Viscoelastic response of the lateral side of the ankle to cyclic inversion: a time course analysis.

Although important, viscoelastic behavior of the ankle's lateral side has rarely been studied. The present study assesses the viscoelastic behavior during cyclic inversions. Eighteen recreationally active healthy males underwent 40 passive cyclic inversions using a Biodex dynamometer at 5 °/s through 80% of maximum range of motion. Energy absorption and restitution and dissipation coefficient were calculated for each repetition. Changes in the mean of the dependent variables for repetitions 1 (R1 ), R5 , R10 , R15 , R20 , R25 , R30 , R35 and R40 were compared by three one-way analyses of variance with repeated measures. There was a significant difference between the means of energy absorption for the selected repetitions from R1 to R20 (P < 0.01), but there was no significant difference between them from R20 to R40 (P > 0.05). There was no significant difference between the means of energy restitution for the selected repetitions (P > 0.05). Whereas there was no significant difference consecutively between the means of dissipative coefficient for the selected repetitions (P > 0.05), there was a significant difference between the means of R30 or R40 relative to the baseline (P < 0.005). The decrease in the energy absorbed and the dissipation coefficient following repeated inversions may be due to the slippage of collagen fibers. The decrease in the shock absorbing ability of the tissues may expose them to injury.

Effects of cyclic static stretch on fatigue recovery of triceps surae in female basketball players.

Static stretch is a safe and feasible method which usually is used before exercise to avoid muscle injury and to improve muscle performance. The purpose of this study was to determine the effects of cyclic static stretch (CSS) on fatigue recovery of triceps surae (TS) in female basketball players. Nine athlete volunteers between 20 and 30 years participated in this study containing two sessions. After warm-up a pressure cuff was fastened above the knee joint and its pressure was increased to 140 mmHg. The subjects were asked to perform one maximum voluntary contraction (MVC) followed by a fatigue test including maximum isometric fatiguing contraction of TS. These steps were similar in both sessions. Then, a two-minute rest was included in the first session while 4 static stretches were performed to TS in the second session. After interventions, one MVC was done and the pressure cuff was released. During these steps, peak torque (PT) and electromyography (EMG) were recorded. The amount of lower leg pain was determined by the visual analogue scale (VAS). The value of PT increased significantly after CSS but its increase was not significant after rest. It seems that the effects of rest and CSS on the EMG parameters, PT and pain are similar.

Modulation of the ipsilateral and contralateral H reflexes following ipsilateral mechanical pressure of the foot in normal subjects.

OBJECTIVE: Mechanoreceptors from the foot sole likely contribute in the reflex regulations. Therefore, it was hypothesized that repetitive low threshold afferents stimulation would have an inhibitory effect on the soleus H-reflexes. METHODS: Sixteen normal subjects voluntarily, participated in the study and were randomly allocated. Subjects were remained in prone position. The Cutaneous Mechanical Pressure (CMP equal to 50% of leg and foot weight) was applied to the ipsilateral lateral and Medial plantar surface by a designed instrument through a square plate (30 x 30 mm). H reflex as an indicator for excitability of motoneurones was bilaterally elicited before and after the application of the CMP. The H-reflex parameters were estimated. RESULTS: Mechanical pressure significantly depressed soleus H-reflex excitability in ipsilateral and contralateral feet in all subjects. CONCLUSION: The demonstration of a decrease in H-reflex excitability as a result of applied pressure to the foot sole suggests that the change in reflex excitability is the result of a common spinal mechanism. The results highlight the modulatory effects that natural stimulation of afferents can have on reflex excitability. SIGNIFICANCE: The placement of a small flat plate, in order to apply pressure to the plantar eminence, may be useful for modulation of muscle tone. In addition, these findings might be useful for reducing spasticity; because spasticity is at least partially caused by hyperexcitability of the motorneuron pool.

Functional assessment of knee joint position sense following anterior cruciate ligament reconstruction.

CONTEXT: The anterior cruciate ligament (ACL) has both mechanical and proprioceptive (sensory) functions. Knee-joint proprioception has been assessed using either reproduction of position or threshold to detect passive motion in non-weight-bearing positions. It has been suggested that a more functional and dynamic/active assessment of proprioception might clarify the effects of injury and reconstruction on the proprioceptive function of ACL at the knee joint. OBJECTIVE: To assess knee joint position sense (JPS) following ACL reconstruction in functional positions. SUBJECTS: Twelve male patients who had undergone ACL reconstruction and 12 male healthy control subjects participated in the study. METHODS AND MAIN OUTCOME MEASURES: JPS was evaluated by reproduction of the angles in weight-bearing position with limb movement into flexion and extension. The dominant knee of healthy subjects and both (reconstructed and uninjured) knees of the patients were tested. Absolute angular error was used as a dependent variable. RESULTS: There was no significant difference between the operated and uninjured knees of patients or between patients and healthy controls (p>or=0.05). These results were measured during two tasks of limb movement into flexion and extension. CONCLUSION: We found no evidence of impaired JPS in weight-bearing positions in subjects with ACL reconstruction at a mean follow-up of 11 months after surgery compared with subjects with healthy knees.

Ten-year experience with preimplantation genetic diagnosis (PGD) at the New York University School of Medicine Fertility Center.

We describe our experience of over 300 cycles of preimplantation genetic diagnosis (PGD) and report clinical pregnancy rates (35%-67%) that support using this technology to screen for genetic disorders and chromosomal abnormalities. In clinical practice for over ten years, PGD offers couples the earliest form of genetic screening and may help improve ongoing pregnancy rates in poor-prognosis patients.

A randomized, single blind placebo controlled clinical trial on the effect of continuous ultrasound on low back pain.

Low back pain (LBP) is a very common problem in primary care and a major cause of disability. There is no evidence for the efficacy of therapeutic modalities such as ultrasound in LBP In a randomized, single blind placebo controlled clinical trial, we aimed to evaluate the effect of continuous ultrasound (US) in patients with non specific LBP Of the fifty eight patients recruited, 10 patients (8 women and 2 men) randomly allocated to ultrasound (n=5) or placebo controlled (n=5) groups. The patients were treated by either US or sham-US for ten sessions, three days per week, every other day. The outcome measures were Functional Rating Index (FRI), Hmax/Mmax ratio and range of motion (ROM), which were measured at baseline, after 5 treatment sessions and at the end of treatment. To analyze the data, The Mann Whitney U test and Wilcoxon Signed Rank test were used. After treatment, both US and placebo groups showed statistically significant decrease in FRI scores indicating improvement in functional ability (p = 0.042 and p = 0.043, respectively). The mean changes of FRI during the second five treatment sessions and after the end of treatment was significantly better in the US group than in the placebo group (p = 0.016 and p = 0.032, respectively). Before and after treatment, the mean H reflex latency and Hmax/Mmax ratio, right and left side were similar in the groups (p > 0.05), and no significant changes were observed in the treatment groups (p > 0.05). After treatment, the extension and lateral flexion range of motion significantly increased in the US group (p = 0.04), but the back movements in the placebo group did not show significant changes (p > 0.05). The present study supports the significant effect of US on LBP, and suggests that US may improve the functional ability of patients with non specific low back pain.

The effect of transcutaneous electrical nerve stimulation on sympathetic skin response.

The aim of present study was to determine whether combination of transcutaneous electrical nerve stimulation (TENS) and acupuncture inhibits sympathetic nerve activity in healthy humans. Multiunit efferent postganglionic sympathetic activity was recorded with Toennies set. In this study, the aim was to obtain latency, amplitude and duration of sympathetic skin response (SSR) and skin temperature (ST) from both hands in 15 healthy subjects. Subjects randomly assigned and everybody participated in all the three groups [Control Group (CG), Acupuncture Group (AG) and Nerve Stimulation Group (NSG)]. TENS (2 Hz, 250 microsecond) was applied over the median nerve of the right elbow in NSG for 20 min, either, TENS was applied over (HE-7) point of the right hand in CG (TENS off) and AG (TENS on) for 20 min. SSR (lat, amp, dur) and ST data was recorded before TENS and for immediate, 5 min and 10 min post--TENS. ST was recorded in distal phalanx of index finger of both hands and SSR was recorded from both hands. TENS in CG did not affect ST and SSR following stimulation. TENS applied at AG and NSG caused a significant increase in ST (P = 0.001), significant increase in latency of SSR (P = 0.001), significant decrease in amplitude of SSR (P = 0.001) and no significant changes were observed in duration of SSR (P > 0.05). Then statistical analysis showed differences between both of groups (AG & NSG) for ST and SSR post--TENS. Transcutaneous electrical nerve stimulation inhibits sympathetic nerve activity in healthy humans.

Role of heat shock protein Hsp25 in the response of the orofacial nuclei motor system to physiological stress.

Although expression of the small heat shock protein family member Hsp25 has been previously observed in the central nervous system (CNS), both constitutively and upon induction, its function in the CNS remains far from clear. In the present study we have characterized the spatial pattern of expression of Hsp25 in the normal adult mouse brain as well as the changes in expression patterns induced by subjecting mice to experimental hyperthermia or hypoxia. Immunohistochemical analysis revealed a surprisingly restricted pattern of constitutive expression of Hsp25 in the brain, limited to the facial, trigeminal, ambiguus, hypoglossal and vagal motor nuclei of the brainstem. After hyperthermia or hypoxia treatment, significant increases in the levels of Hsp25 were observed in these same areas and also in fibers of the facial and trigeminal nerve tracts. Immunoblot analysis of protein lysates from brainstem also showed the same pattern of induction of Hsp25. Surprisingly, no other area in the brain showed expression of Hsp25, in either control or stressed animals. The highly restricted expression of Hsp25 implies that this protein may have a specific physiological role in the orofacial motor nuclei, which govern precise coordination between muscles of mastication and the pharynx, larynx, and face. Its rapid induction after stress further suggests that Hsp25 may serve as a specific molecular chaperone in the lower cholinergic motor neurons and along their fibers under conditions of stress or injury.

Lymphocyte activation via MHC class II antigens.

Class II antigens of the major histocompatibility complex (MHC) have a clear role in restricting cellular interactions and presenting processed antigen to T cells. In addition, a fundamental role for class II antigens in cellular activation has been suggested, following studies which demonstrated that class II antigen binding altered signal transduction in various cell types. We have investigated the role of HLA class II antigens in signal transduction of human B lymphocytes. Resting B lymphocytes proliferate in response to immobilized anti-class II antibodies and intracellular free calcium is increased following cross-linking of anti-class II antibodies. The two dimensional PAGE pattern of resting B lymphocytes was examined and differences were noted after stimulation with either anti-class II antibodies, anti-IgM or PMA. The 2D PAGE pattern following stimulation with anti-class II antibodies was not identical to that observed following stimulation with either anti-IgM or PMA. These data suggest that the activation of B-Go via the class II antigens shares part of the pathway of anti-IgM induced activation but does not follow an identical pathway.

Signal transduction via MHC class II antigens on B lymphocytes.

The role of the MHC class II antigens in the activation of resting human B lymphocytes (B-Go) was examined with respect to both early and late events in the activation process. The (Ca2+)i induced by anti-IgM was enhanced in the presence of, or following pre-incubation with, an anti-MHC class II DR antibody (D1.12). Pre-incubation with a sepharose conjugated antibody (Seph.-D1.12) augmented the proliferation of B-Go in response to a sub-optimal concentration of anti-IgM. The 2D PAGE profile of B-Go differed from that of in vivo activated B lymphocytes. The 2D PAGE profile of B-Go activated by Seph.-D1.12 was not identical to the profile of B-Go activated by either anti-IgM or PMA. These data suggest that the activation of B-Go via the class II antigens shares part of the pathway of anti-IgM induced activation but does not follow an identical pathway.