Publications

CONTEXT

Raloxifene, a selective estrogen receptor modulator, improves cardiovascular risk factors, but its effect on cardiovascular events is unknown.

OBJECTIVE

To determine the effect of raloxifene on cardiovascular events in osteoporotic postmenopausal women.

DESIGN

Secondary analysis of data from the Multiple Outcomes of Raloxifene Evaluation trial, a randomized, double-blind, placebo-controlled trial conducted between November 1994 and September 1999.

SETTING

Outpatient and community settings at 180 sites in 25 countries.

PARTICIPANTS

A total of 7705 osteoporotic postmenopausal women (mean age, 67 years).

INTERVENTION

Patients were randomly assigned to receive raloxifene, 60 mg/d (n = 2557), or 120 mg/d (n = 2572), or placebo (n = 2576) for 4 years.

MAIN OUTCOME MEASURES

Cardiovascular events, including coronary events (myocardial infarction, unstable angina, or coronary ischemia) and cerebrovascular events (stroke or transient ischemic attack), collected as safety end points and subsequently adjudicated by a cardiologist blinded to therapy. Cardiovascular risk at study entry was determined by the presence of multiple cardiovascular risk factors or prior coronary events or revascularization procedure.

RESULTS

In the overall cohort, there were no significant differences between treatment groups in the number of combined coronary and cerebrovascular events: 96 (3.7%) with placebo, 82 (3.2%) with 60 mg/d of raloxifene, and 94 (3.7%) with 120 mg/d of raloxifene. Relative risks (RRs) were 0.86 (95% confidence interval [CI], 0.64-1.15) and 0.98 (95% CI, 0.74-1.30) for 60 mg/d and 120 mg/d of raloxifene, respectively. Similar results were obtained when coronary and cerebrovascular events were analyzed separately. Among the subset of 1035 women with increased cardiovascular risk at baseline, those assigned to raloxifene had a significantly lower risk of cardiovascular events compared with placebo (RR, 0.60; 95% CI, 0.38-0.95 for both raloxifene groups). The number of cardiovascular events during the first year was not significantly different across groups in the overall cohort (P =.94), or among women at increased cardiovascular risk (P =.86) or with evidence of established coronary heart disease (P =.60).

CONCLUSIONS

Raloxifene therapy for 4 years did not significantly affect the risk of cardiovascular events in the overall cohort but did significantly reduce the risk of cardiovascular events in the subset of women with increased cardiovascular risk. There was no evidence that raloxifene caused an early increase in risk of cardiovascular events. Before raloxifene is used for prevention of cardiovascular events, these findings require confirmation in trials with evaluation of cardiovascular outcomes as the primary objective.

Transport of lung liquid is essential for both normal pulmonary physiologic processes and for resolution of pathologic processes. The large internal surface area of the lung is lined by alveolar epithelial type I (TI) and type II (TII) cells; TI cells line >95% of this surface, TII cells <5%. Fluid transport is regulated by ion transport, with water movement following passively. Current concepts are that TII cells are the main sites of ion transport in the lung. TI cells have been thought to provide only passive barrier, rather than active, functions. Because TI cells line most of the internal surface area of the lung, we hypothesized that TI cells could be important in the regulation of lung liquid homeostasis. We measured both Na(+) and K(+) (Rb(+)) transport in TI cells isolated from adult rat lungs and compared the results to those of concomitant experiments with isolated TII cells. TI cells take up Na(+) in an amiloride-inhibitable fashion, suggesting the presence of Na(+) channels; TI cell Na(+) uptake, per microgram of protein, is approximately 2.5 times that of TII cells. Rb(+) uptake in TI cells was approximately 3 times that in TII cells and was inhibited by 10(-4) M ouabain, the latter observation suggesting that TI cells exhibit Na(+)-, K(+)-ATPase activity. By immunocytochemical methods, TI cells contain all three subunits (alpha, beta, and gamma) of the epithelial sodium channel ENaC and two subunits of Na(+)-, K(+)-ATPase. By Western blot analysis, TI cells contain approximately 3 times the amount of alphaENaC/microg protein of TII cells. Taken together, these studies demonstrate that TI cells not only contain molecular machinery necessary for active ion transport, but also transport ions. These results modify some basic concepts about lung liquid transport, suggesting that TI cells may contribute significantly in maintaining alveolar fluid balance and in resolving airspace edema.

We reported previously that mast cell tryptase is a growth factor for dog tracheal smooth muscle cells. The goals of our current experiments were to determine if tryptase also is mitogenic in cultured human airway smooth muscle cells, to compare its strength as a growth factor with that of other mitogenic serine proteases, and to determine whether its proteolytic actions are required for mitogenesis. Highly purified preparations of human lung beta-tryptase (1-30 nM) caused dose-dependent increases in DNA synthesis in human airway smooth muscle cells. Maximum tryptase-induced increases in DNA synthesis far exceeded those occurring in response to coagulation cascade proteases, such as thrombin, factor Xa, or factor XII, or to other mast cell proteases, such as chymase or mastin. Irreversibly abolishing tryptase's catalytic activity did not alter its effects on increases in DNA synthesis. We conclude that beta-tryptase is a potent mitogenic serine protease in cultured human airway smooth muscle cells. However, its growth stimulatory effects in these cells occur predominantly via nonproteolytic actions.

Using a rat model of acid-induced lung injury, we tested the hypothesis that tidal volume reduction at the same level of PEEP (10 cm H(2)O) would diminish the degree of pulmonary edema by attenuating injury to the alveolar epithelial and endothelial barriers. Tidal volume reduction from 12 to 6 to 3 ml/kg significantly reduced the rate of lung water accumulation from 690 microl/h to 310 microl/h to 210 microl/h. Ventilation with either 6 or 3 ml/kg reduced endothelial injury equally as measured by plasma vWf:Ag and permeability to albumin. Plasma RTI40, a marker of type I epithelial cell injury, decreased 46% when tidal volume was reduced from 12 to 6 ml/kg and decreased an additional 33% with 3 ml/kg (p < 0.05). The rate of alveolar epithelial fluid clearance was significantly faster in the 3-ml/kg group (24 +/- 7%/h) compared with 6 ml/kg (15 +/- 11%/h) and 12 ml/kg (3 +/- 6%/h). We conclude that low tidal volume ventilation protects both the alveolar epithelium and the endothelium in this model of acute lung injury. The additional decrease in pulmonary edema with a tidal volume of 3 ml/kg is partly accounted for by greater protection of the alveolar epithelium.