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Biomedical subjects

P Edwards

Publications and source records attributed to P Edwards.

At least 127 records · Page 7Linked to original sources
PubMed1989

The neurological features of early and 'latent' human immunodeficiency virus infection.

Neurological manifestations of unknown cause occurring in patients who become or are HIV antibody positive with presumed normal immune function have been described recently. This report adds a further six cases, all of whom had normal CD4+ cell counts either throughout the period of observation or after the episode of seroconversion. Three had an acute presentation, two in the context of documented seroconversion consisting of one of the following: an encephalitis, an ataxia, and confusion with neuralgic amyotrophy. Three had a subacute disorder occurring at a later phase of HIV infection but before opportunistic infections or neoplasms, and marked by a static mild cognitive deficit. This report extends the range of abnormalities that may be seen at seroconversion and documents the presence of a non-progressive cognitive deficit occurring in the latent phase of HIV infection.

AIDS Dementia Complex↗
PubMed1989

Determination of plasma pyridoxal phosphate levels using a modified apotryptophanase assay.

The development of a simple non-isotopic enzymatic assay for plasma pyridoxal phosphate (PLP) using a modified apotryptophanase procedure is reported. Recovery of added PLP from plasma was 86% and the within-run precision of the assay was 6.5%. Between-run precision was 7.5%. Concentrations of cupric ions as low as 20 mumol/L severely inhibited apotryptophanase activity and this effect of copper was almost completely prevented by the addition of EDTA. The reference plasma PLP range obtained by the apotryptophanase method was found to be between 5 and 50 micrograms/L plasma, with a mean of 17 +/- 10 micrograms/L plasma. The assay requires minimum technical skill and, with the aid of a multisample reaction rate analyser, more than 50 samples could easily be handled within a working day.

Apoenzymes↗
PubMed1989

Characterisation of the first monoclonal antibody against the pronase resistant core of the Alzheimer PHF.

A monoclonal antibody, NOAL 6.423 has been produced which unequivocally identifies a protein which is a constituent of the pronase resistant core of the Alzheimer PHF. Although the site recognised by this antibody is contained somewhere within the highly conserved triple repeat region of the tau molecule, no experiments have succeeded so far in demonstrating NOAL 6.423 reactivity in any brain proteins other than those derived from PHFs. A site which can be recognised by NOAL 6.423 cannot be generated in preparations of normal porcine tau by simple proteolytic cleavage with pronase. Likewise reactivity with the PHF peptide recognised by NOAL 6.423 is not altered by alkaline phosphatase. The unusual properties of NOAL 6.423 are consistent with the possibility that its recognition site is not determined solely by the primary structure of the conserved region of the tau molecule.

Alzheimer Disease↗
PubMed1989

Measurement error in assessing the size of posterior subcapsular cataracts from retroillumination photographs.

Twenty-six eyes with posterior subcapsular opacities of various sizes were photographed with the Neitz-Kawara Retroillumination camera. The outline of the opacity in a single photograph of each opacity was traced onto a transparent plastic overlay twice by two independent outliners. Two methods were used to estimate the area within the outlines of the opacities. In the first, a transparent overlay with a standard grid was used to count the number of boxes within the outlines. The second method used computer planimetry to estimate the area within the tracings. We estimated the measurement error associated with a single outlining of an opacity and the contribution of the measurement error to overall sample size requirements in studies comparing the mean areas of posterior subcapsular opacities. Variability in the measurement techniques contributed fewer than 20 additional subjects to overall sample size estimates, a small contribution to total sample size requirements in most studies. An outliner's inherent variability in outlining an opacity was a much larger contributor to the measurement error than was variability in assessing the area of the outline of the opacity. While within outliner variability was similar for the two persons outlining the opacities, there were systematic differences in the way the two traced the outlines. Variability from the use of separate photographs of the same opacity taken by different photographers was minimal.

Cataract↗
PubMed1989

A simple liquid-chromatographic method for measuring vitamin B6 compounds in plasma.

This relatively simple high-performance liquid chromatographic (HPLC) method for measuring all seven known forms of vitamin B6 in plasma from individuals supplemented with pyridoxine hydrochloride shows good analytical recovery (85-98%) and precision. Within-run and between-run CVs for plasmas supplemented with standards were 4% and 7%, respectively. The major forms of B6 found in unsupplemented plasma from normal subjects were pyridoxal phosphate and 4-pyridoxic acid, with pyridoxal just detectable. The HPLC procedure correlated well (r = 0.94) with a modification of an enzymatic method involving apotryptophanase (Anal Biochem 1972;45:567-76) for measuring plasma pyridoxal phosphate, and also (r = 0.94) with a routine method for determining 4-pyridoxic acid in urine (Clin Chem 1964;10:479-89). Elimination of pyridoxine from the plasma of both normal and hyperoxaluric individuals was shown to be very rapid, with half-lives (t1/2) of 45 and 40 min, respectively. Finally, we present evidence for the existence of two other forms of B6 and discuss the possibility of a new metabolic pathway in vitamin B6 metabolism.

Chromatography, High Pressure Liquid↗
PubMed1988

Viability of ligaments after freezing: an experimental study in a rabbit model.

Our purpose in this study was to assess ligament fibroblast viability after freezing by quantifying the subsequent ability of fibroblasts to synthesize collagen in vitro. Both medial collateral ligament (MCL) complexes from 40 adolescent rabbits were studied. Collagen production was determined by in vitro incubation of ligaments in 3H-proline (a collagen precursor) and subsequent analysis of 3H-hydroxyproline (a marker of newly synthesized collagen). Autoradiographs determined the distributions of ligament cell activity. All right MCL complexes served as fresh controls, providing a baseline of collagen production. Each left MCL was assigned to an experimental group and was either incubated fresh (10 animals); "killed" by drying, multiple freeze thawing, or cycloheximide (six animals); or slowly frozen at -70 degrees C without cryoprotection (24 animals). Collagen production of rapidly thawed ligaments was studied by proline incubation at 1 day, 9 days, or 6 weeks after freezing and was compared with that of contralateral fresh controls. Results demonstrate that some cells in the substance of these rabbit ligaments retained the ability to synthesize collagen in vitro after being frozen for up to 6 weeks. Mean collagen production of frozen ligaments was decreased, but tests of mean and median values as well as ratios were statistically similar to fresh contralateral ligaments in all animals. This postfreezing ligament cell survival and collagen production after -70 degrees C storage may have implications for ligament transplantation.

Animals↗
PubMed1988

The "Pardridge" hypotheses relating to the role of hormone binding proteins in hormone delivery: a critique.

Though the physiological role of specific binding proteins in serum is unknown, and the validity of the "free hormone hypothesis" has been challenged by several authors (including ourselves), we regard Pardridge's widely publicised objections to this hypothesis (and his recent suggestion of the existence of complex biochemical mechanisms causing the release of individual hormones in particular tissues) as deriving from an incorrect analysis of the effects of serum binding proteins on the kinetics of hormone transport, and therefore without foundation. This presentation is intended to substantiate this view.

Chemical Phenomena↗
PubMed1988

Resolution of amyloidosis (AA type) complicating chronic ulcerative colitis.

A 36-yr-old woman was admitted for the investigation of diarrhea, fever, weight loss, and a recurrent painful, red eruption on her forearms. She was found to have total colonic involvement with a nonspecific ulcerative colitis. Vascular and extravascular amyloid (AA type) was present in biopsy specimens of the colon, duodenum, and stomach. There was clinical and radiographic evidence of splenic and hepatic amyloidosis. Moreover, the presence of extravascular colonic amyloid, the absence of renal involvement, the relatively early detection of amyloid, and the resolution of amyloid after treatment make this case unique.

Adult↗
PubMed1988

Genioglossus and breathing responses to airway occlusion: effect of sleep and route of occlusion.

We examined the effect of sleep state on the response of genioglossus muscle (EMGgg) activity to total airway occlusion applied at 1) nasal (N) airway [and thus exposing the upper airway (UAW) to pressure changes] and 2) tracheal (T) airway (thus excluding UAW from pressure changes). A total of 233 tests were performed during wakefulness (W), 98 tests in slow-wave sleep (SWS), and 72 tests in rapid-eye-movement (REM) sleep. Prolongation of inspiratory time (TI) of the first occluded effort occurred in all tests irrespective of behavioral state, with the greatest increase seen in awake N tests. Nasal tests augmented EMGgg activity in the first occluded breath and produced a linear increase in EMGgg during occlusion. The EMGgg activity at any given time during nasal occlusion in SWS was less than that recorded during W tests. There was a marked reduction in EMGgg response to N occlusion during REM sleep. The EMGgg activity during awake T tests was significantly less than that of N tests at any given time during occlusion. There was no relationship between the level of EMGgg activity and asphyxia in T tests performed during SWS and REM sleep. Nasal tests decreased the force generated by the inspiratory pump muscles and the central drive to breathing compared with T tests. These results confirm the important role of the UAW in regulating breathing pattern and indicate that both immediate and progressive load-compensating responses during nasal occlusion are influenced by information arising from the UAW.

Airway Obstruction↗
PubMed1988

Reproducibility of the Early Cataract Detector (Kowa ECD 2000).

We conducted a reproducibility study on the Kowa Early Cataract Detector, a laser light scattering spectroscope that determines the diameter of particles within the lens and designed to quantify changes in particle size in early cataracts. We found good reproducibility in the nuclear region (where changes are homogeneous), but found poor reproducibility in the cortical region (where changes are heterogeneous). We advise careful evaluation of other similar devices before extensive use.

Cataract↗
PubMed1986

Assignment of human 3-hydroxy-3-methylglutaryl coenzyme A reductase gene to q13----q23 region of chromosome 5.

We have used hamster cDNA probes for 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase (HMGCR) to determine the chromosomal location of the human gene for HMG CoA reductase. Southern blot analysis of genomic DNA from 16 independent mouse-human somatic cell hybrids showed that the human gene for HMG CoA reductase resides on chromosome 5. Analysis of Chinese hamster-human somatic cell hybrids selectively retaining human 5 or a portion of it showed that the gene locus for HMG CoA reductase can be assigned to the q13----q23 region of chromosome 5.

Animals↗
PubMed1986

Optical transmission of normal and atheromatous arterial wall: a spectral analysis.

In laser angioplasty one of the factors influencing the immediate damage (and therefore the risk of acute arterial perforation) is the optical absorption characteristics of the target tissue. In an attempt to evaluate the differences in optical absorptive properties, the transmission spectrograms of samples of normal and atheromatous human postmortem aortic wall were measured over the visible spectrum. Optical transmission varied inversely with sample thickness and directly with wavelength through both normal and atheromatous samples. Over the whole visible spectrum atheromatous tissue transmitted less per unit thickness than normal tissue. This differential effect was, however, most pronounced at 500 nm, where atheromatous tissue transmitted light 5-10 times less strongly than normal aortic wall. Such wavelength dependent differential optical absorption could provide a means for the selective photovaporisation of atheroma in laser angioplasty.

Angioplasty, Balloon↗
PubMed1986

Health museums or theme parks: a new approach to intersectoral collaboration.

This paper is an outline of a proposed initiative on intersectoral collaboration in health promotion--collaboration between health, tourist, cultural and entertainment sectors to provide a powerful mass educational experience about the human mind and body. There has been a recent rise in interest in using the technology of museums, science centres, exploratories and theme parks for the promotion of health. This revival is shown to have a historical tradition in the health education museum started in this century in Europe 75 years ago at the Deutsches Hygiene Museum and then spreading to the USA. The proposed Body, Mind, City Museum planned for Liverpool acts as a future model for a new type of health Museum; a mixture of science exploratorium and a Walt Disney-style them park. It is intended that "hand-on" exhibits using interactive video, computers, games and experiences will be used to test people's own capacities or to describe biological functions or processes. This will be combined with park rides and simulations with their inherent appeal of fun, movement and surprise, for example the ride through the blood vessels and the "walk-through brain". This type of venture has a number of special features and advantages; it is truly intersectoral, it may be self-financing, and it can provide a mass audience with a powerful individual experience.

England↗