PubMed Health⌕ Search

Biomedical subjects

D J Nicol

Publications and source records attributed to D J Nicol.

At least 19 recordsLinked to original sources
PubMed1998

Variability of the dishabituation of flexion reflexes for FES assisted gait in spinal injured man.

Flexion reflexes, elicited by surface stimulation, can be used to produce a simple form of stepping in spinal cord injured (SCI) humans. A drawback of this approach is a decreasing magnitude of flexion reflex to repeated presentations of the stimuli (habituation). Pilot data indicated that high intensity stimulation could produce dishabituation of the reflex. The aim of this study was to examine and quantify the inter- and intra-subject variability of the short and long term conditioning effect of high intensity stimulation on the magnitude of flexion reflexes in a larger number of SCI subjects. Dishabituation was observed in all subjects, however the amount of dishabituation observed was small and highly variable. However the use of high intensity conditioning stimulation may offer a means of coping with habituation in a small number of subjects.

Electric Stimulation Therapy↗
PubMed1998

The effects of skin brushing on H reflex amplitude in normal human subjects.

Experiments were performed on twenty-two neurologically normal subjects in order to investigate the effects of skin brushing on H reflex excitability in triceps surae. H reflex amplitude was observed to decrease during brushing of a 2 cm x 10 cm area of skin overlying triceps surae, returning to control levels when brushing ceased. Alterations in the duration of the brushing period did not affect the magnitude of the H reflex inhibition, although increased frequency of brush strokes per minute slightly increased the amount of inhibition observed. Brushing of smaller skin areas overlying the muscle only sometimes resulted in H reflex inhibition. Brushing over other skin areas of the lower limb produced only slight effects on triceps surae H reflex amplitude. Removal of cutaneous input from the skin overlying triceps surae abolished any effects of brushing in this area on H reflex amplitude. These results demonstrate an inhibitory effect of brushing on H reflex excitability in normal subjects. If such results are confirmed in subjects with neurological deficit, they could have implications for the use of brushing in clinical practice.

Adult↗
PubMed1995

Evidence for a human spinal stepping generator.

Flexion reflexes elicited by surface stimulation in spinal cord-injured man have been used to provide limb flexion in gait restoration. In this study, the pattern of the flexion reflexes observed in one subject supports the theory that a spinal stepping generator exists in man.

Accidents, Traffic↗
PubMed1994

Thiamin status in pregnancy as determined by direct microbiological assay.

Serum and red cell thiamin levels were assayed on a group of pregnant Australian women using an automated direct microbiological assay with Lactobacillus fermenti as the test organism. Two of 103 (1.9%) had serum thiamin levels below the reference range and 2 of 67 (3.0%) were found to have red cell thiamin levels below the reference range. Although the mean serum levels between trimesters were not significantly different, there was a significant decrease in the mean red cell thiamin in the third trimester. Repeat red cell thiamin assays on some of the women a number of weeks after the initial assay revealed a decrease ranging from 17.5% to 35.4% with a mean reduction of 27.8%.

Adolescent↗
PubMed1993

Improving limb flexion in FES gait using the flexion withdrawal response for the spinal cord injured person.

In the restoration of gait for paraplegics using functional electrical stimulation, the method most commonly used to produce hip flexion for the swing phase of gait has been the elicitation of the flexion withdrawal response. Several problems have been noted with the response: there is a decrease in the magnitude of the hip flexion to repeated stimuli (habituation); long latency; and inhibition of the response when stimulated bilaterally. These have been characterized and methods for overcoming the problems tested. Results show that increasing stimulation frequency reduces latency. Habituation can be reduced in some subjects by multiplexing two sites of stimulation. Habituation can further be reduced by applying single high-intensity pulses and this has been used in a one-step-ahead controller for regulating hip flexion angle. Inhibition due to bilateral stimulation had been significantly reduced by altering the timing of the stimulation to the two legs.

Adult↗
PubMed1993

Absorption of pteroylpolyglutamates in mothers of infants with neural tube defects.

The ability to hydrolyse and absorb pteroylpolyglutamates (PteGlun) included in a standard meal in mothers who had given birth to an infant with a neural tube defect was tested by comparing them with mothers who had not had any infants with this defect. When compared with control mothers working in the research unit in which the study was performed, case mothers had significantly lower baseline serum and erythrocyte folate levels, and smaller increases in serum folate following the meal containing PteGlun. However, all estimates of folate were similar when case mothers were compared with a group of mothers who were friends of the case mothers. The results show that the higher the baseline levels of serum and erythrocyte folate the greater the increase in serum folate after the test meal. Fitting a model for the serum folate response curve resulted in coefficients which differed significantly between case mothers and all control mothers. We conclude that intestinal hydrolysis of PteGlun taken orally is not impaired in mothers who have had infants with neural tube defects when compared with control mothers with similar baseline folate levels, although the curves describing the response to the meal for the two groups do differ significantly. Further investigation is required to determine the mechanism underlying this difference.

Adult↗
PubMed1991

Dishabituation of the flexion reflex in spinal cord-injured man and its application in the restoration of gait.

The flexion withdrawal reflex, evoked by surface electrical stimulation, has been used to provide hip flexion for the restoration of gait in paraplegics. A major limitation to its use has been the decrease in the magnitude of the response to repeated stimulation (habituation). In this study it was found that by using high intensity stimulation the response could be dishabituated. It was demonstrated that sufficient hip flexion for functional electrical stimulation-assisted gait was maintained using high intensity pulses in a one-step-ahead controller.

Adult↗
PubMed1988

Folic acid.

Explore the source record for details and available documents.

Animals↗
PubMed1983

A simplified colorimetric method for the measurement of glycosylated hemoglobin.

A colorimetric method for the measurement of glycosylated hemoglobin is described. The method is based on the detection of hydroxymethylfurfural liberated from the ketoamine-linked hexose of glycosylated hemoglobin. Rapid hydrolysis is achieved by heating at 120-124 degrees C under pressure, and simplification of the procedure enables the test to be performed in one disposable test tube. Standardization is by means of easily prepared lyophilized human hemoglobin preparations. The test has proven to be reliable and economical in routine use.

Chromatography↗
PubMed1980

Association of retinopathy and glycosylated haemoglobin levels in diabetes mellitus.

One hundred and forty patients with diabetes mellitus were examined in the small mining town of Kalgoorlie, Western Australia. The primary object was to determine the incidence of retinopathy in the diabetic community. One hundred and thirty-eight sets of data were obtained. There were 69 males and 69 females. The diabetes was controlled with orally administered hypoglycaemic agents in 62 patients, in 58 patients with insulin, and in 18 by diet alone. Forty-six of the 138 volunteers (33%), were found to have retinopathy and this included eight of the 14 Aboriginals taking part in the survey. Glycosylated haemoglobin levels ranged from 8.1% to 18.8% (mean 11.7%; SD; 2.28%) of total haemoglobin concentration, and plasma glucose levels from 1.2 mmol/L to 27.3 mmol/L (mean, 9.5 mmol/L, SD, 5.06 mmol/L); there was a positive correlation between levels of glycosylated haemoglobin and plasma glucose (r = 0.63; P less than 0.001). Diabetics with retinopathy had a mean glycosylated haemoglobin level of 12.5% compared with 11.3% in those without this complication. Examination by treatment groups showed that patients with retinopathy whose disease was controlled with insulin had significantly higher levels of glycosylated haemoglobin compared with those without this complication (0.01 greater than P greater than 0.001). Patients whose disease was controlled with orally administered hypoglycaemic agents did not show this difference.

Adolescent↗
PubMed1979

A rapid method for the quantitation of haemoglobin A2.

A rapid accurate and inexpensive technique for the measurement of haemoglobin A2 has been devised. It uses a small plastic device which embodies a miniature chromatographic column and reservoirs for the eluting buffer and eluates. The device is charged with whole blood, pH 8.25 buffer and centrifuged. The eluate is removed and the centrifugation repeated using pH 7.0 buffer to remove the remaining haemoglobin. The haemoglobin concentration in the 2 volumes of eluates is measured in a spectrophotometer at 414 nm and the percentage of HbA2 calculated. Results are similar to those obtained by standard methods.

Adolescent↗