Search PubMed⌕ Search

Biomedical subjects

M Solomonow

Publications and source records attributed to M Solomonow.

At least 91 records · Page 5Linked to original sources
PubMed1989

The role of the hamstrings in the rehabilitation of the anterior cruciate ligament-deficient knee in athletes.

There is ample evidence for the synergy between the knee musculature and ligaments, and the overall maintenance of joint integrity. In fact it could be reasonably concluded that the joint's antagonist muscle acts as a 'regulator' compensating for various internal and external disturbances of the intended movement. Undoubtedly, well conditioned muscles provide substantial improvements in joint stiffness and laxity, and reduce the risk of ligamentous injuries in the elite athlete. More research is needed to delineate the details of the questions which this new approach raises.

Athletic Injuries↗
PubMed1989

The effect of prenatal protein-energy malnutrition on collagen metabolism in fetal bones.

We analyzed various biochemical variables of the bones in fetal rats whose dams were protein-energy malnourished. Dams were randomly divided into two groups and fed either a 6% protein diet as a malnourished group or a 20% protein diet as a control, from day 13 of gestation to day 22, when fetuses were removed. Hexosamine and hydroxyproline contents of the calvaria and hexosamine contents of long bones were greater in the malnourished group than in the controls. Sequential extractability of collagen differed among various bones in the malnourished group and controls. The ratio of alpha:beta obtained from SDS-polyacrylamide gel of neutral salt-soluble collagen tended to increase in the long bones and mandible, and decrease in the calvaria and ribs in the malnourished group. Also, the ratio of alpha 1:alpha 2 tended to be lower in the malnourished group than in the control group in all bones. Protein-energy malnutrition during pregnancy has shown to affect biochemical composition of various fetal bones.

Animals↗
PubMed1989

The RGO Generation II: muscle stimulation powered orthosis as a practical walking system for thoracic paraplegics.

The RGO Generation II reciprocating gait orthosis was jointly developed by Louisiana State University Medical Center and Durr-Fillauer Medical, Inc, to overcome four problems encountered with the existing model: 1) The high energy cost of locomotion; 2) the great arm strength required for patients to stand up from the seated position without assistance; 3) difficulty (especially for patients with hamstring contracture) in remaining standing owing to failure of the knee latch to lock except in full extension; and 4) problems in balancing when ambulating on an incline. The RGO Generation II employs concurrent electrostimulation of the rectus femoris and hamstrings to assist in rising and balancing and a ratchet-type latching device to improve safety and stability in standing. Alternating stimulation of the rectus femoris and contralateral hamstrings are used for locomotion. Testing in six patients with thoracic paraplegia demonstrated an average 30+% reduction in energy expenditure at a walking speed of .05 m/s and a 15+% reduction at .37 m/s; improved mobility and better balance on inclines; and unassisted rising in all patients. Walking range was increased from an average of 100 m to an average of 800 m. More research is needed to provide stair-climbing ability and to further reduce energy expenditure.

Adult↗
PubMed1988

Electromyogram coactivation patterns of the elbow antagonist muscles during slow isokinetic movement.

Electromyograms from the flexor and extensor muscles of normal human elbows were simultaneously recorded during maximal-effort isokinetic movement at 15 degrees/s over the joint's full range of motion. The antagonist electromyogram was normalized with respect to its electromyogram when acting as agonist at maximal effort and plotted as a function of joint angle. The coactivation patterns were nearly inversely related to each muscle's moment arm variations with joint angle, suggesting that the antagonist may have generated constant opposing torque throughout the movement. Female subjects had a statistically significant higher coactivation level of the flexors and extensors compared with that of males, reflecting the increase in joint efficiency associated with daily muscular activity which is manifested by reduction in antagonist activity. The functional role of antagonist coactivation in augmenting ligament stabilizing functions, equalizing the pressure distribution over the articular surface, and regulating the joint's mechanical impedance are discussed. The source of such coactivation appears to be due to proprioceptive and joint kinesthetic afferent input in addition to possible direct common drive.

Adult↗
PubMed1988

Prenatal protein-energy malnutrition alters various biochemical components of the membranous bones in fetal rats.

The effects of prenatal protein-energy malnutrition on the biochemical parameters of the membranous bone were studied using fetal rats. Timed pregnant rats were fed a protein-deficient diet as an experimental group from day 13 of gestation, whereas control dams were fed a normal protein diet. By day 15, radioactive Na2SO4 was injected. On day 22, all fetuses were delivered by cesarean section. The hexosamine content per milligram dry tissue, and the protein and hexosamine contents per guanidine-HCl extract were greater in the mandibles but less in the calvaria of the malnourished group than in those of the controls. Calcium content per gram dry tissue was lower in both bones of the malnourished group. 35S-sulfate uptake per milligram dry tissue or milligram proteoglycan was greater in the malnourished group than in the controls in both bones. The mandible in the malnourished group had less lower-weight molecular proteoglycan subunits in the dissociative condition. Protein-energy malnutrition affects the mandible and calvaria in different ways, although both bones originate from membranous bone. Insufficient degradation of proteoglycan could be the reason for the delay of mineralization in the malnourished bones.

Animals↗
PubMed1987

Effects of excess methionine on collagen metabolism: a study on newborn rat skin.

We studied the biochemical effects of excess methionine intake on the skin of newborn rats. Group 1 pups were intubated with methionine dissolved in 0.1 ml physiological saline solution in the amount of 0.1 g/100 body wt as a control using a gastric needle. Group 2 pups were given 0.2 g/100 g in the same manner as group 1 as an experimental group. They were intubated every other day from day 3 to 13. On Day 15, [14C]proline was injected intraperitoneally into pups and their skin was removed. 14C total and hydroxyproline uptake was examined in the tissue as well as in the sequential extracts. Although excess methionine intake by the pups did not alter the collagen content of their skin, it caused an increase in the content of type III collagen and a decrease in crosslinked collagen. In addition, newly synthesized collagen in the neutral salt extract increased in the excess methionine group, indicating that crosslinked collagen decreases as excess methionine was intubated. The present study demonstrated that excess methionine in the early lactational period altered the nature of the skin collagen of suckling newborn rat pups.

Animals↗
PubMed1987

Gestational protein-energy malnutrition affects the composition of developing skins of rat fetuses and their dams.

1. Various biochemical variables of the skins of rat dams and their fetuses in which protein-energy malnutrition was induced during pregnancy were analysed. 2. One group of dams was fed on a 200 g protein/kg diet as a control and the other was fed on a 60 g protein/kg diet as an experimental group. Each group of dams was fed from day 13 of gestation until day 22. 3. Water, protein and hexosamine concentrations of the fetal skins in the malnourished group were greater than those in the control group, whereas in the dams' skins, protein concentration was greater in the malnourished group than in the control group. 4. Extractability of collagen with neutral salt and pepsin showed no difference between the groups in the skins of fetuses and dams. The content of type III collagen in the fetal skin did not differ between the groups, but was increased in the malnourished dams' skins compared with that of the control group. 5. The present study showed that protein-energy malnutrition during pregnancy significantly affects the metabolism of the skin in both fetuses and their dams. Furthermore, the skins of fetuses and dams are structurally altered in different ways by this nutritional stress.

Animals↗
PubMed1987

Biomechanics of muscle overuse injuries: a theoretical approach.

This article reviews the highlights of biomechanical principles associated with the proper function of the muscle, and extends the discussion to the limits set by the biomechanical concepts that, when exceeded, result in tissue injuries. The principles governing proper muscle functions and its injuries are also used to provide some guidelines for formation of exercise regimens that can minimize potential injuries.

Athletic Injuries↗
PubMed1986

Historical update and new developments on the EMG-force relationships of skeletal muscles.

The EMG-force relationships of skeletal muscles are of significant interest to the orthopedic-biomechanics researcher and have been a topic of interest and controversy for the last three decades. We present the developments reported in the literature, from the early 1950s, relevant to this topic, outlining the details of the controversy and providing additional new information resulting from recent studies. New data clearly illustrate that the EMG-force relationships are dependent on the firing rate and recruitment control strategy used by a muscle. Muscles that use motor unit recruitment to obtain the initial 50% of their maximal force, and use firing rate increase to complement the remaining 50%, have a nearly linear EMG-force relationship. Muscles that use recruitment to obtain 60% and up to 100% of their maximal force demonstrate progressive increase in non-linearity of their EMG-force curves. A clear warning is issued against the indiscriminate use of EMG as a representative of muscle force. The recruitment pattern of the muscle under consideration should first be obtained in such a way that the appropriate EMG-force curve is selected.

Animals↗
PubMed1986

EMG-force model of the elbows antagonistic muscle pair. The effect of joint position, gravity and recruitment.

A piecewise linear model of the elbow antagonistic muscle pair under isometric conditions was developed. The model consists of a linear myoelectric signal-joint force relationship with a mild slope for the force range of 0-30%, and a second, linear segment of steeper slope for the range of 30%-100%. The slope of the agonist, whether biceps or triceps, is fixed for most of the force range at about 1.16 regardless of elbow angle, whereas the slope of the antagonist varies with elbow angle. The antagonist muscle varies its response in such a way that it regulates the net torque about the joint, compensating for the effect of the gravity vector on the joint geometry and limb mass to stabilize the joint. The myoelectric profile of the medial gastrocnemius muscle of the cat during recruitment at synchronous firing rate of 51 pps (maximal tetanic rate) was obtained and compared with the above model. The force-EMG relationship for recruitment was fitted with a second-order polynomial similar but not equivalent to that of the EMG-joint force model. The minor differences were attributed to the effect of the antagonist, proprioception, ligament status and joint geometry.

Animals↗
PubMed1985

A viscoelastic knee brace for anterior cruciate ligament deficient patients.

A biomechanical review of the anterior cruciate ligament deficient knee shows that the unbraced knee undergoes instability once its angular velocity exceeds normal cadence rate. It also shows that various braces that utilize extension limits for purposes of preventing subluxation and tibial rotation introduce abnormal gait and posture responses, which may impose on the patient's activities. A speed-regulated, viscoelastic knee brace has been designed, fabricated, and tested on two patients. The brace allows full range of knee motion and reduces the angular velocity of the tibia from near-full extension to neutral at normal, non-unstabilizing walking speeds. Capability is incorporated for adjusting the terminal angular velocity for each individual patient as well as for the same patient during the recovery period.

Biomechanical Phenomena↗
PubMed1985

A technique for recording the EMG of electrically stimulated skeletal muscle.

A technique for recording the myoelectric activity of electrically stimulated muscle through its motor nerve without the interference of stimuli artifacts has been developed and tested. The technique consists of a wide band differential amplifier with fine intramuscular wire electrodes. The amplified signal is passed through a Chebyshev low pass filter with eight poles at a frequency of 550 Hz. A stimulus calibration study shows that low frequency stimuli had negligible effect on the EMG when set below three times suprathreshold. A test procedure shows artifact-free EMG during action potential rate stimulation as well as during superimposed high frequency recruitment stimulation.

Action Potentials↗
PubMed1983

Control of muscle contractile force through indirect high-frequency stimulation.

With a view to possible application in an orthotic device, study was made of the attenuation of background, indirectly induced muscle tetanus produced by superimposing high-frequency electrical stimulation of the muscle nerve. The effects of varying duration, current and frequency of pulses of the stimulus were outlined, and it was concluded that optimal application might be obtained using a stimulus frequency of 500 Hz, a pulse duration of 50 musec, and varying the frequency to gradate the effect.

Acoustics↗