The release and metabolism of [3H]arachidonic acid from guinea pig perfused lungs in vitro: a simple method for the study of the action of drugs on the release and metabolism of arachidonic acid

We have adapted the radiolabeled, perfused organ technique of Isakson et al. (1976) for use with guinea pig lungs. After incorporation [3H]arachidonic acid was taken up into the lung phospholipids. The injection of bradykinin (1-100 microgram) caused a dose-related release of tritium [3H]. The composition of the tritium released by the lungs was found to be a mixture of cyclo-oxygenase and lipoxygenase metabolites together with some unchanged arachidonic acid. In order to demonstrate how this technique can be utilized to study the effect of drugs on arachidonic acid release and metabolism, the actions of mepacrine and indomethacin on bradykinin-induced [3H] release were studied. Mepacrine (50-200 microM) produced a concentration-related reduction in bradykinin-induced [3H] release whereas indomethacin (10 microM) was without effect on [3H] release. Indomethacin did, however, reduce the levels of cyclo-oxygenase products in the perfusate.

Evoked potentials in severe head injury--analysis and relation to outcome

Somatosensory, visual and auditory cortical and brainstem evoked responses were obtained from 32 patients with severe head injury. A simple count of the number of waves present in the various responses provided the optimum method of analysing the data. The results of each cortical response, but not of the brainstem response, correlated with outcome, and a combined assessment gave the highest correlation. The data provided only slight improvement on predictions based upon clinical features.

Comparison of the actions of U-46619, a prostaglandin H2-analogue, with those of prostaglandin H2 and thromboxane A2 on some isolated smooth muscle preparations

1 The actions of the prostaglandin H2 (PGH2) analogue, U-46619, have been compared with those of PGH2 on thromboxane A2 (TxA2) on a range of isolated smooth muscle preparations in a superfusion cascade system. 2 U-46619 was a potent agonist on guinea-pig lung strip, dog saphenous vein and rat and rabbit aortae. In contrast, U-46619 was weak or inactive on guinea-pig ileum and fundic strip, cat trachea and dog and cat iris sphincter muscles, preparations on which either PGE2 or PGF2 alpha was the most potent agonist studied. 3 PGH2 was active on all of the preparations and displayed little selectivity. On some of the preparations, the actions of PGH2 may have been mediated indirectly by conversion to other prostanoids. 4 In contrast, TxA2 displayed the same pattern of selectivity as U-46619, being a potent agonist on the lung strip and vascular preparations but weak or inactive on the others. 5 It is suggested that U-46619 is a selective TxA2-mimetic and that it should therefore be a valuable tool in the study of the actions of TxA2.

The Prince of Wales Hospital prospective aphakic macular oedema study

A two year study of one hundred and forty five cataract extractions showed a 38% incidence of post operative macular oedema. The leak had resolved in most cases by six months and the only factor of significance in the production of the oedema was preoperative hypertension. The likelihood of obtaining 6/6 vision postoperatively was much lessened in the presence of macular oedema.

Contractile and relaxant actions of prostaglandins on guinea-pig isolated trachea

1 The effects of 12 prostaglandins on guinea-pig isolated trachea have been examined in the presence of indomethacin. Two series of experiments were carried out, the first on preparations without tone ('zero tone'), and the second on preparations with tone induced with acetylcholine ('high tone'). 2 The compounds tested fell into two groups. The first, comprising prostaglandins F1 alpha, F2 alpha, F2 alpha acetal, I2 and Wy 17186, contracted both zero and high tone preparations. The second, comprising prostaglandins A1, A2, B1, B2, E1, E2 and F2 beta, contracted zero, but relaxed high tone preparations. Responses to the second group of compounds are probably the resultant of their contractile and relaxant actions. 3 The order of potency for contracting zero tone preparations was prostaglandin E (PGE) greater than F = 1 = Wy 17186 greater than B greater than A, 2-series compounds being 5 to 18 times more potent than 1-series compounds. 4 The order of potency for relaxing high tone preparations was PGE greater than F beta greater than B greater than A greater than Wy 17186 greater than F alpha = I = 0. There was little difference between the potency of 1- and 2-series compounds. 5 The possible relevance of these results to the interpretation of the effects of prostaglandins on human airways is discussed.

A novel antenatal record to help midwives

An antenatal questionnaire and graph for plotting weight and fundal height gives immediate warning of women at risk in pregnancy in a simple and visually striking way. It saves midwives' time, improves their clinical awareness and gives them more confidence in referring patients.

The donation and transplantation of kidneys: should the law be changed?

It is now eighteen years on since the Human Tissue Act 1961, but this legislation is still unchanged in England, Scotland and Wales. Ian Kennedy, in this paper, lays before us the law as it is, the problems of its interpretation and his opinion of what government should be doing to help clarify the situation and remove some of the problems which exist daily for the doctors who face the dilemma of seeking consent for transplants at the moment of extreme grief for the surviving spouses or relatives of the patient who has been in his care only moments before. Ian Kennedy suggests that by doing nothing the Department of Health and the government are being both callous and less than honest.

Genome of infectious bronchitis virus

Techniques are described for the growth and rapid purification of the avian coronavirus infectious bronchitis virus (IBV). Purified IBV has a sedimentation coefficient of 320S and a buoyant density of 1.22 g/ml in sucrose-deuterium oxide equilibrium gradients. IBV RNA extracted by proteinase K in the presence of sodium dodecyl sulfate and further purified by phenol extraction and gradient centrifugation is single stranded and has a sedimentation coefficient of 64S, as determined by isokinetic gradient centrifugation. Analysis on sucrose gradients under both aqueous and denaturing conditions together with agarose gel electrophoresis in the presence of the chaotropic agent methylmercuric hydroxide gave a value of 8 X 10(6) for the moleclar weight of IBV RNA. This value was confirmed by RNase T1 fingerprinting, which also indicated that IBV RNA is haploid. No evidence was found of subunit structure in IBV RNA. From these results together with the recently reported observation that IBV RNA is infectious and contains a tract of polyadenylic acid (Lomniczi, J. Gen. Virol., in press), we conclude that the genome of the coronaviruses is a single continuous chain of about 23,000 mononucleotides that is of messenger polarity.

Combined alpha- and beta-adrenoceptor blocking drug AH 5158: further studies on alpha-adrenoceptor blockade in anaesthetized animals

1. AH 5158, 5-(1-hydroxy-2-((1-methyl-3-phenylpropyl)amino)ethyl)salicylamide, competitively antagonised phenylephrine-induced vasopressor responses in anaesthetized dogs, thus confirming that the drug possesses alpha-adrenoceptor blocking activity. 2. In contrast, AH 5158 was a relatively ineffective antagonist of vasopressor responses to noradrenaline in anesthetized dogs. Thus, at the lowest dose-level tested (1 mg/kg) AH 5158 abolished the increase in pulse width caused by noradrenaline, but otherwise had little or no blocking effect in doses as high as 10 mg/kg. Propranolol (0.1 mg/kg) also abolished the increase in pulse width caused by noradrenaline. With both drugs this effect is thought to be a consequence of blockade of the beta-adrenoceptor-mediated cardia stimulant action of noradrenaline. 3. The interaction between AH 5158 and noradrenaline in spinal dogs, anaesthetized cats and pithed rats was very similar to that seen in anaesthetized dogs. 4. Noradrenaline pressor responses were effectively antagonized by AH 5158 in anaesthetized dogs pretreated with cocaine. The degree of block was similar to that obtained when phenylephrine was the agonist in untreated dogs. 5. These results are consistent with the hypothesis that AH 5158 blocks a cocaine-sensitive inactivation process for noradrenaline in addition to blocking alpha- and beta-adrenoceptors. The resultant increase in the level of circulating noradrenaline would tend to counteract the adrenoceptor blocking action of the drug. 6. The implications of these findings are discussed.