Time-series changes in intramuscular coherence associated with split-belt treadmill adaptation in humans.

Humans can flexibly modify their walking patterns. A split-belt treadmill has been widely used to study locomotor adaptation. Although previous studies have examined in detail the time-series changes in the spatiotemporal characteristics of walking during and after split-belt walking, it is not clear how intramuscular coherence changes during and after split-belt walking. We thus investigated the time-series changes of intramuscular coherence in the ankle dorsiflexor muscle associated with split-belt locomotor adaptation by coherence analysis using paired electromyography (EMG) signals. Twelve healthy males walked on a split-belt treadmill. Surface EMG signals were recorded from two parts of the tibialis anterior (TA) muscle in both legs to calculate intramuscular coherence. Each area of intramuscular coherence in the beta and gamma bands in the slow leg gradually decreased during split-belt walking. Significant differences in the area were observed from 7 min compared to the first minute after the start of split-belt walking. Meanwhile, the area of coherence in both beta and gamma bands in the fast leg for the first minute of normal walking following split-belt walking was significantly increased compared with normal walking before split-belt walking, and then immediately returned to the normal walking level. These results suggest that cortical involvement in TA muscle activity gradually weakens when adapting from a normal walking pattern to a new walking pattern. On the other hand, when re-adapting from the newly adapted walking pattern to the normal walking pattern, cortical involvement might strengthen temporally and then weaken quickly.

Characterization of Actinobacillus pleuropneumoniae field strains antigenically related to the 3-6-8-15 group from diseased pigs in Japan and Argentina.

The objectives of this study were to determine the serovar of a collection of Actinobacillus pleuropneumoniae strains within the 3-6-8-15 cross-reacting group and to analyze their phenotypic and genetic properties. Based on the serological tests, forty-seven field strains of Actinobacillus pleuropneumoniae isolated from lungs with pleuropneumonia lesions in Japan and Argentina were found to be serovars belonging to the 3-6-8-15 cross-reacting group. By using a capsule loci-based PCR, twenty-nine (96.7%) and one (3.3%) from Japan were identified as serovars 15 and 8, respectively, whereas seventeen (100%) from Argentina were identified as serovar 8. The findings suggested that serovars 8 and 15 were prevalent within the 3-6-8-15 cross-reacting group, in Argentina and Japan, respectively. Phenotypic analyses revealed that the protein patterns observed on SDS-PAGE and the lipopolysaccharide antigen detected by immunoblotting of the reference and field strains of serovars 8 and 15 were similar to each other. Genetic (16S rDNA, apxIIA, apxIIIA, cps, cpx genes, apx and omlA patterns) analyses revealed that the apxIIA and apxIIIA genes of the field strains of serovars 8 and 15 were similar to those of the reference strains of serovars 3, 4, 6, 8 and 15. The results obtained in the present study may be useful for the development of more effective vaccines against disease caused by A. pleuropneumoniae by including the homologous antigens to the most prevalent serovars in specific geographical areas.

Genetic and antigenic characteristics of ApxIIA and ApxIIIA from Actinobacillus pleuropneumoniae serovars 2, 3, 4, 6, 8 and 15.

Apx toxins produced by Actinobacillus pleuropneumoniae are essential components of new generation vaccines. In this study, apxIIA and apxIIIA genes of serovars 2, 3, 4, 6, 8 and 15 were cloned and sequenced. Amino acid sequences of ApxIIA proteins of serovars 2, 3, 4, 6, 8 and 15 were almost identical to those of serovars 1, 5, 7, 9 and 11-13. Immunoblot analysis showed that rApxIIA from serovars 2 and 15 reacts strongly with sera from animals infected with various serovars. Sequence analysis revealed that ApxIIIA proteins has two variants, one in strains of serovar 2 and the other in strains of serovars 3, 4, 6, 8 and 15. A mouse cross-protection study showed that mice actively immunized with rApxIIIA/2 or rApxIIIA/15 are protected against challenge with A. pleuropneumoniae strains of serovars 3, 4, 6, 8, 15, and 2 expressing ApxIII/15 and ApxIII/2, respectively. Similarly, mice passively immunized with rabbit anti-rApxIIIA/2 or anti-rApxIIIA/15 sera were found to be protected against challenge with strains of serovars 2 and 15. Our study revealed antigenic and sequence similarities within ApxIIA and ApxIIIA proteins, which may help in the development of effective vaccines against disease caused by A. pleuropneumoniae.

Acute and subchronic toxicity of 20 kHz and 60 kHz magnetic fields in rats.

Despite increasing use of intermediate frequency (IF) magnetic fields (MFs) in occupational and domestic settings, scientific evidence necessary for health risk assessments of IF MF is insufficient. Male and female Crl:CD(SD) rats (12 per sex per group) were exposed to 20 kHz, 0.20 mT(root mean square, rms) or 60 kHz, 0.10 mT(rms) sinusoidal MFs for 22 h day(-1) for 14 days (acute) or 13 weeks (subchronic). Experiments were duplicated for each frequency to ensure outcome reproducibility, and examinations were blinded for quality assurance. All rats survived without significant clinical signs until the end of experiments. Some changes in body weight between the MF-exposed and control groups were observed over the course of exposure, although the directions of the changes were inconsistent and not statistically significant after subchronic exposure. There were significant differences between MF-exposed and control groups in some organ weights and parameters in hematology and clinical chemistry, but these were minor in magnitude and not repeated in duplicate experiments. Histopathological findings reflecting toxicity were sporadic. Frequencies of other findings were similar to historic data in this rat strain, and findings had no specific relationship to changes in organ weight or parameters of hematology and clinical chemistry in each animal. The changes observed throughout this study were considered biologically isolated and were attributable to chance associations rather than to MF exposure. The results, in particular the histopathological evidence, indicate an absence of toxicity in IF MF-exposed rats and do not support the hypothesis that IF MF exposure produces significant toxicity.

Corticospinal excitability during observation of basketball free-throw movement: Effects of video playback speed and stimulus timing.

Transcranial magnetic stimulation studies have indicated that action observation (AO) modulates corticospinal excitability. Although a few previous studies have shown that the AO of simple motor movements at a slow playback speed facilitates corticospinal excitability more than that at normal playback speed, it is unclear if this effect occurs during the AO of sport-related complex movements. Therefore, we investigated the changes in the motor evoked potential (MEP) amplitudes of the flexor carpi radialis (FCR) and abductor digiti minimi (ADM) muscles during the AO of a basketball free-throw movement at three different playback speeds (100%, 75%, and 50% speeds). Additionally, we evaluated the effects of stimulus timing (holding the ball vs. releasing the ball for shooting) and motor expertise (expert basketball players vs. novices) on the MEP amplitude during the AO. Our results demonstrated that regardless of motor expertise, the MEP amplitude of the FCR muscle was significantly smaller in the 50% speed condition than in the 100% condition. In the ADM muscle, the MEP amplitude was significantly larger when the ball was held after dribbling than when the ball was released. Therefore, it is suggested that corticospinal excitability in specific muscles during the observation of complex whole-body movements is influenced by video playback speed and stimulus timing.

Potential Ketoacidosis Linked to Imeglimin and Metformin Co-administration in a Patient With Type 2 Diabetes.

A 74-year-old woman with type 2 diabetes mellitus developed ketoacidosis within six days of adding metformin to imeglimin treatment. The patient was insulin-sensitive and showed preserved insulin secretion; therefore, insulin insufficiency alone was unlikely to contribute to the development of ketoacidosis. Both imeglimin and metformin partially inhibit complex I in the mitochondrial respiratory chain. Inhibition of mitochondrial respiration can lead to tricarboxylic acid (TCA) cycle suppression. Thus, the entry of acetyl-coenzyme A into TCA cycle is restricted, and it is eventually used in ketogenesis. Therefore, the combination of imeglimin and metformin might have precipitated the development of ketoacidosis.

Metformin-associated Lactic Acidosis Induced by Excessive Alcohol Consumption.

A 65-year-old man with type 2 diabetes who was being treated with metformin developed lactic acidosis following excessive alcohol consumption. While an impaired renal function is a major risk factor for metformin-associated lactic acidosis (MALA), the patient's basal renal function was normal. Alcohol misuse reduces lactate clearance by utilizing nicotinamide adenine dinucleotides for ethanol oxidation, thereby promoting vulnerability to MALA. Nevertheless, as MALA in individuals with a normal renal function is extremely rare, the clinical picture of alcohol-induced MALA is unclear. We delineate the clinical picture and discuss the pathogenesis of alcohol-induced MALA based on our experience and previous case reports.

Absence of reproductive and developmental toxicity in rats following exposure to a 20-kHz or 60-kHz magnetic field.

The use of intermediate frequency (IF) magnetic fields (MFs) in occupational equipment and domestic appliances, such as inductive heating cookers, is increasing. The WHO indicated a lack of scientific evidence needed to assess the health risk of exposure to IF MFs. Male and female rats (24/group) were exposed to a 20 kHz, 0.2 mT(rms) or 60 kHz, 0.1 mT(rms) sinusoidal MF for 22 h/day from 14 days prior to and during mating. Copulated females were exposed until gestation day 7 and sacrificed thereafter. Mated males were sacrificed to examine MF exposure effects on spermatogenesis. Reproductive examinations were blinded, and experiments were duplicated per frequency to ensure reproducibility. No statistically significant, exposure-related changes were found in the estrous cycle, copulation and fertility indices, numbers of corpora lutea and implantation sites, or pre- and postimplantation loss. No reproducible changes were observed in sperm count, motility, or morphological abnormality, or in the weights of testes and epididymides after MF exposure. No significant abnormalities were observed in gross pathology or histopathology of the uterus, ovary, testis, and epididymis in the MF- or sham-exposed groups. MF exposure during the preimplantation period was not toxic to fertility or early embryogenesis under the experimental conditions.

Modulation of Muscle Synergies in Lower-Limb Muscles Associated With Split-Belt Locomotor Adaptation.

Humans have great locomotor adaptability to environmental demands, which has been investigated using a split-belt treadmill with belts on both the left and right sides. Thus far, neuromuscular control in split-belt locomotor adaptation has been evaluated by analyzing muscle activities at the individual muscle level. Meanwhile, in the motor control field, the muscle synergy concept has been proposed. Muscle synergies are considered the fundamental building blocks of movement and are groups of coactive muscles and time-varying activation patterns, thereby, reflecting the neurophysiological characteristics of movement. To date, it remains unclear how such muscle synergies change during the adaptation and de-adaptation processes on the split-belt treadmill. Hence, we chronologically extracted muscle synergies while walking on the split-belt treadmill and examined changes in the number, muscle weightings, and temporal activation patterns of muscle synergies. Twelve healthy young males participated, and surface electromyography (EMG) signals were recorded bilaterally from 13 lower-limb muscles. Muscle synergies were extracted by applying non-negative matrix factorization to the EMG data of each leg. We found that during split-belt walking, the number of synergies in the slow leg increased while an extra synergy appeared and disappeared in the fast leg. Additionally, the areas under the temporal activation patterns in several synergies in both legs decreased. When both belts returned to the same speed, a decrease in the number of synergies and an increase in the areas under the temporal activation patterns of several synergies were temporally shown in each leg. Subsequently, the number of synergies and the areas under the temporal activation patterns returned to those of normal walking before split-belt walking. Thus, changes in the number, muscle weightings, and temporal activation patterns of synergies were noted in the split-belt locomotor adaptation, suggesting that the adaptation and de-adaptation occurred at the muscle synergy level.

Lack of teratological effects in rats exposed to 20 or 60 kHz magnetic fields.

BACKGROUND: A risk assessment of magnetic field (MF) exposure conducted by the World Health Organization indicated the need for biological studies on primary hazard identification and quantitative risk evaluation of intermediate frequency (300 Hz-100 kHz) MFs. Because induction heating cookers generate such MFs for cooking, reproductive and developmental effects are a concern due to the close proximity of the fields' source to a cook's abdomen. METHODS: Pregnant Crl:CD(SD) rats (25/group) were exposed to a 20 kHz, 0.2 mT(rms) or 60 kHz, 0.1 mT(rms) sinusoidal MF or sham-exposed for 22 hr/day during organogenesis, and their fetuses were examined for malformations on gestation day 20. All teratological evaluations were conducted in a blind fashion, and experiments were duplicated for each frequency to confirm consistency of experimental outcomes. RESULTS: No exposure-related changes were found in clinical signs, gross pathology, or number of implantation losses. The number of live fetuses and low-body-weight fetuses as well as the incidence of external, visceral, and skeletal malformations in the fetuses did not indicate significant differences between MF-exposed and sham-exposed groups. Although some fetuses showed isolated changes in sex ratio and skeletal variation and ossification, such changes were neither reproduced in duplicate experiments nor were they common to specific field frequencies. CONCLUSIONS: Exposure of rats to MFs during organogenesis did not show significant reproducible teratogenicity under experimental conditions. Present findings do not support the hypothesis that intermediate frequency MF exposure after implantation carries a significant risk for developing mammalian fetuses.

Characterization of Actinobacillus pleuropneumoniae field strains antigenically related to the 3-6-8-15 group from diseased pigs in Japan and Argentina / Caracterización de cepas de Actinobacillus pleuropneumoniae antigénicamente relacionados al grupo 3-6-8-15 obtenidos de cerdos infectados naturalmente en Japón y Argentina

The objectives of this study were to determine the serovar of a collection of Actinobacillus pleuropneumoniae strains within the 3-6-8-15 cross-reacting group and to analyze their phenotypic and genetic properties. Based on the serological tests, forty-seven field strains of Actinobacillus pleuropneumoniae isolated from lungs with pleuropneumonia lesions in Japan and Argentina were found to be serovars belonging to the 3-6-8-15 cross-reacting group. By using a capsule loci-based PCR, twenty-nine (96.7%) and one (3.3%) from Japan were identified as serovars 15 and 8, respectively, whereas seventeen (100%) from Argentina were identified as serovar 8. The findings suggested that serovars 8 and 15 were prevalent within the 3-6-8-15 cross-reacting group, in Argentina and Japan, respectively. Phenotypic analyses revealed that the protein patterns observed on SDS-PAGE and the lipopolysaccharide antigen detected by immunoblotting of the reference and field strains of serovars 8 and 15 were similar to each other. Genetic (16S rDNA, apxIIA, apxIIIA, cps, cpx genes, apx and omlA patterns) analyses revealed that the apxIIA and apxIIIA genes of the field strains of serovars 8 and 15 were similar to those of the reference strains of serovars 3, 4, 6, 8 and 15. The results obtained in the present study may be useful for the development of more effective vaccines against disease caused by A. pleuropneumoniae by including the homologous antigens to the most prevalent serovars in specific geographical areas.

Los objetivos del presente estudio fueron determinar el serovar de una colección de cepas de Actinobacillus pleuropneumoniae pertenecientes al grupo 3, 6, 8, 15 de reacciones cruzadas y analizar sus propiedades fenotípicas y genéticas. En base a técnicas serológicas se determinó que cuarenta y siete cepas de A. pleuropneumoniae aisladas a partir de pulmones con lesiones de pleuroneumonía en Japón y Argentina pertenecen al grupo 3, 6, 8, 15. Mediante el uso de PCR basado en locus capsulares, veintinueve (96.7%) y una (3.3%) de los aislados japoneses fueron identificados como serovar 15 y 8 respectivamente, mientras que diecisiete (100%) de los aislados argentinos resultaron pertenecer al serotipo 8. Este hallazgo sugirió que los serovares 8 y 15 fueron los prevalentes dentro del grupo 3, 6, 8, 15 en Japón y Argentina, respectivamente. El análisis fenotípico reveló que los perfiles proteicos determinados por SDS-PAGE, y de antígenos lipopolisacáridos estudiados por inmunoblot, de las cepas de referencia y de campo de los serovares 8 y 15 fueron similares entre sí. El análisis genético (Í6S rDNA, apxIIA, apxIIA, cps, genes cpx, apx y los perfiles omlA) reveló que los genes apxIIA y apxIIIA de las cepas de campo de los serovares 8 y 15 fueron similares a sus homólogos de las cepas de referencia de los serovares 3, 4, 6, 8 y 15. Los resultados obtenidos en el presente estudio pueden ser útiles para el desarrollo de vacunas más efectivas contra la enfermedad causada por A. pleuropneumoniae, al posibilitar incluir antígenos homólogos a los serovares prevalentes en las áreas geográficas de interés.

In ovo exposure to nonylphenol and bisphenol A resulted in dose-independent feminization of male gonads in Japanese quail (Coturnix japonica) embryos.

Sex reversal effects of nonylphenol and bisphenol A on the gonads in F(1) (AWE × WE) Japanese quail (Coturnix japonica) embryos were investigated using an in vivo screening model developed previously. The F(1) (AWE × WE) Japanese quail are a useful avian model because sex differentiation is confirmed by the plumage color before hatching, ruled by a criss-cross inheritance. The nonylphenol at 200, 2,000, 20,000, and 200,000 ng/egg and bisphenol A at 20, 200, 2,000, and 20,000 ng/egg were injected into the egg white just before incubation. At 16 d of incubation, embryos were subjected to a complete necropsy, and their gonads were both grossly observed and examined histopathologically and morphometrically. Grossly, genetic sex was confirmed because plumage color coincided completely with the external sex phenotype of the gonads in all embryos. Histopathologically, feminization of the male gonad, called ovotestis, developed in the left testis in all nonylphenol- and bisphenol A-treated groups. The incidence of the lesion in all treated groups was significantly higher than that in the control group, whereas there were no dose-dependent changes in the incidence and area of the ovotestis in both nonylphenol- and bisphenol A-treated groups. The present study revealed that nonylphenol and bisphenol A have a dose-independent potential of ovotestis induction in the Japanese quail embryo.

Endocrine disrupting effects of low dose 17 ß-estradiol (E2) on the Japanese quail (Coturnix japonica) were detected by modified one-generation reproduction study.

Previously, we investigated endocrine disrupting effects of 17 ß-estradiol (E(2)) on Japanese quail (Coturnix japonica) in the avian reproduction test according to the testing guidelines, in which new endpoints such as blood vitellogenin (VTG) concentration in parent quails and pathology of F(1) chicks were added, and consequently these additional endpoints suggested to be sensitive markers for detecting any impacts of endocrine disrupting effects (Shibuya et al., 2005b). In the present study, to investigate low dose effects of estrogenic endocrine disrupting chemicals in birds, the avian reproduction study of E(2) at low dose levels was conducted using Japanese quail with additional endpoints such as observations of F(1) chicks until 10 weeks of age, histopathology of F(1) chicks at 14 days and 10 weeks of age and blood VTG concentration in parent quails. Sixteen pairs of 10-week-old quails were fed a low phytoestrogen diet containing E(2) at 0 (control), 0.3, 3, and 30 ppm for 6 weeks, and parent quails, eggs and offspring were examined. F(1) chicks were maintained up to 14 days or 10 weeks of age. Serum E(2) and VTG concentrations in males of the E(2) 3- and 30-ppm groups and in females of the E(2) 30-ppm groups were significantly elevated. In the E(2) 30-ppm group, two parent females died, and toxic changes such as suppression of body weight gain, decrease in food consumption and atrophic and degenerative changes of the reproductive organs were observed in parent quails. In the same group, the number of eggs laid and the fertility rate of eggs were significantly decreased. In addition, the viability of F(1) chicks in the E(2) 30-ppm group were significantly decreased at 10 weeks of age. On the other hand, no abnormalities described above were observed in any parent quails, eggs and F(1) chicks in the E(2) 3- and 0.3-ppm groups, although the fertility rates of eggs in both groups were decreased and the body weight gain of F(1) females in the E(2) 3-ppm group was significantly suppressed. In the histopathological examination of F(1) chicks maintained up to 10 weeks of age, persistent right oviduct and atrophy of the oviduct gland were observed in females of E(2)-treatment groups with significantly high incidences. Moreover, cystic dilatation and tubular degeneration of the seminiferous tubules and atrophy of the cloacal gland were also observed in males of the E(2)-treatment groups. Thus, the dietary treatment of low dose E(2) (even 0.3 ppm) to parent quails resulted in decreased viability and induction of abnormalities in the oviduct, testis and cloacal gland in F(1) chicks maintained up to 10 weeks of age. These results suggest that additional endpoints such as observations of F(1) chicks until 10 weeks of age, histopathology of F(1) chicks at 14 days and 10 weeks of age and blood VTG concentration in parent quails would be useful and sensitive endpoints for evaluating estrogenic endocrine disrupting effects in the avian reproduction study.