Colin J. Evans

An in‐vivo study of renal cadmium and hypertension

Abstract. A comparative study of renal cadmium burdens in a group of thirty hypertensive patients undergoing treatment and in a group of thirty matched controls is reported, both groups being volunteers selected from a non‐occupationally exposed population. The aim of this study was to investigate the possible involvement of cadmium in the aetiology of hypertension at the chronic low levels of environmental exposure. Renal cadmium levels were measured in vivo, using the technique of partial‐body neutron activation analysis. The results showed that the mean renal cadmium level in the hypertensive group [3‐3 mg (SD 2–3)], was not significantly different from that [4‐4 mg (SD 2–7)], in the normotensive group. Whether the level in the hypertensives depends on the treatment is open to question and will be the subject of further investigation. In addition, the results confirm that kidney cadmium levels are elevated in smokers.

Teaching the humanities: Seminars as metalogues

ABSTRACT In this article I describe a particular way of conceiving a seminar in the humanities—as a ‘metalogue˚s, a learning occasion where the object of study is both a text and the occasion itself, as well as the conscious analogical relation between the two. I argue that this is consonant with the objects of study in the humanities which are not real objects but symbolic objects, representations of relationships whose very nature depends on the relationship between them and the reader. I maintain that a justification for the study of the humanities and a statement of purpose must begin with a statement about the skills and frame of mind that participation in such work fosters, specifically the capacity to think analogically and reflexively and to handle figure-ground (content-process) shifts. I describe two examples of the seminar as metalogue.

Development of a Technique to Measure Bone Aluminium In Vivo Using a CF-252 Neutron Source

Aluminium toxicity still presents a potential hazard to patients with chronic renal failure through the continued use of aluminum-based phosphate binders to prevent hyperphosphataemia. Consequently, there is a need to measure aluminium accumulation in these patients to detect those at risk and to monitor the effectiveness of subsequent treatment. Aluminium in biological fluids, including serum, can be measured by flameless AAS, but there are limitations in extrapolating these findings to the assessment of tissue content (Charhon et al., 1985).

Measurements of Total Body Calcium by Prompt-Gamma Neutron Activation Analysis Using a 252Cf Source

A clinical neutron activation instrument has been developed for in vivo elemental analysis. Utilizing the prompt-capture gamma ray technique, simultaneous total body (TB) measurements of primarily Ca, but also Cl, N, C, and H are routinely performed. This paper describes a technique for the measurement of TBCa (g) that relies on the use of TBCl as an internal standard. The method has been tested with four anthropomorphic phantoms covering a range of body habitus. The mean discrepancy between the measured and known Ca contents was 3.6%. The technique has been applied to two patient groups, and encouraging results were obtained.

Initial Measurements of Platinum Concentration in Head and Neck Tumors Using X-Ray Fluorescence

Currently there is no noninvasive technique generally available in oncology that can discriminate adequately between tumors that are likely to respond to platinum compounds and those that are not. Recently, however, it has been shown that platinum can be measured in vivo,at concentration levels of interest, by the method of X-ray fluorescence1,2 (XRF). It follows that, because the concentration of a drug at its site of action is the principal determinant of response, the application of this method would be of value in obtaining direct pharmacodynamic information about the drug and give the prospect of optimizing the therapeutic ratio.

Prompt Gamma Measurements of Nitrogen and Chlorine in Normal Volunteers

The Swansea in vivo neutron activation analysis (IVNAA) instrument, which is based on a 4 GBq Cf-252 neutron source, has been developed primarily for the prompt-gamma measurement of total body (TB) Ca, N, Cl, H and C, and partial body Cd, using semiconductor (HPGe) and scintillation (HaI) gamma ray detectors (Ryde et al., 1987).

Whole Body Fluid and Electrolyte Assays in “Normal” Volunteers

Potassium, chlorine and water are essential for human life, and therefore the ability to measure these body components is highly desirable. Furthermore, assaying the partition of total body water (TBW) between its intracellular fluid (ICF) and extracellular fluid (ECF) components is a vital part of any study of fluid imbalance. The aim of the research presented here was to assemble, evaluate and deploy a combination of techniques to measure total body potassium, chlorine and water in vivo. Although the following results were obtained from “normal” volunteers, the techniques are also available for clinical use.

Further Observations on Lead Mobilization by Cisplatin

In a previous study2 by the Swansea In Vivo Analysis Research Group (SIVARG), startling evidence was found of lead mobilization to the kidneys under the action of the drug cisplatin during chemotherapy in some patients. Using X-ray fluorescence,3 primarily to measure platinum concentration in kidneys and various tumor sites, lead was discovered to have accumulated in the kidneys of four patients, sufficient to cause the kidney dysfunction commonly associated with this drug. Three projects were therefore undertaken in order to study this apparent mobilization in more detail.

Development of an in Vivo Neutron Activation Analysis Technique to Measure Bone Aluminum

Aluminum toxicity is a well recognized hazard for patients with chronic renal failure, and there is a need to measure aluminum accumulation in these patients to detect those at risk. Although iliac crest bone biopsy allows measurement of tissue aluminum, a noninvasive technique to assess aluminum tissue load is needed. Aluminum in biological fluids, including serum, can be measured by various techniquesl, but there are serious limitations in the extrapolation of either baseline serum Al2,, or the increment in plasma Al following Infusion of the chelating agent deferoxamine3 to assess aluminum tissue load.

Determination of Total Body Calcium by Prompt Gamma Neutron Activation Analysis: Absolute In Vivo Measurements

Sequential TBCa measurements using the prompt gamma ray technique are firmly established and a number of patient groups are under investigation. A technique has been proposed for the absolute measurement of TBCa based upon the use of TBCl as an internal standard. Further work is needed to establish the validity of the method, but the initial results are encouraging.