The possibility that some of the enzymes of the citric acid cycle may be loosely associated into a multienzyme cluster has been investigated using extracts prepared by gentle disruption of cells. Gel filtration and sucrose density gradient centrifugation have shown that five sequential enzymes of the cycle specifically associate into a cluster: fumarase, malate dehydrogenase, citrate synthase, aconitase and isocitrate dehydrogenase. Ultrasonication destroys the abilities of the enzymes to associate. The cluster could catalyse the sequence of reactions leading from fumarate to oxoglutarate and has been found in extracts of several bacterial species as well as rat liver mitochondria.

6 World Health Organisation. defnitions, terminology and format for statistical table related to the peinatal periodand use ofa new cerdficate forcause ofperinatal deaths. Acta

To inform future walking interventions, we sought to identify exercise mediators that are associated with readiness to exercise in persons with either asymptomatic peripheral arterial disease (PAD) or disease risk factors. We enrolled participants excluded from a larger behavioral intervention trial for persons with diabetes mellitus and PAD. Participants completed surveys assessing exercise mediators and stage of readiness to exercise (precontemplation, contemplation, or action). Data were analyzed using nonparametric tests. Participants in the stage of action substituted physical activity as an alternative, rewarded themselves, and committed themselves more than other participants (P < .01). Action participants perceived more benefits to exercise than precontemplation participants (P < .05). Contemplation and action participants had higher outcome expectations for exercise, and action participants received more enjoyment from physical activity than precontemplation participants (P < .05 and P = .05, respectively). Identifying these mediators is important for future exercise interventions and treatments.

We have demonstrated that citrate synthase may be assayed by a simple, discontinuous, spectrophotometric procedure based on the measurement of oxaloacetate utilization with 2,4-dinitrophenylhydrazine. The assay is applicable both to the purified enzyme and to cell extracts, and has the advantage that it can be used in the presence of high concentrations of thiols and thioesters. We have used this new assay in part of our investigations into the inhibitory effects of palmitoyl thioesters on diverse citrate synthases. Both palmitoylCoA and palmitoyl thioglycollate inhibit citrate synthases from pig heart, Bacillus megaterium and Escherichia coli, the E. coli enzyme showing the greatest sensitivity to these effectors. With palmitoyl-CoA the extent of inhibition is time-dependent, but the enzymes can be protected from the effect by the substrates oxaloacetate and acetyl-CoA. Using the dinitrophenylhydrazine assay, we have shown that the thioester bond is essential for inhibition; that is, if the palmitoyl thioesters are cleaved to give a mixture of palmitate and a thiol compound, the inhibitions of pig heart and B. megaterium citrate synthases are eliminated and that of the E. coli enzyme is markedly decreased. INTRODUCTIONCitrate synthase (EC 4.1.3.7) catalyses the reaction:

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In a single centre pilot study, saruplase (20 mg bolus plus 60 mg infusion over 1 h) was administered to twenty patients with an angiographically documented recent massive pulmonary embolism: Miller index of at least 20 and mean pulmonary artery pressure of at least 20 mmHg. The lytic ability of saruplase to cause normalization of haemodynamic parameters over the first 12 h and reperfusion of pulmonary arteries at 24 h was assessed. A decrease of 25 ± 10% in total pulmonary resistance was evident at 30 min. Haemodynamic parameters continued to improve with total pulmonary resistance decreasing by 29 ± 8% and 40 ± 11% at 1 and 12 h respectively. Relative improvement in Miller index 24 ± 6 h after saruplase treatment was 38 ± 9%. Two patients suffered recurrent pulmonary embolism, two severe bleeding events were observed. One patient died following a haemorrhagic stroke. Pulmonary AngiographyPulmonary angiography, using a pigtail catheter was performed with brachial venous access. Contrast medium was injected into the main pulmonary trunk in an anteroposterior position. Angiography was performed both prior to lysis and again at 24 ± 6 h. Standard, large format cut film angiograms were produced. The severity of embolism was assessed by the method of Miller et al. (8). The angiograms were initially scored by the treating physician, but on completion of the trial a central analysis, with blinding of the sequence of angio-

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