Histological changes and risk factor associations in type 2 atherosclerotic lesions (fatty streaks) in young adults.

OBJECTIVES: The purpose of this study was to investigate which histological changes associated with risk factors could contribute to the progression from the initial atherosclerotic lesions including fatty streaks to the advanced lesions. METHODS: We examined the associations of histomorphometric findings in the determined anatomical sites of mid-thoracic aortas (TAs) and left anterior descending coronary arteries (LADs) with major risk factors for atherosclerosis, using a young autopsied series from the the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. The histological classification by the American Heart Association was graded for 1013 TAs and 1009 LADs. Histometric study, including immunohistochemistry, was performed in type 2 lesions (fatty streaks) of TAs from 59 subjects and LADs from 45 ones. RESULTS: For the progression from the initial lesions into the advanced atherosclerotic lesions, the most effective lipid profiles were low plasma HDL-C in TA and elevated serum non-HDL-C in LAD. This lipid profile of each artery correlated with number or density of intimal smooth muscle cell-derived foam cells, respectively. The serum concentration of non-HDL-C correlated with macrophage foam cells in TAs. Hypertension and hyperglycemia were associated with increase of intimal area and/or collagen content in both arteries, but not with either types of foam cell proliferation. Smoking correlated with increased collagen content in TAs. CONCLUSION: There were histologically different ways of progressing from fatty streaks to advanced atherosclerotic lesions depending on the risk factors. For the atherosclerosis progression from type 2 lesions to advanced lesions, increase in number of smooth muscle cell-derived foam cells could be an important indicator.

Tolerance to chronic delta-9-tetrahydrocannabinol (Δ9-THC) in rhesus macaques infected with simian immunodeficiency virus.

Although Δ9-THC has been approved to treat anorexia and weight loss associated with AIDS, it may also reduce well-being by disrupting complex behavioral processes or enhancing HIV replication. To investigate these possibilities, four groups of male rhesus macaques were trained to respond under an operant acquisition and performance procedure, and administered vehicle or Δ9-THC before and after inoculation with simian immunodeficiency virus (SIV(mac251), 100 TCID50/ml, i.v.). Prior to chronic Δ9-THC and SIV inoculation, 0.032-0.32 mg/kg of Δ9-THC produced dose-dependent rate-decreasing effects and small, sporadic error-increasing effects in the acquisition and performance components in each subject. Following 28 days of chronic Δ9-THC (0.32 mg/kg, i.m.) or vehicle twice daily, delta-9-THC-treated subjects developed tolerance to the rate-decreasing effects, and this tolerance was maintained during the initial 7-12 months irrespective of SIV infection (i.e., +THC/-SIV, +THC/+SIV). Full necropsy was performed on all SIV subjects an average of 329 days post-SIV inoculation, with postmortem histopathology suggestive of a reduced frequency of CNS pathology as well as opportunistic infections in delta-9-THC-treated subjects. Chronic Δ9-THC also significantly reduced CB-1 and CB-2 receptor levels in the hippocampus, attenuated the expression of a proinflammatory cytokine (MCP-1), and did not increase viral load in plasma, cerebrospinal fluid, or brain tissue compared to vehicle-treated subjects with SIV. Together, these data indicate that chronic Δ9-THC produces tolerance to its behaviorally disruptive effects on complex tasks while not adversely affecting viral load or other markers of disease progression during the early stages of infection.

Associations of arterial tissue lipids with coronary heart disease risk factors in young people.

OBJECTIVE: To examine the associations of the coronary heart disease (CHD) risk factors with lipid composition of arterial tissue in 397 autopsied subjects 15-34 years of age from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. METHODS AND RESULTS: We measured esterified cholesterol, free cholesterol, and phospholipid in the left circumflex coronary artery and two segments of the abdominal aorta, one of which is more susceptible to advanced atherosclerosis than the other, and also measured the major CHD risk factors. Non-HDL cholesterol concentration was positively associated, and HDL cholesterol concentration was negatively associated, with tissue lipids in the left circumflex coronary artery and the abdominal aorta. Hypertension was positively associated with tissue lipids in both arteries. Hyperglycemia was associated with tissue lipids in the left circumflex coronary artery and smoking with lipids in the abdominal aorta. PDAY risk scores summarize the effects of the CHD risk factors on advanced atherosclerosis. These risk scores, computed from the mutable risk factors, were associated with tissue lipids in the left circumflex coronary artery and both segments of the abdominal aorta. CONCLUSIONS: The CHD risk factors are associated with lipids in arterial tissue just as they are associated with gross and microscopic lesions. These results support the proposal that early control of risk factors is likely to prevent or delay progression of atherosclerosis and prevent or delay the onset of CHD.

Histological topographical comparisons of atherosclerosis progression in juveniles and young adults.

BACKGROUND: The histologically topographic comparisons on atherosclerosis progression among three anatomical sites, mid-thoracic and lower abdominal aorta and left anterior descending coronary artery (LAD) were performed using a young population (age 15-34 years) from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study. METHODS AND RESULTS: The histological classification based on the American Heart Association grading scheme showed that in the thoracic aorta type 2 lesions (numerous macrophage foam cells with fine particles but no pools of extracellular lipid) appeared in the first 10-year age group, with no significant change in prevalence in the next 10 years. Lesions greater than type 2 were rarely seen in the thoracic aorta. Although type 2 lesions appeared later in the LAD than in the aorta, the lesions within the LAD progressed rapidly to more advanced lesions (types 4 and 5) or atheroma. Lesion development in the abdominal aorta was intermediate to lesion development in the thoracic aorta and the LAD. CONCLUSIONS: The most striking topographic difference on lesion progression among the three anatomical sites was the vulnerability of type 2 lesions to progress into advanced lesions. The histology study, including immunohistochemistry limited to the type 2 lesions suggested that lesion progression was related to the intimal thickness and the amount of collagen but not to the number of macrophage foam cells.

Aortic rhythmic wrinkling in youth: the PDAY study.

Transverse, white-streak 'wrinkles' in the aorta were first described as Querlinien (cross lines) or Wellenlinien (wave lines) in the German literature in the early 20th century. These rhythmic structures were previously thought to be artifacts of stretching and shrinkage of the aorta. Not until the 1970s was it proposed that the areas of rhythmic wrinkling (RW) might be part of the process of atherosclerosis. We analyzed 2,650 aortas from the Pathobiological Determinants of Atherosclerosis in Youth (PDAY) study for prevalence, extent, and topographical distribution of these areas of RW. Furthermore, we investigated the possible relationship of RW to atherosclerotic sudanophilic stained 'fatty streaks' and elevated intimal lesions called 'raised lesions' (RL). This study provides evidence that (1) the prevalence of RW is fairly high in the aorta and occurs in a specific distribution in both the thoracic and abdominal aorta; (2) RW seems to precede the development of RL, with RL occurring in the same topographical areas as RW; and (3) RW may be associated with the subsequent development of advanced atherosclerosis, particularly raised lesions.