EXHIBIT 3.105

                            CERTIFICATE OF FORMATION

                                       OF

                         NORTHERN INDIANA HOSPITAL, LLC

                  The undersigned, an authorized natural person, for the purpose
of forming a limited liability company, under the provisions and subject to the
requirements of the State of Delaware (particularly Chapter 18, Title 6 of the
Delaware Code and the acts amendatory thereof and supplemental thereto, and
known, identified, and referred to as the "Delaware Limited Liability Company
Act"), hereby certifies that:

                  FIRST: The name of the limited liability company (hereinafter
called the "limited liability company") is Northern Indiana Hospital, LLC.

                  SECOND: The address of the registered office and the name and
the address of the registered agent of the limited liability company required to
be maintained by Section 18-104 of the Delaware Limited Liability Company Act
are Corporation Service Company, 1013 Centre Road, Wilmington, Delaware 19805.

Executed on May 19, 1998

                                                /s/ Michael E. Davis
                                                --------------------------------
                                                Michael E. Davis
                                                Authorized Person