Evaluation of the in situ, time-integrated DGT technique by monitoring changes in heavy metal concentrations in estuarine waters.

Various natural and anthropogenic processes influence heavy metal concentrations within estuaries. In situ, time-integrated DGT measurements made over concurrent tidal phases found significantly higher concentrations of Cu (probability p=0.017), Zn (p=0.003) and Ni (p=0.003) during the flood phase, because the incoming tide passes several point sources. DGT-reactive Cu concentrations significantly decreased with increased tidal-flushing and vice versa within a marina (correlation r=-0.788, p=0.02). DGT measurements also recorded significant increases in Cu (4 out of 4 sites, p<0.001) and Zn (3 out of 4 sites, p< or =0.015) after a 24 mm rainfall event. Finally, DGT-reactive Cu increased significantly (p<0.001) during peak boating times, due to increased numbers of Cu-antifouled boats. This study demonstrates that, with judicious selection of deployment times, DGT measurements enable changes in heavy metal concentrations to be related to various cycles and events within estuaries.

Comparative and serial assays of folate metabolism in anticonvulsant-treated epileptics.

A prospective study of folate metabolism has been conducted in outpatient anticonvulsant-treated epileptics on 68 occasions. An attempt was made to compare the relative sensitivities of serum and red cell measurements of folic acid, lactic dehydrogenase (LD), and 2 hydroxybutyric dehydrogenase (2HBD). The most sensitive indices of folate deficiency appeared to be serum folate, red cell LD, red cell folate, and red cell 2HBD, respectively. The correlation between these measurements was not close, except in comparisons of red cell and serum folate. No easily performed screening test for folate deficiency emerged. Serial changes in these measurements were carried out on 15 patients during an interval of 18 months. No progressive signs of folate depletion appeared during this time. The significance of these findings is discussed.

The Leeds regional quality control scheme for clinical biochemistry: a progress report.

The results from a regional quality control scheme for clinical biochemistry are analysed. Comparison with results from an earlier period shows that the quality of several of the 15 routine analyses has improved. The methods by which the sera are produced and distributed, and the weekly results are analysed, are described. Each of the 25 laboratories receives an individual weekly computer printout within 24 hours of the deadline for the receipt of results. At the end of each six-month period a printout is produced ranking each laboratory for ;accuracy' and ;precision' for each test.

Glycolysis measurements in red cells from drug-treated epileptic and anaemia patients.

Glycolytic activity was measured in red cells from epileptic patients treated with anticonvulsant drugs. These results are compared with measurements of red cell glycolytic activity from megaloblastic anaemia patients and normal controls. The differences obtained between epileptic patients and controls, as well as the differences between anaemia, epileptic patients and controls is discussed.

Parenteral feeding in patients with carcinoma of the esophagus treated by surgery: energy and nitrogen requirements.

Nutritional assessment and requirements of patients with carcinoma of the esophagus treated by surgery are based on three series of patients: 1) the nutritional state of 22 assessed on admission, using recognized nutritional markers, the majority of whom were found nutritionally deficient; notably 72% were in negative nitrogen (N) balance. 2) Another series of 52 patients was based on the relationship between dysphagia and loss of weight and negative N balance; 48% were severely dysphagic and had lost an average 8.5% of their usual weight, and 89% were in negative N balance. Thus, the association between the two clinical markers and the N balance was clearly indicated. 3) Postoperative calorie and N requirements necessary to maintain a positive N balance were assessed and found to be 40 to 45 kcal/kg body wt and 0.2 to 0.25 g N/kg body wt.

Survey of users and providers of recycled water: quality concerns and directions for applied research.

Users and providers of recycled water in Queensland, Australia, were canvassed to ascertain concerns about recycled water quality and directions for applied research. Some 79% of respondents had concerns about recycled water quality including microbiological components, such as viruses, parasites and bacteria, salinity related components, aggregate components, such as pH and solids, nutrients, organic components, including pesticides and endocrine disruptors, as well as quality variability. Relative differences in the proportion of concern for some quality characteristics were observed between the areas of different population density with those from the low population areas being more concerned than those from medium or high areas. Some users and providers observed changes in recycled water quality during distribution including nutrients, chlorine, solids, colour and odour. Some 52% of providers and 19% of current users propose to expand their usage and 30% of non-users propose to commence doing so in the next 5 years. Recycled water quality characteristics identified for applied research included microbiological components, organic components, nutrients and salinity.

Value of measuring C-terminal parathyrin in differential diagnosis of hypercalcemia.

We measured calcium, phosphate, chloride, albumin, C-terminal parathyrin, and beta 2-microglobulin in serum from 102 hypercalcemic patients: 42 with primary hyperparathyroidism and 60 with neoplasia. The calcium concentrations and the discriminant function index of Johnson et al. (Clin Chem 28, 333-338, 1982) were higher in malignant hypercalcemia than in primary hyperparathyroidism. The diagnostic efficiency of the index and of parathyrin concentration was 82% and 78%, respectively. Using the ratio of parathyrin to beta 2-microglobulin increased the diagnostic efficiency to 98%; the ratio of the discriminant index to parathyrin concentration had a diagnostic efficiency of 100%. We conclude that C-terminal assay by itself is no better than the discriminant function index.

In situ, High-Resolution Measurement of Dissolved Sulfide Using Diffusive Gradients in Thin Films with Computer-Imaging Densitometry.

The technique of diffusive gradients in thin films (DGT) has been developed for the measurement of dissolved sulfide. Sulfide species from the sampled waters diffuse through a polyacrylamide hydrogel and then react with pale yellow AgI((s)), incorporated at the surface of a second gel, to form black Ag(2)S((s)). The accumulated sulfide can be measured with a conventional purge-and-trap method followed by colorimetry (methylene blue). This enables the dissolved-sulfide concentration to be calculated under suitable conditions. Alternatively, the color change in the accumulating gel can be used to measure sulfide. A conventional flat-bed scanner, allied to imaging software, provided a densitometric measurement that was quantitatively related to the amount of sulfide accumulated. DGT measurements on synthetic solutions accurately determined the sulfide concentration (95% recovery), thereby confirming the unobstructed diffusion of HS(-) through the gel. The accumulated mass was inversely proportional to the diffusion-layer thickness as theoretically predicted. With the selected geometry, the limit of detection of the densitometric procedure for a 24-h deployment was 0.13 µmol L(-)(1), and the maximum concentration measurable was 60 µmol L(-)(1). When used in anoxic lacustrine waters, DGT provided sensible concentrations. It was also used to measure depth profiles at submillimeter resolution in estuarine surface sediments.

Angiotensin-converting enzyme in sarcoidosis: a British study.

Serum angiotensin-converting enzyme (ACE) activity was measured in 18 healthy controls, 26 patients with active sarcoidosis, 13 patients with inactive sarcoidosis and seven patients with extensive tuberculosis. The serum ACE activity showed no significant difference between male and female in the control or sarcoidosis groups. There was no correlation between ACE activity and age except in the female active-sarcoid group. ACE activity in the active-sarcoid group was significantly higher than in the control, inactive-sarcoid and tuberculosis groups. The ACE activities at Stages I, II and III of the disease were not significantly different.

Parenteral nutrition in carcinoma of the oesophagus treated by surgery: nitrogen balance and clinical studies.

Nitrogen balance studies and clinical observations were made on two groups of patients suffering from obstructive carcinoma of the oesophagus. In 10 patients (group A) parenteral nutrition with a high calorie and nitrogen content was given pre- and early postoperatively. Five patients (group B) received intravenous dextrose/saline solution pre- and postoperatively with no nitrogen supply. Patients in group A had a positive nitrogen balance before and after operation and had a satisfactory postoperative progress. The patients in group B had a negative nitrogen balance until the resumption of oral feeding and their postoperative progress was not as satisfactory as that of patients in group A.