(a) Only a qualified person may be appointed a proxy to vote shares of a professional corporation.
(b) A voting trust with respect to shares of a professional corporation is not valid unless all of its trustees and beneficiaries are qualified persons. But, if a beneficiary who is a qualified person dies or becomes disqualified, a voting trust valid under this subsection continues to be valid for ten months after the date of death or for five months after the disqualification occurred.