The beta very low density lipoprotein present in hepatic lipase deficiency competitively inhibits low density lipoprotein binding to fibroblasts and stimulates fibroblast acyl-CoA:cholesterol acyltransferase

Beta very low density lipoprotein (VLDL) was isolated from a patient with hepatic lipase deficiency. The particles were found to contain apolipoprotein B-100 (apoB) and apolipoprotein E (apoE) and were rich in cholesterol and cholesteryl ester relative to VLDL with pre beta electrophoretic mobility. These particles were active in displacing human low density lipoprotein (LDL) from the fibroblast apoB,E receptor and produced a marked stimulation of acyl-CoA:cholesterol acyltransferase. Treatment of intact beta-VLDL with trypsin abolished its ability to displace LDL from fibroblasts. Incubation of trypsin treated beta-VLDL with fibroblasts resulted in a significant stimulation of acyl-CoA:cholesterol acyltransferase activity. beta-VLDL isolated from a patient with Type III hyperlipoproteinemia and an apoE2/E2 phenotype had a higher cholesteryl ester/triglyceride ratio than the beta-VLDL of hepatic lipase deficiency and contained apoB48. It displaced LDL from fibroblasts to a small but significant extent. The Type III beta-VLDL stimulated acyl-CoA:cholesterol acyltransferase to a level similar to that of trypsin-treated beta-VLDL isolated from the hepatic lipase-deficient patient. These results demonstrate that the cholesterol-rich beta-VLDL particles present in patients with hepatic lipase deficiency are capable of interacting with fibroblasts via the apoB,E receptor and that this interaction is completely due to trypsin-sensitive components of the beta-VLDL. These particles were very effective in stimulating fibroblast acyl-CoA:cholesterol acyltransferase. This stimulation was due to both trypsin-sensitive and trypsin-insensitive components.

Coronary prevention and regression studies updated

There have been a multitude of clinical, animal and epidemiology studies which prove that high serum cholesterol and low density lipoprotein (LDL) cholesterol concentrations are specific causes of coronary artery disease (CAD). Although the variations in experimental design make comparisons difficult, the aggregate results of many human prevention trials since 1960 lead to the definite conclusion that a 10% lowering of serum cholesterol reduces the risk of CAD by one-sixth. Recently, other factors for CAD risk have been identified that will be useful in guiding treatment, namely serum high density lipoprotein (HDL) cholesterol, apolipoproteins B and AI, HDL triglycerides and phosphatidylcholine to free cholesterol ratio. Studies have shown that aggressive drug and diet therapy slows progression and causes regression of atheromas. Primary prevention of CAD is obviously preferable to secondary prevention. Also, the evidence to date indicates that prevention of CAD through lifestyle changes should begin in childhood.

A alpha and A beta class II I-A determinants of antigen-specific T-helper factor and its antigen-nonbinding chain

Antigen-specific T-helper factor (ThF) of CBA (H-2k) origin in the picryl (TNP) contact sensitivity system (Mr 60-70 kDa) was reduced with dithiothreitol under mild conditions. Affinity chromatography on antigen yielded an antigen-binding chain (Mr 20-30 kDa) and an antigen-nonbinding chain (Mr 40-50 kDa). Both chains were glycoproteins and were bound by lentil lectin. Affinity chromatography on anti-I-A monoclonal antibodies showed that I-A determinants occurred on the complete molecule and on the antigen-nonbinding, but not on the antigen-binding, chain. In contrast, five different monoclonal antibodies to I-E alpha failed to absorb ThF. Moreover, the complete molecule and the I-A+ antigen-nonbinding chains had determinants of the alpha and beta chains of I-A and conformational determinants which are based on both chains. Sequential absorption and elution showed that A alpha and A beta determinants occurred on the same molecular complex. These data suggest a minimal model of ThF as a two-chain disulfide-bonded structure with an antigen-binding chain and a separate I-A+ antigen-nonbinding chain which behaves as a single unit in phosphate-buffered saline and has elements of both A alpha and A beta.

Apolipoprotein CIISt. Michael. Familial apolipoprotein CII deficiency associated with premature vascular disease

A 60-yr-old woman and her brother, products of a consanquinous mating, were chylomicronemic. The chylomicronemia in both subjects was found to be due to the absence of functional apoCII. A mutant form, designated apoCIISt. Michael (apoCIIs), was identified by two-dimensional electrophoresis and Western blot using anti-apoCII antiserum. The isoelectric point of apoCIIs was similar to that of normal apoCII, but its apparent molecular weight was 3,000 greater. Tryptic peptides of apoCIIs were identified that had retention times in reverse-phase high pressure liquid chromatography and amino acid compositions indistinguishable from that of residues 1 to 48 and 51 to 55 of normal apoCII. The complete sequence of apoCIIs was deduced from a combination of the sequence analysis of tryptic peptides corresponding to residues 56 through 96 and the known sequence of the apoCII gene. ApoCIIs differed from apoCII at residue 70 where Gln70 was replaced by Pro70 and the sequence terminated with Pro96. This is consistent with a base insertion in the codon for Asp69 or Gln70 in the apoCII gene and a subsequent translation reading frame shift. Both patients were homozygous for apoE-4. This and the absence of normal apoCII is consistent with homozygozity at the apoE-CII gene locus on chromosome 19. Both siblings and several relatives had premature ischemic vascular disease, in contrast with its apparent absence in other apoCII-deficient families.

F1 mice make two species of antigen-specific, parental haplotype-restricted, T-helper factor whose restrictions correspond to the phenotype of the I-A determinants that they bear

Antigen-specific T-helper factor (ThF) bears I-A determinants and is I-A restricted in its action. This I-A restriction may be explained by ThF binding, and hence approximating antigen to its own I-A determinants, thereby facilitating recognition by the T cell (I-A presentation theory), or by a recognition site for I-A on the ThF which approximates the antigen to I-A+ antigen-presenting cells (I-A recognition theory). When ThF is produced in F1 mice there may be a dissociation between the I-A phenotype of the ThF and the I-A restriction of any recognition site for I-A. In practice, ThF is made by spleen cells from (CBA x B10)F1 [(H-2k x H-2d)F1] mice pretreated with cyclophosphamide (100 mg/kg) and immunized with picrylated parental spleen cells intravenously (3 x 10(7)). This procedure produces haplotype-restricted contact sensitivity (corresponding to the parental cells) but the unfractionated F1 ThF does not show haplotype-specific restriction in its action. In fact, the F1 mice produces two species of ThF, each bearing determinants of the I-A molecule of one parental haplotype (k or d). When the two species were separated with monoclonal anti-I-Ak and anti-I-Ad antibodies, the genetic restriction in their action corresponded to the phenotype of the I-A determinants that they carried. In a further experiment, F1 ThF was split into its constituent antigen-binding (Ag+) and antigen non-binding (Ag-) chains by reduction, and the two species of Ag- chains separated with monoclonal anti-I-A antibodies. After complementation with the Ag+ chain, the two species of Ag- chains showed genetic restriction in their action that corresponded to the phenotype of the I-A determinants that they carried. These findings support the I-A presentation hypothesis that antigen-specific ThF acts by approximating antigen to its own I-A determinants, and hence facilitates recognition by I-A-restricted T cells.

Structure of apolipoprotein C-IIToronto, a nonfunctional human apolipoprotein

We previously reported a family with apolipoprotein C-II (apoC-II) deficiency characterized by the presence of a mutant apoC-II, apoC-IIToronto. We now report the purification and primary structure of apoC-IIToronto. The sequence of apoC-IIToronto is identical to that of normal apoC-II from residues 1-68. It differs from residue 69, where Asp69-Gln70-Val71-Leu72-Ser73-Val74- Leu75-Lys76-Gly77-Glu78-Glu79 is replaced by Thr69-Lys70-Phe71-Phe72-Leu73-Cys74. This is consistent with the deletion of a nucleotide in the codon for either Thr68 or Asp69 and a translation reading frame shift.

Usefulness of gas chromatographic profiles of plasma total lipids in diagnosis of phytosterolemia

A Cambodian male (aged 5 years and 9 months) presented with subcutaneous and tendon xanthomas in association with hypercholesterolemia. He was erroneously diagnosed as having familial hypercholesterolemia and treated with a low cholesterol diet (+/- cholestyramine) to which he did not respond. A determination of plasma total lipid profile by high-temperature gas chromatography revealed elevated plasma levels of free and esterified plant sterols along with the hypercholesterolemia. Introduction and maintenance of a diet low in cholesterol and plant sterols resulted in significant reduction in the blood concentration of these sterols, which returned to pretreatment level upon discontinuation of the low sterol regimen. The rapid identification and quantitation of the plant sterols by high-temperature gas chromatography provides a sensitive means of distinguishing phytosterolemia, which might be more common than previously suspected, from other forms of dyslipidemia, and for following the course of any treatment.

Nonspecific T suppressor factor (nsTsF) cascade in contact sensitivity: nsTsF-1 causes an Ly-1+2- I-A+ immune T cell to produce a second, genetically restricted, nsTsF-2

We studied the mode of action of the nonspecific T suppressor factor (nsTsF-1) made in the picryl (TNP) system when T acceptor cells armed with antigen-specific TsF are triggered by antigen in the context of I-J. This suppressor factor does not inhibit the passive transfer of contact sensitivity directly, as shown by its failure to inhibit passive transfer by immune cells deprived of I-A+ cells. Its immediate target is an immune, antigen-specific, Ly-1+2-, I-A+ T cell. This cell, which may be regarded as a T suppressor effector cell (Ts-eff-2), produces nsTsF-2 when exposed sequentially to nsTsF-1 and antigen. This nsTsF subsequently inhibits the passive transfer of contact sensitivity. The action of nsTsF-2 is MHC genetically restricted. As the nsTsF-2 bears I-A determinant(s), this raises the possibility that it may act by combining with the recognition site for I-A on the T cell that mediates contact sensitivity.

Nonspecific T suppressor factor (nsTsF) cascade in contact sensitivity: nsTsF-1 causes an Ly-1+2- I-A+ immune T cell to produce a second, genetically restricted, nsTsF-2

We studied the mode of action of the nonspecific T suppressor factor (nsTsF-1) made in the picryl (TNP) system when T acceptor cells armed with antigen-specific TsF are triggered by antigen in the context of I-J. This suppressor factor does not inhibit the passive transfer of contact sensitivity directly, as shown by its failure to inhibit passive transfer by immune cells deprived of I-A+ cells. Its immediate target is an immune, antigen-specific, Ly-1+2-, I-A+ T cell. This cell, which may be regarded as a T suppressor effector cell (Ts-eff-2), produces nsTsF-2 when exposed sequentially to nsTsF-1 and antigen. This nsTsF subsequently inhibits the passive transfer of contact sensitivity. The action of nsTsF-2 is MHC genetically restricted. As the nsTsF-2 bears I-A determinant(s), this raises the possibility that it may act by combining with the recognition site for I-A on the T cell that mediates contact sensitivity.

Fatty acid composition of individual plasma steryl esters in phytosterolemia and xanthomatosis

The bulk of the plasma plant sterol in phytosterolemia occurs in the esterified form and is carried mostly in the low and high density lipoproteins. We have determined the fatty acid composition of the individual plasma steryl esters from a newly discovered subject with phytosterolemia and xanthomatosis. For this purpose the intact steryl esters were subject to high temperature gas liquid chromatography (GLC) on a polar capillary column, which separated the major esters on the basis of molecular weight and degree of unsaturation of the fatty acids. The saturated and unsaturated sterols esterified to saturated, monoenic, dienoic and tetraenoic fatty acids were identified by GLC analysis of the sterol moieties of the corresponding AgNO3-TLC fractions of the steryl esters. The GLC results were confirmed by reversed phase high performance liquid chromatography combined with mass spectrometry via direct liquid inlet interface. It was found that, in general, each fatty acid was esterified to the same complement of sterols, and that the esterified sterols possessed a composition comparable to that of the free plasma sterols, which was comprised of about 75% cholesterol, 6% campesterol, 4% 22,23-dihydrobrassicasterol and 15% beta-sitosterol. The fatty acid composition of the steryl esters differed from that of the 2-position of the plasma phosphatidylcholines, which contained significantly less palmitic and oleic and more linoleic acid. On the basis of these results and a review of the literature it is suggested that the plasma cholesteryl and plant steryl esters in phytosterolemia originate from both synthesis in plasma via the lecithin-cholesterol acyltransferase and synthesis in tissues via the acylCoA-cholesterol acyltransferase.

The association of dyslipoproteinemia with corneal arcus and xanthelasma. The Lipid Research Clinics Program Prevalence Study

The prevalence rates of xanthelasma and corneal arcus were computed for normolipidemic and dyslipoproteinemic participants in the Lipid Research Clinics population surveys. The prevalence of both xanthelasma and corneal arcus increased with age, was highest in persons with type II phenotype, and usually low in those with type IV phenotype. The relative effects of age and use of gonadal hormones were different in the two lesions. Both xanthelasma and corneal arcus were associated with increased levels of plasma cholesterol and low-density lipoprotein cholesterol (LDL-C), especially in young males. In general, persons with either lesion had increased odds of having type IIa dyslipoproteinemia but decreased odds of having type IV. Xanthelasma and corneal arcus were highly associated with each other, especially in young people. There was no consistent univariate association of xanthelasma and corneal arcus with smoking, alcohol consumption, blood pressure, obesity, sedentary lifestyle, family history of ischemic heart disease, or glucose and uric acid plasma concentrations. Adjusted odds ratios for ischemic heart disease in participants with xanthelasma and corneal arcus were generally increased, except in older female nonusers of gonadal hormones, in whom they were significantly decreased. Neither xanthelasma nor corneal arcus showed a consistent association with manifestations of peripheral arterial disease. Thus the clinical findings of xanthelasma or corneal arcus, especially in young people, seem to identify persons with plasma lipoprotein abnormalities.

Customary diet, anthropometry, and dyslipoproteinemia in selected North American populations. The Lipid Research Clinics Program Prevalence Study

The intake of nutrients, determined by 24 hr diet recall, and body measurements were obtained in 8250 free-living white study participants divided into 20 to 49 and 50 + age groups for males and female nonusers and users of gonadal hormones. They were classified into dyslipoproteinemia (DLP) phenotypes: hyperHDL, hypoHDL, IIA, hpypoLDL, IV, and normal. The dyslipoproteinemia DLP phenotypes, compared with the normal, had biologically meaningful differences in nutrient intake and indexes of obesity that were most marked for males aged 20 to 49 years as shown in the table (below). Those with the hyperHDL phenotype were thinner and ingested more energy and more alcohol and less carbohydrate as percent kilocalories (%kcal). Individuals classified as hypoHDL were fatter and tended to ingest less energy and less alcohol as %kcal. Persons with the type II phenotype were fatter and ingested less energy. Those with hypoLDL tended to be thinner and ingested more energy. Individuals with the type IV phenotype were fatter, ingested less energy and carbohydrate and more alcohol as %kcal. Similar trends were observed in female nonusers of hormones aged 20 to 49 and to a lesser extent in the 50 + age groups and in female users of hormones. Dietary protein, cholesterol, total fat, and polyunsaturated and saturated fatty acids had no consistent associations with DLP phenotype, and sucrose and starch had no association independent of total carbohydrate. This is the first evidence of an association of customary diet and DLP phenotypes in the free-living population. Equating energy intake with energy expenditure, persons with the high-risk phenotypes, IIA, IV, and hypoHDL, compared with the normal, had decreased energy expenditure and were fatter, whereas those with the low-risk phenotypes, hyperHDL and hypoLDL, had increased energy expenditure and were thinner.

Identification of coagulase-negative Staphylococci isolated from urinary tract infections

Coagulase-negative Staphylococci isolated from urinary tract infections were identified using the API Staph-Ident System. Organisms were excluded if there was no sign of pyuria or if normal urethral flora was present in significant amounts. While Staphylococcus saprophyticus and Staphylococcus epidermidis accounted for 81% of the isolates from females, 87% of isolates from males were S. epidermidis, Staphylococcus warneri, or Staphylococcus haemolyticus. The females fell into two main age groups, those with infections due to S. saprophyticus (mean age 25 years) and those due to other Staphylococci (mean age 40-49 years). All males were in a single age group (mean age 70-74 years) irrespective of the infecting agent. In males, S. warneri was associated with cellular changes in the bladder. No similar association was apparent with the other organisms. The results suggest that, apart from S. saprophyticus, three species of Staphylococcus (S. epidermidis, S. haemolyticus, S. warneri) account for most urinary tract infections, irrespective of the sex of the patient.

Two-chain disulphide-bonded structure of antigen-specific T-helper factor: both chains are necessary for activity and their interaction is I-A restricted

The molecular structure of the antigen-specific T-helper factor (ThF) which augments contact sensitivity in mice was studied. ThF was split into two types of polypeptide chain by mild reduction and alkylation; one antigen binding (which determined the specificity), the other non-antigen binding. The two chains were, by themselves, inactive but complemented each other and reconstituted biological activity. In addition, a genetic restriction was observed in the complementation of the two chains which mapped to the I-A subregion of the H-2 complex.

Comparisons of specific crosses from Duroc, Hampshire and Spot backcross sows

One hundred 3/4 Duroc-1/4 Landrace (DDL), 3/4 Hampshire-1/4 Landrace (HHL) and 3/4 Spot-1/4 Landrace (SSL) backcross sows were randomly mated to Yorkshire boars to produce a total of 299 litters and 3,271 pigs to determine the effect of dam breeding on preweaning and postweaning performance of the pigs and litters. Litter sizes born and born alive were not significantly different among the three dam breeds studied. However, litter sizes alive at 21 d out of HHL sows were significantly larger than litter sizes out of SSL sows, while the litter sizes out of DDL sows were intermediate to the other two dam breeds. The DDL sows had significantly heavier litters at birth than did SSL sows, but the dam breeds did not differ in the weights of their litters at 21 and 42 d. Pigs out of DDL sows were heaviest at birth but weighed the least at 21 d, while pigs out of SSL sows were heaviest at 21 and 42 d of age. Pigs out of HHL sows weighed the least at birth and at 42 d. There were no significant differences among the dam breeds in the survival rate of their pigs. In the postweaning period, pigs out of HHL sows were the slowest growing and took the most days to reach 100 kg. Feed conversion and average daily feed consumption did not differ significantly among the three dam breeds studied.

Comparative studies of triacylglycerol structure of very low density lipoproteins and chylomicrons of normolipemic subjects and patients with type II hyperlipoproteinemia

The triacylglycerols of very low density lipoproteins (VLDL) and of chylomicrons were analyzed in the fasting and postabsorptive states from normolipemic subjects and patients with Frederickson's Type II hyperlipoproteinemia, who subsisted on free choice diets, standard diets excluding lard, or were given a breakfast enriched in lard. The VLDL and chylomicrons were obtained by conventional ultracentrifugation, and the triacylglycerols were isolated by thin-layer chromatography (TLC). Representative sn-1,2-, sn-2-3- and sn-1,3-diacylglycerols were generated by partial Grignard degradation of the triacylglycerols and a stereospecific hydrolysis by phospholipase C of the mixed sn-1,2(2,3)-diacyl phosphatidylcholines prepared as intermediates. Representative sn-2-acylglycerols were obtained by hydrolysis with pancreatic lipase. Positional distribution of the fatty acids was established by subtracting in turn the fatty acid composition of the sn-2-position from the fatty acid composition of the sn-1,2- and sn-2,3-diacylglycerols. The molecular association of the fatty acids in the diacylglycerol moieties was determined by gas-liquid chromatography with mass spectrometry (GC/MS) of the tertiary-butyldimethylsilyl (t-BDMS) ethers. The molecular association of the fatty acids in the triacylglycerols was determined by 1-random 2-random 3-random calculation following experimental validation of the distribution. The results confirm a marked asymmetry in the positional distribution of the fatty acids in all triacylglycerol samples, with the palmitic acid predominantly in the sn-1-position, the unsaturated acids about equally divided between the sn-2- and sn-3-positions, and the stearic acid divided about equally between the sn-1- and sn-3-positions. The overall structure of the VLDL and chylomicron triacylglycerols from patients and control subjects was characterized by a non-correlative distribution of fatty acids under all dietary conditions.

Leucocyte esterase determination as a secondary procedure for urine screening

The use of a dipstick to detect leucocyte esteraseuria (Chemstrip L) was compared with the visualisation of leucocytes in a Gram stained smear for the detection of pyuria. The sensitivity and specificity of the two systems using the predictive value theory were similar. The use of a dual screening procedure (automation plus dipstick) allowed reliable 4 h screening of urine specimens for the detection of urinary tract infections.

Apolipoprotein C-II deficiency associated with nonfunctional mutant forms of apolipoprotein C-II

Two previously unidentified apolipoproteins (apo) designated apo C-II-X and C-II-Y have been found in plasma of homozygotes and obligate heterozygotes of a family with apo C-II deficiency. Because the plasma of homozygotes do not activate lipoprotein lipase, apo C-II-X and C-II-Y are apparently nonfunctional. These apolipoproteins have isoelectric focusing points of 5.15 and 5.54, respectively, compared with 4.88 and 4.74 for the known isomorphs, C-II-1 and C-II-2, respectively. They have approximately similar molecular weights to apo C-II-1 and C-II-2 on two-dimensional sodium dodecyl sulphate-glycerol-polyacrylamide slab gel electrophoresis. They do not form insoluble antigen-antibody complexes with antibodies to apo C-II in single antibody immunodiffusion or electroimmunoassay systems. However, using a double-antibody technique in which immunoblotting is coupled with polyacrylamide isoelectric focusing slab gel electrophoresis, apo C-II-1, C-II-2, C-II-X, and C-II-Y have similar reactivity with antibodies to apo C-II. In this family the presence of apo C-II-X and C-II-Y discriminates obligate heterozygotes from normal subjects.