Between-days reliability of H-reflexes in human flexor carpi radialis

OBJECTIVES: To assess between-day reliability of the latency and peak-to-peak amplitude of a technique to elicit the H-reflex and M response of the flexor carpi radialis (FCR) and the ratio of maximum H-reflex and M-response amplitude (Hmax/Mmax). DESIGN: Test-retest reliability study. SETTING: Electrophysiology laboratory at a university. PARTICIPANTS: Fifteen consecutively recruited healthy volunteers (8 men, 7 women; age range, 22-65y). INTERVENTION: Volunteers were tested on 2 separate days at the same time of day for H-reflex and M response by stimulating the median nerve in the cubital fossa in the presence of a standardized voluntary contraction of the FCR muscle. MAIN OUTCOME MEASURES: Onset latencies, peak-to-peak amplitudes, and Hmax/Mmax. RESULTS: Latency measurements of H-reflex and M response showed excellent reliability between days, as did the maximum amplitude of the M response. The maximum amplitudes of the H-reflex and Hmax/Mmax ratio were less reliable but still within acceptable limits. CONCLUSIONS: The H-reflex and M response can be reliably elicited in the FCR. This technique provides a useful clinical tool for diagnostic purposes during the course of neurologic disorders and in preclinical and postclinical intervention studies.     

Effects of aflatoxin B1 on the growth processes of spermatogenic cell series in adult male rats

Dietary aflatoxins produce a disease state known as aflatoxicosis and disturbance of spermatogenesis is one of its serious outcomes. In this study, we evaluated the chronic effects of oral administration of aflatoxin B1 on spermatogenic cell series in adult Wistar male rats. Twenty-eight adult Wistar male rats were selected and allocated into four groups. The control group was administered sterile distilled water and the test groups; T1, T2, T3 received 0.8, 1.6, 3.2 ppm/1 cc distilled water/animal/day, respectively, for 48 days by gavage. The population of spermatogonia types A, B, and spermatozoa were significantly decreased in all test groups (p?<?0.001), but primary spermatocytes and spermatids showed a significant decrease (p?<?0.01) only in group T3. We conclude that the oral administration of aflatoxin B₁ can decrease spermatogenic cells in a dose-dependent mode.     

Pulsatile control of the human masticatory muscles

Spectral analysis of jaw acceleration confirmed that the human mandible 'trembles' at a peak frequency around 6 Hz when held in its rest position and at other stationary jaw openings. The 6 Hz tremor increased during very slow movements of the mandible, but other lower-frequency peaks became prominent during more rapid jaw movements. These lower-frequency peaks are likely to be the result of asymmetries in the underlying, voluntarily produced, 'saw-tooth' movements. In comparison, finger tremor at rest and during slow voluntary movements had a mean peak frequency of about 8 Hz: this frequency did not change during rhythmical finger flexion and extension movements, but the power of the tremor increased non-linearly with the speed of the movement. The resting jaw tremor was weakly coherent with the activity of the masseter and digastric muscles at the tremor frequency in about half the subjects, but was more strongly coherent during voluntary movements in all subjects. The masseter activity was at least 150 deg out of phase with the digastric activity at the tremor frequency (and at all frequencies from 2.5–15 Hz). The alternating pattern of activity in antagonistic muscles at rest and during slow voluntary movements supports the idea that the masticatory system is subject to pulsatile control in a manner analogous to that seen in the finger.     

Accuracy of an electromagnetic tracking device for measuring hip joint kinematics during gait: effects of metallic total hip replacement prosthesis, source-sensor distance and sensor orientation

The present study sought to investigate the effects of source-sensor distance, sensor orientation and the effects of metallic total hip replacement (THR) prostheses on the accuracy of the 3Space Tracker System (3STS). Using a simulated hip joint, the angles measured by the 3STS with six different source-sensor distances and two source-sensor orientations were recorded. Then the angles measured in the absence and presence of three different THR prostheses were compared. Both source-sensor distance and sensor orientation affects the accuracy of the 3STS. Measurements were only affected by the presence of one type of prosthesis. The 3STS was equally reliable, but less accurate with source-sensor distances of more than 25 cm. The small angular error and insensitivity of this device to the presence of some metallic THR prostheses make it a useful measurement tool for gait studies performed before and after THR surgery.     

Differential modulation of tremor and pulsatile control of human jaw and finger by experimental muscle pain

Resting tremor is seen in both the limbs and in the trigeminal motor system. These rhythmical perturbations are the result of alternating activation of antagonistic muscles, and these increase in amplitude during slow, voluntary movements. In the present study, we examined the effect of experimental muscle pain on finger and jaw tremor. The tremor in the mandible and in the middle finger was measured on separate occasions, at rest and during two constant-velocity movements. Pain was then induced by the infusion of hypertonic saline into a jaw-closing muscle (masseter) or into a finger extensor muscle (extensor digitorum longus, EDL). During masseter pain, the power at the peak tremor frequency of the mandible decreased significantly both when the jaw was at rest and during voluntary jaw movements at two velocities. In contrast, pain in EDL resulted in a significant increase in the power of finger tremor only during the two speeds of voluntary movement. No change in the peak tremor frequency was seen in either the finger or the jaw during pain. The most likely explanation for these data is that muscle pain tonically modulates the amplitude of the outputs from the central "pulsatile control" generators that drive the alternating activation of antagonistic muscles which produce tremor at rest and during movements. This modulation is in the opposite direction for systems controlling jaw and hand, suggesting a specific interaction of the nociceptive afferents with separate central oscillators. Electronic Publication     

Experimental diabetes negatively affects the spermatogonial stem cells’ self-renewal by suppressing GDNF network interactions

The present study was done to analyse the time-dependent effects of diabetes on Sertoli cells–spermatogonial stem cells’ (SSCs) network interaction by focusing on glial cell line-derived neurotrophic factor (GDNF) and its special receptors, gfrα1 and c-RET as well as the Bcl-6b. In total, 40 Wistar rats were considered in; control, 20, 45 and 60 days diabetes-induced groups. An experimental diabetes was induced by STZ. The GDNF, gfrα1, c-RET and Bcl-6b expressions were evaluated. The serum level of testosterone, tubular repopulation (RI) and spermiogenesis (SPI) indices, general histological alterations, germ cells, mRNA damage, sperm count and viability were assessed. The diabetes, in a time-dependent manner, diminished mRNA and protein levels of GDNF, gfrα1, c-RET and Bcl-6b versus control group (p < .05), enhanced percentage of seminiferous tubules with negative RI, SPI, and diminished Leydig and Sertoli cells distribution, serum levels of testosterone, sperm count and viability. Finally, the number, percentage of cells and seminiferous tubules with normal mRNA content were significantly (p < .05) diminished. In conclusion, as a new data, we showed that the diabetes by inducing severe mRNA damage and suppressing GDNF, gfrα1, c-RET and Bcl-6b expressions, potentially affects the Sertoli–SSCs’ network and consequently inhibits the SSCs’ self-renewal process.