GUARANTY OF OBLIGATIONS

Exhibit 10.28

GUARANTY OF OBLIGATIONS

THIS GUARANTY OF OBLIGATIONS (this “ Guaranty ”) is executed as of September 18, 2008 by JEFFREY L. RUSH, an individual, MARK D. TOOTHACRE, an individual, ELIZABETH A. POWELL, an individual, KIMBERLY B. COCHRANE, an individual, and ROBERT A. ROSENTHAL, an individual (collectively, “ Guarantor ”), in favor of NATIONWIDE HEALTH PROPERTIES, INC. , a Maryland corporation (“ Lender ”).

RECITALS

A. Lender has agreed to make a loan in the principal amount of $47,500,000 (the “ Loan ”) to PDP Pomerado LLC, a California limited liability company ( “ Borrower ”), pursuant to the terms and conditions of that certain Secured Promissory Note of even date herewith to be executed by Borrower in favor of Lender (the “ Note ”). The obligations due from Borrower to Lender under the Note are secured by that certain Leasehold Deed of Trust, Assignment of Rents, Security Agreement, Financing Statement and Fixture Filing (the “ Deed of Trust ”), which creates a lien, inter alia, on Borrower’s leasehold interest in certain real property located in the City of Poway, County of San Diego, State of California, as more particularly described in the Deed of Trust. All initially-capitalized terms used and not otherwise defined herein shall have the meanings given such terms in the Deed of Trust. The Note and Deed of Trust (together with any and all amendments, modifications, restatements or extensions thereof), and all other documents, agreements or instruments executed by Borrower in favor of Lender in connection with the Loan, shall be hereinafter collectively referred to as the “ Loan Documents .”

B. Guarantor acknowledges and agrees that Lender would not have been willing to make the Loan to Borrower unless Guarantor was willing to execute and deliver this Guaranty.

AGREEMENTS

NOW, THEREFORE, in consideration of Lender making the Loan to Borrower, and other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, Guarantor agrees as follows:

Guarantor hereby absolutely and unconditionally guarantees to Lender the following (collectively, the “ Guaranteed Obligations ”):

(a) the full, complete and timely payment when due, by acceleration or otherwise, of all obligations of Borrower now or hereafter existing under the Note and other Loan Documents, whether for principal, interest, fees, expenses or otherwise;

(b) the full, complete and timely performance by Borrower of all covenants, indemnities and other obligations under the Deed of Trust and the other Loan Documents, including, without limitation, any indemnity or other obligations of Borrower which survives the expiration or earlier termination of the Loan Documents; and

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(c) all costs of collection or enforcement incurred by Lender in exercising any remedies provided for in the Note or the other Loan Documents at law or in equity with respect to the matters set forth in clauses (a) and (b), inclusive, above.

Except as otherwise expressly set forth herein, the aggregate liability of Guarantor under this Guaranty shall not exceed the sum of $7,136,250, plus interest on the full principal amount outstanding and payable under the Note and costs and expenses incurred in enforcing or collecting under this Guaranty. The foregoing monetary cap shall not apply to any liability of Guarantor arising under this Guaranty by reason of any of the following:

(a) The misapplication of Insurance Proceeds under the terms of the Deed of Trust;

(b) The misapplication of Condemnation Proceeds under the terms of the Deed of Trust;

(c) The misapplication of Rents under the terms of the Deed of Trust;

(d) Waste committed on the Trust Estate or damage to the Trust Estate as a result of the intentional misconduct or negligence of Borrower or Guarantor, or any removal or disposal of any of the Trust Estate in violation of the terms of the Deed of Trust;

(e) Any mechanic’s liens, materialmen’s liens or other liens not paid to the appropriate payee which could create liens on any portion of the Trust Estate;

(f) The breach by Borrower or Guarantor of any of its respective obligations and indemnities under the Loan Documents relating to hazardous or toxic substances or compliance with environmental laws and regulations, it being understood that nothing herein shall be deemed to limit, impair or reduce said obligations and indemnities;

(g) Fraud or material misrepresentation by Borrower or Guarantor or, if Guarantor knew or would have known thereof by exercising reasonable supervision of such persons, by any principals, officers or employees of Borrower or by any guarantor, any indemnitor or any agent, employee or other person authorized or apparently authorized to make statements or representations on behalf of Borrower;

(h) The failure of Borrower to maintain the types and levels of insurance required under the terms of the Deed of Trust; and

(i) The assertion by Borrower or Guarantor of any cause of action against Lender relating to the Loan, that Lender has any liability whatsoever to Borrower or Guarantor, or that Lender is a partner or joint venturer of Borrower or has any liability as such.

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Upon the occurrence of an Event of Default (as defined in the Note) and the expiration of any applicable notice and/or cure period thereunder, then upon demand by Lender, Guarantor shall pay within ten (10) days such sums and perform such obligations as required by the Loan Documents, without regard to:

(a) any defense, set-off, or counterclaim which Guarantor or Borrower may have or assert;

(b) whether or not Lender shall have instituted any suit, action or proceeding or exhausted its remedies or taken any steps to enforce any rights against Borrower or any other person to collect all or any part of such sums, either pursuant to the provisions of the Loan Documents or at law or in equity (it being understood that this is a guaranty of payment and not collection, and Guarantor’s liability for such payment shall be primary); or

(c) any other condition or contingency.

Guarantor waives any right of exoneration and any right to require Lender to make an election of remedies. Guarantor covenants and agrees that it shall not cause any default under the Loan Documents. Guarantor’s performance or satisfaction of a portion, but not all, of the Guaranteed Obligations shall in no way limit, affect, modify or abridge Guarantor’s liability for that portion of the Guaranteed Obligations which is not performed and Lender shall have the right to designate the manner in which any payments made by Borrower under the Loan Documents or by Guarantor pursuant to this Guaranty are applied to the Guaranteed Obligations. Without limiting the generality of the foregoing, in the event that Lender receives payment for, or is awarded a judgment in any suit brought to enforce Guarantor’s covenant to perform a portion of the Guaranteed Obligations, such payment or judgment shall in no way be deemed to release Guarantor from its covenant to perform or satisfy any portion of the Guaranteed Obligations which is not satisfied by such payment or the collection of any such judgment. Lender shall be under no obligation whatsoever to exhaust any of its collateral for the Guaranteed Obligations or to pursue any right or remedy it may have under the Loan Documents, at law, in equity or otherwise, or to take any action whatsoever to mitigate or reduce Guarantor’s liability hereunder, notwithstanding the fact that the Loan may be fully matured, the outstanding principal balance thereof may be fully due and payable and Borrower is in default of its obligations under the Loan Documents.

Each Guarantor hereby represents and warrants unto Lender that:

(a) this Guaranty constitutes a legal, valid, and binding obligation of Guarantor and is fully enforceable against Guarantor in accordance with its terms, subject to the effect of bankruptcy, insolvency, reorganization, moratorium or other similar laws of general application and of legal or equitable principles generally and covenants of good faith and fair dealing; and

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(b) this Guaranty is duly authorized, executed and delivered by and binding upon Guarantor.

Any material breach by any Guarantor of the representations and warranties set forth herein shall be a default under this Guaranty.

Guarantor hereby knowingly, voluntarily and unequivocally waives:

(a) all notice of acceptance hereof, protest, demand and dishonor, presentment and demands of any kind now or hereafter provided for by any statute or rule of law;

(b) any and all requirements that Lender institute any action or proceeding, or exhaust any or all of Lender’s rights, remedies or recourse, against Borrower or anyone else as a condition precedent to bringing an action against Guarantor under this Guaranty, it being expressly agreed that the liability of Guarantor hereunder shall be primary and not secondary;

(c) any defense arising by reason of any disability, insolvency, bankruptcy, lack of authority or power, death, insanity, minority, dissolution or any other defense of Borrower, its successors and assigns, Guarantor or, if applicable, any other guarantor of the Guaranteed Obligations (even though rendering the same void, unenforceable or otherwise uncollectible), it being agreed that Guarantor shall remain liable hereon regardless of whether Borrower or any other such person be found not liable thereon for any reason;

(d) the benefits of any and all statutes, laws, rules or regulations applicable in the State of California which may require the prior or concurrent joinder of any other party to any action on this Guaranty or which may require the exhaustion of remedies prior to a suit on this Guaranty, all as amended from time to time;

(e) any failure, omission, delay or lack on the part of Lender or Borrower to enforce, assert or exercise any right, power or remedy conferred on Lender or Borrower in the Loan Documents or this Guaranty or any action on the par