The effects of electromechanical wrist robot assistive system with neuromuscular electrical stimulation for stroke rehabilitation

An electromyography (EMG)-driven electromechanical robot system integrated with neuromuscular electrical stimulation (NMES) was developed for wrist training after stroke. The performance of the system in assisting wrist flexion/extension tracking was evaluated on five chronic stroke subjects, when the system provided five different schemes with or without NMES and robot assistance. The tracking performances were measured by range of motion (ROM) of the wrist and root mean squared error (RMSE). The performance is better when both NMES and robot assisted in the tracking than those with either NMES or robot only (P<0.05). The muscle co-contractions in the upper limb measured by EMG were reduced when NMES provided assistance (P<0.05). All subjects also attended a 20-session wrist training for evaluating the training effects (3-5 times/week). The results showed improvements on the voluntary motor functions in the hand, wrist and elbow functions after the training, as indicated by the clinical scores of Fugl-Meyer Assessment, Action Research Arm Test, Wolf Motor Function Test; and also showed reduced spasticity in the wrist and the elbow as measured by the Modified Ashworth Score of each subject. After the training, the co-contractions were reduced between the flexor carpi radialis and extensor carpi radialis, and between the biceps brachii and triceps brachii. Assistance from the robot helped improve the movement accuracy; and the NMES helped increase the muscle activation for the wrist joint and suppress the excessive muscular activities from the elbow joint. The NMES-robot assisted wrist training could improve the hand, wrist, and elbow functions.

Neuron-restrictive silencer factor is not required for the antiepileptic effect of the ketogenic diet

PURPOSE

The ketogenic diet (KD) has been used as an effective antiepileptic treatment for nearly a century. Inhibition of glycolysis and increased levels of ketone bodies are both known to contribute to the antiepileptic effects of the KD. Neuron-restrictive silencer factor (NRSF), also known as RE-1 silencing transcription factor (REST), is implicated in the antiepileptic effects of the glycolytic inhibitor 2-deoxy-d-glucose (2DG). Glycolytic inhibition is a common feature of the KD and 2DG treatment, leading to the hypothesis that NRSF might also be involved in the antiepileptic effect of the KD. To test this hypothesis, the present study was designed to investigate the role of NRSF in the antiepileptic effect of 2DG, the KD, and acetone in vivo.

METHODS

Kindling was used as a model to test the antiepileptic effects of 2DG, the KD, and acetone on control and NRSF conditional knockout mice (NRSF-cKO; from the intercross of CamKIIα-iCre and NRSF exon 2 floxed mice). After recovery from electrode implantation, adult mice were stimulated twice a day at afterdischarge threshold (ADT) current intensity. In the 2DG- (500 mg/kg) and acetone- (10 mmol/kg) treated groups, drugs were injected intraperitoneally 20 min before each stimulus. In the 2DG group, mice were pretreated with intraperitoneal injections for 3 days in addition to the injections administered before the regular kindling stimulation. In the KD group, mice were fed the KD instead of a control diet until the end of stimulations.

KEY FINDINGS

Compared with control mice, the antiepileptic effect of 2DG was abolished in NRSF-cKO mice, indicating that NRSF is required for the antiepileptic effect of 2DG. In the KD-fed group, kindling development was retarded in both control and NRSF-cKO mice. In the acetone-treated group, inhibition of kindling-induced epileptogenesis was observed in both control and NRSF-cKO mice, similar to the action of the KD.

SIGNIFICANCE

These findings imply that NRSF repression complex is not essential for the antiepileptic effect of the ketogenic diet.

Association of HLA-DRB alleles and pulmonary tuberculosis in North Chinese patients

Human leukocyte antigen (HLA) plays a central role in the regulation of the immune response. HLA class II molecules are essential for T cell-mediated adaptive immunity and present peptide antigens to CD4(+) T cells. Because of its important role in the immune response and its high degree of polymorphism, the HLA system is associated with many diseases. We examined the polymorphisms of HLA-DRB alleles and the sequences of the HLA-DRB promoter region in 97 unrelated patients with pulmonary tuberculosis and in 62 unrelated normal controls of the Han nationality from North China, using PCR with sequence-specific primers and PCR direct sequencing. We found that the frequency of HLA-DRB1*15 was significantly higher in the pulmonary tuberculosis group than in the healthy control group. The P value was 0.001, and the odds ratio was 3.793. The pulmonary tuberculosis group had the same HLA-DRB1 promoter region sequences as the control group. We concluded that the HLA-DRB1*15 allele is associated with pulmonary tuberculosis in the Han nationality from North China. The HLA-DRB1 promoter region sequences had no association with the development of pulmonary tuberculosis.

The presence and expression of the hepatitis B virus in human oocytes and embryos

BACKGROUND

The objective of this study was to explore the potential for vertical transmission of hepatitis B virus (HBV) from parents to offspring via human germ cells.

METHODS

For study samples, 250 oocytes from hepatitis B surface antigen (HBsAg) seropositive women and 578 embryos from couples with at least one HBsAg seropositive partner were collected. HBV DNA in the nuclei of oocytes and embryos was detected by fluorescence in situ hybridization; HBsAg expression was analysed using immunofluorescence; and serum HBV DNA levels were measured by real-time PCR. The HBV infection duration of the women and the serum HBsAg status of their mothers were also examined.

RESULTS

HBV DNA was present in 9.6% (24/250) of oocytes and 14.4% (83/578) of embryos. Rates of HBV DNA positive embryos were similar among couples in which the woman, man or both partners were HBsAg seropositive, 13.1% (57/436), 21.3% (16/75) and 14.9% (10/67), respectively. Rates of positivity in oocytes and embryos were significantly higher in a group with high serum levels HBV DNA than in a group with lower serum levels (P= 0.004 and P= 0.002, respectively). Higher rates of oocyte positivity were found for women whose mothers were HBV infected compared with those with uninfected mothers. Expression of HBsAg was observed in 8.7% (2/28) oocytes and 14.1% (10/71) embryos (P= 0.34).

CONCLUSIONS

The presence of HBV DNA in human oocytes or embryos was related to the women's serum levels of HBV DNA and the infection status of their mothers. The HBV positive embryos were either maternally or paternally dependent. HBV infection may result in vertical transmission to the offspring via germ cells.

Comparison of semen quality and outcome of assisted reproductive techniques in Chinese men with and without hepatitis B

In this study, we aimed to determine the effects of hepatitis B virus (HBV) infection on sperm quality and the outcome of assisted reproductive technology (ART). A total of 916 men (457 HBV-positive and 459 HBV-negative) seeking fertility assistance from January 2008 to December 2009 at the Women's Hospital in the School of Medicine at Zhejiang University were analysed for semen parameters. Couples in which the men were hepatitis B surface antigen (HBsAg)-seropositive were categorized as HBV-positive and included 587 in vitro fertilisation (IVF) and 325 intracytoplasmic sperm injection (ICSI) cycles from January 2004 to December 2009; negative controls were matched for female age, date of ova retrieval, ART approach used (IVF or ICSI) and randomized in a ratio of 1:1 according to the ART treatment cycles (587 for IVF and 325 for ICSI). HBV-infected men exhibited lower semen volume, lower total sperm count as well as poor sperm motility and morphology (P < 0.05) when compared to control individuals. Rates of two-pronuclear (2PN) fertilisation, high-grade embryo acquisition, implantation and clinical pregnancy were also lower among HBV-positive patients compared to those of HBV-negative patients after ICSI and embryo transfer (P < 0.05); IVF outcomes were similar between the two groups (P > 0.05). Logistic regression analysis showed that HBV infection independently contributed to increased rates of asthenozoospermia and oligozoospermia/azoospermia (P < 0.05) as well as decreased rates of implantation and clinical pregnancy in ICSI cycles (P < 0.05). Our results suggest that HBV infection in men is associated with poor sperm quality and worse ICSI and embryo transfer outcomes but does not affect the outcome of IVF and embryo transfer.

Effectiveness of functional electrical stimulation (FES)-robot assisted wrist training on persons after stroke

A functional electrical stimulation (FES)-robot system controlled by subjects' motor intention was developed in our previous study. The effectiveness of the FES-robot on wrist training was investigated in this work. Five hemiplegic subjects with chronic stroke were recruited for an FES-robot assisted wrist training with 20 sessions. After the training, motor improvements were found in the wrist and fingers, represented by significant increase (P < 0.05) in clinical scores of the Fugl-Meyer Assessment (FMA), the Action Research Arm Test (ARAT), and the Modified Ashworth Score (MAS). Muscle coordination in the upper limb was also improved during the training as assessed by electromyography. The increased ARAT scores suggested improved upper limb motor functions, especially in the hand and fingers, compared to no improvement in previous study with only interactive robot-assisted wrist training without FES.

Conditional deletion of NRSF in forebrain neurons accelerates epileptogenesis in the kindling model

Neuron-restrictive silencer factor (NRSF), also known as repressor element-1 silencing transcription factor, is a transcriptional repressor that plays important roles in embryonic development and neurogenesis. Recent findings show that NRSF is upregulated after seizures activity however, the link between NRSF and epileptogenesis remains poorly understood. To investigate the role of NRSF in epilepsy, we employed a Cre-loxp system to specifically delete NRSF in excitatory neurons of the postnatal mouse forebrain. In the kindling model of epileptogenesis, conditional NRSF knockout (NRSF-cKO) mice exhibited dramatically accelerated seizure progression and prolonged afterdischarge duration compared with control mice. Moreover, seizures activity-induced mossy fiber sprouting was enhanced in the NRSF-cKO mice. The degree of upregulation of Fibroblast growth factor 14 and Brain-derived neurotrophic factor (BDNF) following kainic acid-induced status epilepticus was significantly increased in the cortex of NRSF-cKO mice compared with control mice. Furthermore, the derepression of BDNF was associated by activation of PLCγ and PI(3)K signaling pathways. These findings indicate that NRSF functions as an intrinsic repressor of limbic epileptogenesis.

An intention driven hand functions task training robotic system

A novel design of a hand functions task training robotic system was developed for the stroke rehabilitation. It detects the intention of hand opening or hand closing from the stroke person using the electromyography (EMG) signals measured from the hemiplegic side. This training system consists of an embedded controller and a robotic hand module. Each hand robot has 5 individual finger assemblies capable to drive 2 degrees of freedom (DOFs) of each finger at the same time. Powered by the linear actuator, the finger assembly achieves 55 degree range of motion (ROM) at the metacarpophalangeal (MCP) joint and 65 degree range of motion (ROM) at the proximal interphalangeal (PIP) joint. Each finger assembly can also be adjusted to fit for different finger length. With this task training system, stroke subject can open and close their impaired hand using their own intention to carry out some of the daily living tasks.

Incorporating ultrasound-measured musculotendon parameters to subject-specific EMG-driven model to simulate voluntary elbow flexion for persons after stroke

BACKGROUND

This study was to extend previous neuromusculoskeletal modeling efforts through combining the in vivo ultrasound-measured musculotendon parameters on persons after stroke.

METHOD

A subject-specific neuromusculoskeletal model of the elbow was developed to predict the individual muscle force during dynamic movement and then validated by joint trajectory. The model combined a geometrical model and a Hill-type musculotendon model, and used subject-specific musculotendon parameters as inputs. EMG signals and joint angle were recorded from healthy control subjects (n=4) and persons after stroke (n=4) during voluntary elbow flexion in a vertical plane. Ultrasonography was employed to measure the muscle optimal length and pennation angle of each prime elbow flexor (biceps brachii, brachialis, brachioradialis) and extensor (three heads of triceps brachii). Maximum isometric muscle stresses of the flexor and extensor muscle group were calibrated by minimizing the root mean square difference between the predicted and measured maximum isometric torque-angle curves. These parameters were then inputted into the neuromusculoskeletal model to predict the individual muscle force using the input of EMG signals directly without any trajectory fitting procedure involved.

FINDINGS

The results showed that the prediction of voluntary flexion in the hemiparetic group using subject-specific parameters data was better than that using cadaveric data extracted from the literature.

INTERPRETATION

The results demonstrated the feasibility of using EMG-driven neuromusculoskeletal modeling with direct ultrasound measurement for the prediction of voluntary elbow movement for both subjects without impairment and persons after stroke.

A-type GABA receptor as a central target of TRPM8 agonist menthol

Menthol is a widely-used cooling and flavoring agent derived from mint leaves. In the peripheral nervous system, menthol regulates sensory transduction by activating TRPM8 channels residing specifically in primary sensory neurons. Although behavioral studies have implicated menthol actions in the brain, no direct central target of menthol has been identified. Here we show that menthol reduces the excitation of rat hippocampal neurons in culture and suppresses the epileptic activity induced by pentylenetetrazole injection and electrical kindling in vivo. We found menthol not only enhanced the currents induced by low concentrations of GABA but also directly activated GABA_A receptor (GABA_AR) in hippocampal neurons in culture. Furthermore, in the CA1 region of rat hippocampal slices, menthol enhanced tonic GABAergic inhibition although phasic GABAergic inhibition was unaffected. Finally, the structure-effect relationship of menthol indicated that hydroxyl plays a critical role in menthol enhancement of tonic GABA_AR. Our results thus reveal a novel cellular mechanism that may underlie the ambivalent perception and psychophysical effects of menthol and underscore the importance of tonic inhibition by GABA_ARs in regulating neuronal activity.

Limbic epileptogenesis in a mouse model of fragile X syndrome

Fragile X syndrome (FXS), caused by silencing of the Fmr1 gene, is the most common form of inherited mental retardation. Epilepsy is reported to occur in 20-25% of individuals with FXS. However, no overall increased excitability has been reported in Fmr1 knockout (KO) mice, except for increased sensitivity to auditory stimulation. Here, we report that kindling increased the expressions of Fmr1 mRNA and protein in the forebrain of wild-type (WT) mice. Kindling development was dramatically accelerated in Fmr1 KO mice, and Fmr1 KO mice also displayed prolonged electrographic seizures during kindling and more severe mossy fiber sprouting after kindling. The accelerated rate of kindling was partially repressed by inhibiting N-methyl-D-aspartic acid receptor (NMDAR) with MK-801 or mGluR5 receptor with 2-methyl-6-(phenylethynyl)-pyridine (MPEP). The rate of kindling development in WT was not effected by MPEP, however, suggesting that FMRP normally suppresses epileptogenic signaling downstream of metabolic glutamate receptors. Our findings reveal that FMRP plays a critical role in suppressing limbic epileptogenesis and predict that the enhanced susceptibility of patients with FXS to epilepsy is a direct consequence of the loss of an important homeostatic factor that mitigates vulnerability to excessive neuronal excitation.

Quantitative evaluation of motor functional recovery process in chronic stroke patients during robot-assisted wrist training

This study was to investigate the motor functional recovery process in chronic stroke during robot-assisted wrist training. Fifteen subjects with chronic upper extremity paresis after stroke attended a 20-session wrist tracking training using an interactive rehabilitation robot. Electromyographic (EMG) parameters, i.e., EMG activation levels of four muscles: biceps brachii (BIC), triceps brachii (TRI, lateral head), flexor carpiradialis (FCR), and extensor carpiradialis (ECR) and their co-contraction indexes (CI) were used to monitor the neuromuscular changes during the training course. The EMG activation levels of the FCR (11.1% of decrease from the initial), BIC (17.1% of decrease from the initial), and ECR (29.4% of decrease from the initial) muscles decreased significantly during the training (P<0.05). Such decrease was associated with decreased Modified Ashworth Scores for both the wrist and elbow joints (P<0.05). Significant decrease (P<0.05) was also found in CIs of muscle pairs, BIC&TRI (21% of decrease from the initial), FCR&BIC (11.3% of decrease from the initial), ECR&BIC (49.3% of decrease from the initial). The decreased CIs related to the BIC muscle were mainly caused by the reduction in the BIC EMG activation level, suggesting a better isolation of the wrist movements from the elbow motions. The decreased CI of ECR& FCR in the later training sessions (P<0.05) was due to the reduced co-contraction phase of the antagonist muscle pair in the tracking tasks. Significant improvements (P<0.05) were also found in motor outcomes related to the shoulder/elbow and wrist/hand scores assessed by the Fugl-Meyer assessment before and after the training. According to the evolution of the EMG parameters along the training course, further motor improvements could be obtained by providing more training sessions, since the decreases of the EMG parameters did not reach a steady state before the end of the training. The results in this study provided an objective and quantitative EMG measure to describe the motor recovery process during poststroke robot-assisted wrist for the further understanding on the neuromuscular mechanism associated with the recovery.

The therapeutic effects of myoelectrically controlled robotic system for persons after stroke--a pilot study

In this study, a myoelectrically controlled robotic system with one degree of freedom was developed to assist elbow training in the horizontal plane for patients after stroke. The system could provide assistive extension torque which was proportional to the amplitude of the subject's processed and normalized electromyograhpic (EMG) signal from triceps. The system also provided different resistive torques during movement, which were based on the maximum isometric voluntary extension (MIVE) and flexion (MIVF) torques. A study investigated its effect after 20-session of training for four weeks on the functional improvement of the affected arm in 3 subjects after stroke. Outcome measurements on the muscle strength at the elbow joint showed that there were increases in the MIVE and MIVF torques of the affected arms of all the subjects after the four-week rehabilitation training. The subjects could also reach a more extended position without the assistance of the robotic system than that before the four-week training.

Effects of liver fibrosis on verapamil pharmacokinetics in rats

1. Liver fibrosis is the compensatory state of cirrhosis. In the long asymptomatic period, it is imperative to select a proper dosing regimen for drugs that are applicable to hepatic fibrosis owing to altered pharmacokinetics and bioavailability. The present study was designed to observe the changes in verapamil pharmacokinetics in rats with early liver fibrosis with respect to alterations in cytochrome P450 3A (CYP3A) and P-glycoprotein (P-gp). 2. A rat liver fibrosis model was successfully established using several inducers, including a high-fat diet, alcohol and carbon tetrachloride. After rats received a single intravenous or oral dose of verapamil (5 mg/kg), the plasma concentrations of verapamil were determined at scheduled time-points using HPLC. The activity of hepatic and small intestinal microsomal erythromycin N-demethylase (a marker for CYP3A) and the expression of small intestinal cyp3a and multidrug resistance (mdr) mRNA were compared between normal rats and rats with liver fibrosis. 3. The results showed that when verapamil was administered intravenously, the area under the curve (AUC), elimination half-life (T((1/2)(K10))) and mean residence time (MRT) increased significantly, whereas clearance (Cl) decreased, in rats with liver fibrosis compared with normal rats. After oral administration of verapamil, the AUC, (T((1/2)(K10))) and maximum concentration (C(max)) increased, Cl decreased and the absorption half-life (T((1/2)(K01))) and time to peak concentration (T(max)) were unchanged compared with normal rats. The oral bioavailability of verapamil was 32.9% in normal rats and 34.4% in rats with liver fibrosis. Furthermore, decreased CYP3A activity in the liver was accompanied by upregulated cyp3a9/18 and unchanged mdr mRNA in the small intestine compared with normal rats. Expression of cyp3a9/18 and mdr mRNA in the intestine was significantly inhibited by verapamil. 4. The results suggest that the lowered Cl and increased AUC of verapamil after intravenous and oral administration in rats with liver fibrosis were due to downregulation of CYP3A in the liver. The absorption rate of verapamil in rats with liver fibrosis was unchanged because mdr was unchanged and cyp3a was inhibited in the intestine by verapamil itself. There was no notable difference in oral bioavailability between normal rats and rats with liver fibrosis.

Coactivations of elbow and shoulder muscles in hemiplegic persons with chronic stroke during robot-assisted training

The motor recovery procedure of chronic stroke during robot-assisted training has not been well studied previously. In this work, we analyzed the variations in the coactivating patterns of elbow and shoulder muscles (biceps, triceps lateral, anterior deltoid, and posterior deltoid) in hemiplegic persons with chronic stroke (n=4) during a 20-session's interactive robot-assisted treatment. Significant decreases in muscle cocontractions (P<0.05) for all muscle pairs started from the 8th session of the training. Improvements were also observed in motor scores of Fugl-Meyer and modified Ashworth scale after the treatment. The results suggested an increased dexterity and selective control on individual muscles for both elbow and shoulder joints in a designed task after the robot-assisted training.

Differential roles of NR2A- and NR2B-containing NMDA receptors in activity-dependent brain-derived neurotrophic factor gene regulation and limbic epileptogenesis

Fleeting activation of NMDA receptors (NMDARs) induces long-term modification of synaptic connections and refinement of neuronal circuits, which may underlie learning and memory and contribute to pathogenesis of a diversity of neurological diseases, including epilepsy. Here, we found that NR2A and NR2B subunit-containing NMDARs were coupled to distinct intracellular signaling, resulting in differential BDNF expression and extracellular signal-regulated kinase 1/2 (ERK1/2) activation. Selective activation of NR2A-containing NMDARs increased BDNF gene expression. Activation of NR2B-containing NMDARs led to ERK1/2 phosphorylation. Furthermore, selectively blocking NR2A-containing NMDARs impaired epileptogenesis and the development of mossy fiber sprouting in the kindling and pilocarpine rat models of limbic epilepsy, whereas inhibiting NR2B-containing NMDARs had no effects in epileptogenesis and mossy fiber sprouting. Interestingly, blocking either NR2A- or NR2B-containing NMDARs decreased status epilepticus-induced neuronal cell death. The specific requirement of NR2A and its downstream signaling for epileptogenesis implicates attractive new targets for the development of drugs that prevent epilepsy in patients with brain injury.

Firing properties of motor units during fatigue in subjects after stroke

The purpose of this work was to investigate the electromyographic (EMG) fatigue representations in muscles of subjects after stroke at the level of motor unit, based on the analysis of mean power frequency (MPF) in the power density spectrum (PDS) for intramuscular EMG and our previous modeling and experiment studies on the neuromuscular transmission failure (NTF). NTF due to the local muscular fatigue had been captured in motor unit signals from healthy subjects during a submaximal fatigue contraction previously. In this study, the EMG signals for the biceps brachii muscles were collected by needle electrodes from the affected and unaffected arms of six hemiplegic subjects after stroke, and from the dominated arm of six healthy subjects during a full maximum voluntary contraction (MVC) and a subsequent 20% MVC. The MPF of EMG trials detected intramuscularly during the full and 20% MVCs, and the parameters of motor unit action potential trains (MUAPTs) during 20% MVC were analyzed in three groups: the normal (from healthy subjects), unaffected (from subjects after stroke), and affected (from subjects after stroke). It was found that during the full MVC the MPFs of the normal and unaffected groups decreased more than the affected when monitored by a moving time window of 2 s. The comparison on the overall MPF during the full MVC for these three groups over the whole time course of the EMG signal (18 s) were: the affected overall MPF was higher than the unaffected (P < 0.05); and the unaffected overall MPF was larger than the normal (P < 0.05). However, no significant decrease in MPF was found for these three groups during 20% MVC. The NTF was captured in most MUAPTs in the groups of the normal and unaffected rather than in the affected group, symbolized by the lowered rates of change (RCs) of firing rate (FR) (P < 0.05), more MUAPTs with positive RCs of maximum oscillation (MO) in MUAPT power density spectra (P < 0.05), and the significant higher RCs of minimum inter-pulse interval (MINI) (P < 0.05) in the normal and unaffected compared to the affected group. Enhanced neural drives to the motor units of the unaffected and affected groups were observed during 20% MVC, which possibly came from the bilateral neural inputs due to the disinhibition of the ipsilateral projections in subjects after stroke. For identifying the fatigue associated with NTF, the motor unit firing parameters, FR, MINI, and MO, were more sensitive than the MPF. The results obtained in this work provided a further understanding on the EMG of the fatigue processes in paretic and non-paretic muscles during voluntary contractions.

[Effects of melatonin on the induction of long term potentiation in the hippocampal CA3 area of rats]

AIM

To study the effect of melatonin on the induction of LTP in CA3 area of hippocampus and to investigated its possible mechanisms.

METHODS

Melatonin and other drugs (Tacrine or DNQX) were microinjected into the CA3 area. By using extracellular electrophysiological recordings to observe the changes of the slope of fEPSP in the CA3 area.

RESULTS

(1) Evoked potential and the induction of LTP were depressed by different concentration of melatonin (0.2 microg/microl, 1 microg/microl and 5 microg/microl). As the melatonin concentration increased, the induction of LTP was blocked more obviously. (2) Melatonin could attenuate the excitation effect of Tacrine (inhibitor of AChE) on LTP. (3) Inhibition of the melatonin-induced on LTP attenuated by DNQX.

CONCLUSION

The application of melatonin in rats inhibits the induction of LTP in the hippocampal CA3 area. The action of melatonin on the induction of LTP may be through the modulation of not only non-NMDA receptors but also cholinergic system.

The mechanomyography of persons after stroke during isometric voluntary contractions

This study was to investigate the properties of mechanomyography (MMG), or muscle sound, of the paretic muscle in the affected side of hemiplegic subjects after stroke during isometric voluntary contractions, in comparison with those from the muscle in the unaffected side of the hemiplegic subjects and from the healthy muscle of unimpaired subjects. MMG and electromyography (EMG) signals were recorded simultaneously from the biceps brachii muscles of the dominant arm of unimpaired subjects (n=5) and the unaffected and affected arms of subjects after stroke (n=8), when performing a fatiguing maximal voluntary contraction (MVC) associated with the decrease in elbow flexion torque, and then submaximal elbow flexions at 20%, 40%, 60% and 80% MVCs. The root mean squared (RMS) values, the mean power frequencies (MPF, in the power density spectrum, PDS) of the EMG and MMG, and the high frequency rate (HF-rate, the ratio of the power above 15Hz in the MMG PDS) were used for the analysis. The MMG RMS decreased more slowly during the MVC in the affected muscle compared to the healthy and unaffected muscles. A transient increase could be observed in the MMG MPFs from the unaffected and healthy muscles during the MVC, associated with the decrease in their simultaneous EMG MPFs due to the muscular fatigue. No significant variation could be seen in the EMG and MMG MPFs in the affected muscles during the MVC. The values in the MPF and HF-rate of MMG from the affected muscles were significantly lower than those from the healthy and unaffected muscles (P<0.05) at the high contraction level (80% MVC). Both the MMG and EMG RMS values in the healthy and unaffected groups were found to be significantly higher than the affected group (P<0.05) at 60% and 80% MVCs. These observations were related to an atrophy of the fast-twitch fibers and a reduction of the neural input in the affected muscles of the hemiplegic subjects. The results in this study suggested MMG could be used as a complementary to EMG for the analysis on muscular characteristics in subjects after stroke.

Effects of hepatic fibrosis on ofloxacin pharmacokinetics in rats

The purpose of the present work was to study the pharmacokinetics of ofloxacin, a poorly metabolised drug, in experimental hepatic fibrosis. The possible roles of small intestinal P-glycoprotein (P-gp) and cytochrome P450 (CYP) in the bioavailability of ofloxacin were also evaluated. Rat hepatic fibrosis model was successfully induced using complex factors including carbon tetrachloride, ethanol and high fat. After rats received a single oral or intravenous dose of ofloxacin (40 mg kg(-1)), the plasma concentrations of ofloxacin were monitored at the scheduled time using spectrofluorimetric assay. Plasma concentration-time profiles were comodeled using compartmental method. Meanwhile, microsomal CYP isoenzymatic levels and P-gp expression in small intestines were compared between normal and hepatic fibrosis rats. When ofloxacin was administered intravenously, C(max) and the distribution half-life increased significantly in comparison with normal group, whereas the distribution rate constants, the apparent volume of distribution decreased. Oral ofloxacin bioavailability was significantly altered in hepatic fibrosis rats. AUC and C(max) were reduced, while the absorption half-life, peak time and elimination half-life significantly were prolonged, suggesting that both the extent and the rate of ofloxacin absorption were decreased. Furthermore, the increases in the levels of microsomal ethoxyresorufin O-deethylase and erythromycin N-demethylase were accompanied with up-regulation of mdr 1a mRNA in the small intestines of hepatic fibrosis rats when compared to those of the normal rats. The Results showed that pharmacokinetics of ofloxacin could be altered in hepatic fibrosis. Up-regulated P-gp expression and increased CYP isoenzymatic activities of small intestines in hepatic fibrosis rats may contribute to the decreased bioavailability and increased elimination of ofloxacin after oral administration.

The genetic epidemiology of alopecia areata in China

BACKGROUND

Alopecia areata (AA) is hypothesized to be an organ-specific autoimmune disease with genetic predisposition and an environmental trigger. There are few clinical data in Asians.

OBJECTIVES

To describe the genetic epidemiological features of AA patients in China and to determine the possible genetic model for AA.

METHODS

Data for 1032 patients with AA were obtained by questionnaire in the Institute of Dermatology of Anhui Medical University in China from 2001 to 2003. Complex segregation analysis and heritability analysis were performed using Falconer's method, EPI INFO 6.0 and SAGE-REGTL programs.

RESULTS

In total, 1032 AA patients (male/female ratio 1.1 : 1) were enrolled, representing 0.94% of the total number of cases seen in our outpatient clinic during that time. The mean +/- SD age of onset was 28.98 +/- 13.43 years. The difference between the mean age of onset in males and females was not significant. Most patients (82.6%) experienced their first episode of AA within the first four decades of life. A positive family history of AA was obtained in 87 patients (8.4%). The prevalence of AA in first-, second- and third-degree relatives of the proband with AA was 1.6%, 0.19% and 0.03%, respectively. These figures were higher than those in controls. A greater severity and longer duration of AA were seen in the early onset group than in the late-onset group. The early onset group also had more affected first- and second-degree relatives. The heritability of AA in first-, second- and third-degree relatives was 47.16%, 42.53% and 22.29%, respectively. Based on the REGTL results, the best model was a polygenic additive model for AA.

CONCLUSIONS

The effect of genetic factors is strong in AA, but environmental factors such as infection and psychological stress may still play an important role. Our findings on the genetics of AA are consistent with a polygenic additive mode of inheritance.

Oscillations in the power spectra of motor unit signals caused by refractoriness variations

The refractory period of a motor unit is an important mechanism that regulates the motor unit firing, and its variation has been found in many physiological cases. In this study, a new observation that an increase in the motor unit refractoriness results in an enhancement of oscillations, or ripple effects, in the motor unit output power density spectra (PDS) has been identified and studied. The effects of the refractoriness variation on the PDS of motor unit firing were investigated on three levels: theoretical modeling, simulation and electromyographic (EMG) experimentation on human subjects. Both theoretical modeling and simulation showed the enhanced oscillations, ripple effects, in MUAPT PDS, given the increase in the refractoriness. It was also found that the extent of the increment in output PDS oscillation could be related to the motor unit size and the mean firing rate of the stimulation. A needle EMG experiment on biceps brachii muscles of five healthy human subjects was carried out during isometric contraction at 20% maximum voluntary contraction (MVC) for 20 s with a fatigue effort proceeded by MVC. The increased oscillations in the PDS of the real MUAPTs were observed with the rising of the motor unit refractoriness due to fatigue. The study gives new information for EMG spectra interpretation, and also provides a potential method for accessing neuromuscular transmission failure (NTF) due to fatigue during voluntary contraction.