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Biomedical subjects

R Lancaster

Publications and source records attributed to R Lancaster.

At least 19 recordsLinked to original sources
PubMed2001

Snapshots of five clinical ethics committees in the UK.

Each of the following papers gives an account of a different UK clinical ethics committee. The committees vary in the length of time they have been established, and also in the main focus of their work. The accounts discuss the development of the committees and some of the ethical problems that have been brought to them. The issues raised will be relevant for other National Health Service (NHS) trusts in the UK that wish to set up such a committee.

Committee Membership↗
PubMed2000

Growth of porcine kidneys in their native and xenograft environment.

The increased survival of hDAF pig-to-primate renal xenografts for up to two months has afforded the opportunity to study physiological aspects such as organ growth. Experimental evidence exists of species restriction of the activity of growth hormone, although growth itself is also controlled by a number of other endocrine, paracrine and autocrine substances. This study consisted of four parts: (1) measurement of pig kidney size according to pig body weight; (2) measurement of pig kidney size according to pig age; (3) serial length measurement of pig-to-primate renal xenografts; (4) correlation of terminal weight of renal xenograft with age and histology. The xenografted pig kidneys in a primate recipient grow as they would in the pig for the first two weeks after transplantation. After this time there is a reduction in the rate of increase in the length of the xenograft. Over the same period, changes in weight are greatly increased by the presence of rejection. This observational study supports the notion that regulation of growth of a xenotransplanted porcine kidney occurs.

Animals↗
PubMed1998

Dynamic cortical activity in the human brain reveals motor equivalence.

That animals and humans can accomplish the same goal using different effectors and different goals using the same effectors attests to the remarkable flexibility of the central nervous system. This phenomenon has been termed 'motor equivalence', an example being the writing of a name with a pencil held between the toes or teeth. The idea of motor equivalence has reappeared because single-cell studies in monkeys have shown that parameters of voluntary movement (such as direction) may be specified in the brain, relegating muscle activation to spinal interneuronal systems. Using a novel experimental paradigms and a full-head SQUID (for superconducting quantum interference device) array to record magnetic fields corresponding to ongoing brain activity, we demonstrate: (1), a robust relationship between time-dependent activity in sensorimotor cortex and movement velocity, independent of explicit task requirements; and (2) neural activations that are specific to task demands alone. It appears, therefore, that signatures of motor equivalence in humans may be found in dynamic patterns of cortical activity.

Brain↗
PubMed1997

Characterization of pigs transgenic for human decay-accelerating factor.

BACKGROUND: To prevent the central role played by complement activation in the hyperacute rejection of pig organs transplanted into primates, pigs transgenic for human decay-accelerating factor (HDAF) have recently been produced. The data presented here extend previous immunohistochemical findings by documenting the immunological characterization and the levels of expression of HDAF in these transgenic pigs. METHODS: Animals from 30 independently derived lines were included in this study. HDAF expression was characterized by immunoprecipitation and epitope mapping. Quantitative analysis was performed by radiometric assays followed by Scatchard analysis and by double-determinant radioimmunoassay. Deposition of iC3b on porcine aortic endothelial cells was determined by radioimmunoassay. DNA slot-blot analysis and densitometric scanning were used to evaluate HDAF transgene copy number. RESULTS: The integrity of HDAF expressed by these transgenic pigs could be demonstrated. HDAF was present in 72% of the organs analyzed, although considerable variation in expression occurred, both between animals and within the same pig. High levels of HDAF on porcine aortic endothelial cells resulted in iC3b deposition at levels as low as that detected on human endothelial cells. Twenty-six organs expressed levels of HDAF greater than those observed in the equivalent human tissue. HDAF expression did not correlate with the number of copies of the transgene incorporated into the porcine genome. CONCLUSIONS: Transgenic pigs, which express levels of functional HDAF even greater than those observed in humans, have successfully been produced. Pigs transgenic for human complement inhibiting molecules could represent a source of organs for future clinical xenotransplantation.

Animals↗
PubMed1997

The development and testing of a competency-focused psychiatric nursing clinical evaluation instrument.

This article presents the development of a competency-focused psychiatric clinical evaluation instrument for the junior year of a baccalaureate program. Initially, 80 competencies were identified and categorized into six subscales. Competency achievement was measured by the Bondy Criterion Matrix (1983). Pilot setting generated an overall alpha (alpha) of 0.89 with item reliabilities ranging from 0.16 to 0.95. Testing of the revised Psychiatric Nursing Performance Appraisal Instrument (PsychNPAI) with another group of students (N = 51) generated an overall alpha = 0.96. Subscale alphas ranged from 0.82 to 0.92. These clinical subscales correlated significantly with related aspects of the didactic content in the course. The National League for Nursing Psychiatric Achievement Test correlated significantly with the overall course grade but not with PsychNPAI. The faculty and students perceive that the PsychNPAI clarifies expected outcomes and increases confidence in performance appraisal.

Clinical Competence↗
PubMed1983

Genetically determined oxidation capacity and the disposition of debrisoquine.

1 The disposition in urine of debrisoquine and its hydroxylated metabolites has been studied in subjects of the 'extensive metabolizer' (EM; n = 5) and 'poor metabolizer' (PM; n = 5) phenotypes. The 4-hydroxylation of debrisoquine by PM subjects following a 10 mg oral dose was capacity-limited and displayed significant dose-dependency over a range of 1-20 mg. In contrast, the EM subjects' ability to perform this metabolic oxidation did not deviate from first-order kinetics over a dose range of 10-40 mg. 2 The disposition of debrisoquine in plasma following a 10 mg oral dose has been studied in EM (n = 4) and PM (n = 3) subjects. Whilst PM subjects displayed significantly higher plasma levels of debrisoquine at all time points following 1 h post-dosing, and higher values for areas under the plasma concentration-time curve (EM: 105.6 +/- 7.0 ng ml-1 h; PM: 371.4 +/- 22.4 ng ml-1 h, 2P less than 0.0001), neither debrisoquine plasma half-life (EM: 3.0 +/- 0.5 h; PM: 3.3 +/- 0.4 h) nor renal clearance of the drug (EM: 152.8 +/- 30.3 ml min-1; PM: 137 +/- 4.5 ml min-1) displayed significant inter-phenotype differences. 3 The results of these investigations show that the phenotyping of individuals for debrisoquine oxidation status by means of a 'metabolic ratio' derived from a single 0-8 h urine sample has a sound kinetic basis. The kinetic differences between the two phenotypes would strongly suggest that the metabolic defect manifested in PM subjects is one of pre-systemic elimination capacity.

Administration, Oral↗