Acute onset of constrictive pericarditis due to acute myelomonocytic leukemia: A case and literature review.

We herein present a fatal case of constrictive pericarditis (CP) due to acute myelomonocytic leukemia (AMML) in a patient who initially complained of an acute onset of chest pain two days after COVID-19 vaccination. An autopsy revealed pericardial infiltration of leukemic cells. CP is rarely associated with leukemia and only 14 cases have been reported in the literature. The etiology of CP in previous reports included leukemic infiltration, graft-versus-host disease, drug-induced, post-radiation, autoimmune, and otherwise unidentified. This case indicates that leukemic infiltration can cause CP and that clinicians should include leukemia in the differential diagnosis of CP.

Analysis of Financial Factors Which Driving the Operating Margins of 880 Public Hospitals in Japan Using a Business Intelligence System.

Management improvement was strongly required at public hospital and Local Incorporated Administrative Agency hospitals in Japan. We analysed financial statements of 880 public hospitals using Business Intelligence System. In order to raise the efficiency of management, it is important to have patients with a high profitability (seriously ill patients) at municipal hospitals; whereas, in Local Incorporated Administrative Agency hospitals, avoiding producing ordinary losses and not incurring excessive expenses will be important for management improvement.

Relationship between medial gastrocnemius muscle stiffness and the angle between the rearfoot and floor.

The present study examined the stiffness in the medial gastrocnemius muscle at various angles between the rearfoot and the floor. Six healthy young men participated in the study. A triangle support was attached to the force plate. Each participant placed their forefoot and rearfoot onto the force plate and the triangle support, respectively. Electrical stimulation was applied to the medial gastrocnemius muscle using Ag-AgCl surface electrodes. The center of pressure was measured with the force plate, and electrically-induced fluctuation of the center of pressure was extracted using a Kalman filter. Measurements were performed at 10°, 20°, and 30°angles of the triangle support. The transfer function from the stimulation to the fluctuation was identified, and the poles of the transfer function were used to estimate the medial gastrocnemius muscle and ankle stiffness. The muscle stiffness increased as the angle of the triangle support increased.

Estimation of tibialis anterior muscle stiffness during the swing phase of walking with various footwear.

The current study examined stiffness in the tibialis anterior muscle during the swing phase of walking while wearing various footwear. Seven healthy young men participated in this study. Participants were instructed to walk on a treadmill at 3 km/h while wearing sports shoes, slippers, or slippers with belts. The common peroneal nerve was electrically stimulated every two steps at toe-off during walking. Mechanomyograms (MMGs), electromyograms, and ankle angle were measured. Evoked MMG was extracted using a Kalman filter and subtraction of walking acceleration. The transfer function from the electrical stimulation to the evoked MMG was identified using a singular value decomposition method, and the natural frequency of the transfer function was calculated as an index of muscle stiffness. The natural frequency did not show a clear relationship with footwear type. Four participants showed the lowest natural frequency when they wore slippers with belts. The remaining subjects showed the lowest natural frequency when they wore slippers or shoes. These contrasting findings may have been caused by different degrees of adaptation of participants to the footwear.

System identification of velocity mechanomyogram measured with a capacitor microphone for muscle stiffness estimation.

A mechanomyogram (MMG) measured with a displacement sensor (displacement MMG) can provide a better estimation of longitudinal muscle stiffness than that measured with an acceleration sensor (acceleration MMG), but the displacement MMG cannot provide transverse muscle stiffness. We propose a method to estimate both longitudinal and transverse muscle stiffness from a velocity MMG using a system identification technique. The aims of this study are to show the advantages of the proposed method. The velocity MMG was measured using a capacitor microphone and a differential circuit, and the MMG, evoked by electrical stimulation, of the tibialis anterior muscle was measured five times in seven healthy young male volunteers. The evoked MMG system was identified using the singular value decomposition method and was approximated with a fourth-order model, which provides two undamped natural frequencies corresponding to the longitudinal and transverse muscle stiffness. The fluctuation of the undamped natural frequencies estimated from the velocity MMG was significantly smaller than that from the acceleration MMG. There was no significant difference between the fluctuations of the undamped natural frequencies estimated from the velocity MMG and that from the displacement MMG. The proposed method using the velocity MMG is thus more advantageous for muscle stiffness estimation.

Muscle stiffness estimation using a system identification technique applied to evoked mechanomyogram during cycling exercise.

The aims of this study were to develop a method to extract the evoked mechanomyogram (MMG) during cycling exercise and to clarify muscle stiffness at various cadences, workloads, and power. Ten young healthy male participants were instructed to pedal a cycle ergometer at cadences of 40 and 60 rpm. The loads were 4.9, 9.8, 14.7, and 19.6 N, respectively. One electrical stimulus per two pedal rotations was applied to the vastus lateralis muscle at a knee angle of 80° in the down phase. MMGs were measured using a capacitor microphone, and the MMGs were divided into stimulated and non-stimulated sequences. Each sequence was synchronously averaged. The synchronously averaged non-stimulated MMG was subtracted from the synchronously averaged stimulated MMG to extract an evoked MMG. The evoked MMG system was identified and the poles of the transfer function were calculated. The poles and mass of the vastus lateralis muscle were used to estimate muscle stiffness. Results showed that muscle stiffness was 186-626 N /m and proportional to the workloads and power. In conclusion, our method can be used to assess muscle stiffness proportional to the workload and power.

Systemes analysis of interactions between microRNAs and genes in hepatocellular carcinoma.

MicroRNAs (miRNAs) are short noncoding RNAs and can regulate gene expression at the transcriptional and/or translational levels. There is mounting evidence that miRNAs play an important role in the control of the dynamics of localized gene expression. Expression profiling of miRNA in various cancers revealed that miRNA profiles could discriminate malignancies from their counter parts. In this study, to investigate the localized effect of miRNA in cancer, we analyzed gene and miRNA expressions in hepatocellular carcinoma (HCC) and surrounding nontumor tissues. Based on gene expression levels around miRNAs, we investigated how many miRNAs correlated positively/negatively in expression with genes in the vicinity. Next, the Pearson correlation coefficients were compared between the HCC and nontumor tissues. The results imply that the relationship between the intronic miRNAs and their host genes was altered in HCC, and that feedback loops including the host gene, intronic miRNA, target genes might be formed in HCC.

System identification of evoked mechanomyogram from abductor pollicis brevis muscle in isometric contraction.

The purpose of this study is to verify the applicability of a sixth-order model to the mechanomyogram (MMG) system of the parallel-fibered muscle, which was identified from the MMG of the pennation muscle. The median nerve was stimulated, and an MMG and torque of the abductor pollicis brevis muscle were measured. The MMGs were detected with either a capacitor microphone or an acceleration sensor. The transfer functions between stimulation and the MMG and between stimulation and torque were identified by the singular value decomposition method. The torque and the MMG, which were detected with a capacitor microphone, DMMG, were approximated with a second- and a third-order model, respectively. The natural frequency of the torque, reflecting longitudinal mechanical characteristics, did not show a significant difference from that of the DMMG. The MMG detected with an acceleration sensor was approximated with a fourth-order model. The natural frequencies of the AMMG reflecting the muscle and subcutaneous tissue in the transverse direction were obtained. Both DMMG and AMMG have to be measured to investigate the model of the MMG system for parallel-fibered muscle. The MMG system of parallel-fibered muscle was also modeled with a sixth-order model.

Comparison of displacement and acceleration transducers for the characterization of mechanics of muscle and subcutaneous tissues by system identification of a mechanomyogram.

The purpose of this study was to clarify the performance of transducers for the mechanical characterization of muscle and subcutaneous tissue with the aid of a system identification technique. The common peroneal nerve was stimulated, and a mechanomyogram (MMG) of the anterior tibialis muscle was detected with a laser displacement meter or an acceleration sensor. The transfer function between stimulation and the MMG was identified by the singular value decomposition method. The MMG detected with a laser displacement meter, DMMG, was approximated with a second-order model, but that detected with an acceleration sensor, AMMG, was approximated with a sixth-order model. The natural frequency of the DMMG coincided with that in the literature and was close to the lowest natural frequency of the AMMG. The highest natural frequency of the AMMG was within the range of the resonance frequencies of human soft tissue. The laser displacement meter is suitable for the precise identification of the MMG, which has a natural frequency of around 3 Hz. The acceleration transducer is suitable for the identification of the MMG with natural frequencies of tens of hertz.

Association of muscle hardness with muscle tension dynamics: a physiological property.

This study aimed to investigate the relationship between muscle hardness and muscle tension in terms of length-tension relationship. A frog gastrocnemius muscle sample was horizontally mounted on the base plate inside a chamber and was stretched from 100 to 150% of the pre-length, in 5% increments. After each step of muscle lengthening, electrical field stimulation for induction of tetanus was applied using platinum-plate electrodes positioned on either side of the muscle submerged in Ringer's solution. The measurement of muscle hardness, i.e., applying perpendicular distortion, was performed whilst maintaining the plateau of passive and tetanic tension. The relationship between normalised tension and normalised muscle hardness was evaluated. The length-hardness diagram could be created from the modification with the length-tension diagram. It is noteworthy that muscle hardness was proportional to passive and total tension. Regression analysis revealed a significant correlation between muscle hardness and passive and total tension, with a significant positive slope (passive tension: r = 0.986, P < 0.001; total tension: r = 0.856, P < 0.001). In conclusion, our results suggest that muscle hardness depends on muscle tension in most ranges of muscle length in the length-tension diagram.

System identification of the mechanomyogram from single motor units during voluntary isometric contraction.

A mechanomyogram (MMG) from single motor units of the anconeus muscle in voluntary isometric contraction was recorded from seven subjects using a spike-triggered averaging technique. The MMG system, in which the input was an ideal impulse and the output was the MMG detected with an acceleration sensor, was identified as the fifth-order model by the subspace-based state-space model identification method. The transfer function of the MMG system was factorized to the second- and the first-order models. The second-order model was compared to the standard form of the second-order model, and its resonance frequency was calculated. The resonance frequencies of the second-order models were 166 ± 61 and 93 ± 27 Hz, which were within the range of the values estimated from mechanical impedance in the literature. The equivalent mechanical model of the MMG system of the single motor unit was proposed on the basis of the fifth-order model. The model might be useful to evaluate the visco-elastic properties of the anconeus muscle.

System identification of mechanomyograms detected with an acceleration sensor and a laser displacement meter.

The purpose of this study is to investigate the transfer functions of mechanomyograms (MMGs) detected with an acceleration sensor and a laser displacement meter. The MMGs evoked by electrical stimulation to the peroneal nerve were recorded on the skin of the tibial anterior muscle. The displacement MMG (DMMG) and the acceleration MMG (AMMG) systems were identified using a singular value decomposition method. The appropriate order of the AMMG system was six and that of the DMMG system was four. The undamped natural frequencies of the systems were compared to resonance frequencies of human soft tissue. Some of the undamped natural frequencies estimated from the AMMG systems agreed with the resonance frequencies in the literature but others were lower than the resonance frequencies. The undamped natural frequencies estimated from the DMMG systems were lower than the resonance frequencies.

System identification of mechanomyogram evoked by common peroneal nerve stimulation.

In the quantitative assessment of a system, a description of the low-order transfer function model is important. The objective of this study was to identify the system of a mechanomyogram (MMG) with SubSpace-based State Space model IDentification (4SID). The input data consisted of the electrical stimulation of the common peroneal nerve, which made the anterior tibial muscle contract. The output data consisted of the evoked MMG. We applied Fourier transform to the MMG signal and obtained a power spectrum. The 10th-order model was estimated by the 4SID method. It was suggested that the frequency band separation of the power spectrum reflected the types of recruited muscle fiber. The results suggest that the MMG is a linear system which can be estimated in the lower-order transfer function model by applying the 4SID to each frequency band.

Relationship between muscle tension and hardness in isolated frog muscle with electrical stimulation.

Muscle hardness increases as the contractile level increases. This increase is caused by changes in structure of the muscle fiber and blood flow; however, the mechanism of increasing hardness has not been clearly demonstrated. The objective of this study was to investigate the relationship between isolated frog muscle tension and hardness. Gastrocnemius muscles were mounted horizontally in a chamber. The femur was fixed, and the Achilles tendon was attached to a stretching device. The muscle tension and hardness were measured during various muscle stretches and with and without electrical stimulation. We applied two protocols. In the first, the muscle was stimulated and then stretched, whereas, in the second, it was stretched and then stimulated. The muscle hardness was proportional to the muscle tension at each amount of stretching in both protocols. There were no significant differences between protocols 1 and 2, although the stretch enhancement of the muscle force was expected in protocol 1. In our experiments, the muscle length corresponds to the ascending limb of the length-tension curves of a sarcomere. The results of this study suggest that the relationship between muscle tension and hardness was not affected by the stretch enhancement in the ascending limb of the length-tension curve. The slope of the regression line between the muscle tension and hardness decreased as the amount of the stretch increased. The decrease of the slope might be caused by structural changes in the filaments.

Effects of spinal recurrent inhibition on motoneuron short-term synchronization.

Spinal recurrent inhibition linking skeleto- motoneurons (alpha-MNs) via Renshaw cells (RCs) has been variously proposed to increase or decrease tendencies toward synchronous discharges between alpha-MNs. This controversy is not easy to settle experimentally in animal or human paradigms because RCs receive, in addition to excitatory input from alpha-MNs, many other modulating influences which may change their mode of operation. Computer simulations help to artificially isolate the recurrent inhibitory circuit and thus to study its effects on alpha-MN synchronization under conditions not achievable in natural experiments. We present here such a study which was designed to specifically test the following hypothesis. Since many alpha-MNs excite any particular Renshaw cell, which in turn inhibits many alpha-MNs, this convergence-divergence pattern establishes a random network whose random discharge patterns inject uncorrelated noise into alpha-MNs, and this noise counteracts any synchronization potentially arising from other sources, e.g., common inputs (Adam et al. in Biol Cybern 29:229-235, 1978). We investigated the short-term synchronization of alpha-MNs with two types of excitatory input signals to alpha-MNs (random and sinusoidally modulated random patterns). The main results showed that, while recurrent inhibitory inputs to different alpha-MNs were indeed different, recurrent inhibition (1) exerted rather small effects on the modulation of alpha-MN discharge, (2) tended to increase the short-term synchronization of alpha-MN discharge, and (3) did not generate secondary peaks in alpha-MN-alpha-MN cross-correlograms associated with alpha-MN rhythmicity.

Evaluation of spasticity in the ankle of a hemiplegic subject using a step-like response.

The objective of this study is to propose a new indices to evaluate spasticity in the ankle joint of hemiplegic patients. Each subject sat on a bed with one foot supported with a jig, which was used to measure the response of the ankle joint angle. The subject was instructed to relax and not to generate voluntary force. A step-like load was applied to dorsiflex the ankle joint. The ankle joint angle and electromyograms of the soleus and tibialis anterior muscle were recorded. First, the step-like response was approximated with a mathematical model, which is based on musculoskeletal and physiological characteristics using the least squares method in order to estimate net inertia and the elastic and viscous coefficients of the foot. The torque generated by the elastic component was then estimated. The normalized elastic torque was approximated with a dumped sinusoid using the least squares method. The time constant and frequency of the normalized elastic torque were calculated. We propose two indices estimated from the relationships between the time constant and the frequency. One of the indices reflected the step-like load dependency. The other reflected the difference from healthy subjects. Both indices increased as the Ashworth scale increased.

Quantitative evaluation of spasticity in upper limbs in hemiplegic subject using a mathmatical model.

This is a proposal for a new technique for evaluating spasticity in the upper limbs of hemiplegic patients. Each subject sat on a chair or stood up, and his or her forearm was extended or flexed by a physician. The subject was instructed to relax. The elbow joint angle, torque, and electromyograms (EMGs) of the biceps brachii, triceps brachii, and brachioradialis muscles were measured. The relationship between the elbow joint angle and torque was approximated with a mathematical model, which consisted of elastic components depending on both muscle activities and elbow joint angle, by the least squares method. The inertia and visco-elastic coefficients were obtained. The elbow angle response was then estimated with the obtained inertia and visco-elastic coefficients by the Runge-Kutta method, and the estimated elbow angle was compared to the observed one. The relationships between the elbow angle and torque were approximated well with the model. Next, the average elasticity was calculated and compared to the modified Ashworth scale. The average elasticity had a tendency to increase as the Ash- worth scale increased. In addition, the average elasticity varied depending on the posture of the subjects.

Relationship between muscle hardness estimated by the indentation method and muscle contractile level.

The purpose of this study was to investigate the relationship between muscle contractile level and hardness by the indentation method. Eleven healthy male subjects were involved in this study. The subjects put their arms horizontally on a table. The subjects were instructed to keep the isometric contractile force constant at three elbow angles. The indentation depth and reaction force of the biceps brachii muscle were measured, and electromyogram (EMG) were done. First, EMGs before and during the indentation were compared. The EMGs showed no significant increase during the indentation. The indentation did not affect muscle activities. Next, the force indentation depth curves were approximated with the non-linear Voigt model by the least square method, and the indices of the elasticity and the viscosity were estimated. Then the relationship between the indices and the contractile levels were investigated. The contractile level was the force normalized by that in the maximum voluntary contraction. The elastic indices increased almost linearly as the contractile levels increased. The relationships at different elbow angles did not show significant differences. However, the characteristics of the viscous indices varied depending on the subjects.

Static and dynamic input-output relations of the feline medial gastrocnemius motoneuron-muscle system subjected to recurrent inhibition: a model study.

The physiological function of spinal recurrent inhibition is still a matter of debate because of the experimental difficulty or impossibility of observing recurrent inhibition at work in normally behaving animals. The purpose of this study was to investigate, by computer simulation, the role of recurrent inhibition in shaping the input-output (I/O) relationships between descending command signals (DCS) as inputs and motoneuron (MN) and Renshaw cell (RC) firing rates and muscle force as outputs. Changing the spatial (topographical) distribution of recurrent inhibition from nonhomogeneous (as in the standard model) to homogeneous did not alter the I/O relationships significantly, while changing the functional distribution related to MN types did. Altering the global gain of recurrent inhibition, as happens naturally in various motor acts, changes the slopes and positions (at high inputs) of the I/O relationships, making recurrent inhibition a suitable means of gain control. Coupling a decrease in recurrent inhibitory gain with an increase in DCS input, as could occur during slow dynamic contractions, would increase the MN and force gains during the act. Short dynamic ramp-and-hold DCS inputs generate MN firing patterns, to which recurrent inhibition contributes interspike-interval variability and damped oscillations, which are related to issues of tremor and its control.

A model of the feline medial gastrocnemius motoneuron-muscle system subjected to recurrent inhibition.

Recurrent inhibition in the mammalian spinal cord is complex, and its functions are not yet well understood. Skeletomotoneurons (alpha-MNs) excite, via recurrent axon collaterals, inhibitory Renshaw cells (RCs), which in turn inhibit alpha-MNs and other neurons. The anatomical and functional structure of the recurrent inhibitory network is nonhomogeneous, and the gain and filtering characteristics of RCs are modulated by inputs circumventing alpha-MNs. This complex organization is likely to play important roles for the discharge and recruitment properties of alpha-MNs. Modeling this system is a way of investigating hypothesized roles for normal functioning including muscle fatigue and different forms of physiological pathological tremor. In this paper, a detailed model including alpha-MNs, RCs, and the muscle fibers innervated by the alpha-MNs is presented. Outlines of the experimental data underlying the model and the modeling philosophy and procedure are presented. Then the behavior of a RC model is compared with experimental data reported in the literature. Model and experimental data agree well for burst responses elicited by synchronous single-pulse activation of different numbers of motor axons. In addition, the static relation between motor-axon activation rate and RC firing rate agree fairly well in model and experiment, and the same applies to the dynamic responses to step changes in motor-axon rate. The ultimate objective is to use this model in probing the role of recurrent inhibition in the control and stability of (isometric) muscular force under normal and altered conditions occurring during fatigue and muscle pain.