Last week, a couple of old stalwart Irish situations started to shift into tried and tested shapes. Stand up Siptu.

On Thursday, the union refused to allow Aer Lingus chief executive Dermot Mannion address a "private" meeting, and decided on a "protective ballot" for industrial action if the company does something it doesn't like.

Now we must endure the usual routine of whispers and counter-whispers around a cacophony of banging union, management and government drums. In the end, as we all know, the airline will be sold. All that is at stake is how much money pre-election generosity will stuff into workers' pockets and pensions.

On the brighter side, that familiar Elan rush of excitement rose in investors' bellies on a more positive than expected recommendation from the advisory committee convened by the Federal Drugs Authority on Tysabri, the company's multiple sclerosis drug.

It had been expected that the committee would recommend approval of Tysabri, which was withdrawn last year after the death of patients trialling it in combination with another drug as a 'second-line' treatment for MS. But the icing on the cake was the majority vote that Elan should be approved for use as a 'firstline' treatment.

Elan's shares jumped by nearly 25% in New York last Wednesday on the hope Tysabri may be back on the market next month. And after being suspended for a day and a half in Dublin, the stock was up by 26% at one stage on Thursday when trading reopened, closing up by 15%.

It's a crazy hedge fund heaven out there, with 1015% of Elan's market capitalisation changing hands daily in New York recently. The FDA will give its decision on Tysabri by the end of the month, and this could mean lots and lots more money for Elan.

With investors enthralled afresh by the usual hope and expectation, watch the gambling take off on the really big play: Alzheimer's.

Whatever about Tysabri's potential, the belief is that getting an Alzheimer's vaccine out onto the market might just bring Elan back to the big time . . . to that long ago, far away $65 heyday of June 2001.

The Alzheimer's vaccine is in phase two testing, and the hope is to get it into phase three by the end of this year or early next year.

On average, a drug in phase two testing has only a 25% chance of getting to market, but trials by Elan and partner Wyeth are, by all accounts, going well.

One pundit suggests that getting the drug to phase three would prompt a "stampede" of investors and "would be like Tullow Oil striking one of the biggest oilfields in the world". Uncharitably, the same observer suggests that "like Tullow, Elan wouldn't know what to do with it".

Unkind, unkind, but remember what they say about interesting times.

Let's hope the all too familiar Elan cycle - the investor fever, the collapse, the recriminations, the financially smarting Dublin stockbrokers - is broken this time around.

Maybe we should thank Siptu for campaigning to keep our feet planted firmly on the ground.