The Effects of Long-Term Muscle Disuse on Neuromuscular Function in Unilateral Transtibial Amputees

The purpose of this study was to determine: (1) whether individuals with unilateral transtibial amputations (ITTAs), who habitually disuse the quadriceps muscles of their amputated limb, provide an effective model for assessing the effects of long-term muscle disuse; and (2) the effects of such disuse on quadriceps muscle strength and neuromuscular function in this population. Nine ITTAs and nine controls performed isometric voluntary knee extensions in both limbs to assess maximal voluntary torque (MVT) and rate of torque development (RTD). The interpolated twitch technique and EMG normalised to maximal M-wave assessed neural activation, involuntary (twitch and octet) contractions assessed intrinsic contractile properties, and ultrasound images of the vastus lateralis assessed muscle architecture. Clinical gait analysis was used to measure knee kinetic data during walking at an habitual speed. ITTAs displayed 54-60% lower peak knee extensor moments during walking in the amputated than intact/control limbs, but the intact and control limbs were comparable for loading during walking and muscle strength variables, suggesting the intact limb provides a suitable internal control for comparison to the disused amputated limb. MVT and RTD were ~60% and ~75% lower, respectively, in the amputated than intact/control limbs. The differences in MVT appeared associated with ~40% and ~43% lower muscle thickness and neural activation, respectively, whilst the differences in RTD appeared associated with the decline in MVT coupled with slowing of the intrinsic contractile properties. These results indicate considerable changes in strength and neuromuscular function with long-term disuse, that could not be predicted from short-term disuse studies. This is the peer reviewed version of the following article: The Effects of Long-Term Muscle Disuse on Neuromuscular Function in Unilateral Transtibial Amputees, which has been published in final form at Experimental Physiology. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Version

MECHANICS OF AMPUTEE JUMPING – CONSIDERATION FOR LOADING

Amputees must develop compensatory mechanisms to overcome the constraints imposed by a mechanical prosthesis. In completing a bilateral countermovement jump, amputees must accommodate the limited ankle dorsiflexion angle and adapt to the limited plantar-flexor moment that occurs at the prosthetic joint. The aim of this research was to determine the loading on the limbs and the joint kinetics adopted by transtibial amputees in order to achieve a jump. Six amputee (AMP) and 10 able-bodied (AB) participants performed maximal vertical jumps on two force plates while kinematic data was recorded using a 9-camera VICON infrared system. The amputees did not jump as high as the AB participants. The AMPs raised the prosthetic heel from the floor to compensate for the restricted motion at the ankle. Consequently, kinematic symmetry was maintained at the knee and the hip. The knee flexion places the prosthetic shank in a more horizontal position. This is a vulnerable position due to the reduced strength in the knee extensors as a consequence of the amputation. In order to reduce the instability and loading at the knee, the maximum propulsive vGRF on the prosthetic side was reduced and the intact limb assumed a dominant role. Until amputees can take the loading on the prosthetic side, it is not recommended that they participate in jumping

THE EFFECTS OF AGING ON THE HIP AND SPINAL MOTIONS IN THE GOLF SWING

The purpose of this study was to determine the effect of aging on the kinematics of the lumbar spine and hips in the golf swing. Aging was shown to alter the joint coupling but not the magnitude of joint loading

MECHANICS OF AMPUTEE JUMPING – JOINT WORK

The purpose of this study was determine if dynamic elastic response (DER) prostheses could absorb energy in the eccentric phase of a vertical jump performed by trans-tibial amputees phase and return this energy in the propulsive phase. Further, given the active nature of the ankle, the study aimed to determine the mechanisms required at the remaining joints to compensate for the pathological ankle. Six amputee (AMP) and 10 able-bodied participants (AB) performed maximal vertical jumps on two force plates which were synchronised with a 9-camera VICON infra red system. The amputees did not jump as high as the AB participants. Only minimal negative work was recorded at the prosthetic ankle in the eccentric phase which resulted in minimal positive work at the ankle in the concentric phase. The intact side produced greater work than the affected side in the concentric phase. The amputees generally adopted a hip strategy to generate positive work. The work recorded at the knee was reduced on the intact and affected side and indicates the prosthesis influences the movement on both sides. To enable amputees to participate in activities which require jumping, prostheses need to be developed and amputees need to be taught how to adjust their biomechanics to store and release energy in the prosthesis

Relationships between pyrimidine metabolism and sensitivity to alkylating agents in Aspergillus nidulans.

Relationships between pyrimidine metabolism and sensitivity to alkylating agents in Aspergillus nidulans

Some factors affecting transformation of Aspergillus nidulans - Problems and progress.

Some factors affecting transformation of Aspergillus nidulans - Problems and progress

A sodium fluoride sensitive mutant of Aspergillus nidulans

Fluoride is a widely spread naturally occurring substance in many foods and is used extensively for industrial purposes. The addition of fluoride to drinking water has been assumed to be safe. However, a number of studies have indicated that sodium fluoride is both genotoxic and cytotoxic to mammalian cells (Tsutsui et al. 1984 Mut. Res. 139:193-198). There is conflicting evidence suggesting that NaF is not genotoxic (Kram et al. 1978 Mut. Res. 57:51-55; Martin et al. 1979 Mut. Res. 66:159-167; Li et al. 1987 Mut. Res. 192:191-202) and can suppress the activity of polyfunctional alkylating agents (Obe and Slacik-Erben 1973 Mut. Res. 18:369-371)

Smart SU-8 Pillars Implemented in a Microfluidic Bioreactor for Continuous Measurement of Glucose

In this contribution we explore a new and simple approach for immobilizing enzymes like glucose oxidase on SU-8 surfaces to develop a smart substrate integrated in microfluidics. SU-8 is a well known photoresist often used in microfluidic prototyping. Immobilization of enzymes on such substance can open new possibilities in the microfabrication of enzyme biosensors and bioreactors. To demonstrate the consistency of this approach, we describe the design, fabrication and the simple functionalization of a microfluidic bioreactor employing smart SU-8 pillars for continuous amperometric measurement of glucose. The results reveal the possibility of simply binding enzymes on SU-8 surface. Moreover, a significant improvement in the linear response range is observed compared to the previous published amperometric microfluidic glucose sensors