【求助】一个美国专利变更及到期问题？

欧转专利网上的专利法律状态如下：
INPADOC legal status
The EPO does not accept any responsibility for the accuracy of data and information originating from other authorities than the EPO; in particular, the EPO does not guarantee that they are complete, up-to-date or fit for specific purposes.

Legal status (INPADOC) of US4877830

US F 7245287 A (Patent of invention)
PRS Date : 1987/10/23
PRS Code : AS02
Code Expl.: ASSIGNMENT OF ASSIGNOR\'S INTEREST
NEW OWNER: F. HOFFMANN-LA ROCHE AND CO., AKTIENGESELLSCHAFT, 12
EFFECTIVE DATE: 19870729

PRS Date : 1987/10/23
PRS Code : AS02
Code Expl.: ASSIGNMENT OF ASSIGNOR\'S INTEREST
NEW OWNER: DOBELI, HEINZ
EFFECTIVE DATE: 19870729

PRS Date : 1987/10/23
PRS Code : AS02
Code Expl.: ASSIGNMENT OF ASSIGNOR\'S INTEREST
NEW OWNER: HOCHULI, ERICH
EFFECTIVE DATE: 19870729

PRS Date : 1990/11/06
PRS Code : CC
Code Expl.: CERTIFICATE OF CORRECTION

PRS Date : 1998/12/23
PRS Code : AS02
Code Expl.: ASSIGNMENT OF ASSIGNOR\'S INTEREST
NEW OWNER: ROCHE DIAGNOSTIC SYSTEMS, INC. 1080 U.S. HIGHWAY 2
EFFECTIVE DATE: 19981217

PRS Date : 1998/12/23
PRS Code : AS02
Code Expl.: ASSIGNMENT OF ASSIGNOR\'S INTEREST
NEW OWNER: HOFFMANN-LA ROCHE INC.
EFFECTIVE DATE: 19981217

请问：
1.专利变更以后它的实施日期也变更吗？
2.就这个专利来说，它什么时候到期呢？

因合并故做过申请人变更

有一个分案申请  授权US5047513

1987年7月13日  申请   没有extended patent terms

现在应该已经到期(2008年1月10日)

供参考

Total Assignments: 4
Patent #:
  
4877830
  
Issue Dt:
  
10/31/1989
  
Application #:
  
07072452
  
Filing Dt:
  
07/13/1987
Inventors:
  
HEINZ DOBELI, ERICH HOCHULI
Title:
  
METAL CHELATE RESINS
Assignment: 1
Reel/Frame:
  
004772/0839    Recorded: 10/23/1987    Pages: 2
Conveyance:
  
ASSIGNMENT OF ASSIGNORS INTEREST.
Assignor:
  
F. HOFFMANN-LA ROCHE & CO. AKTIENGESELLSCHAFT, A SWISS COMPANY
  
Exec Dt:
  
07/29/1987
Assignee:
  
HOFFMANN-LA ROCHE INC., NUTLEY, NEW JERSEY A CORP. OF NEW JERSEY
Correspondent:
  
JON S. SAXE
HOFFMANN-LA ROCHE INC
340 KINGSLAND STREET
NUTLEY, NJ 07110
Assignment: 2
Reel/Frame:
  
004772/0841    Recorded: 10/23/1987    Pages: 2
Conveyance:
  
ASSIGNMENT OF ASSIGNORS INTEREST.
Assignors:
  
DOBELI, HEINZ
  
Exec Dt:
  
07/29/1987
HOCHULI, ERICH
  
Exec Dt:
  
07/29/1987
Assignee:
  
F. HOFFMANN-LA ROCHE & CO., AKTIENGESELLSCHAFT, 124-184 GRENZACHERSTRASSE, BASEL, SWITZERLAND A SWISS COMPANY
Correspondent:
  
JON S. SAXE
HOFFMANN-LA ROCHE INC
340 KINGSLAND STREET
NUTLEY, NJ 07110
Assignment: 3
Reel/Frame:
  
009719/0669    Recorded: 02/05/1999    Pages: 10
Conveyance:
  
MERGER AND CHANGE OF NAME
Assignor:
  
ROCHE DIAGNOSTIC SYSTEMS, INC.
  
Exec Dt:
  
12/11/1998
Assignee:
  
ROCHE DIAGNOSTICS CORPORATION
9115 HAGUE ROAD
INDIANAPOLIS, INDIANA 46250
Correspondent:
  
ROCHE DIAGNOSTICS CORPORATION
D. MICHAEL YOUNG, ESQ.
9115 HAGUE ROAD
INDIANAPOLIS, IN 46250-0457
Assignment: 4
Reel/Frame:
  
009662/0139    Recorded: 12/23/1998    Pages: 3
Conveyance:
  
ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS).
Assignor:
  
HOFFMANN-LA ROCHE INC.
  
Exec Dt:
  
12/17/1998
Assignee:
  
ROCHE DIAGNOSTIC SYSTEMS, INC.
1080 U.S. HIGHWAY 202
BRANCHBURG, NEW JERSEY 08876
Correspondent:
  
HOFFMANN-LA ROCHE INC.
GEORGE W. JOHNSTON
PATENT LAW DEPARTMENT
340 KINGSLAND STREET
NUTLEY, NJ 07110