we need to talk about nitrogen

I have often mentioned in my various writings that the Haber-Bosch process produces as much reactive nitrogen as the natural nitrogen fixation, and that half of the world population's N content comes out of this synthesis. Yet I didn't really know anything about the ecological impact that doubling the global nitrogen turnover produces. I recently found out that it is a very complex biogeochemical network we're messing with, and we don't nearly understand what the consequences may be.

In an attempt to understand this issue a bit better, I have written a feature article about it, which is out in Current Biology today, and, I'm pleased to report, freely accessible to all:

We need to talk about nitrogen
Current Biology Vol 22, No 1, R1-R4

Photo: A 1921 vintage reactor from a Haber Bosch plant, now on display at the University of Karlsruhe. Source: Wikipedia

blood transfusion risks

Many blood transfusions may increase risks, doctors warn, the Guardian reports, apparently based on a story in New Scientist. Well, I agree completely, but then the piece goes on rambling about how boffins don't understand why blood that has been stored is often doing more harm than good.

In fact, last October, two independent and very convincing papers (one was actually commissioned to check the findings of the other, because of the enormous importance of the issue!) showed that there is a very simple reason, and a very simple way to fix the problem.

Fresh blood contains nitric oxide (NO) bound to hemoglobin, which it loses within hours of storage. NO is needed as a signal to widen the blood vessels. So old blood without NO will lack the vessel-dilating effect and thus the oxygen provision may be no better than or even worse than what the patients could achieve with their own blood. The problem is easy to fix, as NO can be added to the stored blood before transfusion, making it good as new.

I reported all that in Chemistry World and in this blog entry, back in October. Naively, I would have hoped that by now medics would have made moves to implement the fix, rather than scratching their heads over a question that has already been answered.

fresh blood

Researchers have found that over-generous blood transfusions can do more harm than good. Ironically, the measure which is supposed to improve oxygen provision to the patient's organs, can have the opposite effect.

Now there is an explanation to this paradox. It appears that the oxygen transport depends on a signalling process by which the red blood cells help to widen the blood vessels, and this involves nitric oxide bound to hemoglobin. Donor blood for transfusion can be legally stored for 42 days, but the nitric oxide disappears within the first few hours of storage, so virtually all stored blood samples are deficient in that respect.

While this sounds quite scary, there is a silver lining in that the NO content can be restored.

Read my story here:

Blood transfusion risk explained