Genetic cholesteryl ester transfer protein deficiency caused by two prevalent mutations as a major determinant of increased levels of high density lipoprotein cholesterol.

Genetic determinants of HDL cholesterol (HDL-C) levels in the general population are poorly understood. We previously described plasma cholesteryl ester transfer protein (CETP) deficiency due to an intron 14 G(+1)-to-A mutation(Int14 A) in several families with very high HDL-C levels in Japan. Subjects with HDL-C > or = 100 mg/dl (n = 130) were screened by PCR single strand conformational polymorphism analysis of the CETP gene. Two other mutations were identified by DNA sequencing or primer-mediated restriction map modification of PCR products: a novel intron 14 splice donor site mutation caused by a T insertion at position +3 from the exon14/intron14 boundary (Int14 T) and a missense mutation (Asp442 to Gly) within exon 15 (D442G). The Int14 T mutation was only found in one family. However, the D442G and Int14 A mutations were highly prevalent in subjects with HDL-C > or = 60 mg/dl, with combined allele frequencies of 9%, 12%, 21% and 43% for HDL-C 60-79, 80-99, 100-119, and > or = 120 mg/dl, respectively. Furthermore, prevalences of the D442G and Int14 A mutations were extremely high in a general sample of Japanese men (n = 236), with heterozygote frequencies of 7% and 2%, respectively. These two mutations accounted for about 10% of the total variance of HDL-C in this population. The phenotype in a genetic compound heterozygote (Int14 T and Int14 A) was similar to that of Int14 A homozygotes (no detectable CETP and markedly increased HDL-C), indicating that the Int14 T produces a null allele. In four D442G homozygotes, mean HDL-C levels (86 +/- 26 mg/dl) were lower than in Int14 A homozygotes (158 +/- 35 mg/dl), reflecting residual CETP activity in plasma. In 47 D442G heterozygotes, mean HDL-C levels were 91 +/- 23 mg/dl, similar to the level in D442G homozygotes, and significantly greater than mean HDL-C levels in Int14 A heterozygotes (69 +/- 15 mg/dl). Thus, the D442G mutation acts differently to the null mutations with weaker effects on HDL in the homozygous state and stronger effects in the heterozygotes, suggesting dominant expression of a partially defective allele. CETP deficiency, reflecting two prevalent mutations (D442G and Int14 A), is the first example of a genetic deficiency state which is sufficiently common to explain a significant fraction of the variation in HDL-C in the general population.

Effects of ML-236b (compactin) on sterol synthesis and low density lipoprotein receptor activities in fibroblasts of patients with homozygous familial hypercholesterolemia.

We studied biochemical genetics of low density lipoprotein (LDL) receptor mutations in fibroblasts from six homozygous and five heterozygous patients with familial hypercholesterolemia (FH). Three of six homozygotes are receptor-negative type and the other three homozygotes are receptor-defective type. In the cells from three receptor-negative homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 0.5+/-0.3 ng/mg protein (mean+/-SEM), 14+/-8 and 8+/-6 ng/mg protein per 6 h (four normal cells; 44+/-3, 386+/-32, and 1,335+/-214 ng/mg protein per 6 h), respectively. In the cells from three receptor-defective homozygotes, the receptor binding, internalization, and degradation of (125)I-LDL were 6+/-2, 29+/-8, and 90+/-32 ng/mg protein per 6 h, respectively. In these six homozygotes, two pairs of siblings are included. Two siblings in the same family were classified as receptor-negative and two siblings in another family were classified as receptor-defective. The receptor-negative phenotypes and the receptor-defective phenotypes bred true in individual families. The cells from five heterozygotes showed approximately 46% of the normal activities of receptor.ML-236B, competitive inhibitor of 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMG-CoA reductase), completely inhibited the incorporation of [(14)C]acetate into digitonin-precipitable sterols in fibroblasts from normal subjects and heterozygous and homozygous patients with FH with the concentration of 0.5 mug/ml. However, at 0.05 mug/ml of ML-236B sterol synthesis in fibroblasts from homozygotes was not completely suppressed in contrast to normal and heterozygous cells. Moreover, after preincubation with 0.05 mug/ml of ML-236B for 24 h in medium containing lipoproteins, sterol synthesis in the cells from receptor-negative homozygote showed 75% of the initial activity compared with that of 25% without preincubation. In the cells from a normal subject and a heterozygote, sterol synthesis was inhibited even after preincubation. These results suggest that (a) the inhibitory effect of ML-236B is overcome in homozygote cells by their high intracellular levels of HMG-CoA reductase and (b) that a higher dose of ML-236B may be required to lower serum cholesterol levels in FH homozygotes than in heterozygotes.

Cloning and characterization of CLLD6, CLLD7, and CLLD8, novel candidate genes for leukemogenesis at chromosome 13q14, a region commonly deleted in B-cell chronic lymphocytic leukemia.

Chromosome 13q14 deletions constitute the most common structural aberration in B-cell chronic lymphocytic leukemia (B-CLL). We constructed a high-resolution physical map covering the critical deleted region in B-CLL at 13q14 and flanking sequences. The order and position of both genomic markers and known genes were determined precisely. Three novel genes, CLLD6, CLLD7, and CLLD8, were isolated and characterized. The predicted protein sequence of CLLD6 revealed no homology with known proteins. However, both CLLD7 and CLLD8 predicted proteins contain known functional domains. CLLD7 has both an RCC1 and a BTB domain, and could thus be involved in cell cycle regulation by chromatin remodeling. CLLD8 contains a methyl-CpG binding, a preSET and a SET domain, suggesting that CLLD8 might be associated with methylation-mediated transcriptional repression. Mutation analysis of hematopoietic tumor cell lines and B-CLL tumor samples revealed no point mutations within the coding region of these three novel genes. The functional domains present within CLLD7 and CLLD8 suggest that the proteins may be involved in critical cellular processes such as cell cycle and transcriptional control and could therefore be directly or indirectly involved in leukemogenesis.

Characterization of the 13q14 tumor suppressor locus in CLL: identification of ALT1, an alternative splice variant of the LEU2 gene.

Chromosome 13q14 deletions constitute the most common genetic abnormality in chronic lymphocytic leukemia (CLL). To identify the putative tumor suppressor gene targeted by 13q14 genomic loss, we completely sequenced and characterized a segment of 790 kb at 13q14 spanning the minimal region of loss in CLL. Transcribed sequences in the region were identified through database homology searches and exon-prediction analysis. Two-hundred kb at the centromeric end of the sequence contain five CpG islands, three previously identified genes LEU5/RFP2, LEU2, and LEU1, seven of seven EST clusters composed of >10 ESTs, and a large number of predicted exons. Homology searches against the mouse EST database have allowed us to identify a highly conserved alternative first exon of the LEU2 gene, giving rise to a novel transcript, ALT1 (GenBank accession no. AF380424), which originates within a G+C region in the vicinity of the D13S272 marker. Two novel 3' exons of LEU2 were also identified and are present in both LEU2 and ALT1 transcripts. However, we have not identified any mutations in leukemia cases, or alterations in expression of mRNAs in the region, that might directly implicate these mRNAs in the pathology of CLL. The centromeric end of the sequence, where all reported genes are located, contains twice the expected amount of ALU repeats, whereas the telomeric end is LINE1 rich and contains four LINE1 elements longer than 4 kb, including two full-length LINE1 sequences. This feature of the sequence may favor the occurrence of chromosomal rearrangements and may confer instability to the region, resulting in deletions that may inactivate an as yet unidentified tumor suppressor.

Clinical features of hypertrophic cardiomyopathy caused by a Lys183 deletion mutation in the cardiac troponin I gene.

BACKGROUND: Mutations that cause hypertrophic cardiomyopathy (HCM) have been identified in 9 genes that code proteins in the sarcomere. Previous reports have demonstrated that cardiac troponin I (cTnI) gene mutations may account for familial HCM; however, the clinical characteristics and prognosis of patients with HCM caused by cTnI gene mutations are not known. METHODS AND RESULTS: We analyzed cTnI gene mutations in 130 unrelated probands with HCM and their families to clarify the genotype-phenotype correlations. We identified 25 individuals in 7 families with a Lys183 deletion (Lys183 del) mutation in exon 7 of the cTnI gene. The disease penetrance in subjects aged >20 years was 88% by echocardiography and 96% by ECG. Sudden death occurred in 7 individuals of 4 families at any age. Overall, 7 (43.8%) of 16 individuals aged >40 years had left ventricular systolic dysfunction, and 3 (18.8%) displayed dilated cardiomyopathy-like features. Of affected individuals, 4 of 5 individuals aged >40 years followed by echocardiography showed septal thinning and decreased fractional shortening during >5 years of follow-up. CONCLUSIONS: The Lys183 del mutation in the cTnI gene in patients with HCM is associated with variable clinical features and outcomes. HCM caused by the Lys183 del mutation has a significant disease penetrance. This mutation is associated with sudden death at any age and dilated cardiomyopathy-like features in those aged >40 years. However, it remains unclear whether screening of families with HCM for this mutation will be useful in patient management and counseling.

Noninvasive prediction of coronary atherosclerosis by quantification of coronary artery calcification using electron beam computed tomography: comparison with electrocardiographic and thallium exercise stress test results.

OBJECTIVES: This study was designed to compare the usefulness of electron beam computed tomography for prediction of coronary stenosis with that of electrocardiographic (ECG) and thallium exercise tests. BACKGROUND: Electron beam computed tomography can quantify coronary calcifications; however, its clinical value has yet to be established. METHODS: Using the volume mode of electron beam computed tomography, we studied 251 consecutive patients who underwent elective coronary angiography because of suspected coronary artery disease and compared the results with those of ECG and thallium exercise tests. The total coronary calcification score was calculated by multiplying the area ( > or = 2 pixels) of calcification (peak density > or = 130 Hounsfield units) by an arbitrarily weighted density score (0 to 4) based on its peak density. The mean of two scans was log transformed. RESULTS: Calcification was first noted in women in the 4th decade of life, approximately 10 years later than its occurrence in men. Among patients with advanced atherosclerosis (two- and three-vessel disease), calcification scores were uniformly high in women but ranged widely in men. Nine percent of patients with significant stenoses ( > or = 75% by densitometry) had no calcification. The calcification scores of patients with significant stenosis in at least one vessel were significantly higher than those of patients without significant stenosis in the study group as a whole and in most patient subgroups classified according to age and gender. A cutoff calcification score for prediction of significant stenosis, determined by receiver operating characteristic curve analysis, showed high sensitivity (0.77) and specificity (0.86) in all study patients; sensitivity was similarly high even in older patients ( > or = 70 years) and was enhanced in middle-aged patients (40 to < or = 60 years). The difference in specificity between calcification scores and ECG exercise test results had borderline significance (p = 0.058) and that between calcification scores and thallium test results was significant (p = 0.001). The latter difference became small but remained significant (p = 0.01) even after the reevaluation of thallium test results in light of each subject's clinical data. CONCLUSIONS: Quantification of coronary artery calcification with electron beam computed tomography noninvasively predicted angiographically confirmed coronary stenosis. Results obtained with this method were at least as useful and potentially better in some patient groups than those obtained with thallium and ECG exercise testing.

Coronary calcification and coronary atherosclerosis: site by site comparative morphologic study of electron beam computed tomography and coronary angiography.

OBJECTIVES: We compared, on a site by site basis, the morphologic features of coronary calcifications determined by electron beam computed tomography (EBCT) and angiographically defined coronary atherosclerosis. BACKGROUND: Quantification of coronary calcification using EBCT is clinically useful for the prediction of coronary stenosis. However, the relation between calcification and angiographic findings has not been evaluated by site. METHODS: We studied 251 consecutive patients who underwent elective coronary angiography for suspected coronary artery disease by EBCT and analyzed findings by site. Coronary calcifications were classified according to their length and width versus the diameter of the coronary artery in which the calcification was observed as: none, spotty, long, wide and diffuse. RESULTS: Coronary calcifications were found in 666 (27%) of 2,470 segments. The positive predictive value (PPV) of coronary calcification for significant stenosis (> or = 75% densitometric narrowing) and for all angiographically detectable atherosclerotic lesions in a segment was 0.36 and 0.80, respectively. The PPV for significant stenosis and all atherosclerotic lesions was 0.04 and 0.17 in none, 0.18 and 0.59 in spotty, 0.32 and 0.87 in long, 0.40 and 0.84 in wide and 0.56 and 0.96 in diffuse calcifications, respectively. The PPV for both significant stenosis and all lesions differed significantly (p = 0.001) among the morphologic groups. Of the 105 eccentric significant stenoses, 54 (53%) were classified as long or diffuse calcifications. Of the 95 significant stenoses with multiple irregularities, 61 (64%) showed diffuse calcification. CONCLUSIONS: Morphologic evaluation of coronary calcifications using EBCT improved the prediction of coronary stenosis on a site by site basis and provided information related to angiographic morphology.

Left ventricular systolic dysfunction during exercise and dobutamine stress in patients with hypertrophic cardiomyopathy.

OBJECTIVES: We sought to characterize stress-induced left ventricular systolic dysfunction in patients with hypertrophic cardiomyopathy (HCM). BACKGROUND: Myocardial ischemia and diastolic dysfunction occur in patients with HCM. We hypothesized that, in the setting of transient myocardial ischemia, left ventricular systolic dysfunction occurs during exercise and dobutamine stress. METHODS: We studied 39 patients with HCM but without obstructive symptoms at rest or coronary artery disease. A continuous ventricular function monitor equipped with cadmium telluride detectors (VEST) was used to evaluate left ventricular function during supine bicycle ergometer exercise. Dobutamine stress echocardiography (DSE) was also performed. The left ventricular ejection fraction (LVEF) and regional wall motion were determined from echocardiographic images. RESULTS: Changes in the LVEF correlated between exercise and dobutamine stress (r = 0.643, p < 0.0001). The LVEF decreased more than 5% at peak exercise in 17 of patients (group II), while the other patients had normal responses (group I). New regional wall motion abnormalities during dobutamine infusion were detected in 18 of 110 (16.4%) segments in group I and 42 of 85 (49.4%) segments in group II. Decreased or unchanged regional wall motion occurred more frequently in hypertrophied segments than in nonhypertrophied segments (p < 0.0001). There were significant inverse correlations between the LVEF responses during both stresses and the number of abnormal segments noted during dobutamine stress in all patients (VEST: p < 0.005; DSE: p < 0.0005). Signs of left ventricular obstruction were observed in 11 of 39 patients during DSE. However, there was no significant correlation between the LVEF response and the dobutamine-induced left ventricular pressure gradient. CONCLUSIONS: Exercise-induced systolic dysfunction occurred in 50% of patients with HCM. In these patients, regional wall motion abnormalities were present in hypertrophied segments.

PRKAR1A gene mutation in patients with cardiac myxoma.

BACKGROUND: PRKAR1A gene encodes the type 1A regulatory subunit of protein kinase A. The mutation of this gene causes Carney complex which is an autosomal dominant multiple neoplasia syndrome characterized by spotty pigmentations, endocrine overactivity and cardiac myxoma. We hypothesized that cardiac myxoma may be associated with PRKAR1A gene mutation and determined whether mutation in the PRKAR1A gene is the cause of familial and sporadic cardiac myxoma. METHODS: We studied seven patients (three males and four females) with cardiac myxoma. Two of them had familial cardiac myxoma complicated with Carney complex. The other five patients were characterized as sporadic cardiac myxomas. We analyzed the PRKAR1A gene of all patients by the polymerase chain reaction (PCR)-single-strand conformation method, followed with direct sequence analysis. RESULTS: We identified a novel mutation (494delTG) in exon 4A of the PRKAR1A gene in the patients with Carney complex. A 16-year-old proband had a left atrial myxoma, pituitary adenoma and skin pigmentation. His father also had left atrial myxoma and skin pigmentation. In contrast, no mutations in the PRKAR1A gene were identified in the other five patients with sporadic cardiac myxomas. CONCLUSIONS: These results suggest that mutation of the PRKAR1A gene may be associated with familial cardiac myxoma in Carney complex but may not be associated with sporadic cardiac myxoma.

Sodium-induced cardiac aldosterone synthesis causes cardiac hypertrophy.

High sodium intake causes cardiac hypertrophy independently of increases in blood pressure. Aldosterone is synthesized in extraadrenal tissues such as blood vessels, brain, and heart. Effects of 8 weeks of high sodium intake on cardiac aldosterone synthesis, as well as cardiac structure, mass, and aldosterone production, levels of mRNA coding for aldosterone synthase (CYP11B2) and the angiotensin II AT1 receptor, were studied in normotensive Wistar-Kyoto (WKY) rats. Isolated rat hearts were perfused for 2 hr, and the perfusate was analyzed by high-performance liquid chromatography and mass spectrometry. Aldosterone synthase activity was estimated from the conversion of [14C]deoxycorticosterone to [14C]aldosterone. Levels of mRNA for CYP11B2 and AT1 receptor were determined by competitive polymerase chain reactions. A high sodium intake for 8 weeks produced left ventricular hypertrophy without elevation of blood pressure. Plasma aldosterone concentrations and plasma renin concentrations were decreased by high sodium intake. Aldosterone production, activity of aldosterone synthase, and expression of mRNA for CYP11B2 and AT1 receptor were increased in hearts of rats with high sodium intake. These results suggest that high sodium intake increases cardiac aldosterone synthesis, which may contribute to cardiac hypertrophy independently of the circulating renin-angiotensin-aldosterone system.

Genetic analysis of aldosterone synthase in patients with idiopathic hyperaldosteronism.

Idiopathic hyperaldosteronism (IHA) is characterized by hypertension with excessive production of aldosterone, potassium loss, and suppression of the renin-angiotensin system. We compared activity of aldosterone synthase and expression of CYP11B2 messenger RNA (mRNA) in mononuclear leukocytes (MNL) from patients with IHA to findings in leukocytes from patients with aldosterone-producing adenoma and normal controls. Aldosterone synthase activity was estimated from conversion of [14C]deoxycorticosterone to [14C]aldosterone. Levels of CYP11B2 mRNA were determined by competitive PCR. In the same subjects, we sought the chimeric CYP11B1/CYP11B2 that is candidate gene for glucocorticoid-remediable hyperaldosteronism. Southern blot analysis and a long PCR method were used to detect the chimeric gene. Direct sequencing of the CYP11B2 also was performed. No chimeric genes or mutations in the coding region of the CYP11B2 were found in genomic DNA from these patients. However, both aldosterone synthase activity and CYP11B2 mRNA expression were greater in mononuclear leukocytes of patients with IHA than those of patients with aldosterone-producing adenoma or controls. These results suggest that regulatory factors of the CYP11B2 gene, e.g. unidentified aldosterone-stimulating substances or abnormalities in the promoter region of the CYP11B2 gene in patients with IHA resulting in oversecretion, may cause overexpression of mRNA of CYP11B2.

Mechanisms of FK 506-induced hypertension in the rat.

-Tacrolimus (FK 506) is a powerful, widely used immunosuppressant. The clinical utility of FK 506 is complicated by substantial hypertension and nephrotoxicity. To clarify the mechanisms of FK 506-induced hypertension, we studied the chronic effects of FK 506 on the synthesis of endothelin-1 (ET-1), the expression of mRNA of ET-1 and endothelin-converting enzyme-1 (ECE-1), the endothelial nitric oxide synthase (eNOS) activity, and the expression of mRNA of eNOS and C-type natriuretic peptide (CNP) in rat blood vessels. In addition, the effect of the specific endothelin type A receptor antagonist FR 139317 on FK 506-induced hypertension in rats was studied. FK 506, 5 mg. kg-1. d-1 given for 4 weeks, elevated blood pressure from 102+/-13 to 152+/-15 mm Hg and increased the synthesis of ET-1 and the levels of ET-1 mRNA in the mesenteric artery (240% and 230%, respectively). Little change was observed in the expression of ECE-1 mRNA and CNP mRNA. FK 506 decreased eNOS activity and the levels of eNOS mRNA in the aorta (48% and 55%, respectively). The administration of FR 139317 (10 mg. kg-1. d-1) prevented FK 506-induced hypertension in rats. These results indicate that FK 506 may increase blood pressure not only by increasing ET-1 production but also by decreasing NO synthesis in the vasculature.

Vascular aldosterone in genetically hypertensive rats.

We have reported that aldosterone is synthesized and cytochrome P450aldo mRNA exists in the vasculature. To clarify the pathophysiological role of vascular aldosterone in hypertension, we compared aldosterone production in the mesenteric arteries of stroke-prone spontaneously hypertensive rats (SHRSP) with that in Wistar-Kyoto rats (WKY). The expressions of mRNA of cytochrome P450aldo, mineralocorticoid receptor, and alpha 1, Na,K-ATPase in the mesenteric arteries were compared between the two groups. Aldosterone concentration in the perfusate of the vasculature was measured by radioimmunoassay after purification with high-performance liquid chromatography. Cytochrome P450aldo and mineralocorticoid receptor mRNA levels were quantified by Southern blot analysis of the products of reverse-transcribed polymerase chain reaction. Levels of alpha 1 Na,K-ATPase mRNA were measured by Northern blot analysis. Vascular aldosterone and cytochrome P450aldo mRNA levels of 2-week-old SHRSP were significantly increased compared with those of age-matched WKY. However, vascular aldosterone in 4- and 9-week-old SHRSP did not differ from that in age-matched WKY. Expression levels of mineralocorticoid receptor mRNA in the vasculature of 4- and 9-week-old SHRSP were significantly increased compared with those in age-matched WKY. Concentrations of vascular alpha 1 Na,K-ATPase mRNA of 2-, 4-, and 9-week-old SHRSP also were significantly higher than those in age-matched WKY. These results suggest that vascular aldosterone contributes to the pathophysiology of hypertension in SHRSP in the early stage.

Brain nitric oxide synthase messenger RNA in central mineralocorticoid hypertension.

The mechanism underlying the central hypertensinogenic effects of mineralocorticoids remains unclear. Given that nitric oxide (NO) is thought to act at autonomic sites in the brain to regulate arterial blood pressure, the effects of the potent mineralocorticoids aldosterone and 19-noraldosterone on the abundance of neuronal NO synthase (nNOS) mRNA in the brain were investigated. Wistar-Kyoto rats received a continuous intracerebroventricular infusion of aldosterone or 19-noraldosterone (5 ng/h) from an implanted osmotic minipump for 4 weeks. Total RNA was purified from microdissected tissue blocks containing the hypothalamus, dorsal medulla, rostral ventrolateral medulla, or caudal ventrolateral medulla, and changes in the abundance of nNOS mRNA were determined with a semiquantitative competitive polymerase chain reaction method. Blood pressure was significantly increased in rats 2, 3, and 4 weeks after the onset of intracerebroventricular aldosterone or 19-noraldosterone infusion compared with that in animals receiving vehicle. Subcutaneous infusion of either mineralocorticoid had no effect on blood pressure. Compared with controls, rats treated with aldosterone or 19-noraldosterone for 4 weeks showed significant decreases in the amount of nNOS mRNA in the hypothalamus and rostral and caudal ventrolateral medulla. These data suggest that reduced nNOS activity may contribute to the increase in blood pressure in rats with central mineralocorticoid-induced hypertension.

Regulation of aldosterone synthase in human vascular endothelial cells by angiotensin II and adrenocorticotropin.

Mineralocorticoids have been suggested to act on blood vessels, leading to increased vasoreactivity and peripheral resistance. Aldosterone is synthesized locally in blood vessels and participates in the hypertrophy of vascular smooth muscle cells. In this study we examined the effects of angiotensin II (ANG II), potassium, and ACTH on the production of aldosterone, the activity of aldosterone synthase, and the expression of CYP11B2 and CYP11B1 messenger ribonucleic acid (mRNA) in cultured human vascular endothelial cells. Human vascular endothelial cells were incubated with ANG II, potassium, or ACTH with or without [14C]deoxycorticosterone ([14C]DOC). Incubation medium was collected, and chromatography was preformed in a reverse phase high performance liquid chromatography system. The concentration of aldosterone in the incubation medium was measured using RIA after separation with the high performance liquid chromatography system. The activity of aldosterone synthase was estimated by the conversion of [14C]DOC to [14C]aldosterone. The levels of CYP11B2 and CYP11B1 mRNA were determined by competitive PCR. ANG II, potassium, and ACTH increased the production levels of aldosterone in a dose-dependent fashion. Both ANG II and potassium increased the conversion of [14C]DOC to [14C]aldosterone, but ACTH did not significantly increase the conversion. Both ANG II and potassium increased the concentration of CYP11B2 mRNA, but not that of CYP11B1 mRNA. Tumor necrosis factor reduced ANG II- and potassium-induced aldosterone synthesis and CYP11B2 mRNA levels. ACTH did not influence the expression of CYP11B2 mRNA. These results suggest that vascular aldosterone synthase is controlled by ANG II and potassium at the transcriptional level.

Effect of adrenocorticotropin stimulation on the synthesis of 19-noraldosterone in man.

The hormone, 19-noraldosterone, which was recently shown to be synthesized and produced in the human adrenal gland, exhibits potent mineralocorticoid and hypertensinogenic activities. This hormone is controlled in part by the renin-angiotensin system. We studied the effects of ACTH stimulation on the synthesis of 19-noraldosterone in vitro and in six normal men. 19-Noraldosterone was measured by a specific RIA after the urine extract or incubation medium was purified by high performance liquid chromatography. The 24-h urinary excretion of 19-noraldosterone increased approximately 4-fold during the administration of ACTH (40 U, injected im twice daily for 3 days). Virtually identical responses were observed with aldosterone, 18-hydroxycorticosterone, 18,19-dihydroxycorticosterone, and 18-hydroxy-19-norcorticosterone. Glomerulosa cells isolated from human adrenals were incubated with angiotensin II (10(-7), 10(-8), and 10(-9) mol/L) or ACTH (10(-8), 10(-9), and 10(-10) mol/L). Angiotensin II and ACTH increased the production of 19-noraldosterone dose-dependently from isolated glomerulosa cells. The secretion of aldosterone, 18-hydroxycorticosterone, 18,19-dihydroxycorticosterone, and 18-hydroxy-19-norcorticosterone in response to angiotensin II and ACTH was identical to that of 19-noraldosterone. These observations suggest that 19-noraldosterone is stimulated by the renin-angiotensin system as well as ACTH.

Treatment of homozygous patients with familial hypercholesterolemia by double-filtration plasmapheresis.

Two homozygous patients with familial hypercholesterolemia were treated by double-filtration plasmapheresis. The plasma separated by the first filter was subsequently led to the second filter of ethylene vinylalcohol co-polymer hollow fibers, which trap very low density lipoprotein (VLDL), intermediate density lipoprotein (IDL) and low density lipoprotein (LDL) preferentially to other plasma constituents. Serum, VLDL, IDL, LDL cholesterol levels decreased by 55, 68, 59 and 55%, respectively. HDL cholesterol levels decreased by 39%. Immunoglobulins and fibrinogen levels decreased significantly. Cutaneous and tendinous xanthomas became smaller. off

Removal of apolipoprotein E-enriched high density lipoprotein by LDL-apheresis in familial hypercholesterolaemia: a possible activation of the reverse cholesterol transport system.

The presence of apo E-containing HDL in familial hypercholesterolaemia was investigated and its removal by LDL-apheresis using a dextran sulphate cellulose column was demonstrated by measurement of the apo E/apo A-I molar ratio of serum and by nondenaturing polyacrylamide gel electrophoresis followed by immunoblotting. The molar ratios of apo E/apo A-I in the density greater than 1.063 kg/l fraction of serum obtained from two homozygous patients with familial hypercholesterolaemia were higher (0.021 and 0.030) than that from normal subjects (mean +/- SE 0.011 +/- 0.002) (P less than 0.05). Polyacrylamide gel electrophoresis and immunoblotting showed an increase in apo E-containing HDL similar to HDL2, in the plasma obtained from the homozygous patient with familial hypercholesterolaemia. The increased amounts of apo E-enriched HDL were removed from plasma by adsorption with a dextran-sulphate cellulose column. These results suggested that LDL-apheresis using the dextran-sulphate cellulose column, may cause an increase in the turnover rate of the apo E-containing HDL and thus facilitate cholesterol removal from the peripheral tissues.

A new low density lipoprotein apheresis system using two dextran sulfate cellulose columns in an automated column regenerating unit (LDL continuous apheresis).

We describe a new low density lipoprotein (LDL) apheresis system using dextran sulfate cellulose column in an automated column regenerating unit (LDL continuous apheresis). Two columns containing 150 ml of dextran sulfate cellulose were used, and the whole extracorporeal circulation was about 400 ml in volume. After 600 ml of plasma was adsorbed into the first column, the second column was used as an adsorbent and meanwhile the first column was regenerated. Thus, the 2 columns were used alternately without losing the potency of the columns. As the apparatus was automatically controlled by a computerized unit, no extra manipulation is necessary compared with the conventional single-column method. By treating 4-5 liters of plasma, non-high density lipoprotein (HDL)-cholesterol levels decreased by 63-71%, and HDL-cholesterol levels remained unchanged. Thus, this new method of LDL apheresis can safely reduce LDL-cholesterol to any desired level and will be applicable for the treatment of child and adult family hypercholesterolemic patients with severe coronary heart disease.

Coronary ectasia in a homozygous patient with familial hypercholesterolemia.

A 23-year-old man with homozygous familial hypercholesterolemia was found to have coronary ectasia by coronary angiography. This case showed generalized xanthomatosis and severe hyper low density lipoproteinemia, and his cultured skin fibroblasts showed LDL receptor activities compatible with the receptor-defective homozygous type of familial hypercholesterolemia. Coronary angiography showed fusiform aneurysmal involvements in the right coronary artery and left circumflex artery, and 50% stenosis in the right coronary artery and left anterior descending artery. Thus, homozygous familial hypercholesterolemia produces coronary ectasia as well as premature coronary stenosis.