High-frequency oscillations in human electromyograms during voluntary contractions

Spectral analysis was used to identify correlated sinusoidal frequency components in left and right side diaphragm electromyographic (EMG) recordings from human subjects during voluntary deep inspirations. In 31 of 33 subjects bilaterally correlated high-frequency oscillations were found in broad or narrow bands in the range of 60-84 and 16-40 Hz. To determine if such oscillations were associated also with bilaterally symmetric, phasic, voluntary activation of nonrespiratory muscles, we obtained EMG signals from left and right masseter muscles during clenching of the jaw; left and right sternomastoid muscles during lifting of the head against gravity; and left and right biceps muscles during lifting of a weighted bar. Weakly correlated frequency components, mainly at frequencies below 60 Hz, were found in the left and right masseter EMGs on at least one trial from 12 of 17 subjects. No bilaterally correlated frequency components were found during phasic contraction of biceps and sternomastoid muscles. Power spectra of biceps EMGs, however, sometimes exhibited peaks indicative of oscillations that were not bilaterally correlated. In nine subjects, correlated frequency components in the 60-84 Hz range were found in intercostal EMGs from the axillary region of the fifth interspace during voluntary deep inspirations but not during postural contractions. We conclude that high-frequency oscillations in the range of 60-84 Hz in diaphragm and intercostal EMGs are associated particularly with respiratory activation of respiratory muscles. These results support the hypothesis that high-frequency oscillations may be a manifestation of control of muscular contraction via a central pattern generator.     

Distribution patterns of vimentin-immunoreactive structures in the human prosencephalon during the second half of gestation

Neuronal migration is guided by long radially oriented glial fibres. During late stages of development radial glial cells are transformed into astrocytes. A predominant intermediate filament protein within radial glial cells and immature astrocytes is vimentin. In this study fetal brain sections were used to demonstrate the transient features of vimentin-positive radial glia. In the lower half of the cerebral wall of the 6th gestational month bundles, curvature, and crossing of vimentin-positive fibres are regularly seen. Moreover, fibres terminating on vessels are observed. In the upper half fibres are radially oriented; when ascending towards the pial surface the number and diameter of fibres appears conspicuously decreased. Radially aligned fibres display numerous varicosities. In the 8th month the bulk of vimentin-positive fibres is encountered next to the ganglionic eminence and below isocortical cerebral fissures. The dentate gyrus is conspicuous due to its high amount of immunolabelled fibres. Furthermore, densely packed fibres are visible within the internal and external capsule and in the vicinity of the anterior commissure. Radial glial somata are found in the proliferative areas as well as in the adjacent white matter. In the latter location bipolar, monopolar and stellate vimentin-positive cells are present. The results demonstrate an area-specific distribution pattern of vimentin-positive structures which can be correlated with migrational events. Areas maturing late in development for instance, reveal dense immunolabelling in the 8th month. The orientation and position of radial fibres point to an additional developmental role of these fibres, i.e. their involvement in the guidance of growing axons. Moreover, the arrangement and morphology of vimentin-positive fibres, such as retraction of fibres or occurrence of varicosities, are indicative of degenerative events. Accordingly, a transformation of radial glial somata, their displacement towards the white matter and finally the growth of stellate processes can clearly be demonstrated.     

Differential growth patterns of the abdominal aorta and vertebrae during childhood

The adult vertebral level of the splanchnic branches of the abdominal aorta relies on a complex series of fusion and regression steps during embryological development, such that variation is common. Little is known however regarding the anatomy of the abdominal aorta in children. This study aimed to investigate the spatial relationship between the abdominal aorta and the vertebral column during childhood development to inform clinical management of pediatric patients. Retrospective multislice computed tomography abdominopelvic angiograms of children aged neonate to 19 years (n = 232) were used to examine vertebral levels of the celiac trunk (CoT), superior mesenteric artery (SMA), inferior mesenteric artery (IMA), and aortic bifurcation (AB) using multiplanar formatting views in OsiriX. The abdominal aorta length, AB angle, and displacement of the aorta from the midline were quantified with the effect of age and sex analyzed using multinomial logistic regression and general linear models. The most frequent origins of CoT, SMA, IMA, and AB were T12, L1, L3, and L4, respectively, with significant variation in vertebral level for each vessel. SMA level was significantly more proximal with age, and CoT and AB demonstrated marked sex differences in vertebral level. As the age of the child increased, AB angle decreased, aortic displacement increased, and the length of the abdominal aorta increased at a slower velocity to the vertebral column (P < 0.001). Our study highlights the variation of the location and geometry of the abdominal aorta in children; this knowledge will positively impact pediatric surgical approaches and endovascular procedures. Clin. Anat. 32:783–793, 2019. © 2019 Wiley Periodicals, Inc.     

Increased Uterine NK-Derived IFN-γ, and TNF-α in C57BL/6J Mice during Early Gestation

Natural killer （NK） cells are bone marrow-derived lymphocytes. They produce cytokines that regulate the development of acquired immunity. In view of their accumulation at the maternal-fetal interface, uterine natural killer （uNK） cells are also thought to play essential roles during pregnancy. Our results compared the differences of cytokine secretion profile by NK cells in uterine endometrium, liver, spleen and peripheral blood, and focused on the cytokines secretion by uNK cells. It was demonstrated that the expression of IFN-γ and TNF-α in uterine endometrium of pregnant mice are lower than those in liver, but they increase significantly during pregnancy. Our study showed that the number of uNK cells was increased significantly during pregnancy. They produced more IFN-γ and TNF-α than other organ-derived NK cells, and they also secreted minor amount of IL-4 and IL-5. The results indicated that the IFN-γ and TNF-α produced by uNK cells ensured a successful pregnancy progress.     

Optimized analysis of surface electromyograms of the scalenes during quiet breathing in humans

Studying the inspiratory recruitment of the scalenes is clinically relevant, but the interpretation of surface electromyographic (EMG) recordings is difficult. The aim of this study was to optimize an averaging method to analyze the surface EMG activity of the scalenes. Ten healthy subjects were studied. Nasal flow and surface EMG of the right scalene were recorded during 15 min epochs of quiet breathing. In four subjects, needle scalene EMG was also recorded. The flow signal was used to trigger the ensemble averaging of the ventilatory wave forms from 80 consecutive breaths. In eight cases, this evidenced a phasic inspiratory activation of the scalenes and permitted the determination of the electromechanical inspiratory delay (134+/-55 ms) and post-inspiratory activity (811+/-233 ms). When simultaneously available, surface and intramuscular recordings provided identical results. An averaging method triggered from a respiratory flow signal can identify and characterize a low phasic inspiratory activity of the scalenes within a noisy surface signal.     

Daily changes in the blood composition of conscious pigs with catheters in foetal and uterine vessels during late gestation

1. Catheters were inserted into the foetal carotid artery and maternal middle uterine artery and vein in twenty foetuses from fifteen sows, 91-105 days pregnant. Blood samples were collected from foetal and maternal circulations for periods of 7-21 days after surgery.2. Blood gas tensions, pH, packed cell volume (PCV) and the levels of glucose, fructose and lactic acid in conscious pigs were followed in foetal and maternal bloods during late pregnancy.3. Foetal blood gas tensions, pH, PCV, lactic acid and glucose levels did not change markedly during the last 20-25 days of gestation. Blood fructose concentration fell during this period with the greatest change occurring after 100 days gestation. Foetal and maternal blood pH values were higher than those reported in the sheep, cow, mare and rhesus monkey.4. Small changes in P(CO2) and pH in foetal carotid blood were associated with similar changes in maternal uterine venous blood, so that gradients between sow and foetus remained relatively constant.5. Daily changes in maternal blood glucose levels were associated with smaller changes in foetal blood glucose and fructose levels. Blood glucose concentrations in foetal blood were generally 40-70% of maternal concentrations. Over-all relationships between maternal blood glucose and foetal blood fructose concentrations were masked by the independent fall in foetal fructose levels with age.6. The present findings have been compared with previous observations on acute, anaesthetized preparations in pigs, and chronic preparations in other domestic animals.     

Transfer patterns of integron-associated and antibiotic resistance genes in S. flexneri during different time intervals in Tianjin,China

Background: Shigella is one of the common genera of pathogens responsible for bacterial diarrhoea in humans. According to World Health Organisation (WHO), 800,000–1,700,000 patients in China were infected with Shigella spp. in 2000, and Shigella flexneri is the most common serotype (86%). Objectives: We investigated the transfer patterns of integron-associated and antibiotic resistance genes in S. flexneri during different time intervals in the city of Tianjin in the People’s Republic of China. Materials and Methods: The integrase-encoding and variable regions of the integrons of the bacterial strains were amplified by polymerase chain reaction (PCR), followed by gene sequencing. Fifty-six S. flexneri strains, 32 of which were stored in our laboratory and the other 24 were isolated from tertiary hospitals in Tianjin during different time intervals, were tested for their sensitivity to 12 antibiotics by using the Kirby–Bauer antibiotic testing method (K-B method). Results and Conclusion: Of the 32 strains of S. flexneri isolated from 1981 to 1983 and stored in our laboratory, class 1 integron was detected in 28 strains (87.50%), while 27 strains (84.37%) harboured an aminoglycoside resistance gene, aadA, in the variable region of their integrons. Class 1 integron was identified in 22 (91.67%) of the 24 S. flexneri strains isolated from 2009 to 2010, whereas the variable region and 3′-end amplification were not present in any of the strains. Class 2 integron was not found in the 1981–1983 group (group A) of strains; although 19 (79.17%) of the 24 strains in the 2009–2010 group (group B) possessed class 2 integron, and the variable region of the integron harboured dfrA1 + sat1 + aadA1 genes, which, respectively, mediate antibiotic resistance to trimethoprim, streptothricin and streptomycin. Seventeen strains of the total 56 possessed both class 1 and 2 integrons. Strains belonging to group A were highly resistant to tetracycline, chloramphenicol and a combination of trimethoprim-sulfamethoxazole; 65.63% of the strains were multi-resistant to three or more antibiotics. In group B, the strains showed high resistance to ampicillin, trimethoprim-sulfamethoxazole, piperacillin and tetracycline; 83.33% of the strains were multi-resistant to three or more antibiotics. Class 1 and 2 integrons exist extensively in S. flexneri, and the 3′-conserved segments of class 1 integron may have deletion or other types of mutations. Comparing the antibiotic and multi-drug resistance of group A with that of group B, it is apparent that the antibiotic resistance and the incidence of genes that confer multi-drug resistance have increased over the years in S. flexneri.     

Linear and non-linear analysis of surface electromyograms in weightlifters

The present research was aimed at investigating the peculiarities of surface electromyogram (sEMG) signals in 12 weightlifting athletes (WLA) and 9 control subjects (control group, CG) The sEMG signals were recorded from both vastus lateralis muscles during 20 s isometric contractions made at 30% and 60% of the maximal voluntary contraction (MVC). Ground reaction force (vertical component) was recorded using a force plate. The sEMG was analysed in the frequency domain and the median frequency (MDF) was computed over successive 1 s epochs. A non-linear technique, recurrence quantification analysis was also applied to assess the presence and time course of deterministic structures in sEMG. The percentage of determinism (%DET) was used as a synthetic parameter to quantify the amount of regularly repeating sEMG waves within the signal itself (bursts). In 5 WLA the sEMG displayed a clear burst activity centred at 11 Hz. These bursts were correlated with force output oscillations and were evident both at 30% and 60%MVC. The MDF decay with time was more evident in WLA than in CG subjects. The %DET increased in WLA, this increase being more evident during 60%MVC contractions. Our results seemed to suggest a special disposition among WLA for the development of long-term changes in firing probability during sub-maximal isometric exercise. The MDF and %DET data provided indications of a greater involvement of fast twitch muscle fibres in WLA than in CG. Electronic Publication     

Abnormal stimulation of the thyrotrophin receptor during gestation

Pregnancy induces physiological alterations in thyroid function which may make difficult the interpretation of results of thyroid hormone measurement. A state of hyperstimulation of the thyroid gland is common in early pregnancy. In a few cases, thyroid hormone values will deviate from the normal range, which corresponds to the gestational transient thyrotoxicosis. This syndrome is closely associated with hyperemesis gravidarum. The relationship between the two syndromes, demonstrated by epidemiological studies, has been illustrated by an exceptional case of familial recurrent gestational thyrotoxicosis presenting as hyperemesis gravidarum due to hypersensitivity of the thyrotrophin receptor to hCG. However, the exact mechanisms of hyperemesis gravidarum have not yet been identified. Gestational transient thyrotoxicosis has to be distinguished from Graves' disease, because the latter is associated with potential maternal and fetal complications when thyrotoxicosis is not controlled, whereas the former has usually a favourable outcome. The existence of other cases of thyroid hypersensitivity or hCG endowed with abnormal thyrotrophic activity is suspected. They may be identified only by assessment of the thyroid function in cases of hyperemesis gravidarum. The identification of these cases would be helpful to understand the mechanisms of specificity of glycoprotein hormone receptors.     

Skeletal development in fetuses of rats consuming alcohol during gestation

Sprague-Dawley female rats were fed either 20% ethanol in drinking water and rat chow ad libitum (alcohol group) or were pair-fed to the alcohol group, with starch substituted isocalorically for ethanol (pair-fed group) or were fed rat chow and tap water ad libitum. After 4 weeks they were bred and the alcohol group was changed to 30% ethanol in water. On day 20 of gestation the fetuses were removed and stained with Alcian Blue and Alizarin Red S. The skeletons were examined for the appearance of ossification centers and the ossification centers in the fore- and hindlimbs were measured. Fetuses from the alcohol group weighed significantly less than those of the two control groups. Ossification centers expected to appear in the skull on day 20 were absent in most of the alcohol group fetuses, but present in the control fetuses. There were fewer ossification centers in the sternum and in the limbs, and the ossification of vertebral centra has progressed less (both anteriorly and posteriorly) in the alcohol fetuses than in the controls. Dimensions of the ossification centers in the limbs were less in the alcohol fetuses than in the controls. No gross malformations were seen in any of the fetuses. It is concluded that by day 20 of gestation skeletal development is retarded by approximately one day in the fetuses of rats given alcohol prior to and throughout gestation.     

Comparison of visual evoked potentials to stationary and to moving patterns

Summary Human averaged visual evoked potentials (VEPs) have been recorded to the onset, reversal and offset of motion of a visual noise pattern as in the previous paper; and to the appearance and disappearance of stationary and of moving noise patterns. These VEPs have been compared.The VEPs to motion-reversal and -offset and pattern-appearance were very similar in waveform and scalp-distribution, and in inter-subject variation; and all three components of each of these VEPs reversed polarity between upper and lower half-field stimulation.Motion-onset and pattern-disappearance VEPs were similar to each other but very different from the former group of VEPs; and they did not clearly exhibit polarity reversal between the upper and lower half-fields.The pattern-appearance and -disappearance VEPs were largest for stationary patterns, and all components were steadily reduced as the stimulus velocity was increased.Previous research implies that the motion-reversal VEPs are genuine responses to changes in the motion as such. From the data presented in this and the previous paper it is concluded that the motion-offset and -onset VEPs likewise may be largely the product of motion-sensitive mechanisms when the stimulus velocity is less than about 10dg/sec.     

Morphological and immunohistochemical differentiation patterns of rabbit uterine epithelium in vitro

We describe morphological and immunohistochemical changes of uterine epithelium from immature rabbits in vitro in response to hormonal treatments, using a matrix-coated semipermeable filter. These investigations were compared to in vivo studies of uterine epithelium from immature rabbits treated with estrogen and/or progesterone. In vitro, polarization of the epithelium seems to be best developed under progesterone dominance, and the pattern of cell organelles is similar to those seen in vivo. Two types of apical protrusions could be observed in cultures treated with progesterone, some shaped like domes, containing cell organelles, and some irregular in shape with small lucent vesicles. Both types of apical differentiation are typical for the in vivo situation. In vitro, estrogen leads to a more pseudostratified growth pattern of the cells. They develop apical protrusions with big vesicles probably containing mucin, as in vivo. Treatment with both steroid hormones leads to a heterogeneous response of the uterine epithelial cells in culture, some cells responding more to the estrogen, others to the progesterone whereas in vivo the progesterone-dominant features are obvious. Immunohistochemistry of uteroglobin in monensin-treated cultures gives evidence for uteroglobin secretion in all cultures, but to a lesser extent in the untreated, and this is strongly increased in cultures treated with estrogen and progesterone. These results correspond to observations made in vivo. This in vitro cell culture method seems therefore to provide a useful model for investigating the regulatory mechanisms of sexual steroid hormones and the cell biology of uterine receptivity.     

Multi-joint coordination during walking and foothold searching in the Blaberus cockroach. I. Kinematics and electromyograms

Cockroaches were induced to walk or search for a foothold while they were tethered above a glass plate made slick with microtome oil. We combined kinematic analysis of leg joint movements with electromyographic (EMG) recordings from leg extensor muscles during tethered walking and searching to characterize these behaviors. The tethered preparation provides technical advantages for multi-joint kinematic and neural analysis. However, the behavioral relevance of the tethered preparation is an important issue. To address this issue, we evaluated the effects of tethering the animals by comparing kinematic parameters of tethered walking with similar data collected previously from cockroaches walking freely on a treadmill at the same speeds. No significant differences between tethered and treadmill walking were found for most joint kinematic parameters. In contrast, comparison of tethered walking and searching showed that the two behaviors can be distinguished by analysis of kinematics and electrical data. We combined analysis of joint kinematics and electromyograms to examine the change in multi-joint coordination during walking and searching. During searching, middle leg joints extended during swing rather than stance (i.e., walking) and the coordination of movements and extensor motor neuron activity at the coxa-trochanteral and femur tibia joints differed significantly during walking and searching. We also found that the pattern of myographic activity in the middle leg during searching was similar to that in the front legs during walking.     

An ultrasound investigation into the morphology of the human abdominal wall uncovers complex deformation patterns during contraction

The abdominal wall components, specifically muscle and connective tissue, must meet and accommodate a wide range of force demands for torso movement, spine stabilization, and respiration. It has a composite laminate nature that may lend itself to facilitating the required tissue responses. The purpose of this exploratory study was to examine the deformations of the abdominal wall connective tissues, with a special focus on both the internal oblique aponeurosis and the tendinous intersections of the rectus abdominis, using ultrasound imaging, during relatively simple contractions of the abdominal musculature. There were two main findings of this study: (1) deformations occurred in nearly 50% of contractions that would be characterized by a simultaneous expansion in multiple planes; (2) the laterally generated forces of the oblique and transverse muscles transfer a great deal of force across the rectus abdominis muscle and sheath, leading to a lateral movement of the rectus muscle during abdominal contraction.     

Effects of air ventilation during stationary exercise testing

The impact of air ventilation on performance and physiological responses during stationary exercise in the laboratory was studied. Fourteen well-trained cyclists performed three exercise tests on a cycle ergometer, each separated by a 1-week interval. The first test was a graded test to determine the power output corresponding with the 4-mmol l^–1 lactate level. Tests 2 and 3 were 30-min constant-load tests at a power output corresponding with this 4-mmol l^–1 lactate threshold. One constant-load test was performed in the absence (NAV), whilst the other was performed in the presence (AV) of air ventilation (3 m s^–1). During the constant-load tests, heart rate, tympanic temperature, blood lactate concentration and oxygen uptake (O₂) were measured at 10-min intervals and at the end of the test. Differences between the two test conditions were evaluated using paired t-tests. During NAV, 12 subjects interrupted the test due to premature exhaustion (exercise duration <30 min), versus only seven in AV (P<0.05). At the end of the test tympanic temperature was 35.9 (0.2)°C in AV and was higher in NAV [36.7 (0.2)°C, P<0.05]. Exercise heart rate increased at a faster rate during NAV [+2.2 (0.3) beats min^–1] than during AV [+1.5 (0.2) beats min^–1, P<0.05]. Blood lactate concentration and O₂ were similar between conditions. Air ventilation is essential to prevent an upward shift in the lactate:heart rate as well as the power output:heart rate relationship during laboratory exercise testing and indoor exercise training.