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Biomedical subjects

P Oliver

Publications and source records attributed to P Oliver.

69 records · Page 4Linked to original sources
PubMed1983

Preservation of ultrastructure of cells cultured on protein-hydroxyethylmethacrylate hydrogels.

A method for studying the ultrastructure of cells grown on hydroxyethylmethacrylate (HEMA) hydrogels is described. Under normal conditions, HEMA hydrogels tend to swell when placed in hypotonic solutions and to shrink during alcohol dehydration. To overcome this severe swelling and/or shrinking, all solutions used during the fixation procedure are made in Puck's saline G, and dehydration is accomplished with a graded series of ethanol solutions prepared with Puck's saline G and polyethylene glycol. Infiltration of the sample with embedding material is achieved with the aid of a vacuum oven. Our findings suggest that the cells cultured on collagen hydrogels are ultrastructurally indistinguishable from those cultured on tissue-culture plastic. In addition, the unusual crater-like topography of the hydrogel can be utilized as an experimental aid in the study of cell attachment and spreading.

Acrylates↗
PubMed1981

Ultrastructural studies of a polygonal myofilament network in cultured rat aortic smooth muscle cells.

Cultured rat aortic smooth muscle cells (SMC) were examined by electron microscopy and found to contain polygonal networks of 75 A degrees thin myofilament bundles. The cells also had large bundles of longitudinally aligned thin myofilaments with periodically spaced dense bodies. Abundant plasmalemmal vesicles were present at the cell periphery, and the cells were connected by desmosomes. Intercellular spaces contained sparse amounts of elastic fibers, a material generally present in SMC cultures. Analyses of amino acids by automated column-chromatography showed that isodesmosine and desmosine, two amino acid residues unique for elastin, were present. Accordingly, it was concluded that polygonal networks, previously detected solely in cultured nonmuscle cells, were present in SMC. Other findings suggest 1) a change in myofilament arrangement takes place during cell migration, and 2) rat aortic SMC grown in tissue culture flasks is an important experimental tool in the study of cell motility since such myofilament rearrangements were observed to occur up to fourteen days in first passage.

Animals↗
PubMed1981

Formation of elastic fibers and elastin in rabbit aortic smooth muscle cell cultures.

Cultured rabbit aortic smooth muscle cells produce elastic fibers and elastin in their extracellular matrix. Morphological analyses of elastic fibers indicate that they consist of two distinct components which play a major role in elastic early fiber formation namely, the amorphous component and the "microfibrillar" component. During elastogenesis, the early fiber consists of small bundles of filaments. Later, clearly distinguishable small conglomerates of amorphous material are found distributed among the bundles of filaments. The mature elastic fibers have large conglomerates of amorphous material with the filaments present within the interstices. Long term cultures of these cells in the second passage continue to accumulate elastin. The crosslinking amino acid isomers desmosine and isodesmosine, which are unique to insoluble elastin, increase with time in culture. Twenty-four hour pulses with 14C-proline followed by measurements of 14C-hydroxyproline in the collagenase resistant protein of the cell layer show that the synthesis of insoluble elastin is constant up to the 14 week period studied from the time the amorphous material becomes evident ultrastructurally.

Amino Acids↗
PubMed1979

Intranasal approach to the sella turcica.

A transseptal approach to the sella turcica is described which is entirely intranasal and avoids the sublabial incision. The first incision is unilateral along the caudal edge of the septum, and the second incision is made across the base of the nasal columella. This allows the speculum to open the width of both nasal chambers, giving adequate exposure. The septal cartilage is either preserved or resected except for a caudal strut. The difficult dissection of mucosa from the nasal floor and maxillary crest is avoided. This technique is rapid and straightforward and results in a cosmetically acceptable scar.

Humans↗
PubMed1977

The effect of a drug-resistance factor on recombination and repair of DNA in Escherichia coli K12.

The presence in recipient strains of Escherichia coli K12 of the plasmid R46 greatly reduced the yield of recombinants from crosses with several Hfr strains and virtually abolished the formation of recombinants by PI transduction without, however, significantly affecting the transfer of the F prime from a strain carrying Fgal. The R46 plasmid had paradoxical effects on mutability: it appeared to enhance the yield of mutants following irradiation with ultraviolet ligh but it reduced the number of mutants detectable in unirradiated cultures. The effects of this plasmid on ultraviolet survival of the wild type and several mutants defective for recombination and repair have been measured and the results, in the main, confirm similar observation by Tweats et al. (1976). Not only is the survival of the strain habouring R46 greater than that of the parent strain in all the cases studied, but the survival of ultraviolet irradiated bacteriophage lambda is also greater.

DNA Repair↗
PubMed1977

A novel pleiotropic mutation in Escherichia coli K12 which affects transduction, transformation and rates of mutation.

A mutant strain of Escherichia coli K12, R2721, has been shown to differ from its parent strain, S491, in four associated phenotypic characters as a result of a single mutation. This strain did not give recombinants with DNA transduced by bacteriophage PI or bacteriophage Mu, nor transformats after exposure to R factor DNA: lysates of bacteriophage PI grown on this strain did not appear to contain any transducing particles when tested on normal recipients. Moreover, the reversion rates, both spontaneous and ultraviolet-induced, for two auxotrophic markers were reduced. The frequency of revertants was at least two orders of magnitude lower in cultures of R2721 than in cultures of S491I. Many of the rare revertants for one or other of the auxotrophic markers were found to have regained normal reversion frequencies for the other marker and for the capacity to be transduced. In all other respects, recombination in R2721 appeared normal, the frequency of chromosomal mobilization by and F' factor was unaffected and normal yields of recombinants were obtained from matings with Hfr strains. The only circumstance in which transduction of R2721 was observed was when the capacity to ferment galactose was selected and PI had been grown on a strain carrying lambdadgal when, presumably, integration was effected by the phage-coded gene products. The mutation has been located on the E. coli chromosone map between tonA and pro and has been given the symbol tdi (transduction inhibition). Double mutants, (tdi recA) and (tdi recB), have been isolated and show no unexpected properties.

Chromosome Mapping↗
PubMed1973

Mediastinoscopy.

Explore the source record for details and available documents.

Endoscopes↗
PubMedDate not supplied

Making a difference to practice: clinical benchmarking. Part 1.

In the first of two articles, the authors describe how an internal clinical practice benchmarking group was established in Preston to compare and share examples of best practice. The aim was to ensure consistent high standards of care practice across the trust. Activity related to discharge planning and visiting is used here to illustrate the effectiveness of clinical practice benchmarking as a continuous quality improvement tool. The second article will appear in Nursing Standard on May 3.

Benchmarking↗
PubMedDate not supplied

Making a difference to practice: clinical benchmarking. Part 2.

In the second of two articles, the authors explore further the use of clinical practice benchmarking. In particular, practice related to improving nutritional care for patients, caring for patients with mental health needs and safely transferring critically ill patients is examined. The authors conclude by summarising the value of clinical practice benchmarking and how it made a difference to practice in their trust. The first article appeared in Nursing Standard last week.

Acute Disease↗
PubMedDate not supplied

Making sense of ... head lice.

It is important to eradicate the myth that head lice affect only people with poor hygiene. This paper examines the treatment and management of head lice investigation.

Adolescent↗