Community thrombolysis in the Coromandel region. Audit of the "Cardiac Events in the Coromandel-Assessment Strategy and Triage" (CE-COAST) pilot program.

AIM: To audit the experience of a pilot program for community thrombolysis undertaken within the Coromandel region. METHODS: Community thrombolysis for patients suffering acute myocardial infarction (MI) was undertaken in areas within the Coromandel peninsula greater than half an hour by road from Thames Hospital. Thrombolytic therapy (Retelapse) was given following a discussion and review of a digitally transmitted ECG with the cardiology registrar. Treatment times and patients demographics were prospectively recorded. Subsequent clinical events were by chart review. Comparison of treatment times were made with an historical cohort for the same population which had received in-hospital thrombolysis between 1993 and 1998. RESULTS: Between July 1998 and December 1999, nineteen patients received thrombolysis in the community. There were no arrhythmic events during transportation and no deaths or reinfarctions during hospital stay. Median time from pain onset to thrombolysis was 135 (mean 175.5 +/- 144.9 SD) minutes which equated to a reduction in median time delay of 135 minutes compared to that experienced by the historical cohort (median 270, mean 316.7 +/- 145.8 SD minutes), p=0.0003. CONCLUSION: Community thrombolysis is logistically feasible within the New Zealand setting and results in major time reductions in the treatment of patients with acute MI.

Treatment delays for patients with acute myocardial infarction within the Coromandel region of New Zealand.

AIM: To assess treatment delays incurred by Coromandel patients requiring thrombolytic therapy for acute myocardial infarction at Thames Hospital. METHODS: A chart search was undertaken at Thames Hospital to identify all patients admitted from July 1993 to July 1998 with a diagnosis of acute myocardial infarction who were treated with thrombolytic therapy. Times of pain onset, general practitioner (GP) assessment, transportation, hospital arrival and thrombolytic administration were noted. Additional information, when required, was obtained from the patient's GP or the St Johns Ambulance service. RESULTS: 153 patients were thrombolysed at Thames Hospital over this period, mean age 65.1 years, 36.6% in heart failure. The mean time from pain onset to GP contact was 157.2 minutes and varied from 63.2 minutes in Coromandel Township to 272.5 minutes in Pauanui. Delays from GP contact to thrombolysis were longer for patients living in outlying areas versus Thames and its environs, 169.4 +/- 45.9 versus 125.2 +/- 50.4 minutes (mean +/-SD) respectively, p<0.001. This contributed to a total delay from pain onset to thrombolysis of 316.7 +/- 145.8 minutes for patients in outlying areas versus 269.1 +/- 185.8 minutes for local patients (p=0.014). CONCLUSIONS: Delays in providing thrombolytic therapy for acute infarct patients reflect not only transport times but also delays in seeking initial medical assessment and hospital triage times. Transport times become particularly significant for those outside of Thames and its environs. Only with improved patient education and local delivery of thrombolytic therapy will these delays be adequately addressed.

Argininosuccinate synthetase: essential role of cysteine and arginine residues in relation to structure and mechanism of ATP activation.

We have undertaken studies to identify amino acid residues that are involved in the catalytic mechanism of argininosuccinate synthetase [L-citrulline:L-aspartate ligase (AMP-forming), EC 6.3.4.5] and have found that a cysteine residue and an arginine residue are required for activity. The reactive cysteine residues are accessible to solvent and available to react with 5,5'-dithiobis(2-nitrobenzoic acid) (DTNB). Four cysteine residues, one per subunit, are shown by enzymatic assay to be required for catalytic activity, suggesting that a reactive cysteine lies within the active site of argininosuccinate synthetase. In the presence of sodium dodecyl sulfate, 12 cysteine residues react with DTNB; consequently, all of the half-cystine residues in the native enzyme are present in the reduced sulfhydryl form. We also present evidence for the participation of arginine groups in the binding of ATP and PPi. Modification of argininosuccinate synthetase with [14C]-phenylglyoxal results in incorporation concomitant with loss of catalytic activity of 4 mol of phenylglyoxal per mol of native enzyme (one arginine per active site). ATP and PPi protect the enzyme from phenylglyoxal incorporation. Based on these results, we propose that the essential arginine in the active site participates in the binding of ATP and PPi. The binding of ATP and PPi at the same site is mutually exclusive; this exclusion is in accord with the finding that argininosuccinate synthetase has one reactive arginine residue per active site per subunit. This is consistent with our previously proposed reaction mechanism.

An improved bulk purification method for Escherichia coli elongation factor, Ts.

A bulk purification procedure has been designed to maximize the yield of Escherichia coli elongation factor, Ts, with a minimum of effort and time. The enzyme purification is achieved by DEAE-Sepharose and elongation factor Tu-affinity chromatographies. The typical yield is 150 mg/kg of E. coli (B) cells.

Metabolism of octanoate and its effect on glucose and palmitate utilization by isolated fat cells.

Octanoate is avidly incorporated into triglycerides by isolated rat adipocytes in the presence of glucose via direct esterification without prior beta-oxidation to acetyl CoA. This was shown by separation of the products formed from (1-14C) octanoate into lipid classes using Florisil columns, and after alkaline hydrolysis of the triglyceride fraction, by cochromatogrpahy with authentic fatty acids on reverse-phase Celite columns. The relative contribution of (U-14C) glucose and (1-14C) octanoate to triglyceride synthesis and CO2 formation were studied under a variety of conditions. Concentrations of octanoate below 0.5 mM have a stimulatory effect on the conversion of (U-14C) glucose to CO2, triglycerides and esterified fatty acids. However, a marked depression of fatty acid synthesis from (U-14C) glucose was observed in the presence of millimolar concentrations of octanoate. Octanoate had no effect on the esterification of palmitate, but palmitate strongly depressed the ability of rat adipocytes to esterify octanoate.