Confirmation that heparin is an alternative means of promoting early reperfusion.

BACKGROUND: New strategies to increase coronary patency rate before primary angioplasty are under discussion. We tested the hypothesis that use of a high dose of a standard heparin bolus could achieve an acceptable rate of re-opening occluded infarct-related arteries thus providing an alternative to chemical thrombolysis before admission of the patient to hospital, and a pretreatment for primary angioplasty. METHODS: Forty-eight patients who presented within 12 h of acute myocardial infarction with ST segment elevation were assigned randomly to groups to receive aspirin (200 mg orally) and high-dose standard heparin 300 U/kg as an intravenous bolus (n = 25), or aspirin and placebo bolus (n = 23). Thereafter, all patients underwent coronary arteriography to assess their suitability for primary angioplasty. RESULTS: The high-dose heparin group had greater patency rate (Thrombolysis in Myocardial Infarction grade 2 or 3 flow in the infarct-related artery) than the placebo group (52% compared with 13%, P = 0.006). Hemorrhages related to the puncture site that required blood transfusion occurred in two of 25 and in one of 23 patients in the high-dose heparin and placebo groups, respectively. CONCLUSION: Our study suggests that high-dose standard heparin does have a thrombolytic action when administered as an intravenous bolus.

Thromboembolism in chronic Chagas' heart disease.

Thromboembolic episodes are particularly important in chronic Chagas' heart disease. Systemic and pulmonary embolic phenomena are important complications of the disease. Prophylaxis of the thromboembolic phenomena with anticoagulant therapy should be considered in several clinical forms of the disease. Further studies will have to address the stratification risk issue.

Millennial-scale ocean acidification and late Quaternary decline of cryptic bacterial crusts in tropical reefs.

Ocean acidification by atmospheric carbon dioxide has increased almost continuously since the last glacial maximum (LGM), 21,000 years ago. It is expected to impair tropical reef development, but effects on reefs at the present day and in the recent past have proved difficult to evaluate. We present evidence that acidification has already significantly reduced the formation of calcified bacterial crusts in tropical reefs. Unlike major reef builders such as coralline algae and corals that more closely control their calcification, bacterial calcification is very sensitive to ambient changes in carbonate chemistry. Bacterial crusts in reef cavities have declined in thickness over the past 14,000 years with largest reduction occurring 12,000-10,000 years ago. We interpret this as an early effect of deglacial ocean acidification on reef calcification and infer that similar crusts were likely to have been thicker when seawater carbonate saturation was increased during earlier glacial intervals, and thinner during interglacials. These changes in crust thickness could have substantially affected reef development over glacial cycles, as rigid crusts significantly strengthen framework and their reduction would have increased the susceptibility of reefs to biological and physical erosion. Bacterial crust decline reveals previously unrecognized millennial-scale acidification effects on tropical reefs. This directs attention to the role of crusts in reef formation and the ability of bioinduced calcification to reflect changes in seawater chemistry. It also provides a long-term context for assessing anticipated anthropogenic effects.

Hopping hotspots: global shifts in marine biodiversity.

Hotspots of high species diversity are a prominent feature of modern global biodiversity patterns. Fossil and molecular evidence is starting to reveal the history of these hotspots. There have been at least three marine biodiversity hotspots during the past 50 million years. They have moved across almost half the globe, with their timing and locations coinciding with major tectonic events. The birth and death of successive hotspots highlights the link between environmental change and biodiversity patterns. The antiquity of the taxa in the modern Indo-Australian Archipelago hotspot emphasizes the role of pre-Pleistocene events in shaping modern diversity patterns.