Pseudodominance of lipoprotein lipase (LPL) deficiency due to a nonsense mutation (Tyr302>Term) in exon 6 of LPL gene in an Italian family from Sardinia (LPL(Olbia)).

We analyzed the molecular defect in the lipoprotein lipase (LPL) gene of a young boy from Sardinia who had primary hyperchylomicronemia, pancreatitis, and a complete LPL deficiency in post-heparin plasma. Analysis of LPL gene was performed by using single strand conformation polymorphism (SSCP) and direct sequencing of SSCP-positive region. The proband was homozygous for a C > A transversion in exon 6, which converts the codon for tyrosine at position 302 into a termination codon and eliminates an RsaI restriction site; this allowed the rapid screening of the proband's family members, among whom nine heterozygotes and one additional homozygote were identified. The homozygote was the proband's paternal grandmother who had shown the first clinical manifestation (recurrent pancreatitis) of LPL deficiency at the age of 54 years. LPL mutation carriers showed a mild dyslipidemic phenotype characterized by a reduction of high density lipoprotein-cholesterol (HDL-C) levels, HDL-C/total cholesterol ratio, and low density lipoprotein (LDL) size, associated with a variable increase of triglyceride levels. Five of these carriers were also heterozygotes for beta-thalassemia (Q39X mutation). In these double mutation carriers, plasma HDL-C levels were higher and plasma triglycerides tended to be lower than in carriers of LPL mutation alone. The Tyr302 > Term mutation encodes a truncated protein of 301 amino acids that is probably not secreted by the LPL producing cells. This is the first mutation of LPL gene found in Sardinians.

A 'de novo' point mutation of the low-density lipoprotein receptor gene in an Italian subject with primary hypercholesterolemia.

Severe hypercholesterolemia was found in an 11-year-old boy with no family history of familial hypercholesterolemia. The reduced LDL-receptor activity in cultured skin fibroblasts (40% 125I-LDL degradation as compared with a control cell line) indicated the presence of an LDL-receptor defect. The analysis of the promoter region and the exons of LDL-receptor gene by single strand conformation polymorphism revealed an abnormal migration pattern in exon 1, which was due to a T --> A transversion at nucleotide 28 of the cDNA. This novel mutation causes an arginine for tryptophane substitution at position - 12 of the signal peptide (W-12R) and introduces an AviII restriction site in exon 1. Screening of the mutation by polymerase chain reaction (PCR) amplification of exon 1 and AviII digestion revealed that none of the proband's family members carried the mutation. Non-paternity was excluded after the analysis of a battery of 14 short tandem repeats located in 13 different chromosomes. These results are consistent with the hypothesis that the proband is heterozygous for a 'de novo' mutation of the LDL-receptor gene producing a non-conservative amino acid substitution. We suggest that the change in the net charge of the signal peptide, caused by the addition of a positively charged amino acid, impairs the co-translational translocation of the nascent receptor protein across the endoplasmic reticulum membrane.

LDL apheresis with dextran sulfate and angiotension receptor antagonist (Losartan).

Anaphylactoid reactions during low-density lipoprotein (LDL) apheresis with dextran sulphate adsorption have been reported in patients taking angiotensin converting enzyme (ACE) inhibitors.

Four novel partial deletions of LDL-receptor gene in Italian patients with familial hypercholesterolemia.

In this study, we report four new partial deletions of the LDL-receptor (LDL-R) gene discovered during a survey of 326 Italian patients with familial hypercholesterolemia (FH). All deletions were found in FH heterozygotes whose LDL-R activity in skin fibroblasts ranged from 52% to 43% of the values found in control cells. The size and boundaries of the deletions were defined by Southern blotting and, in some cases, by polymerase chain reaction (PCR) amplification of genomic DNA. The sequence of the deletion joint was performed after the reverse transcription and PCR amplification of the appropriate regions of LDL-R mRNA. FHMassa is a 12-kilobase deletion spanning from intron 2 to intron 10. RT-PCR showed that the mutant allele is transcribed into one major and two minor mRNAs. In the most abundant mRNA species, exon 2 joins exon 11, as expected from DNA analysis. In one minor mRNA, which was sequenced, exon 2 joins exon 13, with exons 11 and 12 skipped as a result of an alternative splicing. FHGenova is a 4-kb deletion spanning from intron 10 to intron 12 and eliminating exons 11 and 12. FHRoma is a 4.7-kb deletion spanning from the 5' end of intron 12 to the middle of intron 14 and eliminating exons 13 and 14. This deletion differs in size from the previously described deletion (FHChieti/Macerata), which is located in the same region of the LDL-R gene but is smaller (3.7 kb).(ABSTRACT TRUNCATED AT 250 WORDS)

Partial duplication of the EGF precursor homology domain of the LDL-receptor protein causing familial hypercholesterolemia (FH-Salerno).

A novel mutation of low density lipoprotein (LDL)-receptor gene was found in an Italian family hypercholesterolemia (FH) patient during a screening of 300 FH patients. The proband as well as her daughter were found to be heterozygotes for the mutation. Binding, internalization, and degradation of 125I-labeled LDL by the proband's fibroblasts were reduced to approximately 50% compared to values found in control cells. DNA analysis by Southern blotting showed that the mutant allele was characterized by an insertion of about 10 kb, which resulted from a duplication of exons 9-14 of the LDL-receptor gene. In addition, Northern blot analysis of the proband's RNA showed, besides the normal sized LDL-receptor mRNA (5.3 kb), an additional mRNA of about 6.2 kb. The junction between exon 14 and the duplicated exon 9 was amplified by polymerase chain reaction (PCR) from the cDNA. The sequence of the amplified fragment showed that exon 14 joined the duplicated exon 9 without changing the reading frame. The derived amino acid sequence indicated that the mutated receptor protein had a partial duplication of the EGF precursor homology domain. Ligand and immunoblotting revealed that proband's fibroblasts contained one-half of the normal amount of LDL-receptor protein (molecular mass 130 kDa) and an abnormally large receptor of approximately 160 kDa. The amount of this abnormal receptor as detected by two monoclonal antibodies (10A2 and 4B3) was found to be approximately 30% that of the normal LDL-receptor present in the same cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Regional cerebral blood flow in familial hypercholesterolemia.

BACKGROUND AND PURPOSE: Although epidemiologic investigations are trying to clarify the role of plasma lipid concentrations (primarily cholesterol and its subfractions) as risk factors for both ischemic and hemorrhagic stroke, little information is available regarding the effect of sustained hypercholesterolemia on cerebral perfusion. METHODS: Regional cerebral blood flow (CBF) was measured by the 133Xe inhalation method in 25 heterozygous patients (four untreated) affected with familial hypercholesterolemia. In 15 patients regional CBF was repeated 20 minutes after intravenous administration of acetazolamide (10 mg/kg body wt) to evaluate cerebrovascular reactivity. Correlations among cerebral perfusion data, present or pretreatment plasma lipid concentrations, and certain other clinical features were assessed by ANOVA. RESULTS: Both basal regional CBF and cerebrovascular reactivity were normal in the vast majority of patients compared with age- and sex-matched normal control subjects. CBF was significantly dependent on pretreatment low-density lipoprotein cholesterol (LDL-C) concentration (P = .005) and the presence of symptomatic ischemic heart disease (P = .015). CBF was only slightly dependent on age (P = .05) and was not dependent on either lipoprotein(a) or present LDL-C concentration. CBF did not differ between treated and untreated patients, and the perfusional increase induced by acetazolamide was not related to any other variable. CONCLUSIONS: Cerebral perfusion and cerebrovascular reactivity were maintained within the normal range despite long-lasting, severe hypercholesterolemia, even if a somewhat lower CBF was found in those patients with the highest LDL-C pretreatment levels. These results are in accord with the epidemiologic data that implicate hypercholesterolemia as a minor risk factor, if a risk factor at all, for intracranial atherosclerosis and ischemic stroke.

A large deletion in the LDL receptor gene--the cause of familial hypercholesterolemia in three Italian families: a study that dates back to the 17th century (FH-Pavia).

In the LDL-receptor gene, a large rearrangement causing hypercholesterolemia was detected in three apparently unrelated families living in northern Italy. In all probands, binding, internalization, and degradation of 125I-LDL measured in skin fibroblasts were found to be 40%-50% of control values, indicative of heterozygous familial hypercholesterolemia (FH). Southern blot analysis revealed that the probands were heterozygous for a large (25-kb) deletion of the LDL-receptor gene eliminating exons 2-12. The affected subjects possessed two LDL-receptor mRNA species: one of normal size (5.3 kb) and one of smaller size (3.5 kb). In the latter mRNA, the coding sequence of exon 1 is joined to the coding sequence of exon 13, causing a change in the reading frame and thereby giving rise to a premature stop codon. The receptor protein deduced from the sequence of the defective mRNA is a short polypeptide of 29 amino acids, devoid of any function. Tracing these three families back to the 17th century, we found both their common ancestor and the possible origin of the mutation, in a region which is called "Lomellina" and which is located in southwest Lombardy, near the old city of Pavia. Therefore we named the mutation "FH-Pavia."

RFLPs of the LDL-receptor gene: their use in the diagnosis of FH and in evaluation of different levels of gene expression on normal subjects.

The usefulness of the RFLPs of the LDL-receptor gene in early diagnosis of Familial Hypercholesterolemia (FH) was investigated in 122 FH-families. Four RFLPs, produced by digestion with the enzymes PvuII, ApaLI and AvaII/XbaI were able to detect the affected gene and to follow the inheritance of the disease in 72 out of 97 families (74%). In the remaining 25 families, unambiguous diagnosis was possible in 66% of the cases by use of PvuII, ApaLI and BstEII/EcoRI RFLPs. The RFLPs were also useful to distinguish true homozygotes from compound heterozygotes and to detect families where recombination events occurred or where hypercholesterolemia was not due to a defect of the LDL-receptor gene. In a normal population PvuII RFLP account for 9.6% of the total variance of the LDL cholesterol levels adjusted for confounding variables. The P2 allele was associated with lower LDL cholesterol concentrations (average excess -9.1 mg/dl). This finding allows us to presume there is a DNA sequence, close to the variable PvuII cutting site in intron 15, which could act as an enhancer of the LDL-receptor gene expression.

Effect of a single daily dose treatment of fenofibrate on plasma lipoproteins in hyperlipoproteinaemia IIb.

The safety and efficacy of a single daily dose of fenofibrate (200 mg) have been evaluated in 12 Type IIB hyperlipidaemic patients in a three-month study. At the same time the pharmacokinetics was studied to check whether this new dosage schedule would give a therapeutic plasma levels of fenofibrate. At the single daily dose of 200 mg, fenofibrate was highly effective, very well tolerated, and it reached therapeutic plasma levels without accumulation. It appears that fenofibrate can usefully be employed at this dosage in hyperlipidaemia, especially since patient compliance is better when only one daily dose need be taken.

Effects of three low-dose oral contraceptive formulations on lipid metabolism.

Three oral contraceptive preparations were studied in 60 healthy women. This randomized, comparative, baseline controlled study was designed to investigate the effects of the preparations on plasma lipids and lipoproteins. The following formulations were studied: a monophasic preparation containing ethinylestradiol and desogestrel (M-DSG) and two triphasic formulations containing ethinylestradiol and gestodene or levonorgestrel respectively (T-GSD and T-LNG). These preparations were studied for six treatment cycles. Total cholesterol and apoprotein B did not change in any group. Low density lipoprotein (LDL) cholesterol was significantly decreased in the groups of women treated with M-DSG and T-GSD respectively. No changes were observed in the T-LNG group. With M-DSG, significant increases were observed in high-density lipoprotein (HDL) cholesterol and HDL3 cholesterol, whilst HDL2 cholesterol did not change. With both T-GSD and T-LNG, no changes were observed in HDL cholesterol, whilst a significant increase in HDL3 cholesterol together with a trend to decrease in HDL2 cholesterol were observed. Apolipoprotein AI increased with the following ranking M-DSG greater than T-GSD greater than T-LNG. The LDL/HDL cholesterol ratio significantly decreased with both M-DSG and T-GSD. In the T-LNG group there was no change in this ratio. Triglycerides increased to the same extent in all treatment groups. As far as concerns the risk of arterial diseases, these three oral contraceptive formulations mostly induced negligible and/or partly favorable changes in plasma lipids and lipoproteins; however, the lipoprotein pattern during M-DSG treatment resulted better than during T-GSD, and the latter turned out to be better than during T-LNG.

PIP: 3 oral contraceptive (OC) preparations were studied in 60 healthy women. This randomized, comparative, baseline controlled study was designed to investigate the effects of the preparations on plasma lipids and lipoproteins. The following formulations were studied: a monophasic preparation containing ethinyl estradiol and desogestrel (M-DSG) and 2 triphasic formulations containing ethinyl estradiol and gestodene or levonorgestrel respectively (T-GSD and T-LNG). These preparations were studied for 6 treatment cycles. Total cholesterol and apoprotein B did not change in any group. Low density lipoprotein (LDL) cholesterol was significantly decreased in the groups of women treated with M-DSG and T-GSD respectively. No changes were observed in the T-LNG group. With M-DSG, significant increases were observed in the high density lipoprotein (HDL) and HDL3 cholesterols, while HDL2 cholesterol did not change. With both T-GSD and T-LNG, no changes were observed in HDL3 cholesterol together with a trend to decrease in HDL2 cholesterol were observed. Apolipoprotein AI increased with the following ranking M-DSG T-GSD T-LNG. The LDL/HDL cholesterol ratio significantly decreased with both M-DSG and T-GSD. In the T-LNG group there was no change in this ratio. Triglycerides increased to the same extent in all treatment groups. As far as the risk of arterial diseases, these 3 OC formulations mostly induced negligible and/or partly favorable changes in plasma lipids and lipoproteins; however, the lipoprotein pattern during M-DSG treatment was better than during T-GSD, and the latter was better than during T-LNG.

Lipoprotein changes induced by pantethine in hyperlipoproteinemic patients: adults and children.

Following a brief outline of current knowledge concerning atherosclerosis and its treatment, the authors describe the results obtained by treating with pantethine (900-1200 mg daily for 3 to 6 months) a series of 7 children and 65 adults suffering from hypercholesterolemia alone or associated with hypertriglyceridemia (types IIa and IIb of Fredrickson's classification). Pantethine treatment produced significant reduction of the better known risk factors (total cholesterol, LDL-cholesterol, triglycerides, and apo-B) and a significant increase of HDL-cholesterol (signally HDL2) and apolipoprotein A-I. The authors conclude with a discussion of these results and of the possible role of pantethine in the treatment of hyperlipoproteinemia, in view of its perfect tolerability and demonstrated therapeutic effectiveness.

Effects of physical activity and diet on lipemic risk factors for atherosclerosis in women.

Serum lipoproteins were studied in active and sedentary young women. The groups were matched for age, body weight, and blood pressure. A quantitative and qualitative evaluation of the diet was performed. In spite of a higher intake of saturated fat and cholesterol, serum concentrations of triglyceride, total cholesterol, and low-density lipoprotein cholesterol in the active group were not significantly different from the controls. Nevertheless, high-density lipoprotein cholesterol (HDL-C) levels were significantly higher in the active subjects even after covariance adjustment for nutrient intake; therefore, the HDL-C increase seems to depend on physical activity "per se" rather than on differences in diet.

[Evaluation of the accuracy of precipitation methods for HDL cholesterol determination]. / Valutazione dell'accuratezza dei metodi di precipitazione per il dosaggio del colesterolo delle HDL.

Several methods for HDL-Cholesterol determination have been proposed; the over-floating cholesterol evaluation after non-HDL lipoproteins precipitation by polyanions with bivalent cations or neutral polymers is practical and not expensive, but it's accuracy and precision must be strictly control led. The Authors, after a review and a quality-check of the most used methods, conclude that the best accuracy for HDL-Cholesterol determination is provided by Dextransulphate-Mg-chloride and Phosphotungstate-Mg-chloride at pH 7,5.

[Influence of alcohol intake and smoking on plasma HDL cholesterol in active and sedentary subjects]. / Interferenza dell'assunzione di alcool e del fumo sulla concentrazione plasmatica del colesterolo HDL in soggetti attivi e sedentari.

The effect of physical activity, of smoking habit and alcohol assumption on plasma HDL-cholesterol has been evaluated in 40 normolipidaemic male active subjects and in 43 non-active ones. The comparison have been performed after covariance adjustment for potentially confounding variables. Physical activity increases and smoking habit decreases HDL-cholesterol plasma levels; no effects depending on alcohol consumption have been found.

[Neurovegetative regulation of gastrin secretion]. / Regolazione neurovegetativa della secrezione gastrinica.

The literature is reviewed in an account of the part played by the adrenergic and cholinergic systems in the regulation of gastrin secretion. As matters now stand, it can be said that, whereas the adrenergic system is capable of activating such secretion, the cholinergic system appears to be capable of modulating it by inhibition rather than stimulation. While it can be agreed that mediation of the adrenergic function occurs via the beta receptors, the possibility that the alpha receptors may also be responsible under certain conditions cannot be ruled out.