This paper made an experimental attempt at this. A device is made up of a temperature controllable heat sink and heat flow detector, which keeps the surface temperature constant and has a heat exchange coefficient comparable to that of the human body surface. The output of this device (total heat exchange) was divided into radiant heat exchange and other heat exchange using a standard radiant heat calibrator, Leslie cube. A phenomenon, in which a wet surface while the surface temperature was low absorbed larger heat than that of the dry surface, was found. And authors named this "hidden heat inflow". As a result of multiple regression analyses, both radiant heat exchange and other heat exchanges are closely related to the surface temperature, and the maximum difference in total heat exchange during the experiment reached 200 kcal/m2/h. It has been suggested that this phenomenon may also occur on the surface of human skin. One of the causes of this "hidden heat inflow" is considered to be the decrease in evaporative cooling due to the decrease in surface temperature. However, this alone cannot explain all of the phenomena, so water vapor aggregation may also be involved. A "hidden heat inflow" as a sufficient heat source for exertional heat stroke or collapse during a marathon race on a cold day was evidenced experimentally.

Ribosome dimerization is essential for the efficient regrowth of Bacillus subtilis.

Ribosome dimers are a translationally inactive form of ribosomes found in Escherichia coli and many other bacterial cells. In this study, we found that the 70S ribosomes of Bacillus subtilis dimerized during the early stationary phase and these dimers remained in the cytoplasm until regrowth was initiated. Ribosome dimerization during the stationary phase required the hpf gene, which encodes a homologue of the E. coli hibernation-promoting factor (Hpf). The expression of hpf was induced at an early stationary phase and its expression was observed throughout the rest of the experimental period, including the entire 6 h of the stationary phase. Ribosome dimerization followed the induction of hpf in WT cells, but the dimerization was impaired in cells harbouring a deletion in the hpf gene. Although the absence of ribosome dimerization in these Hpf-deficient cells did not affect their viability in the stationary phase, their ability to regrow from the stationary phase decreased. Thus, following the transfer of stationary-phase cells to fresh LB medium, Δhpf mutant cells grew slower than WT cells. This observed lag in growth of Δhpf cells was probably due to a delay in restoring their translational activity. During regrowth, the abundance of ribosome dimers in WT cells decreased with a concomitant increase in the abundance of 70S ribosomes and growth rate. These results suggest that the ribosome dimers, by providing 70S ribosomes to the cells, play an important role in facilitating rapid and efficient regrowth of cells under nutrient-rich conditions.

Estimated environmental radionuclide transfer and deposition into outdoor swimming pools.

In 2011, a large radioactive discharge occurred at the Fukushima Daiichi nuclear power plant. This plant is located within a climatically temperate region where outdoor swimming pools are popular. Although it is relatively easy to decontaminate pools by refilling them with fresh water, it is difficult to maintain safe conditions given highly contaminated diurnal dust falls from the surrounding contaminated ground. Our objectives in this paper were to conduct daily radioactivity measurements, to determine the quantity of radioactive contaminants from the surrounding environment that invade outdoor pools, and to investigate the efficacy of traditional pool cleaners in removing radioactive contaminants. The depositions in the paper filterable particulates ranged from 0 to 62,5 Bq/m(2)/day, with the highest levels found in the southern Tohoku District containing Fukushima Prefecture and in the Kanto District containing Tokyo Metro. They were approximately correlated with the ground contamination. Traditional pool cleaners eliminated 99% of contaminants at the bottom of the pool, reducing the concentration to 41 Bq/m(2) after cleaning. Authors recommended the deposition or the blown radionuclides into outdoor swimming pools must be considered into pool regulations when the environments exactly polluted with radionuclides.

Enhanced expression of Bacillus subtilis yaaA can restore both the growth and the sporulation defects caused by mutation of rplB, encoding ribosomal protein L2.

A temperature-sensitive mutation in rplB, designated rplB142, encodes a missense mutation at position 142 [His (CAT) to Leu (CTT)] of Bacillus subtilis ribosomal protein L2. The strain carrying the mutation grew more slowly than the wild-type, even at low temperatures, probably due to the formation of defective 70S ribosomes and the accumulation of incomplete 50S subunits (50S* subunits). Gel analysis indicated that amounts of L2 protein and also of L16 protein were reduced in ribosomes prepared from the rplB142 mutant 90 min after increasing the growth temperature to 45 °C. These results suggest that the assembly of the L16 protein into the 50S subunit requires the native L2 protein. The H142L mutation in the defective L2 protein affected sporulation as well as growth, even at the permissive temperature. A suppressor mutation that restored both growth and sporulation of the rplB142 mutant at low temperature was identified as a single base deletion located immediately upstream of the yaaA gene that resulted in an increase in its transcription. Furthermore, genetic analysis showed that enhanced synthesis of YaaA restores the functionality of L2 (H142L) by facilitating its assembly into 50S subunits.

Multiple rRNA operons are essential for efficient cell growth and sporulation as well as outgrowth in Bacillus subtilis.

The number of copies of rRNA (rrn) operons in a bacterial genome differs greatly among bacterial species. Here we examined the phenotypic effects of variations in the number of copies of rRNA genes in the genome of Bacillus subtilis by analysis of eight mutant strains constructed to carry from two to nine copies of the rrn operon. We found that a decrease in the number of copies from ten to one increased the doubling time, and decreased the sporulation frequency and motility. The maximum levels for transformation activity were similar among the strains, although the competence development was significantly delayed in the strain with a single rrn operon. Normal sporulation only occurred if more than four copies of the rrn operon were present, although ten copies were needed for vegetative growth after germination of the spores. This behaviour was seen even though the intracellular level of ribosomes was similar among strains with four to ten copies of the rrn operon. Furthermore, ten copies of the rrn operon were needed for the highest swarming activity. We also constructed 21 strains that carried all possible combinations of two copies of the rrn operons, and found that these showed a range of growth rates and sporulation frequencies that all fell between those recorded for strains with one or three copies of the rrn operon. The results suggested that the copy number of the rrn operon has a major influence on cellular processes such as growth rate and sporulation frequency.

Single mutations introduced in the essential ribosomal proteins L3 and S10 cause a sporulation defect in Bacillus subtilis.

We introduced single mutations into the rplC and rpsJ genes, which encode the essential ribosomal proteins L3 (RplC) and S10 (RpsJ), respectively, and are located in the S10 gene cluster of the gram-positive, endospore-forming bacterium Bacillus subtilis, and examined whether these mutations affected their growth rate, sporulation, competence development and 70S ribosome formation. Mutant cells harboring the G52D mutation in the L3 ribosomal protein, which is located at the peptidyl transferase center of 50S, accumulated 30S subunit at 45°C, probably due to a defect in 50S formation, and exhibited a reduction in the sporulation frequency at high temperature. On the other hand, mutant cells harboring the H56R mutation in the S10 protein, which is located near the aminoacyl-tRNA site of 30S, showed severe growth defect and deficiency in spore formation, and also exhibited significant delay in competence development.

Expression of a small (p)ppGpp synthetase, YwaC, in the (p)ppGpp(0) mutant of Bacillus subtilis triggers YvyD-dependent dimerization of ribosome.

To elucidate the biological functions of small (p)ppGpp synthetases YjbM and YwaC of Bacillus subtilis, we constructed RIK1059 and RIK1066 strains carrying isopropyl-ß-D-thiogalactopyranoside (IPTG) inducible yjbM and ywaC genes, respectively, in the ΔrelA ΔyjbM ΔywaC triple mutant background. While the uninduced and IPTG-induced RIK1059 cells grew similarly in LB medium, the growth of RIK1066 cells was arrested following the addition of IPTG during the early exponential growth phase. Induction of YwaC expression by IPTG also severely decreased the intracellular GTP level and drastically altered the transcriptional profile in RIK1066 cells. Sucrose density gradient centrifugation analysis of the ribosomal fractions prepared from the IPTG-induced RIK1066 cells revealed three peaks corresponding to 30S, 50S, and 70S ribosome particles, and also an extra peak. Electron microscope studies revealed that the extra peak fraction contained dimers of 70S ribosomes, which were similar to the Escherichia coli 100S ribosomes. Proteomic analysis revealed that the 70S dimer contained an extra protein, YvyD, in addition to those found in the 70S ribosome. Accordingly, strain resulting from the disruption of the yvyD gene in the RIK1066 cells was unable to form 70S dimers following IPTG induction, indicating that YvyD is required for the formation of these dimers in B. subtilis.

Effect of exercise on bone status and body composition in Japanese students.

PURPOSE: We evaluated the effect of exercise on stiffness and fat-free mass (FFM), which consists of bone and muscle, in Japanese students. It is uncertain whether exercise or sports activities will help to accumulate overall peak bone mass in Japanese adolescents. METHODS: A total of 710 Japanese students (age = 15-20 yr) were enrolled. Students who regularly engage in physical exercise were assigned to an exercise group; other students were assigned to a nonexercise group. Body composition, including height, weight, waist circumference, hip circumference, body mass index, and waist-to-hip ratio, were measured and calculated. Lung volume, body volume, and body fat percentage were evaluated by air displacement plethysmography. Fat mass and FFM were derived from body fat percentage and body weight. Bone status, such as speed of sounds, broadband ultrasound attenuation, and stiffness, which is defined as bone density, was assessed by quantitative ultrasound. RESULTS: In both sexes, height, weight, body mass index, circumferences, waist-to-hip ratio, lung volume, and body volume between the exercise and nonexercise groups did not show any significant differences. FFM, speed of sounds, broadband ultrasound attenuation, and stiffness in the exercise group were statistically higher than those in the nonexercise group (P < 0.05). Although stiffness positively correlated with age with the exception of the nonexercise group in females (P < 0.01), stiffness correlated with FFM in the exercise and nonexercise groups in both sexes (P < 0.01). CONCLUSIONS: Ours is the first analysis of a trend in peak bone mass, including the effect of exercise in Japanese students. For Japanese pubertal females who did not have a history of regular exercise, stiffness slowly decreased with age. Exercise habits in early childhood are important in the relationship between stiffness and FFM.

Transcription activity of individual rrn operons in Bacillus subtilis mutants deficient in (p)ppGpp synthetase genes, relA, yjbM, and ywaC.

In Bacillus subtilis a null mutation of the relA gene, whose gene product is involved in the synthesis and/or hydrolysis of (p)ppGpp, causes a growth defect that can be suppressed by mutation(s) of yjbM and/or ywaC coding for small (p)ppGpp synthetases. All 35 suppressor mutations newly isolated were classified into two groups, either yjbM or ywaC, by mapping and sequencing their mutations, suggesting that there are no (p)ppGpp synthetases other than RelA, YjbM, and YwaC in B. subtilis. In order to understand better the relation between RelA and rRNA synthesis, we studied in the relA mutant the transcriptional regulation of seven rRNA operons (rrnO, -A, -J, -I, -E, -D, or -B) individually after integration of a promoter- and terminatorless cat gene. We identified the transcriptional start sites of each rrn operon (a G) and found that transcription of all rrn operons from their P1 promoters was drastically reduced in the relA mutant while this was almost completely restored in the relA yjbM ywaC triple mutant. Taken together with previous results showing that the intracellular GTP concentration was reduced in the relA mutant while it was restored in the triple mutant, it seems likely that continuous (p)ppGpp synthesis by YjbM and/or YwaC at a basal level causes a decrease in the amounts of intracellular GTP.

Exercise-induced liver beta2-microglobulin expression is related to lower IgG clearance in the blood.

Voluntary wheel running exercise induced higher antigen-specific IgG in circulating blood is well recognized in mice. This antibody response may be regulated by an exercise-induced mechanism that protects against IgG catabolism. The recent hypothesis that the beta2-microglobulin gene is implicated in IgG protection is investigated further on mice voluntary wheel running. Male C57BL/6N mice were intraperitoneally immunized with 0.375microg/kg (body weight) of tetanus toxoid to induce primary and secondary antibody responses. At the peak concentration of blood tetanus toxoid specific IgG in this experiment, we administered (125)I-labeled mouse IgG. To determine how (125)I-IgG half-life is prolonged in voluntary wheel running exercised mice, we observed the tissue radioactivity (125)I-IgG. Significantly higher blood IgG concentrations were demonstrated in the exercised group compared to non-exercised group (P<.05). The mean value of radioactivity in the liver was higher in the exercised group (P<.05). Furthermore, extracted IgG concentration of exercised mouse liver was higher than that of non-exercised group (P<.05). Immunohistochemical analysis showed dramatically increased tissue IgG in the liver of the exercised group (P<.05). The gene expression of beta2-microglobulin was up-regulated in the exercised mouse liver (P<.05). There is a significant correlation between liver accumulation of (125)I-IgG and (125)I-IgG concentration in the blood (P<.05). In addition, there is a significant correlation between extracted total hepatic IgG and beta2-microglobulin in the liver (P<.05). These findings indicate that voluntary wheel running exercise-induced liver beta2-microglobulin expression is related to lower IgG clearance in the blood.

Voluntary wheel-running exercise enhances antigen-specific antibody-producing splenic B cell response and prolongs IgG half-life in the blood.

Exercise has been recognized to provoke upregulation of antibodies. However, the mechanism has not been explained. We examined the effects of voluntary wheel-running exercise on the number of cells which produce tetanus toxoid (TT)-specific IgG, as well as serum level and clearance of administered 125I-labeled mouse IgG in the blood. Male C57BL/6N mice were randomly divided into a voluntary wheel-running exercise group and a sedentary group. Mice were intraperitoneally immunized with 0.375 microg/kg of TT to induce primary and secondary anti-TT antibody responses. ELISPOT assays that identified TT-specific antibody production were performed on day 0 (Baseline, n = 8) and 22 (EX: n = 8, Non-EX: n = 8) after initial immunization (primary response) and on day 32 (EX: n = 8, Non-EX: n = 7) and 43 (EX: n = 7, Non-EX: n = 7). To explain why serum TT-specific IgG was elevated in the exercise group, we conducted an 125I-labeled mouse IgG clearance test on day 32. ELISPOT counts of secondary responses to TT immunization were significantly higher in the running group than in the sedentary group (P<0.05). The serum anti-TT specific IgG concentration was also significantly higher in the running group (P<0.05) than in the sedentary on day 32. The values of both groups were relatively lower on day 43. The (125)I-labeled mouse IgG was more rapidly cleared in the non-exercised than in the exercised group (P<0.05). These results show that voluntary wheel running upregulates the TT-specific humoral immune response. These reactions may be partly explained by the accelerated induction of TT-specific IgG-producing cells and prolonged serum IgG half-life with voluntary exercise.