X-Message-Number: 21095
Date: Sat, 08 Feb 2003 16:39:28 +0100
From: Henri Kluytmans <>
Subject: biological things wearing out

Thomas Donaldson wrote :

>In biology things do not simply wear out. That is false as an 
>explanation of aging and equally false when applied to biological
>parts. If they wear out, it will be because the energy and materials
>cost of making new ones is less than the cost of maintaining old

So things do wear out, but if so, it's part of balance.

Yes, I do agree, and my remark should be interpreted in that last 

Quote from article about "Respirocytes" by R. Freitas :

"When tetrameric hemoglobin is freed from the red cell it loses 
effectiveness in three ways. First, it dissociates to dimers 
that are rapidly cleared from circulation by the mononuclear 
phagocytic system (10-30 minute half life) and by the kidneys 
(1 hour half life). Second, it binds O2 more tightly, reducing 
deliverability of O2 during tissue hypoxia. Third, during storage, 
hemoglobin may be oxidized to useless methemoglobin due to the 
absence of the protective enzyme methemoglobin reductase normally 
present in red cells."

This is what made me think that it could be possible that red blood 
cells lose functionality over time. But frankly, I don't know, and it 
was only a guess.

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