Hyponatraemia and mesothelioma.

Hyponatraemia was found in 18 (62%) of 29 patients with histologically proven mesothelioma. The mechanism for the development of the hyponatraemia is discussed. It is suggested that patients with mesothelioma should be monitored for electrolyte abnormalities. If hyponatraemia is found the syndrome of inappropriate secretion of antidiuretic hormone should be suspected as treatment with demethylchlortetracycline may improve the quality of life in an otherwise fatal illness.     

Changes in plasma kininogen levels in rats before ovulation, and after treatment with luteinizing hormone and oestradiol-17 beta

The pre-ovulatory fall in plasma kininogens in rats with 4 day oestrous cycles started between 12.00 and 15.00 h pro-oestrus, reached a maximum decline of 51% by 18.00 h pro-oestrus, and started to recover before ovulation. Because these changes appeared to correspond with the LH-surge, and to follow the peak in plasma oestradiol-17 beta levels, both of these hormones were tested for possible effects on plasma kininogens. Intracardiac injections of 110 IU of equine LH into dioestrous rats were followed by a decline of 30.8 +/- 6.7% in plasma kininogens, 6 h after injection (significant, P less than 0.01). Values were still depressed, but recovering, 12 h after treatment; the reduction was 21.3 +/- 5.8% (significant, P less than 0.01). Controls showed no decline. Injections of oestradiol-17 beta (1.0 micrograms/100 g body weight) produced no significant effects. It is suggested that the LH surge may be responsible, at least in part, for the decline in plasma kininogens seen before ovulation.     

Occupational asthma in an electronics factory: a case control study to evaluate aetiological factors

This is the final part of a study carried out to investigate occupational asthma due to sensitivity to colophony fumes (a component of soldering flux) in an electronics factory. Fifty-eight workers with occupational asthma employed on the main shop floor were investigated. In them the interval between first exposure and sensitisation varied widely with a group becoming sensitive within one to two years of first exposure, and another group whose sensitisation was delayed for three to 23 years. Once sensitised the interval between arriving at work and the onset of daily symptoms seemed to be bimodally distributed, resembling the immediate and late asthmatic symptoms seen on provocation testing. Twenty-three out of 58 had no definite daily deterioration at work but improved at the weekends. Wheeze and breathlessness occurred in the evenings at home in most, and one-third were woken by breathlessness at least on some nights. These 58 cases were compared with 48 controls without occupational asthma who had worked on the same shop floor for at least four years. Mean levels of FEV₁ were significantly worse in the cases before exposure on Monday morning. The cases also had more than twice as much sickness absence as controls. FEV₁ fell by more than 10% over a working shift in 33% of cases and 5% of controls. Atopy (a positive skin prick test to one or more common allergens) and a past history of allergic disease were weakly but significantly associated with being a case. The effects of smoking and a family history of allergic disease were trivial. Prick testing with an antigen derived from the colophony in the solder flux was completely negative, but cases and controls had significantly raised levels of total IgM compared with blood bank controls, perhaps suggesting some previously unrecognised immunological process.     

The neurohypophysial principles of the western brook lamprey, Lampetra richardsoni: Studies in the adult

Pharmacological and purification studies were carried out on lyophilised neurohypophysial tissues from Lampetra richardsoni and on control brain tissues. Crude neurohypophysial extracts contained 5.45 (4.41–6.73) mU/mg dry tissue of oxytocic activity; 3.27 mU/mg dry tissue appeared to be due to a neurohypophysial peptide which showed frog-bladder and other activities typical of arginine vasotocin (AVT). The use of trichloroacetic acid (TCA) and a carboxymethyl cellulose column resulted in a 190-fold purification of the peptide. Assay of the purified principle directly against synthetic AVT by different methods of assay suggested that it was AVT. Partition chromatography supported this finding. Control spinal cord tissues contained only low oxytocic activity (0.27 mU/mg dry tissue), but hindbrain materials showed the surprisingly high potency of 1.39 (1.19–1.62) mU/mg dry tissue. Purification of the hindbrain extract with TCA and carboxymethyl cellulose resolved an oxytocic agent with the thioglycollate lability and chromatographic and pharmacological properties of AVT. It amounted to approximately 0.18 mU/mg dry tissue, or only 12% of the total oxytocic activity present. The purification resolved small amounts of a number of oxytocic agents other than AVT. Some showed chromatographic similarities to oxytocin. However, none was destroyed by sodium thioglycollate. Any true neutral neurohypophysial principle could not have amounted to more than 1% of the AVT present (in terms of oxytocic activity), and there was no positive evidence for its existence in the neurohypophysis. The results suggest that AVT is the only neurohypophysial principle of L. richardsoni.     

Forum Cardio-respiratory effects of nitrous oxide:oxygen:halothane anaesthesia administered to dental outpatients in the upright position

The cardio-respiratory responses of fifty-three healthy dental patients receiving 30% oxygen with nitrous oxide and halothane whilst seated upright are reported. A high degree of sympathetic autonomic activity was noted with considerable lability of the blood pressure and pulse rate. Hypoxaemia caused by respiratory obstruction, unrecognised by the anaesthetist, occurred in approximately 20% of patients at the time of insertion of the prop or pack and during removal of teeth.