Page 33 - Mike's published articles

52 LASERS I body language
E a
Original state (native)
The activation energy required to denature tissue molecules
Denatured state
the thermal process.
With the definition of Ω = 1 being
the threshold for irreversible protein de- naturation, it is worth considering what happens when Ω is greater or less than one (see “Variation of % damaged tissue versus damage level Ω”). This shows the relationship between as Ω and the per- centage of denatured proteins.
The chart below clearly shows that an Ω of one corresponds with a 63.2% dam- age level, while a value of three is required to achieve 95% damage. Diller and Pearce suggest that values of Ω above one are es- sentially meaningless since irreversibility has already been achieved in that tissue.
Interestingly, Takata et al suggest an Ω of 10,000 is equivalent to “third de- gree burns”, yet calculations show that an Ω of only seven will result in 99.9% tissue damage. However, this definition is purely arbitrary. There is no clinical or histological evidence available in the lit- erature to confirm that this assumption is accurate.
It may be that an Ω of two (equivalent to 86.5% denaturation), three (95.0%), four (98.2%) or somewhere else in that range, may actually be necessary to pre- vent sufficient protein re-naturation or regrowth of the existing structure occur- ring. We shall continue with the accepted definition of the onset of irreversible de- naturation (ID) at an Ω value of one.
However, it may be that total dena- turation is not required to induce the de- sired response. In the case of generating new collagen growth, it appears that the existing collagen merely needs to be stim- ulated by the application of external heat.
Our calculations reveal that the actual amount of level of damage, Ω, may be as low as only 0.1 to 0.2. Yet, even this low damage level appears to be sufficient to stimulate the fibroblasts to produce neo- collagenesis.
Irreversible denaturation
It is clear that the target cells must at- tain a temperature, T, which must be maintained for a minimum time, t, to achieve ID (Ω = 1). Consequently, it is not sufficient to simply describe a desired temperature to ensure a successful treat- ment outcome. The associated time for that temperature must also be indicated. The temperature-time combination is a “coupled pair”—quoting one without the other is meaningless.
So, what are the typical (T,t) combi- nations required to achieve ID in hair or blood vessels? These depend on the Arrhe-
above, the temperature corresponding to the activation energy, or Ea.
The activation energy of any tissue differs according to the molecules in question and the denaturation pathways. This is the energy required to break mo- lecular bonds within the tissues and is of- ten referred to as the barrier energy.
It induces a change of state from “na- tive” to “denatured” (see “The activation energy required to denature tissue mol- ecules”).
In essence, Ea determines the tempera- ture at which denaturation of the tissue proteins begins, while the frequency fac- tor, A, dictates the rate at which that de- naturation occurs.
The determination of tissue damage was calculated by Diller and Pearce as the logarithm of the relative concentration of un-denatured tissue.
The level of damage may be calculated by the ratio of the concentration of na- tive tissue, ct, at the end of the thermal insult, at time t1, to the concentration of
native tissue prior to any denaturation, c0, at time t0.
Diller and Pearce showed that the logarithm of the relative concentration of undenatured collagen is the same quan- tity as Ω in the equation above.
The accumulated damage is defined by the dimensionless parameter Ω with the threshold for irreversible damage at a point being defined as Ω = 1. The quantity ct / c0 represents the propor- tion of undamaged tissue at the end of the applied thermal energy. This, therefore, dictates that the proportion of damaged protein may be found as follows:
Ω = - loge(ct / c0) = 1 i.e. ct / c0 = 0.368
Therefore, the proportion of damaged protein, (1 – ct / c0), is 63.2% of the initial concentration. Hence the threshold for irreversible damage, or tissue necrosis, is assumed to occur in tissue when 63.2% of the target tissue has been denatured by
Below: Variation of % damaged tissue versus damage level Ω
95 85 75 65 55 45 35 25 15
5
0.1 0.5 1 1.5 2 2.5 3 4 7
Damage Level
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% Damaged Tissue
Energy