Identification of cholesterol-bound aldehydes in copper-oxidized low density lipoprotein.

Lipid-soluble cholesteryl ester core aldehydes (aldehydes still bound to the cholesterol ring) were identified among the products of copper-catalyzed peroxidation of human low density lipoprotein (LDL). The LDL was exposed to oxygenated buffer and 5 microM CuSO4 for 24 h. The core aldehydes were isolated as the dinitrophenylhydrazones, and were identified by reverse-phase HPLC with mass spectrometry. The major components were the C4-C10 oxoalkanoyl esters of cholesterol and 7-ketocholesterol, and accounted for 1-2% of the cholesteryl linoleate and arachidonate consumed.

Isolation and identification of glycated aminophospholipids from red cells and plasma of diabetic blood.

Glycosylation is a major pathway for posttranslational modification of tissue protein and begins with nonenzymatic addition of carbohydrate to the primary amino groups. Excessive glycation of tissue protein has been implicated in the pathogenesis of diabetes and ageing. While glycation of aminophospholipids has also been postulated, glycated aminophospholipids have not been isolated. Using normal phase HPLC with on-line electrospray mass spectrometry we found glycated ethanolamine phospholipids to make up 10-16% of the total phosphatidylethanolamine (PE) of the red blood cells and plasma of the diabetic subjects. The corresponding values for glycated PE of control subjects were 1-2%.

Cardiomegaly in the juvenile visceral steatosis (JVS) mouse is reduced with acute elevation of heart short-chain acyl-carnitine level after L-carnitine injection.

The long-term administration of L-carnitine was very effective in preventing cardiomegaly in juvenile visceral steatosis (JVS) mice, which was confirmed by heart weight as well as the lipid contents in heart tissue. After i.p. injection of L-carnitine, the concentration of free carnitine in heart remained constant, although serum free carnitine level increased up to 80-fold. On the other hand, a significant increase in short-chain acyl-carnitine level in heart was observed. These results suggest that increased levels of short-chain acyl-carnitine, not free carnitine, might be a key compound in the protective effect of L-carnitine administration in JVS mice.

Lipid composition of platelets from patients with atherosclerosis: effect of purified eicosapentaenoic acid ethyl ester administration.

Although eicosapentaenoic acid (EPA) has been shown to have beneficial effects in the prevention of atherosclerosis, the mechanism by which these effects occur is not entirely clear. We investigated the lipid composition of platelets in paired subjects with and without atherosclerotic disease, either hypercholesterolemic (low density lipoprotein [LDL] cholesterol [Chol] greater than or equal to 170 mg/dl) or normocholesterolemic (LDL-Chol less than 170 mg/dl). Platelets from patients with atherosclerotic disease had a lower phosphatidylcholine (PC)/Chol ratio, when compared with those from patients without atherosclerotic disease, irrespective of LDL-Chol levels. Eleven patients with atherosclerotic disease were treated with purified EPA ethyl ester (1.8 g/day), and changes in lipid composition of platelets were investigated. Plasma levels of total Chol and LDL-Chol decreased significantly after EPA administration. The phospholipid (PL)/Chol ratio and the PC/Chol ratio in platelets from patients with atherosclerotic disease increased significantly after 4-10 wk EPA treatment. The EPA content in platelets increased, while the arachidonic acid (AA) content decreased. EPA-induced changes in the PL/Chol and the PC/Chol ratios of platelets, as well as fatty acyl chain shifts, may be related to the beneficial effects in preventing atherosclerosis, possibly by increase in the membrane fluidity.

Identification of core aldehydes among in vitro peroxidation products of cholesteryl esters.

Synthetic cholesteryl 5-oxovalerate and 9-oxononanoate were used as reference standards for the isolation and identification of cholesteryl ester core aldehydes from tert-butyl hydroperoxide/Fe++ oxidation of synthetic and natural cholesteryl esters. The core aldehydes were recovered from the peroxidation products by thin-layer chromatography as the free aldehydes or the 2,4-dinitrophenylhydrazones and were identified, respectively, by gas-liquid chromatography (GLC) and by GLC combined with mass spectrometry (GC/MS) or by reverse-phase high-performance liquid chromatography (HPLC) and by HPLC with MS (LC/MS). The core aldehydes produced by peroxidation of cholesteryl linoleate were identified as mainly 9-oxononanoates of cholesterol and oxycholesterols, with smaller amounts of the 8-oxooctenoates, 10-oxodecenoates, 11-oxoundecenoates and 12-oxododecenoates. Peroxidation of cholesteryl arachidonate yielded 5-oxovalerates of cholesterol and the oxycholesterols as the main products with smaller amounts of the 4-oxobutyrates, 6-oxohexenoates, 7-oxoheptenoates, 8-oxooctenoates, 9-oxononenoates, 9-oxononadienoates and 10-oxodecadienotes. The oxycholesterols resulting from the peroxidation of the steroid ring were identified as mainly 7-keto-, 7 alpha-hydroxy- and 7 beta-hydroxy-cholesterols and 5 alpha,6 alpha- and 5 beta,6 beta-epoxy-cholestanols. Cholesteryl palmitate and oleate did not yield core aldehydes in the present peroxidation system. In these esters, the sterol and linoleic acid moieties appeared to be oxygenated at about the same rate, while the arachidonic acid moiety reacted more rapidly than did the sterol moiety.

[Cardiac myxoma metastatic to the brain].

A case of cardiac myxoma presenting as metastatic brain tumor are reported. The patient was a 44-year-old man. One year prior to this admission, he had suffered stroke, which was characterized by right hemiparesis and dysarthria. The computed tomographic (= CT) scan of the head at that time showed a low density on the left basal ganglia and the echocardiogram suggested a left atrial myxoma. At surgery, a polypoid myxoma attached to the atrial septum was totally removed. Right hemiparesis was improved and the patient was discharged. A few months later, the patient was evaluated for multiple cutaneous masses and diagnosed by biopsy as metastatic myxoma. The patient's condition remained unchanged until this admission. In March 1985, the patient had a tonic-clonic convulsion marching from right hand and developed right hemiplegia with drowsy. An echocardiogram failed to reveal recurrence of the cardiac myxoma. A CT scan revealed a 5-cm, relatively circumscribed, low density mass in the left fronto-parietal lobe, ring mottled enhancement after contrast administration and more enhancement in the delayed scanning of 45 min. Craniotomy showed a tender, friable tumor with a yellowish cyst fluid, but apparently not invading the brain parenchyma. After complete excision of the mass, there was rapid lessing in the hemiplegia and improvement in the level of consciousness. A contrast-enhancement CT scan performed 2 weeks after craniotomy revealed no evidence of residual tumor. Pathohistological examination showed spindle-shaped and stellate cells which formed clusters and contained large amounts of acid polysaccharides as demonstrated by the alcian blue method.(ABSTRACT TRUNCATED AT 250 WORDS)

Lipid ester-bound aldehydes among copper-catalyzed peroxidation products of human plasma lipoproteins.

We have isolated the core aldehydes (aldehydes still bound to parent molecules) of phosphatidylcholine (PC) and cholesteryl esters (CE) from copper-catalyzed peroxidation of human plasma low (LDL) and high (HDL) density lipoproteins. The aldehydes were isolated by extraction with acidified chloroform-methanol containing 2,4-dinitrophenylhydrazine. The 2,4-dinitrophenylhydrazone (DNPH) derivatives formed were resolved by reversed phase high performance liquid chromatography (HPLC) and identified by on-line quadrupole mass spectrometry (LC/MS). The major PC core aldehydes from oxidized LDL and HDL were identified as 1-palmitoyl-(1-stearoyl) 2-(9-oxononanoyl)-, 1-palmitoyl-(1-stearoyl) 2-(8-oxooctanoyl)-, and 1-palmitoyl-(1-stearoyl) 2-(5-oxovaleroyl)-sn-glycerols after phospholipase C digestion of the DNPH derivatives of the phospholipids. The major aldehydes from peroxidation of cholesteryl esters were the 9-oxononanoyl, 8-oxooctanoyl, and 5-oxovaleroyl esters of cholesterol and 7-ketocholesterol. The core aldehydes were estimated to account for a minimum of 1-2% of the consumed linoleate and arachidonate esters. A relatively smaller yield of the PC core aldehydes from LDL compared to HDL was attributed to the presence of greater amounts of phospholipases in LDL than in HDL. More comparable yields of PC core aldehydes were obtained in the presence of phenylmethylsulfonylfluoride, which inhibits phospholipases. We conclude that peroxidation of LDL and HDL results in formation of detectable amounts of cholesteryl and glycerophospholipid esters containing aldehyde functions. The yield of PC aldehydes varies with the activity of the platelet activating factor (PAF) acetyl hydrolase.

Oxidized low density lipoprotein induces apoptosis in cultured human umbilical vein endothelial cells by common and unique mechanisms.

Oxidized low density lipoprotein (oxLDL) induces apoptosis in vascular cells. To elucidate the mechanisms involved in this apoptosis, we studied the apoptosis-inducing activity in lipid fractions of oxLDL and the roles of two common mechanisms, ceramide generation and the activation of caspases, in apoptosis in human umbilical vein endothelial cells treated with oxLDL. We also studied the effects of antioxidants and cholesterol. oxLDL induced endothelial apoptosis in a time- and dose-dependent fashion. Apoptosis-inducing activity was recovered in the neutral lipid fraction of oxLDL. Various oxysterols in this fraction induced endothelial apoptosis. Neither the phospholipid fraction nor its component lysophosphatidylcholine induced apoptosis. oxLDL induced ceramide accumulation temporarily at 15 min in a dose-dependent fashion. Two inhibitors of acid sphinogomyelinase inhibited both the increase in ceramide and the apoptosis induced by oxLDL. Furthermore, a membrane-permeable ceramide (C2-ceramide) induced endothelial apoptosis. These findings demonstrated that ceramide generation by acid sphingomyelinase is indispensable for the endothelial apoptosis induced by oxLDL. Inhibitors of both caspase-1 and caspase-3 inhibited the apoptosis, suggesting that oxLDL induced apoptosis by activating these cysteine proteases. The antioxidants butylated hydroxytoluene and superoxide dismutase but not catalase inhibited the apoptosis induced by oxLDL or 25-hydroxycholesterol. This suggests not only that superoxide plays an important role but also that a critical interaction between oxLDL and the cell takes place on the outer surface of the membrane, because superoxide dismutase is not membrane-permeable. Exogenous cholesterol also inhibited the apoptosis. Our study demonstrated that neutral lipids in oxLDL induce endothelial apoptosis by activating membrane sphingomyelinase in a superoxide-dependent manner, as well as by activating caspases.

Metastasizing atrial myxoma: a case with multiple subcutaneous tumours.

We report a case with rapidly growing subcutaneous and intra-muscular tumours that were identical histopathologically to a pre-existing left atrial myxoma. No invasion of visceral organs or skeleton was found. This is a very rare case of metastasizing myxoma with wide dissemination and rapid metastastic growth, despite the benign appearance of the original tumour.