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A colorimetric procedure for determination of small amounts of cyanide and thiocyanate, involving the synthesis of a pyridine dyestuff by the reaction of pyridine and an aromatic amine, has been simplified for the estimation of thiocyanate alone in biological fluids. Replacement of benzidine with p-phenylenediamine in the colorimetric reaction has both improved the precision of the analytical procedure and avoided a carcinogenic hazard. This method has been used to follow the decrease in plasma thiocyanate associated with abstinence from cigarette smoking, and its subsequent increase upon resumption. It has also been used to measure the plasma and urinary thiocyanate concentrations of patients suffering from the particular toxic amblyopias—tobacco amblyopia and Leber’s hereditary optic atrophy— believed to be associated with cyanide toxicity, and to follow the increased thiocyanate concentrations that accompany significant improvements in the patients’ vision brought about by various treatments.

Pompholyx in nickel-sensitive subjects can be induced by orally-administered nickel, but only by a high dose. Ingestion of 5.6 mg nickel consistently worsened the pompholyx, often with a mild toxic erythema or patch test site flare, but lower doses of nickel failed to excite reactions more frequently than did a placebo, in a double-blind study. The metabolism of nickel is complex and there was considerable variation between three normal individuals in their absorption and excretion of an orally-administered nickel load. Patients may show similar variability which could be of importance clinically, although in only one of five subjects with acute eczema was the serum nickel raised, and then only marginally. The exact role of dietary nickel in perpetuating the hand dermatitis of sensitive subjects remains unclear.

In the west of Scotland the incidence of dialysis encephalopathy has been confined to three geographical areas where the concentration of aluminium in the water supply is greatly increased owing to the addition of aluminium sulphate. Eight patients with encephalopathy who dialysed at home in these areas had greatly increased serum aluminium concentrations, and a significant correlation was found between serum aluminium concentrations and the concentrations of aluminium in the water supply. This study provides further evidence that the dialysis encephalopathy syndrome is due to aluminium intoxication, the major source of aluminium being the water supply from which dialysis fluid is prepared.

SUMMARYThe effect of an environmental temperature of 28-30' C. and a relative humidity of 35-45 per cent on the protein metabolic response to injury of one or more major long bones of the lower limbs has been studied in 29 male patients and 28 similar controls housed at 20-22OC. The metabolic response was reduced at the higher temperature compared with the controls, the more severely injured showed a greater metabolic response than the less severely injured, and the ameliorating influence of environmental temperature was more noticeable in the former. The metabolic response seems to be principally one of catabolism of muscle, with increased urinary excretions of potassium, creatine, and zinc in the urine correlating well with those of nitrogen at 20" C. but not at 30' C. The response (i.e., catabolism of muscle) was not affected by post-injury diet at 2 0 ' C. ambient temperature. There was a reduction in the disturbance of the plasma proteins.In general, the patients tolerated the warm drier conditions. Owing to the intrinsic difficulty in assessing minor changes in bone healing it was not possible to assess what, if any, beneficial change occurred in the fracture site. From our experimental observations on the rat and the work of others on burned patients the reduction in heat production at the higher ambient temperature is accompanied by an enhanced rate of healing of surface wounds.THE metabolic response to injury is both local and general. It is with the latter in its post-shock manifestations following moderate to severe physical injury to the limbs of man that this report is concerned, and, in particular, with the effect on this response of raising the environmental temperature to the zone of 68 thermoneutrality for clothed man (28-30' C.). This topic has been of considerable interest to those working in the field of metabolic response to trauma

A microdiffusion technique has been used to separate and concentrate the nanomole amounts of cyanide in whole blood, and to permit its simplified colorimetric estimation (1). With this technique cyanide was measured in whole blood from normal smokers, normal nonsmokers, and patients suffering from tobacco amblyopia. Cyanide was also measured in whole blood from vitamin B12-deficient and normally fed Wistar rats. From the experimental animal results and results from patients, it is suggested that a more suitable index of cyanide exposure may be the alteration of plasma thiocyanate rather than the direct determination of whole blood cyanide.

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