Those Elusive Micronuclei - - -

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Dr Deco

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Hello: Readers [andA34735]

I decided to post a reply made to A34735 in the belief that other might enjoy reading about this topic of micronuclei in barophysiology.

Micronuclei: What are They?

Micronuclei cannot be seen at room temperature. They are exceedingly small, much smaller than a red blood cell, for example. Surprisingly, when water, for example, is heated, the micronuclei expand to form vapor bubbles that are very easily visible.

If they cannot be seen, where did the idea arise? :confused: Measurements of the tensile strength of water indicate that it requires hundred of atmospheres of negative pressure to form a bubble in denucleated water. That expansion force exceeds, by considerable amounts, what is applied when bubbles form in most situations.

What is “Tensile Strength”?

When a material is pulled apart, it is said to be under tension. That a solid can rip apart is clear, but the same occurrence in a liquid is not at all obvious. However, if a liquid is placed in a cylinder [with no air space present] with a piston, it is found that certain tension must be applied before the piston can be pulled out and the liquid essentially splits- forms a bubble. It was found experimentally that a liquid has a different tensile strength depending on how much pressure was applied prior to applying tension [pulling the piston]. Naturally, the first thought is that the pressure applied forces minute bubbles into solution. These were considered to be micronuclei.

Calculations based on theory indicated that the true tensile strength of water must be more than 1,000 atmospheres, much higher than had ever been measured in the laboratory. Micronuclei were postulated to be present [essentially impurities] although their origin was unknown. Thermal movement of water molecules were postulated to provide a range of “holes” in water. Bigger holes were rare but possible. With increasing temperature, the holes became bigger and more numerous.

Where Did the Idea of Nuclei in Tissue Arise?

These were introduced into decompression theory by Edmund Newton Harvey in the early 1940s. Harvey first noted bubble formation during his studies of ultrasound and its effects on biological samples in the late 1920s. The low-power devices of the time could not possibly form bubbles in liquids, he reasoned. Something must be there that is simply enlarged by the ultrasound wave.

How nuclei form in tissues and how long they persist are points of contention.

It is a basic premise of physics that nuclei [or microbubbles] are present if a reduced pressure is applied to a solid or liquid, and then bubbles appear. It is only in decompression physiology that the idea that bubbles FORM anew from nothing [de novo] has persisted. In all other areas of science, whether this is bubble formation from ultrasound or in volcanic lava, nuclei are assumed present.

What about Nuclei in Decompression?

These are thought to reside on surfaces [wall nuclei] rather than in the fluids, themselves [stream nuclei]. They might form, or more precisely be enlarged, from hydrodynamic mechanisms from exercise [my theory]. They are gaseous and not visible under a microscope since they are so minute.:cool2:

Dr Deco :doctor:
 
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