The incidence and time-related changes in cardiovascular diseases (intracerebral hemorrhage, cerebral infarction, myocardial infarction) were prospectively studied in the two study-populations which were recruited from Hisayama residents, aged 40 or over, in 1961 (first cohort) and in 1973-74 (second cohort), respectively. Cases which had developed into cardiovascular diseases were clinically or pathologically ascertained. The prevalence of hypertension and its manifestation on electrocardiogram decreased in the second cohort, while subjects with hypercholesterolemia or obesity increased.
The average annual incidence of intracerebral hemorrhage was 3.1/1, 000, and that of cerebral infarction was 9.0/1, 000 for men of the first cohort during follow-up (1961-70), while 1.2/1, 000 and 5.5/1, 000 for men of the second (1974-83), respectively, the difference being significant. Cerebral infarction for women was also reduced in the second cohort with the average annual incidence of 3.8/1, 000 from 6.1/1, 000 for the first (p<0.05). Intracerebral hemorrhage for men and myocardial infarction for both sexes did not diminish in the recent population. This evidence is ascribable to the drop of the prevalence of hypertension. The mortality figures from intracerebral hemorrhage and cerebral infarction during 24-year follow-up of the Hisayama study, which were based on death certificates, were corrected by pathological diagnosis. Death rates by intracerebral hemorrhage for men steeply declined throughout the period, which was similar to those of the whole Japan.
Mortality from intracerebral hemorrhage for women, however, was much less than that of the whole Japan from the initiation of the study, keeping almost the same level through the studyperiod. Vital statics of Japan revealed that mortality from cerebral infarction slightly increased until early or middle 1970's, and decreased afterwards. Corrected mortality from cerebral infarction by pathological diagnosis for Hisayama residents, however, constantly showed a down-ward trend and this was accelerated since late 1970's. Based on the results obtained from the study, the quality and reliability of death certificate information was discussed.

View full abstract

Analogy of arteriosclerosis with inflammation is recently pointed out by many investigators. It is not a simple rivival of Virchow's theory, but is a natural result of rapid accumulation of informations concerning various chemical mediators, growth factors and many other related matters.
Response to injury hypothesis by Ross and Glomset brought arteriosclerosis near to inflammation. According to their hypothesis, various injuries of endothelial cells initiate stepwise sequences finally resulting in arteriosclerosis.
Both inflammation and arteriosclerosis have common features, namely disturbances of vascular permeability, cell infiltration, mesenchymal cell proliferation, neovascularization, fibrosis and calcification. Predominant inflammatory cells in arteriosclerosis are macrophages, lipophages and lymphocytes, whereas neutrophils, plasma cells, lymphocytes and macrophages are main participants in inflammation.
The most notable difference in atherosclerosis is fat deposition and lipophages as compared with ordinary inflammatory processes. Inflammation of the blood vessel walls i.e. vasculitis is now recognized as an important background lesion of arteriosclerosis. Takayasu arteritis usually affects elastic arteries. In the aged with Takayasu arteritis, remarkable atherosclerosis with extensive medial destruction was observed. In polyarteritis nodosa and systemic lupus erythematosus, an increase in occlusive lesions is noted recently with improvement of their prognosis. Lipid deposition with fibrous intimal thickening is observed in the arteries.
We compared the degree of intimal thickening of the coronary arteries in autopsy cases with polyarteritis nodosa and with systemic lupus erythematosus, and their age and sex-matched controls.
In polyarteritis nodosa, cases of the 4th to 6th decades, degree of intimal thickening of the coronary artery is remarkable as compared with the controls. But after the 7th decade, the degree is the similar in the both groups.
In systemic lupus erythematosus, we could not confirm difference in the intimal thickening as compare with the controls. In collagen-vascular diseases, significance of occlusive arterial lesions including atherosclerosis becomes more serious and is worthy to note in clinical and pathological points of view. Inflammatory cell reactions associated with atherosclerotic lesions recently attracted attention of many investigators. Presence of Tlymphocytes in the intima was reported, but both T- and B-lymphocytes were observed in the adventitia. Role of inflammation and immunity in the atherogenesis was discussed.

View full abstract

Pravastatin sodium (hereafter referred as pravastatin), lovastatin and simvastatin are known as the strong inhibitors of HMG-CoA reductase, the rate limiting enzyme of cholesterol biosynthesis. They are now under clinical trials or already on a market. The first potent inhibitor of the enzyme was ML-236B (compactin), the mother compound of pravastatin. Among the many derivatives of ML-236B including microbial and chemically synthesized ones, pravastatin was selected by its potency and tissue-selective inhibition.
Pravastatin selectively inhibited the sterol synthesis in liver and intestine, the major sites of cholesterogenesis, but only weakly inhibited in other organs including hormone producing ones. In contrast to pravastatin, lovastatin inhibited the sterol synthesis not only in liver and intestine but also in other organs. The findings were supported by the experiments using various kinds of isolated and cultured cells. These different features in tissue selectivity could be ascribed the difference in cellular uptake of these drugs.Pravastatin showed a hypolipidemic activity in dogs, monkeys, rabbits and WHHL rabbits, an animal model for familial hypercholesterolemia (FH) in man. Moreover, pravastatin demonstrated a preventive activity on the progression of coronary atherosclerosis and xanthoma in immature WHHL rabbit. In clinical trials, pravastatin exhibited a potent hypolipidemic activity at a low dose, 5mg b. i. d., even in FH patients. In the long-term trial (15 month), LDL cholesterol was reduced by 27.2%, while HDL cholesterol was inversely increased by 9.2%. No serious side effect and abnormal laboratory finding was reported in these trials.
HMG-CoA reductase inhibitors including pravastatin, lovastatin and simvastatin are the most potent cholesterol lowering drugs among currently available, with less side effects. In particular, pravastatin is expected to have a preventive effect on the progression of atherosclerosis and xanthoma in hypercholesterolemic subjects.

View full abstract

Low density lipoprotein (LDL) is well recognized as one of the major risk factors for developing coronary heart diseases. In spite of intensive development of LDL-lowering drugs, there still exist those patients with refractory hyperlipidemia, whose plasma LDL level is not sufficiently lowered by drugs. LDL apheresis—direct removal of plasma LDL from circulating blood—is expected as the most promising treatment for those refractory patients. Various techniques, such as immunoadsorbent utilizing anti-LDL antibody, have been tried to achieve the selective removal of LDL. However, none of them were widely used, because of complication, poor selectivity and so forth.
To establish a safe and effective LDL apheresis system, we chose synthetic affinity adsorbent as the LDL-removing device of the system. Synthetic polyanion compounds were employed as the affinity ligands for LDL adsorbent to simulate anion-rich sequences of LDL binding sites in human LDL receptor. Among various polyanion compounds, those polyanions with sulfate or sulfonate groups and hydrophilic backbone were found to have strong affinity for LDL. On the other hand, polyanions with carboxyl groups showed poorer affinity. Dextransulfate (DS) was selected as the affinity ligand of LDL adsorbent for its high affinity and low toxicity. The influence of its charge density and molecular weight on the affinity for LDL was studied. The affinity rapidly increased with an increase of charge density, then reached at constant value. Little affinity was found for both DS monomer (glucosesulfate) and DS with higher molecular weight than 10⁴ dalton, while DS with middle molecular weight showed strong affinity.
Middle molecular weight DS was immobilized on cellulose hard gel to give LDL adsorbent for clinical application. The adsorbent demonstrated an excellent selectivity for LDL and VLDL in vitro. Adsorption of HDL and major plasma proteins was almost negligible. Further study on the LDL binding mechanism revealed that DS directly interacts with positively charged site on LDL, which demonstrates the nature of the interaction is same as that of LDL receptor.
LDL adsorption column (Liposorber^TM) packed with the LDL adsorbent and polysulfone hollow fiber plasma separator (Sulflux^TM) were developed for efficient LDL apheresis system. Clinical investigation proved this system is capable of intensively lowering plasma LDL level without affecting major plasma components.

View full abstract

High density lipoproteins (HDL) are known to play an important role in protecting the vasculature from atherosclerosis. We investigated cholesteryl ester transfer protein activity (CETPA) and postheparin lipolytic activities in 27 patients with familial hyperalphalipoproteinemia (FHALP). CETPA was measured using ³H-cholesteryl ester-HDL₃ and VLDL+LDL as a donor and acceptor of cholesteryl ester, respectively. Postheparin lipolytic activities were measured using the nonradioisotopic method of Nozaki et al. (Clin. Chem., 30: 748-751, 1984).
CETPA was significantly lower in FHALP patients than in normal controls (p<0.001). We found 4 probands with complete deficiency of CETPA. In these patients, cholesteryl ester was accumulated in the HDL² fraction, which was also rich in apolipoprotein E. High performance liquid chromatography (HPLC) and analytical ultracentrifugation revealed that the low density lipoprotein (LDL) was small and polydispersed and that the HDL of patients with a complete deficiency of CETPA was markedly larger than normal HDL.
In patients with FHALP, CETPA was not significantly correlated to HDL-cholesterol levels, when patients with a complete CETPA deficiency were excluded.
Lipoprotein lipase (LPL) activity was significantly higher in FHALP patients than in normolipidemic controls (p<0.001), while the average hepatic triglyceride lipase (H-TGL) activity in patients with FHALP was not significantly different from that of normal subjects. However, two patients showed very low H-TGL activities and showed signs of corneal opacification and coronary heart disease.
Our data show that cholesteryl ester transfer protein and H-TGL play very important roles in controlling serum HDL-cholesterol levels. We have classified FHALP into two types: FHALP with a CETPA deficiency and FHALP with low H-TGL activity.

View full abstract

The implications of phospholipid methyltransferase on prostacyclin (PGI₂) generation in cultured human vascular endothelial cells (HUVEC) were investigated. HUVECs were isolated and cultured from human umbilical cord veins. PGI₂ released from HUVEC was assayed by RIA, and cytosolic free Ca++ concentrations ([Ca⁺⁺]i) were measured using fura-2/AM. Results were as follows: Ca⁺⁺ ionophore A23187 (A23187, 10-6M), bradykinin (BK, 10-5M) or thrombin (Th, 10 unit/ml) increased [Ca⁺⁺]_i and PGI₂ generation. Pretreating HUVEC with EGTA had no effect on the basal [Ca⁺⁺]_i and PGI₂ levels, but suppressed their enhancement by A23187 or Th, and diminished them by BK. Pretreatment with 3-deazaadenosine (DAA, 10-4M, 30min) suppressed [Ca⁺⁺]_i increase and PGI₂ generation markedly by BK, and also inhibited effects induced by A23187 and Th.
These results suggest that basal PGI₂ generation was maintained mainly by mobilization from the Ca⁺⁺ pools, and its enhancement by BK was dependent on the influx of extracellular Ca⁺⁺. The activated phospholipid methyltransferase with the increase of [Ca⁺⁺]_i contributed to enhanced PGI₂ generation induced by A23187, BK and Th.

View full abstract

High density lipoproteins (HDL) may play an important role in removing cholesterol from peripheral tissue and deliver it to the liver, acting as a shuttle in reverse cholesterol transport. The mode of interaction between the liver and HDL, however, has not yet been clarified.
We investigated catabolism of human HDL in a human hepatoma cell line Mahlavu. The binding of ¹²⁵I-Iabeled HDL at 4°C was time-dependent and reached completion within 2hr. The observed binding rates of ¹²⁵I-labeled HDL at 4°C and the uptake and degradation at 37°C indicated the presence of both specific and non-specific HDL binding sites. Non-specific binding occured in proportion to the concentration of ¹²⁵I-Iabeled HDL. Specific binding of ¹²⁵I-labeled HDL accounted for 60% (at 4°C) and 75% (at 37°C) of total binding capacity. The association and degradation of ¹²⁵I-labeled HDL was inhibited by the addition of unlabeled HDL, but not LDL, suggesting HDL specificity. The lysosomal degradation of ¹²⁵I-labeled HDL was time-dependent and inhibited only 10% and 20% by chloroquine at 50μM and 100μM concentrations, respectively. This finding suggested that HDL was metabolized through a non-lysosomal pathway.
There was a marked difference in the degradation modes of ¹²⁵I-labeled HDL between fibroblasts and Mahlavu cells. The degradation of ¹²⁵I-labeled HDL by Mahlavu cells increased over time, while only a small portion of ¹²⁵I-labeled HDL was degraded by fibroblasts. This data shows that hepatocytes such as Mahlavu cells have HDL receptors which are considerably different from those of fibroblasts. This cell line provides a good model for analyzing interactions between HDL and hepatocytes in humans.

View full abstract

Mechanism of restenosis after PTCA suggests that platelets play an important role in this response. Since a stable PGI₂ analogue, U-61, 431F (group U), has strong platelet inhibitory action, we investigated the preventing effect of U-61, 431F on restenosis and other complications in patients undergoing PTCA. The effect was compared with control (group C). There was no difference in patients background in the two groups. No abrupt coronary occlusion or other cardiac events were observed in group U, but there was two events in group C. Though there was no significant difference in the results between the 2 groups, group U showed lower patient restenosis rate (group U: group C 33.3%:57.1%) and lesion restenosis rate (group U: group C 25.0%:37.5%) based on follow-up angiography. No serious adverse effect was observed in the group U. Thus U-61, 431F may be effective in preventing acute cardiac events during PTCA and restenosis after PTCA.

View full abstract

Lipids content, triglyceride (TG) production and its secretion in the liver were examined to explore the mechanism of hypertriglyceridemia (HTG) in puromycin aminonucleoside-induced nephrotic rats. Plasma TG, total cholesterol, phospholipid and apoprotein B concentrations in nephrotic rats were about 4-5 times higher than those in control rats. The HTG in nephrosis was mainly due to the elevation of TG-rich lipoprotein (TRL)-TG concentration. Despite remarkable increase in plasma and TRL lipids levels, lipid contents in liver were not significantly increased in nephrotic rats. [³H]-glycerol was injected into portal vein and the radioactivity of endogenous labeled TG in liverr was measured to access the ability for hepatic TG production. Neither the radioactivity nor the specific activity of TG was increased in nephrotic liver compared to the liver of control rats. Triton WR 1339, a potent inhibitor of TRL-TG removal, was injected to assume TRL-TG secretion rate. TRL-TG secretion rate was not increased in nephrotic rats. In addition, the TG/protein ratio in nephrotic TRL was two times as high as that of control, which was similar to the ratio of TRL in their post-Triton plasma. These results demonstrate that HTG in nephrosis is not simply due to increased hepatic TRL-TG production, but suggest that the catabolic defect of TRL-TG may be the more predominant abnormality to cause substantial HTG in this syndrome.

View full abstract