Abnormal expression of p27kip1 protein in levator ani muscle of aging women with pelvic floor disorders – a relationship to the cellular differentiation and degeneration

Table 1 Semiquantitative evaluation of the fast to slow twitch transition

Stage of muscle fiber	Fiber	Type II	Type I	Cytoplasmic	Fiber size
(myotube) differentiation	Type^a	staining^b	staining	p27
1 - resting fast (young)	fast	+++	-	-	normal
2 - transitory 1	trans 1	+++	++	-	normal or increased
3 - transitory 2	trans 2	++	+++	+	normal or increased
4 - transitory 3	trans 3	-	+++	++	normal or increased
5 - resting slow (mature)	slow	-	+++	-	normal
6 - early deg (aging)	deg 1–2	-	+++	++	normal
7 - late deg (regressing)	deg 3–4	-	+++	+++	fragmented

^a fast = fast twitch fibers; trans 1 = early, trans 2 = mid, trans 3 = late transition of fast- to slow twitch fibers; slow = slow twitch fibers; deg 1–2 = early, deg 3–4 = advanced degeneration (shrinking and fragmentation; see Fig. 3, D-F for examples, and Fig. 6 for staging). ^b Semiquantitative grading: -, none; +, weak; ++, moderate; +++, strong (see Fig. 3 to 6 for corresponding densities).

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