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Biomedical subjects

G Barnes

Publications and source records attributed to G Barnes.

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

Determinants of gait performance following spinal cord injury.

Measurement of lower extremity muscle strength and the energy expenditure during walking was taken in 36 spinal cord injury patients to assess functional mobility. Patients were categorized according to the type of orthotic prescription (knee-ankle-foot orthosis [KAFO] or ankle-foot orthosis [AFO]) or upper extremity assistive device (cane, crutches, or walker) used during gait. The rates of O2 consumption per minute, O2 cost per meter, heart rate, respiratory quotient, velocity, cadence, and peak axial load exerted by the arms on upper extremity assistive devices were measured. The Ambulatory Motor Index (AMI), derived from the manual muscle grades of both lower limbs, was used as the indicator of the degree of paralysis. The AMI was strongly correlated with the percentage increase in the rate of O2 consumption above normal (p less than .0001), O2 cost per meter (p less than .0001), peak axial load (p less than .0001), velocity (p less than .0001), and cadence (p less than .0001). Differences in these parameters among patient groups categorized according to the type of orthotic prescription (no KAFO, one KAFO, two KAFOs) or upper extremity assistive device (no device, cane or one crutch, two crutches, or walker) were attributable to differences in the AMI. The AMI, therefore, could be used as a reliable clinical indicator of functional mobility after spinal cord injury.

Adult↗
PubMed1988

Evidence for Drosophila P element transposase activity in mammalian cells and yeast.

Drosophila P element transposase expression is limited to the germline by tissue-specific splicing of one of its three introns. Removal of this intron by mutagenesis in vitro has allowed both P element excision and transposition to be detected in Drosophila somatic tissues. In order to determine if P element transposase can function in other organisms, we have expressed modified P elements either lacking one intron or lacking all three introns in mammalian cells and yeast, respectively. Using an assay for P element excision, we have detected apparent excision events in cultured monkey cells. Furthermore, expression of the complete P element cDNA is lethal to Saccharomyces cerevisiae cells carrying a mutation in the RAD52 gene, indicating that double-stranded DNA breaks are generated, presumably by transposase action.

Animals↗
PubMed1988

Biomechanical basis of optimal scoliosis surgical correction.

For an optimal approach to surgical correction of scoliosis, it was deemed desirable to biomechanically simulate the set of corrective forces applied by alternative internal fixation systems, so as to determine and apply the internal fixation system producing the best correction under safe levels of forces applied by the fixation systems to the spinal structures. To this end, we have developed, and presented here, (1) a spinal finite-element model relating the applied corrective forces to the corrected spinal configurations, (2) a method for determining the stiffness of the patient's spine prior to surgery, (3) computerized finite-element analysis simulation of alternative internal correction-fixation systems, so as to determine the most efficacious system, (4) instrumentations for surgically implementing the recommendations of the surgical simulation analysis and (5) comparisons of the model-simulated and surgically-obtained corrected spinal configurations. These procedures together constitute the biomechanical foundations of scoliosis surgical correction.

Biomechanical Phenomena↗
PubMed1988

Oral rehydration in infantile diarrhoea in the developed world.

Acute diarrhoea is an important health problem in developed countries, particularly in young children. The attack rates for viral diarrhoea are similar in developed and developing countries. Rotavirus is the most common pathogen, followed by adenovirus. Bacterial diarrhoea is less common in developed than developing countries. The 2 most common bacterial pathogens are Campylobacter jejuni and Salmonella. The most serious consequence of diarrhoea is dehydration, and the treatment for this is the same whatever the pathogen. Recently, there have been major changes in the management of diarrhoea with emphasis on oral rehydration and early feeding. Two controversial areas are the sodium content of solutions designed for developed countries and the best route of administration of fluids to children with moderately severe dehydration. There have been 4 randomised controlled trials in developed countries comparing oral and intravenous rehydration. The findings have confirmed the experience in developing countries that most children without shock can be rehydrated orally, thus substantially reducing the need for intravenous fluids. It is important to give physiologically balanced solutions which contain 2% glucose and 50 to 90 mmol/L of sodium. Many of the commercially available oral solutions are appropriate for rehydration and maintenance of hydration in infants with diarrhoea of all types. They are recommended particularly for the prevention of dehydration in children of all ages with severe diarrhoea and for the treatment of dehydration. Children with mild diarrhoea and no dehydration can be given commercial clear fluids diluted with water, or homemade solutions made with table sugar and water. Salt must not be used. Babies should continue on breast milk or formula with extra water. Education is the key to successful oral rehydration, and the ultimate aim should be the prevention of dehydration.

Diarrhea, Infantile↗
PubMed1988

The postpolio syndrome. An overuse phenomenon.

Persons with good recovery of function following their initial poliomyelitis are now, more than 30 years later, experiencing new weakness, fatigue, and muscle pain. The likelihood of muscle overuse being the cause of this late functional loss was investigated by dynamic electromyography (EMG) and foot-switch stride analysis in 34 symptomatic patients. Manual testing grouped the muscles, with strong (S) encompassing Grades Good (G) and Normal (N) while weak (W) included Fair plus (F+) to zero (0). After testing quadriceps and calf strength, the patients fell into one of four classes: strong quadriceps and calf (SQ/SC), strong quadriceps and weak calf (SQ/WC), weak quadriceps and strong calf (WQ/SC), or combined weak quadriceps and calf (WQ/WC). Quantified EMG (normalized by the manual muscle test EMG) defined the mean duration and intensity of the quadriceps, soleus, lower gluteus maximus, and long head of the biceps femoris during walking. Overuse was defined as values greater than the laboratory normal (mean + 1 SD). Each muscle exhibited instances of overuse, normalcy, and sparing. The biceps femoris was the only muscle with dominant overuse (82%). Quadriceps overuse was next in frequency (53%). Soleus activity infrequently exceeded normal function (34%), but this still represented more than twice the intensity and duration of the other muscles. Gluteus maximus action was also seldom excessive (34%). The patients averaged two muscles with excessive use during walking. Gait velocity of the SQ/SC strong group was highest (71% of normal) while the three categories that included weak muscles had walking speeds in the range of 50% of normal. The finding of muscle overuse during a single free-speed walking test that does not attain normal velocity supports the concept of muscle overuse being the cause of the patient's dysfunction.

Adult↗
PubMed1988

Comparable energy expenditure after arthrodesis of the hip and ankle.

The energy expenditure and gait characteristics of eleven subjects who had a unilateral arthrodesis of the hip and ten subjects who had a unilateral arthrodesis of the ankle were measured during a twenty-minute walking trial. Oxygen consumption was determined and heart rate, respiratory rate, and step frequency were monitored. The average walking speed for both groups was sixty-seven meters per minute, which is 84 per cent of normal gait velocity. After an arthrodesis of the ankle, the average rate of oxygen consumption was 12.0 milliliters per kilogram of body weight per meter, which is 3 per cent more than normal. The oxygen cost averaged 0.166 milliliter per kilogram per meter, resulting in a gait efficiency of 90 per cent. After arthrodesis of the hip, the mean rate of oxygen consumption was 14.9 milliliters per kilogram of body weight per meter, which is 32 per cent greater than normal. The oxygen cost, 0.223 milliliter per kilogram per meter, represented a gait efficiency of 53 per cent. The physiological energy expenditure by the subject after an arthrodesis of the hip was found to be significantly greater than after an arthrodesis of the ankle and was more than that reported previously after a total hip arthroplasty for unilateral degenerative disease.

Adult↗
PubMed1987

Comparison of the MCMI and MMPI-168 as psychiatric inpatient screening inventories.

The Millon Clinical Multiaxial Inventory (MCMI) has been recently developed as an alternative to the Minnesota Multiphasic Personality Inventory (MMPI) and shares some of its psychometric advantages and disadvantages with the MMPI-168, a short form of the MMPI. The current study compared the structure and utility of the MCMI and MMPI-168 for a general hospital inpatient psychiatric population. Overall, the two instruments were highly correlated and found to have conceptually similar factor structures. Empirical comparison of the factor structures indicated that construct validity is greatest for neurotic traits. Both instruments demonstrated a similar utility in predicting discharge diagnosis.

Adolescent↗
PubMed1986

Perinatal dietary exposure to soy lecithin: altered sensitivity to central cholinergic stimulation.

The effects of perinatal exposure to soy lecithin preparation (SLP) on the development of cholinergic responses in the rat brain were examined by assessing the ability of intracisternally administered carbachol to stimulate 33Pi incorporation into phospholipids in vivo, an effect of carbachol mediated by muscarinic cholinergic receptors. Maternal intake of SLP produced a suppression of the cholinergic response in the offspring, an effect which was specific in that basal (unstimulated) incorporation rates were not reduced (in fact, they eventually became elevated), nor was the response to another neurotransmitter (dopamine) compromised. The effect occurred early in the preweanling stage, a period in which SLP exposure also enhances development of cholinergic nerve terminals. These results suggest that SLP exposure has a major effect on cholinergic synaptic development and reactivity, followed by secondary changes in other neurotransmitter pathways and by more generalized effects on basal membrane phospholipid turnover.

Animals↗
PubMed1986

The chronic mental patient and community psychiatry: a system in trouble.

In Canada, as elsewhere, there has been a shift away from institutional care toward community care for chronic mental patients. This transition has not occurred without some difficulties arising. In this paper, various major issues pertaining to the care of chronic mental patients in the Canadian health care system are discussed, including problems associated with deinstitutionalization; the defining characteristics and epidemiology of chronic mental illness in Canada; and the debate over the optimal setting in which to provide housing and treatment for chronic mental patients.

Canada↗
PubMed1986

Biomechanical analysis and simulation of scoliosis surgical correction.

In scoliosis, presurgical determination of each patient's segmental spinal stiffness will permit model simulation of the surgical correction. It also permits calculation of the optimal combination of corrective forces applied to the spine by the internal fixation system. This information can help to optimize the surgical procedure, especially if calculated forces and corrections can be monitored during surgery. To this end, a finite-element model of the spine has been developed that determines segmental stiffness from data of spinal geometries, derived from the radiographs of the patient, taken with incremental distraction applied to the head. On this model, custom-tailored combinations of corrective forces are applied incrementally until optimal correction is obtained, for safe levels of distraction and lateral forces. With variations in the computer software, any desired surgical instrumentation system can be simulated. Instrumented distractor and compression forceps have been fabricated to monitor surgical forces and displacements, and to permit eventual implementation of the model recommendations. Comparison of surgically acquired correction with that predicted by the model is then carried out. Data on complete analysis of two cases of idiopathic scoliosis are presented. They show significant variations in segmental and interpatient stiffness values, and how spinal stiffness governs the amount of correction gained by the nature and magnitude of corrective forces.

Adult↗
PubMed1985

Severe illness caused by the products of bacterial metabolism in a child with a short gut.

An 8-year-old boy with a short gut had six episodes of metabolic acidosis and neurological dysfunction over a 1 month period. The neurological features consisted of a depressed conscious state, confusion, aggressive behaviour, slurred speech and ataxia. The organic acid profile of urine demonstrated increased amounts of lactic, 3-hydroxypropionic, 3-hydroxyisobutyric, 2-hydroxyisocaproic, phenyllactic, 4-hydroxyphenylacetic and 4-hydroxyphenyllactic acids. Of the lactic acid 99% was D-lactic acid. The anaerobic gut flora consisted almost entirely of Lactobacilli in unusually large numbers. A course of vancomycin prevented further episodes. A urinary organic acid profile may be diagnostic when a person with a short gut develops metabolic acidosis or an unusual encephalopathy and bacterial metabolites should be considered in other patients with unusual combinations of organic acids in the urine.

Acidosis↗
PubMed1985

Regulated expression of endonuclease EcoRI in Saccharomyces cerevisiae: nuclear entry and biological consequences.

In an investigation to determine how proteins are localized within the nucleus of a cell, we demonstrate that the restriction endonuclease EcoRI is able to enter and function within the nucleus of Saccharomyces cerevisiae when this prokaryotic protein is synthesized in vivo. The EcoRI endonuclease was produced in yeast under the transcriptional control of a regulated yeast promoter by ligating a DNA fragment containing only coding sequences for the endonuclease to the promoter element of the yeast GAL1 gene (the structural gene for galactokinase, EC 2.7.1.6). Yeast cells harboring a plasmid containing this promoter-gene fusion are able to grow under conditions that repress transcription from the GAL1 promoter. However, under inducing conditions, these yeast cells are unable to grow. Moreover, rad52 mutants, which are deficient in the repair of double-strand breaks, are more sensitive to the presence of the promoter-gene fusion plasmid than are wild-type cells. We demonstrate that the EcoRI endonuclease activity is present in lysates prepared from yeast transformants grown under conditions that induce transcription of GAL1, but this activity is not detectable in cells grown under conditions that repress transcription from the promoter. Furthermore, analysis of yeast chromosomal DNA shows that the endonuclease enters the yeast nucleus and cleaves DNA specifically at EcoRI recognition sites.

Biological Transport↗
PubMed1985

Urinary catecholamines in essential hypertension: results of 24-hour urine catecholamine analyses from patients in the Medical Research Council trial for mild hypertension and from matched controls.

Four consecutive 24-h urine samples were collected from 134 male and 134 female placebo-treated patients in the Medical Research Council Trial for Mild Hypertension. Similar samples were collected from age and sex-matched normotensive controls. On the fourth day noradrenaline excretion was 22.05 +/- 1.01 nmol/mmol creatinine in the hypertensives compared with 22.22 +/- 1.16 nmol/mmol creatinine in the controls. Adrenaline excretion on the same day was 6.13 +/- 0.33 nmol/mmol creatinine in the hypertensive subjects compared with 6.32 +/- 0.38 nmol/mmol creatinine in the controls. There was no significant difference for either catecholamine between the two groups. However, in the control group there was a highly significant correlation between excretion of adrenaline and systolic blood pressure (r = 0.218, p = 0.0004) and between noradrenaline excretion and systolic blood pressure (r = 0.200, p = 0.001). Catecholamine excretion and blood pressure were not significantly correlated in the hypertensive patients. There were no significant correlations in either group between catecholamine excretion and heart rate, caffeine intake, nicotine consumption or the Bortner self-assessment score of personality type. This study has found no evidence of elevated sympathoadrenal activity in mild hypertensives. The correlations in the control group may reflect the role of sympathoadrenal activity in acute fluctuations in blood pressure or may suggest that the level of blood pressure within the 'normal' range depends in part on the level of sympathoadrenal activity.

Adult↗
PubMed1984

Ceruloplasmin receptors of erythrocytes.

Mammalian erythrocytes have been shown to bind 125I labeled ceruloplasmin. Binding was reversible and specific. Scatchard analysis yielded linear plots with a Kd of approximately 5nM. The binding site appeared to be a protein located on the cell surface. A ceruloplasmin binding protein with a molecular weight of 60,000 daltons was isolated from human erythrocytes. Erythrocytes which were not protected by ceruloplasmin's antioxidant properties, did not bind ceruloplasmin. Our results provide evidence for the presence of ceruloplasmin receptors in the erythrocyte membrane. It is proposed that the antioxidant activity of ceruloplasmin may play a role in determining the lifespan of circulating red cells.

Animals↗
PubMed1984

Inhibition of ceruloplasmin and other copper oxidases by thiomolybdate.

The dietary antagonism between copper and molybdate salts prompted a study of the inhibition of copper enzymes by thiomolybdate (TM). TM strongly inhibited the oxidase activity of five copper oxidase with I50% values in the 1-5 microM range. The mechanism of the TM effect on the copper oxidase, ceruloplasmin (Cp) (E.C. 1.16.3.1), was studied in detail. In Vmax vs. E plots, TM gave parallel data suggesting irreversibility but a large number of TM molecules per Cp were required. The inhibition of Cp by TM could not be reversed by dialysis. Isolation of TM-inhibited Cp on Sephadex G-10 did not yield any active Cp molecules. Cu(II) did not restore any inhibited oxidase activity. Gel electrophoresis supported the covalent binding of Cp by TM without any extensive change in protein structure. EPR results confirmed that Cu(II) is reduced to Cu(I) after reaction with TM. However, the Mo(VI) in MoS4(2-) did not change in oxidation number. Analysis of the TM-Cp compound accounted for all six Cu atoms as found in native Cp. The data suggest the covalent binding of sulfide to Cp copper. TM also inhibited the activity of ascorbate oxidase, cytochrome oxidase, superoxide dismutase, and tyrosinase. However, no inhibition of carbonic anhydrase, a zinc enzyme, was observed at 1 mM TM.

Animals↗