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Biomedical subjects

R Earlam

Publications and source records attributed to R Earlam.

At least 19 recordsLinked to original sources
PubMed1994

Of an extracellular matrix in human pre-corneal tear film.

A theory relating viscosity to fluid flow rates in human tear film was developed and from that theory arises a relationship between viscosity, tear-film thickness and vertical drainage rates at the air-tear interface. Human tears were collected in capillary tubes at rates, on average, of less than 1 microliter min-1. Protein concentration was slightly higher than values reported in the literature and electrophoretic distributions of tear-film proteins were normal. Viscosity of the tear films were measured at 35 degrees C (physiological temperature). Vertical flow rates of tear film were measured in the inter-blink period either by observing the movement of lipid plaques at the air-tear interface or by observing naturally occurring contaminant specs (size around 1 micron). Tear film vertical flow rates were at least an order of magnitude lower than those predicted from collected tear-fluid viscosity measurements. It was concluded that collected tears are not representative of the whole pre-corneal tear film and that the tear film includes a fluid flow-inhibiting matrix whose structural components have a longer time-constant of exchange than the soluble proteins of the collected tear fluid.

Adult↗
PubMed1993

The incorporation of gel pressure into the irreversible thermodynamic equation of fluid flow in order to explain biological tissue swelling.

After the Donnan osmotic potential derived theory of corneal stromal swelling was suggested (Hodson, 1971) it later was proposed, and verified experimentally, (Elliott et al., 1980) that the theory could be applied even in situations where there were no bounding cellular membranes attached to the corneal stroma. This was a paradox. The central problem with swelling in the absence of membranes (i.e. with a gel boundary whose reflexion coefficient is essentially zero) is that the driving force is not readily understandable as osmotic (but see Oster & Peskin, 1992) and yet the magnitude of the swelling fitted quantitatively with Donnan theory. We believe that we have resolved this paradox with a new and expanded irreversible thermodynamic relationship for fluid flows into and across biological tissues. In the course of the derivation, fresh concepts arise: for example the relationship of salt disparity is described which forbids diffusible salt-generated chemical and osmotic potentials to be simultaneously at equilibrium in the presence of ionised macromolecules and this relationship is developed to generate a new intrinsic thermodynamic property which is termed gel pressure and which drives fluid flow. Gel pressure provides a theoretical basis for biological tissue swelling. Microscopically, gel pressure is identified as the electrostatic potential developed by the mutual repulsion of the fixed matrix charges.

Animals↗
PubMed1993

Trauma centres.

Explore the source record for details and available documents.

Cost-Benefit Analysis↗
PubMed1991

An MRC prospective randomised trial of radiotherapy versus surgery for operable squamous cell carcinoma of the oesophagus.

The objective of the trial was to determine whether there was any difference in survival rates after operable cases of squamous cell carcinoma of the oesophagus were treated by radiotherapy or surgery. It was designed as a prospective, randomised, multicentre trial in the United Kingdom, after staging as potentially operable, and it was planned to enter 100 patients per annum for 4 years, with a minimum follow-up of 5 years, after pre-entry staging of patients under 75 years of age by barium swallow, chest radiographs, oesophagoscopy, biopsy, bronchoscopy and CT scanning. The protocol was published in July 1986; the trial started in January 1987 and was stopped in June 1988 when only 31 patients from 16 centres were entered, although 30 centres had ethical committees' approval and were willing to start the trial. Interventions were to be as follows: 1. Surgery. According to the practice of that particular surgeon and classified as (a) curative resection if the surgeon considered that no macroscopic tumour was left behind, and (b) palliative if incompletely resected. 2. Radiotherapy. (a) Prescribed minimum corrected tumour dose of 5000 cGy with daily dose of 250 cGy in 20 fractions over 4 weeks. (b) Prescribed minimum corrected tumour dose of 6000 cGy with daily dose of 200 cGy in 30 fractions over 6 weeks. The endpoint was to be survival at 1, 2 and 5 years. The trial was discontinued after 18 months because of lack of recruitment and thus the question whether operable squamous cell cancer of the oesophagus, staged before treatment with CT scanning, is to be treated by radiotherapy or surgical resection remains unanswered. It is unlikely that a phase III trial will ever have sufficient support from surgeons to find the answer.

Aged↗
PubMed1984

Oesophageal cancer treatment in North East Thames region, 1981: medical audit using Hospital Activity Analysis data.

Figures from the Hospital Activity Analysis in the North East Thames region in 1981 were used to perform a medical audit on oesophageal cancer treatment. Four hundred and forty four patients were admitted with this diagnosis; 80 had been intubated without a thoracotomy or laparotomy, and 73 had had surgery (two thirds radical and one third palliative) with an overall operative mortality of 33%. Fifty five patients had had radiotherapy and 179 patients had no recorded operation or investigation. One hundred and seventy seven different consultants had looked after all these inpatients, most being general surgeons. Only five consultants had looked after 10 or more patients each year. From a calculated estimate of a total 286 patients in the region, 28% had palliative intubation and 25% had surgery; 20% of all the patients had radiotherapy either as a radical or palliative treatment, the remainder having no recorded therapeutic procedure. One hundred and eighty seven patients (66% of the calculated total) died in hospital. Investigation and treatment do not seem to be limited by lack of money, but money is being wasted by admitting patients for terminal care into acute hospital beds. It would be more humane for these patients to die at home or in a hospice if they wished.

Aged↗
PubMed1982

Malignant oesophageal strictures: a review of techniques for palliative intubation.

A review of the different designs for palliative oesophageal intubation tubes confirms Souttar's original suggestion that they should be flexible, incompressible, non-traumatic, compact, have an adequate lumen and stay in place. The internal diameter should be at least 10 mm. The thickness of the wall should be about 1 mm. The length will vary according to the stricture and should be as short as possible, provided that the proximal rim prevents future longitudinal growth occluding the lumen. Various methods of achieving the ability to stay in place are described, which comprise either a large proximal rim or a roughened barrel. No details about results are given because the original patient populations vary so much. Success probably depends more on the technical expertise and experience of the surgeon than specific variations in design.

Esophageal Neoplasms↗
PubMed1981

Benign oesophageal strictures: historical and technical aspects of dilatation.

A review of the different bougies used over the years confirms that the dilators presently available are adequate for the conservative management of oesophageal benign strictures. Most of these are of an old but well-tested design. Several additional techniques may have to be tried in difficult patients. Dysphagia can be relieved by the passage os size 39 FG bougies but many will wish to increase this to 60 FG, if it is possible. Failure of conservative management by dilatation only can be defined as (a) technical impossibility to dilate sufficiently to relieve the dysphagia, which is rare, or (b) when the patient or the surgeon considers the procedure is being done too frequently, which must be measured in FG for the bougie and weeks for frequency. The more expert the surgeon becomes at dilatation, the safer it will become, and the necessity for surgical intervention will be less frequent.

Aged↗
PubMed1980

Oesophageal squamous cell carcinoma: I. A critical review of surgery.

Authors writing an oesophageal cancer include adenocarcinoma to a variable extent--between 1 and 75 per cent--but the true incidence of this histological type is about 1 per cent. Most adenocarcinomas are gastric in origin, involving the lower oesophagus, have a lower operative mortality than in the middle or upper one-third of the oesophagus and poorer prognosis than squamous cell carcinoma, but there is no alternative treatment to surgery. Squamous cell carcinoma of the oesophagus, separated incompletely but as far as possible, has been analysed by reviewing data on 83 783 patients in 122 paERS. After trying to standardize the data, it appears that of 100 patients with the condition, 58 will be explored and 39 have the tumour resected, of whom 13 will die in hospital. Of the 26 patients leaving hospital with the tumour excised, 18 will survive for 1 year, 9 for 2 years and 4 for 5 years. Oesophageal resection for squamous cell carcinoma has the highest operative mortality of any routinely performed surgical procedure today.

Adenocarcinoma↗
PubMed1980

Oesophogeal squamous cell carcinoms: II. A critical view of radiotherapy.

There has been no controlled trial of radiotherapy versus surgery for squamous cell carcinoma of the oesophagus. Radiotherapy is generally used for those patients with extensive disease or those who are unfit for surgery. In spite of this, the 1-year survival of 18 per cent is similar to that for surgically treated patients and there is no equivalent operative mortality. The 5-year survival is 6 per cent compared with that for surgery of 4 per cent. There are no results available to suggest what would happen if a patient with a localized tumour, technically suitable for surgical resection, were treated instead by radiotherapy.

Carcinoma, Squamous Cell↗