Fit first: Functional Medicine Zurich

The antibody experiment

In an in vitro thymulin experiment, zinc created a three-dimensional feature that monoclonal antibodies could recognise. The feature is called an epitope: the part an antibody recognises. Antibodies directed against the zinc-coupled form also inhibited its biological activity. I admire this economical pairing. A change in recognition came with a change in what the molecule could do.

Zurich conjures a watchmaker's bench: parts laid out, a bridge lowered into place, a fit that has to be exact. That is an analogy, of course. The chemical finding is more interesting than the picture. Zinc helped give this peptide a recognisable form, and the antibody experiment connected that form to activity. A list of ingredients would miss the most absorbing part of the story.

Thymulin and zinc

Thymulin is a peptide made by thymic epithelial cells whose activity depends on zinc binding in an equimolecular ratio. In the earlier metal-removal experiment, biological activity disappeared in a cell-based rosette assay and returned with zinc salts. Other metals restored activity to a lesser extent; the optimal metal-to-peptide ratio was 1:1.

I picture thymulin's assembly as the difference between possessing the parts and having them in working relation. It gives the word functional some welcome friction. In this case there is an experimental way to ask about function, rather than treating the word as a general expression of approval.

The clinical question begins after that chemistry: whether changing the system improves health in a particular group of people. The human zinc-deficiency study and the mouse lung gene-therapy experiment ask very different questions. Their separate preparations and subjects deserve separate consideration.

Choose an experiment

The zinc-binding essay stays close to molecular recognition and the cell experiments. The human serum assay moves into adults with mild zinc deficiency, where an activity measurement complicated the picture from plasma zinc.

For a longer biological timescale, there is the ageing thymus: observations in people beside experiments in old mice and cultured mouse tissue. The delivery essay puts a mouse gene-therapy result alongside human cell work and rheumatoid arthritis trials. The awkward differences between these experiments seem more useful than a smooth story in which every finding points toward the same intervention.