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Biomedical subjects

R A Gibson

Publications and source records attributed to R A Gibson.

126 records · Page 7Linked to original sources
PubMed1983

Dietary lipid modulation of rat liver mitochondrial succinate: cytochrome c reductase.

Diets supplemented with high levels of either saturated fatty acids or unsaturated fatty acids were fed to adult rats for a period of 9 weeks and changes in the liver mitochondrial membrane phospholipid fatty acid composition and thermal behaviour of succinate: cytochrome c reductase were determined. The dietary treatment induced a change in the omega 6 to omega 3 unsaturated fatty acid ratio in the membrane lipids, with the ratio being highest with the unsaturated fatty acid and lowest with the saturated fatty acid diet. Arrhenius plots of succinate: cytochrome c reductase activity exhibited differences in both critical temperature (Tf) and Arrhenius activation energy (Ea) depending on the type of dietary treatment. The Tf was elevated from 23 degrees C in control to 32 degrees C in the saturated fatty acid-supplemented group. No significant effect on the Tf was observed in the unsaturated fatty acid-supplemented group however higher Ea values were observed due to the unsaturated fatty acid diet. The changes in succinate: cytochrome c reductase are probably due to changes in the lipid-protein interactions in the membrane, induced by the dietary lipid supplementation.

Animals↗
PubMed1983

Thermal phase transitions in sheep, rat and rabbit surfactant lipids detected by differential scanning calorimetry.

1. The thermal behaviour of sheep, rat and rabbit pulmonary surfactant lipids was investigated using high sensitivity differential scanning calorimetry (DSC). 2. Phase transitions were evident in the surfactant lipids from all three animals, with the upper limit of the phase transition being 30.1 C in the sheep, 36.8 C in the rat and 36.3 C in the rabbit. 3. The relatively greater fluidity of the sheep surfactant lipids in comparison to those of the rat and rabbit was due primarily to differences in their palmitic acid content.

Animals↗
PubMed1981

Fatty acid composition of human colostrum and mature breast milk.

The fatty acid composition of human milk obtained on individual samples from 120 mothers early (day 3 to 5) and later (day 40 to 45) in lactation were determined by argentation thin-layer and gas chromatographic procedures. In comparison with mature milk, human colostrum was characterized by a lower percentage of saturated fatty acids including medium chain length acids, a higher percentage of monounsaturates, and a lower level of linoleic and linolenic acids, but a higher percentage of their long chain polyunsaturated derivatives. It is concluded that in view of their levels in breast milk, the polyenoic derivatives of linoleic and linolenic acids must be taken into account when assessing infant foods.

Chromatography, Gas↗
PubMed1981

Reduction of corneal sensitivity after retinal detachment surgery.

Corneal sensitivity measurements were performed on both eyes of 57 patients after they were subjected to unilateral retinal detachment surgery, the unoperated eyes acting as controls. A marked decrease in corneal sensitivity was found in eyes that were treated with encircling bands, but no significant change of sensitivity could be detected in eyes in which localised radial or circumferential silicone sponge explants alone had been employed. It would appear that encirclement procedures lower the sensitivity of the cornea, and this may continue as a long-term effect.

Adolescent↗
PubMed1980

Effect of sampling on fatty acid composition of human colostrum.

Samples of colostrum were taken from 19 subjects before and after infant feeding, 3 and 5 days post partum. Milk samples were analyzed by argentation and gas chromatography for 30 fatty acids contained in the lipid fraction. Although small differences were observed between day 3 and day 5 samples, the fatty acid composition of the milk did not vary on either of the days between samples taken before and after nursing. It is concluded that a single sample taken any time during the feeding is representative of the entire nursing.

Colostrum↗
PubMed1980

Observer variation in ophthalmology.

Data collected by clinicians and nurses from patients with clinically diagnosed lens opacities revealed that there was poor repeatability of the description of the position of lens opacities, statistically significant observer variation in determining visual acuity, and good repeatability as to what visual tasks the patient can perform. It is suggested that clinicans should give more weight to the visual handicap revealed by performance of visual tasks in making a decision for cataract surgery than at present.

Activities of Daily Living↗
PubMed1976

Purification of gibberellic acid-induced lysosomes from wheat aleurone cells.

Using isopycnic density gradient centrifugation, lysosomes were concentrated in a single region of a sucrose-Ficoll gradient (p = 1-10 g cm-3), well separated from most other cell organelles. Gibberellic acid-induced lysosomes were found to be rich in alpha-amylase and protease but not ribonuclease. The lysosomal band also contained a majority of the NADH2-cytochrome c reductase, a marker enzyme for endoplasmic reticulum, found in the gradient. Examination of electron micrographs revealed that a purified band of lyosomes contained at least 3 vesicle types, ranging in size from 0-1 to 0-5 mum. The significance of these findings to proposed mechanisms of action of gibberellic acid is discussed.

Amylases↗
PubMed1972

Lysosomal nature of hormonally induced enzymes in wheat aleurone cells.

The subcellular distribution of the enzymes alpha-amylase, protease and ribonuclease in wheat aleurone layers after treatment with gibberellic acid was determined by differential centrifugation. Of the alpha-amylase 56% was precipitable from cell homogenates, indicating that it is a particulate enzyme. Similar results were recorded with protease. Particulate alpha-amylase showed distinct structural latency, and membrane-rupturing mechanical or chemical treatments were required to release the enzyme in an active form; the results were completely analogous to results with lysosomal enzymes found in animal tissues. The identification of the hormonally induced enzymes as lysosomal suggests that the hormonal mechanism may be more closely associated with extracellular enzyme synthesis rather than with nucleic acid metabolism.

Amylases↗
PubMedDate not supplied

Implementing a councilor model: process and outcomes.

The councilor model of shared governance was implemented at the Central Arkansas Veterans Healthcare System in January 1995. The goal was to reduce, eliminate, and consolidate nursing committees, enhance communication, and increase the decision-making abilities and opportunities of staff members. A study was conducted to determine the perceptions of the nursing staff relative to the culture of the organization after implementation of the model. The authors describe the process and outcomes of the resulting performance improvement processes, organizational redesign, and outcomes of this initiative.

Arkansas↗
PubMedDate not supplied

Relationships between pulmonary function and plasma fatty acid levels in cystic fibrosis patients.

Nineteen patients with cystic fibrosis (CF) were studied to determine whether plasma fatty acids correlated with severity of their lung disease as assessed by pulmonary function testing. Results were compared with 19 normal subjects of similar age and sex. Linoleic acid content of all lipid fractions was significantly lower in CF patients than controls including cholesterol ester fraction (CF 31%, control 50%, p less than 0.001), triglyceride fraction (7.6 to 16.6%, p less than 0.001), and phospholipid fraction (13.9 to 21.7%, p less than 0.001). Mean 20:3 omega 9/20:4 omega 6 ratio for CF patients was higher in all lipid classes and was suggestive of essential fatty acid deficiency. Correlations were found to exist between most pulmonary function parameters and fatty acids of plasma phospholipids but not any other lipid class. Positive correlations were found between all ventilatory tests and total omega 3 polyunsaturated fatty acids and also 22:5 omega 3 and 22:6 omega 3. There was no correlation between total saturated fatty acids, total monounsaturates, total omega 6 fatty acids, or triene/tetraene ratios and pulmonary function. Positive correlations were found between pulmonary function parameters and certain omega 6 polyunsaturates including 20:4 and 22:4 but not 18:2.

Adolescent↗
PubMedDate not supplied

Decreased lung surfactant disaturated phosphatidylcholine in sudden infant death syndrome.

The lipid composition of lung surfactant obtained by lung lavage at autopsy in 40 infants dying from the sudden infant death syndrome (SIDS), was compared to that obtained from 12 infants dying from other causes (control group). Analysis of the lipids from the two groups showed no major difference in the proportions of the various phospholipid classes particularly the predominant component, phosphatidylcholine (PC), which was present at 60.7 +/- 0.9% (mean +/- S.E.) of the total phospholipids in the SIDS group and 57.9 +/- 2.9% in the control group. However the proportion of the PC present as the disaturated form (DSPC), was significantly (P less than 0.01) reduced in the SIDS group (65.8 +/- 1.6%) in comparison to the control group (77.4 +/- 3.5%). The proportion of DSPC present in the PC fraction of SIDS infants in the high-risk age range of 1-26 weeks (63.9 +/- 1.9%) was also significantly reduced (P less than 0.01) in comparison to the total control group of infants. For infants older than 26 weeks, significant differences in the proportion of DSPC in PC were not observed between SIDS and control groups. A functional consequence of the observed reduction in the DSPC content of lung surfactant of SIDS infants could be a greater degree of fluidity of the surfactant, particularly at exhalation. Such a biophysical change in surfactant properties could have a profound influence on lung function and be a causative factor in sudden infant death.

Age Factors↗
PubMedDate not supplied

Somatic mosaicism in Fanconi anemia: molecular basis and clinical significance.

Approximately 25% of patients with Fanconi anemia (FA) have evidence of spontaneously occurring mosaicism as manifest by the presence of two subpopulations of lymphocytes, one of which is hypersensitive to cross-linking agents (e.g. mitomycin C) while the other behaves normally in response to these agents. The molecular basis of this phenotypic reversion has not yet been determined. We have investigated 8 FA patients with evidence of mosaicism. Epstein-Barr virus-immortalized lymphoblastoid cell lines established from these patients exhibited an IC50 for mitomycin C of 25 to > 100 nM compared to a mean of 2 +/- 2 nM for 20 nonmosaic FA patients and 49 +/- 11 nM for 8 healthy controls. In 3 patients who were compound heterozygotes for pathogenic FAC gene mutations the molecular mechanism of the mosaicism was investigated by haplotype analysis. The results indicated that an intragenic mitotic recombination must have occurred leading to a segregation of a wild-type allele in the reverted cells and suggested two patterns of recombination. In 1 patient a single intragenic crossover between the maternally and paternally inherited mutations occurred associated with markers located distally to the FAC gene; in the other 2 patients (sibs) the mechanism appears to have been gene conversion resulting in segregants which have lost one pathogenic mutation. In 6 of the 8 patients the hematological symptoms were relatively mild despite an age range of 9-30 years.

Adolescent↗