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Biomedical subjects

G Lyons

Publications and source records attributed to G Lyons.

At least 109 records · Page 6Linked to original sources
PubMed1985

A rapid, inexpensive, quantitative, general-purpose densitometer and its application to one-dimensional gel electrophoretograms.

We describe the construction of a densitometer based on a TV camera linked to an IBM personal computer (PC) using commercially available components. We discuss some of the problems of accurate quantitative densitometry using low-cost video systems, and describe the manner in which absolute optical density values may be recorded. We describe a digital analysis routine designed to quantitate unresolved bands on noisy one-dimensional electrophoretograms.

Costs and Cost Analysis↗
PubMed1985

Influences of testosterone on contractile proteins of the guinea pig temporalis muscle.

The present study outlines the changes in contractile proteins which occur during sexual differentiation of the guinea pig temporalis muscle. This is an androgen sensitive muscle, which in the female progresses from a fetal phenotype to a muscle rich in IIa fibers, and in the male, undergoes a further switch to an almost pure IIb fiber phenotype. We show the IIa to IIb transition in the male involves a change in myosin heavy chain synthesis (Figure 39), a corresponding change in the mobility of native myosin isozymes run on pyrophosphate gels (Figure 43), and changes in the proportions of the alpha and beta subunits of tropomyosin (Figure 41). Myosin light chains appear to be unaltered in this transformation.

Animals↗
PubMed1985

Failed intubation. Six years' experience in a teaching maternity unit.

Between 1978 and 1983, the tracheas of eight patients could not be intubated in the maternity unit of St James' University Hospital, Leeds. The incidence of failed intubation on our labour ward is approximately one for every 300 general anaesthetics given. The results of postoperative investigation in the patients are reported.

Adult↗
PubMed1985

Does plasma transferrin regulate iron absorption?

It has been suggested that transferrin that has recently donated its iron to receptor sites is 'activated' to take up iron more avidly from donor tissues. The hypothesis was tested in vitro in a system in which use was made of the different electrophoretic mobilities of normal and desialated transferrin. Recently desaturated transferrin and native apotransferrin were added in equal amounts to a solution of radioactive ferric citrate to produce various end saturations. The resultant mixture was electrophoresed on 5.4% polyacrilamide gel, which was then sliced and counted for 59Fe counts. The size of the 2 radioactive peaks was then compared and expressed as a ratio. Using this in vitro system no supporting evidence could be found for the hypothesis that diferric transferrin which has just donated its iron is able to bind available iron more avidly than native apotransferrin.

Apoferritins↗
PubMed1982

The influence of retinoids on cultivated human keratinocytes.

Cultured keratinocytes afford an excellent opportunity to study the influence of retinoids on the behavior of a stratified squamous epithelium and the interaction of keratinocytes with substrate. We have found that all-trans-retinoic acid retards the formation of colonies, dose not influence attachment, and causes increased shedding of cells from the cultures. Retinoids do not influence the relative abundance of the keratin polypeptides. Our observations are on human neonatal foreskin-derived keratinocytes grown in Dulbecco's modified Eagle medium containing 20% fetal bovine serum. Because fetal bovine serum contains vitamin A, our findings represent differences between low and high levels of vitamin A.

Cell Adhesion↗
PubMed1981

Biochemical changes in intervertebral disc degeneration.

The distribution of the principal matrix components, collagen, proteoglycans and water, across the diameter of human normal and degenerate intervertebral discs was compared. Little difference in collagen distribution was noted between normal and degenerate tissue but water and proteoglycan content decreased with degeneration, particularly in the centre of the disc. Proteoglycans of the nucleus pulposus and annulus fibrosus of normal and degenerate intervertebral discs were examined. In comparison with monomers of normal tissues, degenerate disc proteoglycans were of larger average hydrodynamic size and had a higher glucosamine to galactosamine ratio. Proteoglycans were digested with chondroitinase ABC and passed over an HS-Sepharose 2B affinity column. A greater proportion of the keratan sulphate-protein cores from degenerate disc were capable of interaction with the immobilized hyaluronate. Loss of aggregating ability was associated with diminution in size of the core. It is suggested that a large proportion of proteoglycans from normal disc have undergone a degree of degradation in the hyaluronate binding region and that proteoglycan synthesis in this tissue is slower than in degenerate tissue.

Adult↗
PubMed1979

Glycosaminoglycan synthesis by human chondrosarcoma.

Human chondrosarcoma of low-grade malignancy was cultured in the presence of 35S-sulphate and 3H-glucosamine. The glycosaminoglycans isolated were fractionated on Ecteola cellulose and electrophoresed on cellulose acetate membranes before and after treatment with chondroitinase AC or Streptomyces hyaluronidase. The results demonstrated the in vitro synthesis of hyaluronate, chondroitin sulphate and keratan sulphate. The presence of keratan sulphate of large average chain length (congruent to 15 monosaccharides) supports the contention that chain length of keratan sulphate is inversely proportional to the degree of malignancy.

Bone Neoplasms↗
PubMed1979

Maternal blood-gas tensions (PAO2-PaO2), physiological shunt and Vd/Vt during general anaesthesia for Caesarean section.

Measurements of maternal blood-gas tensions, (PAO2-PaO2), calculated pulmonary venous admixture (physiological shunt) and deadspace/tidal volume ratio (VD/VT) were made in 14 patients undergoing Caesarean section. Measurements were carried out after induction of general anaesthesia, and before delivery, with the patient tilted to the left. With a mean inspired oxygen concentration of 67.5% mean PaO2 was 44.3 kPa, mean (PAO2-PaO2) 18.4 kPa, mean Vd/Vt 32% and mean physiological shunt 9.5%. The findings are compared with published values for non-anesthetized pregnant patients.

Anesthesia, General↗
PubMed1978

Hyaluronate in articular cartilage: age-related changes.

Articular cartilage of fetal calves, calves, and steers together with normal and osteoarthrotic human cartilage was analyzed for hyaluronate. The hyaluronate content increased with maturation in healthy tissue, particularly in regions of maximum contact, but was low in diseased cartilage.

Aging↗
PubMed1976

Pulmonary valvulotomy under inflow stasis for isolated pulmonary stenosis.

One hundred ten patients were operated upon between 1961 and 1972 for isolated pulmonary stenosis by the inflow stasis technique. Analysis of the preoperative and postoperative clinical and catheterization data define the role of inflow stasis as an acceptable method of pulmonary valvulotomy except in relieving stenosis due to a dysplastic pulmonary valve. Patient ages ranged from 2 days to 36 years. All underwent preoperative catheterization and 69 (63%) were restudied postoperatively. Mean preoperative and postoperative peak systolic gradients were 93 and 23 mm Hg, respectively. Mean valve areas before and after operation were 0.38 and 1.10 cm2/m2. Operative mortality was 3.6% (4 patients), and there was 1 late death. Two of the dead were children 2 and 9 days old, respectively. Four patients required reoperation for residual gradients; 2 had dysplastic pulmonary valves. The overall results were excellent or good in 78%, fair in 15%, and poor in 7%. Patients with dysplatic pulmonary valves were in the poor or fair group, and it is recommended that the inflow stasis technique not be used for this type of pulmonary stenosis. The excellent surgical exposure, adequate time for valvulotomy, low morbidity, and freedom from problems of cardiopulmonary bypass are reasons for continued use of this technique for treatment of selected patients with pulmonary valve stenosis.

Adolescent↗
PubMedDate not supplied

Extraction and estimation of ATP from human spermatozoa.

This study attempts to provide guidelines for the extraction and estimation of ATP from spermatozoa. The conditions of extraction of ATP from spermatozoa using trichloroacetic acid were optimized. The efficiency of this extraction procedure was compared to that using boiling Tris buffer. Three commercially available kits which use the firefly luciferase assay for ATP and two luminometers were evaluated for the measurement of the spermatozoa extracts. Elevated levels of Mg2+ and/or Ca2+ did not interfere with the extraction of ATP by trichloroacetic acid or with the subsequent estimation of the nucleotide.

Adenosine Triphosphate↗
PubMedDate not supplied

An environmentalist's vision of operationalizing the precautionary principle in the management of chemicals.

In Europe and elsewhere, there is compelling evidence that humans, wildlife, and the environment are being damaged by man-made chemicals. Recognizing that regulatory initiatives are needed to try to prevent harm before it occurs in the future, the precautionary principle has become a focus of attention on both sides of the Atlantic. The authors suggest a way to implement the precautionary principle in the management of chemicals, outlining how this guiding principle can be given a practical relevance within regulatory initiatives to reduce the risks posed by chemicals currently traded in the European Union and elsewhere.

Commerce↗