Search PubMed⌕ Search

Biomedical subjects

J Perry

Publications and source records attributed to J Perry.

At least 127 records · Page 7Linked to original sources
PubMed1982

Electromyographic gait analysis before and after operative treatment for hemiplegic equinus and equinovarus deformity.

Gait electromyograms were obtained before and after tendon transfer, lengthening, or release in twenty-seven hemiplegic patients with equinus or equinovarus deformities. Abnormal patterns of muscle activity almost always were present preoperatively in the gastrocnemius, soleus, tibialis posterior, flexor hallucis longus, flexor digitorum longus, peroneus brevis, and tibialis anterior muscles in these patients. The surgical procedures to correct the foot deformities altered the gross patterns of activity of most of the muscles operated on by very little. Of particular importance to the surgeon was the finding that the pattern of activity of the muscles whose tendon was transferred, lengthened, or released was not altered after operation. This finding makes the preoperative gait electromyogram a useful means of determining the appropriate surgical plan, since it is an indication of the type of muscle activity to expect postoperatively.

Adult↗
PubMed1982

Urinary folate loss following inactivation of vitamin B12 by nitrous oxide in rats.

Rats were injected with [2-14C]H4PteGlu daily for 3 d and thereafter one group left in air and a second group in an atmosphere of nitrous oxide/oxygen (1/1). Nitrous oxide inactivates cobalamin. The N2O-treated rats excreted large amounts of L. casei-active folate into the urine. The urinary folate co-chromatographed with authentic 3H-labelled 5-methyltetrahydrofolate. Both groups of animals excreted 14C-labelled breakdown products in the urine but there was no evidence of increased folate catabolism in the N2O-treated rats. It was concluded that the folate deficiency that develops in the N2O-treated rat is due to massive urinary loss of folate. This appears to be secondary to impaired cellular uptake of folate which leads to a raised plasma folate level.

Animals↗
PubMed1982

The functional cost of dislocation following total hip arthroplasty.

The consequences of dislocation following total hip arthroplasty were assessed using quantitative gait analysis. As a preliminary study, a review of 18 patients having undergone hip arthroplasty without dislocation provided as understanding of the improvement in gait in the first two years after surgery. Seven patients with a single dislocation and six patients with multiple dislocations were compared with patients matched according to age and preoperative gait characteristics and who experienced an uncomplicated recovery following hip arthroplasty. One year after surgery patients with a single dislocation could not be differentiated from the matched patients with respect to gait velocity and single limb support time. However, patients, with multiple dislocations walked significantly slower and had a significantly decreased single limb support time in the involved extremity than their respective matched patients.

Aged↗
PubMed1981

Changes in tissue folates accompanying nitrous oxide-induced inactivation of vitamin B12 in the rat.

The anesthetic gas, nitrous oxide, oxidizes cob(I)alamin and thus inactivates methionine synthetase which requires cobalamin as a coenzyme. The effect on folates in liver, kidney, marrow, plasma, and brain in rats breathing a 1/1 nitrous oxide/oxygen mixture is described. There is loss of folate from tissues, most marked in liver, that affects folate polyglutamates to a greater extent than folate monoglutamates. Both methyl- and nonmethyl-analogues are affected. There is a transient rise in the levels of 5-methyltetrahydropteroylpolyglutamate in all tissues 8 h after starting nitrous oxide, which falls thereafter. In marrow and brain there is also a transient rise in methyltetrahydropteroylmonoglutamate. Plasma folate increased markedly throughout the period of exposure to nitrous oxide. It is suggested that these changes are due to the action of nitrous oxide in depressing tissue uptake of folate from plasma, in promoting loss of folate into urine and in inhibiting folate polyglutamate synthesis.

Animals↗
PubMed1981

Recovery of tissue folates after inactivation of cobalamin by nitrous oxide. The significance of dietary folate.

The anesthetic gas, nitrous oxide (N2O), oxidizes the cobalt moiety in the vitamin B12 molecule and in this way inactivates methionine synthetase which requires reduced cobalamin. In rats this is followed by a disappearance of folates from the tissues, this loss being most marked in the liver. Returning the animals to a normal atmosphere leads to restoration of most of the pre-N2O folate levels within 5 days. The plasma folate, which rises on exposure to N2O, falls within several hours. The restoration of tissue folates does not take place if the rats are placed on a low folate diet after withdrawal from an N2O environment. Thus the fall in tissue folate levels is due to loss from the body either by excretion or increased catabolism and not to redistribution of folate. Return of normal folate levels requires a dietary source of folate.

Animals↗
PubMed1981

Surface versus intramuscular electrodes for electromyography of superficial and deep muscles.

The relative selectivity of surface electrodes placed over the gastrocnemius and soleus muscles in the standard manner was determined by comparing the electromyogram from these electrodes to the electromyogram from wire electrodes inserted into the soleus, gastrocnemius, and tibialis posterior muscles. Muscle activity was elicited in 11 normal subjects by performing six manual muscle tests. Three of the tests followed the standard technique and three were modifications designed to provide better differentiation of muscle action. All electromyographic data were quantified by computer integration and normalized to cancel out sampling inconsistency. None of the muscle tests totally restricted activity to the designated muscle, but the tests did determine which was the strongest participant. During the standard specific gastrocnemius and soleus muscle tests, the corresponding surface electrode provided a lower electromyogram than did the matching wire electrode; that is, the surface-to-wire-electrode ratio was less than one (gastrocnemius = 0.74, soleus = 0.58). This ratio was greater than one when the electromyogram was being recorded from one muscle while testing another muscle (gastrocnemius = 1.55, soleus = 1.92). The mathematical model relating surface-electrode values to the wire-electrode data from all three muscles identified 60 percent of the surface gastrocnemius electrode electromyogram as arising from that muscle, while only 36 percent of the soleus surface electrode data related to the activity of the soleus: Sg = .19Ws + 60Wg + .13Wt + .08Wo and Ss = .36Ws + .31Wg + .22Wt + .11Wo.

Electrodes↗
PubMed1981

Functional evaluation of Rolfing in cerebral palsy.

Rolfing is a technique which involves the use of pressure on areas of the body in which muscle tendons adhere to each other rather than sliding over one another in the normal way. In this study, a series of 10 patients with mild, moderate or severe cerebral palsy underwent Rolfing Treatment, and the results were evaluated. Mildly impaired patients made gains in velocity, stride length and cadence; the moderately impaired group made only minor gains in velocity; and the severely impaired did not improve by any of the criteria used in this study. Muscle strength and electromyography were not altered appreciably in any of the patients. While the effects of treatment on range of motion were highly variable, increased muscle tightness in the hip and knee flexors, hip internal rotators, hip adductors and plantar flexors was noted. These results indicate that Rolfing can lead to improved performance in mildly affected patients because they possess the neurological capacity to make use of increased tissue mobility, and thus avoid contractures. However, the increased muscle tightness which can occur probably outweighs any benefit which moderately or severely impaired patients may derive from the treatment.

Adolescent↗
PubMed1981

The effect of nitrous oxide-induced inactivation of cobalamin on plasma amino acid levels in the rat.

Rats were maintained in an atmosphere of equal volumes of oxygen/nitrous oxide (1/1) for up to 7 d and plasma levels of methionine, glycine, serine, histidine, homocysteine and S-methylcysteine were measured. There was a fall in plasma methionine and a rise in plasma serine levels. There were no significant changes in glycine and histidine levels. Homocysteine and S-methylcysteine were not detected in rat plasmas. The fall in plasma methionine was due to loss of cobalamin-dependent methionine synthetase activity. The rise in plasma serine may be due to decline in its metabolism via methenyltetrahydrofolate cyclohydrolase which is concerned in oxidizing the methenyl-carbon ( =CH-), initially derived as a methylene-carbon (-CH2-)from serine, to formate (-CHO).

Amino Acids↗
PubMed1981

Changes in plasma folate levels in rats inhaling nitrous oxide.

Inhalation of nitrous oxide, which inactivates vitamin B12, is followed by a rise in the plasma folate level. The concentration of plasma folate remains elevated throughout the period of exposure to nitrous oxide. Returning the rats to the air is followed by a fall to pre-exposure plasma folate levels within 24 h.

Animals↗
PubMed1981

Role of sulphasalazine in the aetiology of folate deficiency in ulcerative colitis.

Only two (2.5%) of 80 outpatients with histologically proven ulcerative colitis had folate deficiency associated with anaemia or macrocytosis. Mean folate absorption, measured using micrograms/kg body weight of a tritium-labelled physiological folate derivative, 5-methyltetrahydroteroylglutamic acid, in six newly diagnosed patients was 76.7% (normal greater than 95%) but fell to 69.4% after three months' treatment with sulphasalazine. Mean difference in individual patients was 7.5% +/- 5.2% (SD) (p less than 0.02). Mean folate absorption in four patients with megaloblastic anaemia or macrocytosis which developed during treatment with sulphasalazine was 66.3%. This rose to 82.4% after the drug was stopped. Mean difference in individual patients was 16.6 +/- 6.6% (SD) (p less than 0.001). All patients who developed anaemia or macrocytosis with sulphasalazine had additional reasons for folate deficiency. These included coeliac disease, severe nutritional deficiencies, and haemolysis. It was concluded that sulphasalazine impairs folate absorption but this only becomes significant if other reasons for folate deficiency are also present.

Adult↗
PubMed1981

EMG-force relationships in skeletal muscle.

This article reviews the history of attempts to define in quantitative terms the relationship between a processed electromyographic signal and the corresponding force produced by skeletal muscle. Numerous reports have indicated a linear relationship between isometric force and rectified, integrated EMG. These reports, the nature of their experiments, and the disagreements among them are reviewed. Particular attention is given to the effects of the signal processing in the final results, including type and location of electrodes, amplification, signal isolation, etc. The effect of joint position and level of muscular effort in the isometric case are discussed. Various proposed mathematical models of the force-EMG relationship are presented and analyzed. The concluding section of the paper summarizes the current areas of agreement and disagreement and comments on the feasibility of obtaining force-EMG relation in the presence of movement.

Animals↗
PubMed1981

Rocker shoe as walking aid in multiple sclerosis.

Evaluation of rocker shoes as a walking aid for multiple sclerosis patients included a mechanical analysis of the shoes, establishment of clinical criteria for appropriate patient selection, and laboratory gait measurements of patients with and without rocker shoes. Patient fitting demonstrated that the most significant measurement, the roll point, must be about 2cm proximal to the 1st metatarsal head. A snug fit as well as the addition of a heel strap was required to hold the shoe on the foot so its mechanical assistance was consistent. Rocker shoes were effective only in patients who still retained the ability to walk independently; retention of adequate hip and calf strength proved critical. Basic gait deficit was plantar flexion less than 15 degree while standing, leading to knee hypertension and forward trunk leaning, inadequate knee flexion and toe drag in swing, general awkwardness and fatigue. Gait improvement with the rocker shoes varied with clinical classification. Normal velocity and stride characteristic in rocker shoes were accompanied by a marked decrease in net energy cost. A mean saving of 150% of normal energy was gained with rocker shoes.

Adult↗