In order to clarify the clinical characteristics of the diseases over nineties the principal cause of death, major pathological findings and clinical diagnoses were correlated in 92 autopsied cases of nonagenarians and centenarians. The agewise prevalences of moderate and severe atherosclerosis in the aorta, cerebral, coronary and iliac to femoral arteries were also investigated in 1452 consecutive autopsies in the aged.
In the principal causes of death of nonagenarians and centenarians the respiratory diseases such as pneumonia and suffocation or misswallowing were the most frequent and found in 37.0%. The diseases of digestive organs, mainly cancer of the stomach and biliary tract were observed in 25%. The cardiovascular diseases such as myocardial infarction and congestive heart failure were found in 16.3%. The neurological diseases, mainly cerebral strokes, were found in 10.9%, and the urinary tract infections were observed in 6.5%. The death for senility was found in 2.2%.
The major pathological findings and the incidences observed in nonagenarians and centenarians were cerebral infarction in 41.3%, cerebral bleeding in 6.5%, pneumonia in 39.6%, lung cancer in 8.7%, myocardial infarction in 23.9%, valvular heart disease in 13.0%, gastric cancer in 12.0%, cholecystitis in 9.8%, cancer of the biliary tract in 6.5% and urinary tract infection in 15.2%.
The underdiagnoses to the major pathological findings were observed in 31.2%. The percentages of major false negative diagnoses were 31.6% in cerebral infarction, 62.5% in lung cancer, 50.0% in myocardial infarction (22.7% when small myocardial infarctions were excluded), 54.5% in gastric cancer (27.3% when early mucosal cancers were excluded), 50.0% in the cancer of biliary tract, 66.7% in the cancer of pancreas, and 66.7% in cholecystitis. The false positive diagnoses were observed in 7.7%.
The cancer was found in 34.8%, and the affected organs were stomach, lung, biliary tract, colon and pancreas in order of predilection.
The incidences of moderate and severe atheroscleroses in aorta, cerebral, coronary, and iliac to femoral arteries were increased lineally with the age from sixties to nineties, indicating the agewise progression of atherosclerosis. However, risk factors for the atherosclerosis such as hypertension, hyperlipidemia, high hematocrit decreased in the elderly, and the aging seemed to be the important factor for the progression of atherosclerosis.
The nonagenarians and centenarians were not the specially selected group, but in the extension of ordinary aged population from the viewpoint of the characteristics of the diseases and complications as well as the severity of atheroscleroses. Although the aggressive examinations or treatments were sometimes difficult to perform for the multi-morbidity, complications and senility, it should be realized that they had multiple diseases such as cardiovascular, infectious and malignant diseases.

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Lipoprotein lipase activity has been characterized in solubilized form as a post heparin lipolytic activities. However, membrane-supported enzymes have different reaction velosities than do solubilized enzymes. Recent studies (R. J. Havel, 1973) have shown that human triglyceride rich lipoproteins are the active substrates for the lipoprotein lipase from different sources.
In this study, active catalytic rate on the vascular surface of rat heart for human chylomicron and very low density lipoprotein has been determined.
Materials and Methods
The experimental procedures for determination of membrane supported lipoprotein lipase activity are fundamentally that described by C. J. Fielding, 1974. The heart isolated from male Spragu Dawley rat after overnight fast and was perfused with a modefied recirculating Langendorff apparatus. The components of perfusate are as followed; Krebs-Henseleit bicarbonate buffer gassed with 95% O₂ and 5% CO₂, 4% v/v of 1.063<d fraction of human plasma, 3.5% w/v of Bovine Serum Albumin (Fraction V) and ³H-labeled human chylomicron or very low density lipoprotein as substrate. The substrate were prepared from both healthy human and the patient with low carboxyl-terminal glutamic acid lipoprotein which was provided by R. J. Havel, UCSF Cardiovascular Research Institute. During the perfusion through the rat heart without arrythmia, 6 or 8 duplicate 0.2ml samples were drawn every 2min. and after extraction of ³H-triglyceride, the kinetic constants, V_max and K_m, were calculated.
Results
The triglyceride of healthy human chylomicron or very low density lipoprotein was obvious during the perfusion through the rat heart. More than 1.0μmol/ml of triglyceride at the begining of the perfusion showed zero order elimination curve, and first order kinetics were shown in less than 0.1μmol/ml of triglyceride concentration. The calculated V_max and K_m were 0.061μmol/min., 0.082m mol in chylomicron and 0.037μmol/min., 0.065m mol in very low density lipoprotein, respectively. On the other hand, any hydrolysis of triglyceride was not observed in the perfusion of low carboxyl-terminal glutamic acid lipoprotein.
Conclusion
Since healthy human triglyceride rich lipoprotein be able to hydrolyze during rat heart perfusion and kinetic constants are similar to previously reported that of rat lipoprotein, it is suggested that the human lipoprotein is an active substrate of the lipoprotein lipase supported on vascular surface of rat heart. It was also demonstrated that abnormal protein component of human plasma, low carboxyl-terminal glutamic acid, inhibits lipoprotein lipase activity in situ.
This experimental model should facilitate to study not only solid-bound enzyme activity but also lipoprotein metabolism on vascular surface of the heart in human subjects.

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