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Secretory products of freshly isolated human circulating blood cells such as platelets, monocytes, and B lymphocytes, but not T lymphocytes, have previously been shown to enhance low density lipoprotein (LDL) metabolism by arterial wall cells. This study was undertaken to evaluate how secretory factor(s) from mononuclear cells that had been stimulated by concanavalin A (Con A) alters LDL receptor activity by cultured human skin fibroblasts. Conditioned medium from Con A-stimulated mononuclear cells produced an increase of 125I-LDL degradation accompanied by increased thymidine incorporation into DNA. The effect of conditioned medium from the Con A-stimulated mononuclear cells was mediated by the LDL receptor pathway. Degradation of HDL and methylated LDL, neither of which is taken up by the classical LDL receptor pathway, was not affected. The conditioned medium from these Con A-stimulated cells also failed to stimulate fluid pinocytosis, as measured by the uptake of [14C]sucrose. Some strains of fibroblasts, deficient in LDL receptors, responded to the conditioned medium from the Con A-stimulated mononuclear cells by increasing the very small amounts of LDL degraded by these cells. Fibroblasts from other homozygous familial hypercholesterolemic cell strains were unresponsive, however. The effect on LDL receptors was characterized by an increase in LDL receptor number without a change in the affinity of LDL for its receptor. Thus stimulated mononuclear cells secrete mitogens that also stimulate LDL receptor activity in human skin fibroblasts.

Incubation of low density lipoprotein(s) (LDL) with either lipoprotein lipase or hepatic lipase led to modification of the core lipid composition of LDL. Both lipases modified LDL by substantially reducing core triglyceride content without producing marked differences in size, charge, or lipid peroxide content in comparison to native LDL. The triglyceride-depleted forms of LDL that result from treatment with these two enzymes were degraded at approximately twice the rate of native LDL by human monocyte-derived macrophages (HMDM). Lipase-modified LDL degradation was inhibited by chloroquine, suggesting lysosomal involvement in LDL cellular processing. The increased degradation by macrophages of the LDL modified by these lipases was accompanied by enhanced cholesterol esterification rates, as well as by an increase in cellular free and esterified cholesterol content. In a patient with hepatic triglyceride lipase deficiency, degradation of the triglyceride-rich LDL by HMDM was approximately half that of normal LDL. Following in vitro incubation of LDL from this patient with either lipoprotein or hepatic lipase, lipoprotein degradation increased to normal. Several lines of evidence indicate that LDL modified by both lipases were taken up by the LDL receptor and not by the scavenger receptor. 1) The degradation of lipase-modified LDL in nonphagocytic cells (human skin fibroblast and arterial smooth muscle cells) as well as in phagocytic cells (HMDM, J-774, HL-60, and U-937 cell lines) could be dissociated from that of acetylated LDL and was always higher than that of native LDL. A similar pattern was found for cellular cholesterol esterification and cholesterol mass. 2) LDL receptor-negative fibroblasts did not degrade lipase-modified LDL. 3) A monoclonal antibody to the LDL receptor inhibited macrophage degradation of the lipase-modified LDL. 4) Excess amounts of unlabeled LDL competed substantially with 125I-labeled lipase-modified LDL for degradation by both macrophages and fibroblasts. Thus, lipase-modified LDL can cause significant cholesterol accumulation in macrophages even though it is taken up by LDL and not by the scavenger receptor. This effect could possibly be related to the reduced triglyceride content in the core of LDL, which may alter presentation of the LDL receptor-binding domain of apolipoprotein B on the particle surface, thereby leading to increased recognition and cellular uptake via the LDL receptor pathway.

High density lipoprotein (HDL) binds to cell surface receptors and promotes selective removal of excess cholesterol from intracellular pools. The activity of this receptor is up-regulated when cells become loaded with cholesterol, but the relative degree of up-regulation depends on the growth state of the cells. The current study demonstrates that treatment of proliferating fibroblasts with gamma-interferon (IFN) increases the activity of the HDL receptor in association with a decrease in the rate of cell proliferation. Addition of IFN during the growth phase reduced the number of cells but had little effect on total cell protein, indicating that IFN inhibited cell proliferation but produced larger cells. IFN treatment increased the number of high affinity receptors for HDL on the surface of cholesterol-loaded fibroblasts, whether receptor binding was expressed per cell or per unit of cell surface area, cell protein, or cell cholesterol. IFN treatment also appeared to increase the amount of 110-kDa HDL binding protein in fibroblast membranes that has been postulated to represent the HDL receptor molecule. The IFN-induced increase in HDL receptor activity was associated with an enhanced ability of HDL3 to remove cholesterol from intracellular pools. These results are consistent with the hypothesis that inhibition of cell proliferation increases HDL receptor-mediated transport of excess cholesterol from cells, possibly to rid cells of cholesterol that accumulates in response to a reduced rate of membrane synthesis.

Partially purified platelet-derived growth factor stimulates low density lipoprotein binding and degradation in cultured aortic smooth muscle cells of monkeys by increasing the number of available low density lipoprotein receptors. When platelet-derived growth factor was added to quiescent cells, low density lipoprotein binding increased within 4-8 hr. Stimulation of low density lipoprotein receptor activity preceded stimulation of DNA synthesis by platelet-derived growth factor by 8-12 hr. Enhancement of endogenous cholesterol synthesis by platelet-derived growth factor preceded stimulation of low density lipoprotein receptor activity. These findings suggest that the platelet-derived growth factor can increase both the exogenous and endogenous supplies of cholesterol to the cell for its use during cell proliferation.

The interaction of high density lipoprotein with its putative receptor stimulates translocation and efflux of intracellular sterols by a process involving activation of protein kinase C. This study shows that activation of cAMP-dependent protein kinase also stimulates efflux of intracellular sterols. When intracellular sterol pools of cholesterol-loaded cultured human skin fibroblasts and bovine aortic endothelial cells were radiolabeled with the biosynthetic precursor [3H]mevalonolactone, high density lipoprotein3 (HDL3)-mediated 3H-sterol efflux was enhanced by addition of the adenylylcyclase activator forskolin, the phosphodiesterase inhibitors theophylline and 3-isobutyl-1-methylxanthine, and the cAMP analogues N6-benzoyl-cAMP (N6-cAMP) and 8-thiomethyl-cAMP. The effect of N6-cAMP was abolished by an inhibitor of cAMP-dependent protein kinase (H8). The enhanced sterol efflux was independent of receptor binding of HDL3, as similar effects were observed in the presence of tetranitromethane-modified HDL3, which lacks receptor binding activity. N6-cAMP stimulated efflux of several subspecies of newly synthesized sterols, including cholesterol. Elevation of cAMP levels increased the proportion of radiosterols that were accessible to treatment of cells with the enzyme cholesterol oxidase, suggesting that activation of cAMP-dependent protein kinase stimulates translocation of sterols from intracellular compartments to the plasma membrane where they desorb from the cell surface. Thus, at least two distinct protein kinase signalling pathways modulate transport of intracellular sterols in cholesterol-loaded cells.

The spontaneous turnover of plasma-membrane sterols, as measured by their transfer to the endoplasmic reticulum, was measured in quiescent cultured human skin fibroblasts and monkey arterial smooth-muscle cells. The plasma-membrane sterol pool was pulse-labelled with trace amounts of either [3H]desmosterol or [3H]cholesterol. We then measured the enzymic conversion of [3H]desmosterol into [3H]cholesterol and of [3H]cholesterol into [3H]cholesteryl esters in intact cells. Depending on the probe used, markedly different transfer or conversion rates were found in these cells. In quiescent human skin fibroblasts, incubated in a serum-free medium, about 1.1% of the plasma-membrane [3H]desmosterol was converted into [3H]cholesterol/h, whereas in monkey arterial smooth-muscle cells the corresponding rate was 0.4%. Under similar experimental conditions, these cells esterified less than 0.02% (fibroblasts) and 0.12% (smooth-muscle cells) of the plasma-membrane [3H]cholesterol/h. The movement of sterols from the plasma membrane to the endoplasmic reticulum, as measured by the conversion of [3H]desmosterol into [3H]cholesterol was not blocked by colchicine, but was markedly enhanced by 3% (w/v) dimethyl sulphoxide. In all, these results indicate that plasma-membrane sterols of cultured cells are continuously transferred to the interior of the cell at a rate substantially higher than previously appreciated. This turnover of plasma-membrane sterol molecules took place even when there was no mass transfer of sterols into the cells.

Cultured cells have on their cell surface a specific high-affinity binding site (receptor) for high density lipoproteins (HDL) which appears to promote cholesterol efflux. In this study we characterized the cellular mechanisms involved in HDL receptor-mediated transport of cholesterol from cultured human fibroblasts and bovine aortic endothelial cells. HDL3, chemically modified by tetranitromethane (TNM-HDL3), is not recognized by this receptor and was used as a control for efflux not mediated by HDL receptor binding. HDL3 and TNM-HDL3 were found to be equally effective in causing efflux of plasma membrane cholesterol radiolabeled with [3H]cholesterol. However, HDL3 was much more effective than TNM-HDL3 in causing efflux of [3H]cholesterol associated with intracellular membranes. By measuring movement of endogenously synthesized [3H]cholesterol to the plasma membrane, and into the medium, we found that HDL3 induced a rapid movement of [3H]cholesterol from a preplasma membrane compartment to the plasma membrane that preceded [3H]cholesterol efflux. This effect was not observed with TNM-HDL3. Thus, receptor binding of HDL3 appears to facilitate removal of cellular cholesterol from specific intracellular pools by initiation of translocation of intracellular cholesterol to the plasma membrane.

Cultured extrahepatic cells possess a specific high affinity binding site (receptor) for high density lipoprotein (HDL) that is induced by cholesterol delivery to cells. To characterize the binding recognition site(s) on HDL, the ability of HDL to interact with cultured human fibroblasts was assayed after chemical alteration of specific apoprotein amino acid residues. Reduction and alkylation, acetylation, and cyclohexanedione treatment of HDL3 had little or no effect on its cellular binding. Treatment of HDL3 with tetranitromethane (TNM), however, caused a large dose-dependent decrease in binding, with maximum inhibition at 3 mM. Amino acid analysis of the TNM-treated particles showed specific alteration of tyrosine residues, but sodium dodecyl sulfate-gel electrophoresis demonstrated apoprotein cross-linking coincident with decreased binding. These results suggest that modification of HDL tyrosine residues and/or cross-linking of HDL apoproteins alters the ligand site recognized by the HDL receptor. Gradient gel electrophoresis, molecular sieve chromatography, and electron microscopy showed only minor changes in size distribution and shape of HDL3 particles after treatment with 3 mM TNM, but at higher TNM concentrations, coalescence and aggregation of particles was evident. Treatment of HDL3 with 3 mM TNM affected neither its promotion of the low affinity (receptor-independent) cholesterol efflux from cells nor its ability to accept cholesterol from an albumin suspension, yet promotion of high affinity (receptor-dependent) cholesterol efflux from cells was abolished. The finding that TNM treatment of HDL3 decreases both its receptor binding and its promotion of cholesterol efflux from cells without substantial alteration of its physical properties supports the hypothesis that the HDL receptor functions to facilitate cholesterol transport from cells.

A method is described for dispersing C14-labeled triglyceride in plasma to form low density fat particles which are similar in size, flotation and electrophoretic mobility to the particulate fat present in plasma during fat absorption. The removal rate in man of a trace dose (less than 1 mg) of this preparation of radioactive particulate fat is rapid. Small loads (2 g) of unlabeled lymph or emulsified fat given simultaneously significantly prolong the removal rate. This rate is comparable to that observed after administration of a similar load of labeled human chylomicrons.

Obesity and mild carbohydrate intolerance tend to coexist in man. Obesity per se increases basal insulin secretion and insulin responses to glucose, while mild carbohydrate intolerance is associated with impaired insulin responses. Adiposity may cause decreased tissue sensitivity to insulin and reduced glucose uptake, which in turn leads to hyperinsulinism. Prolonged obesity may unmask genetic diabetes at an earlier stage to account in part for their frequent association. Abnormal insulin secretion and reduced sensitivity to its action also may be responsible for alterations of fat mobilization observed only in the presence of both obesity and mild carbohydrate in tolerance.

When human subjects were given 1 gm. of d-glucuronolactone orally the ascorbic acid levels in plasma increased. There was an excess renal excretion of 8 mg. per hour of ascorbic acid accompanied by an excess excretion of 0.2 mg. per hour of xylulose.When the same subjects were given 1 gm. of d-glucuronic acid orally there was no increase in ascorbic acid levels in blood. Although no significant increase was noted in urinary ascorbic acid levels, the excess excretion of xylulose in the urine was 8.1 mg. per hour.The infusion of a dog with 1 gm. of d-glucuronolactone or d-glucuronic acid caused an increase in the ascorbic acid levels in blood. The renal excretion of ascorbic acid was 10.3 mg. per hour during the experiments with d-glucuronolactone and 11 mg. per hour during the experiments with d-glucuronic acid. The xylulose excretion was not significantly changed.

The unmasking of latent diabetes and aggravation of preexisting abnormalities in carbohydrate tolerance are well-known consequences of corticosteroid administration.1 The occasional occurrence of lipemia (milky plasma) in patients receiving high doses of glucocorticoids has suggested that administration of these drugs also may be associated with rather profound disturbances in lipid metabolism. Two patients were observed in whom marked lipemia and symptomatic diabetes developed while they were receiving high-dosage corticosteroid therapy for collagen disorders. One patient was studied in detail in order to explore the pathogenesis of this syndrome.Results of these investigations indicate that gross lipemia in such patients is a reversible form of exogenous lipemia which results from impaired metabolism of dietary fat. PATIENT SUMMARIES PATIENT 1. —A 16-year-old boy entered the Children's Orthopedic Hospital because of generalized weakness and diffuse muscle pain. He had been well until one month prior to admission when stomatitis, dysphagia, and generalized

A man with peripheral atherosclerosis manifested concurrent postsurgical hypothyroidism and braod-β disease (type 3 hyperlipoproteinemia). In the presence of both, low-density lipoprotein levels remained normal, but very low-density lipoprotein (VLDL) levels were markedly increased, β-migrating, and rich in cholesterol. During replacement therapy with levothyroxine, cholesterol and triglyceride levels were initially reduced to normal, and the diagnosis of broad-β disease became uncertain. Its persistence was suggested by the relative prominence of Sf12-100 lipoproteins, the cholesterol-rich composition of VLDL subfractions and of chylomicrons persisting late after an orally administered fat load, the preponderance of slower-migrating lipoproteins in the Sf20-60 subfraction. With time, moderate hyperlipoproteinemia returned, and broad-β disease was again clearly evident. Thus, secondary factors may interact with the primary metabolic defect to influence the chemical, and possibly clinical, expression of broad-β disease.

Plasma obtained after intravenous administration of heparin contains enzymatic activity catalyzing the hydrolysis of triglyceride (TG) in vitro.This activity is also apparent in vivoand results in a decrease in total plasma TG, an increase in products of TG hydrolysis, and a shift of the plasma lipoprotein spectrum from very low density to higher density fractions (1). From prior studies it appeared that no change occurred in total plasma cholesterol or phospholipid (1).Recent studies have shown that postheparin plasma also contains enzymatic activity catalyzing the hydrolysis of the phospholipids phosphatidyl ethanolamine or phosphatidyl choline (lecithin) in vitro(2,3). Hydrolysis occurs at the α’(C-1) fatty acid with the production of β (C-2) lyso derivatives. Results in the present study indicate that lipoprotein lecithin is hydrolyzed in parallel with TG in vivoafter intravenous heparin, and thus provide evidence for the in vivoaction of postheparin plasma phospholipase in man.Methods.Blood samples were obtained from 12 normal adult male subjects prior to and again after rapid intravenous administration of 5000 units of heparin.Plasma cholesterol and T G were analyzed after extraction in chloroform-methanol (2: 1, v: v) by standard AutoAnalyzer techniques(5).

The behavior of a radioactive triglyceride-plasma complex prepared in vitro was compared to that of an “RE test emulsion” in normal and RE hyperfunctional rats. The removal rate and organ distribution of the particulate fat tracer was not influenced by RE hyperfunction. However, the corresponding dose of the “RE test emulsion” was removed more rapidly from plasma in RE hyperfunctional rats. Thus the particulate fat tracer does not appear to be removed by a phagocytic process and therefore behaves more like native lipid particles than foreign emulsified material.The capable technical assistance of Mrs. Betty Lyons and Miss Jackie Dempsey is gratefully acknowledged.

A young puppy with hyperlipemia presumably associated with lipoprotein lipase deficiency is reported. It appears that this rare abnormality of lipid metabolism may occur in mammals other than man.

A variety of abnormalities of glucose, insulin, and triglyceride transport have been observed in uremia. Most of these abnormalities appear to be interrelated and are reversible with amelioration of the uremic state.

Tolbutamide (Orinase), given intravenously to normal and diabetic patients caused a reduction of non-esterified fatty acid concentration only in those subjects who responded with hypoglycemia. Diabetics responding to tolbutamide with a prolonged depression of blood sugar showed a comparably sustained reduction of the fatty acid fraction.

The comparative effects of dietary starch and dextrose on plasma tri-glyceride levels were studied on a metabolic ward in 2 lipemic patients. Plasma triglyc-erides were elevated when these subjects ingested a virtually fat free diet. Substitution of starch for the high dextrose formula produced no further change in plasma triglyc-erides. Caloric restriction in one patient resulted in a marked decrease in triglyceride even though he continued to eat an 85% carbohydrate, 15% protein formula. Both patients complained of a feeling of fullness and had trouble finishing an isocaloric high starch diet. These observations show that isocaloric starch diets did not decrease plasma triglycerides but that caloric restriction while a high carbohydrate diet is fed, will result in lower plasma triglyceride levels. They suggest that, unless careful supervision of dietary intake is maintained, the effects of carbohydrate substitutions in diet may be related to changes in caloric balance rather than to the type of carbohydrate ingested.

IMPORTANCE: Home visiting programs targeting the school readiness of preschool children (age range, 4-5 years) show promise in short-term and quasi-experimental studies but rarely are evaluated with rigorous designs and follow-up assessments. OBJECTIVES: To examine the sustained effects of a preschool home visiting program on child and family competencies and on child need for services 4 years later. DESIGN, SETTING, AND PARTICIPANTS: In a randomized clinical trial, individual families with preschool children were assigned to receive the Research-Based and Developmentally Informed–Parent home visiting program (REDI-P) (intervention group) or math home learning games in the mail (control group). Follow-up assessments occurred in third grade. Families were recruited from 24 Head Start centers in 3 Pennsylvania counties serving rural and urban areas. Four-year-old children from 200 low-income families participated. Families were recruited in fall 2008 and fall 2009. The follow-up data used were collected in spring 2013 and spring 2014. The analyses were conducted in 2016 to 2017. INTERVENTIONS: REDI-P visits followed a well-specified curriculum, with 10 home visits during preschool and 6 booster visits in kindergarten. Parents received coaching to enhance parent-child relationships and home learning materials to support child development and school readiness. MAIN OUTCOMES AND MEASURES: Intervention focused on boosting competencies in academic performance and social-emotional adjustment and reducing child problems at home. Direct assessments, teacher ratings, and parent reports were collected. In addition, third-grade teachers recorded all services that children needed and received at school. RESULTS: Two hundred participating children (110 [55.0%] white, 52 [26.0%] black, and 38 [19.0%] Latino; 112 [56.0%] male) had a mean (SD) age of 4.45 (0.29) years at the start of intervention. Third-grade outcomes were available for 153 (76.5%) of the initial sample and revealed statistically significant effects on multiple measures in each competency domain. In addition, REDI-P reduced child need for educational and mental health services at school. Significant effect sizes were small to moderate, averaging approximately one-third of 1 SD (Cohen d = 0.27 to 0.45). Mediation models demonstrated that intervention effects on services were accounted for by intervention effects on the targeted competencies. CONCLUSIONS AND RELEVANCE: REDI-P produced sustained benefits evident 4 years after intervention, significantly reducing child need for school services. The results of this study appear to validate the value of preschool home visiting as a strategy to help close the gap in school readiness and child well-being associated with poverty.

There has been widespread coverage in the news media recently of the claim that the drinking of homogenized milk is a cause of excessive mortality from coronary artery disease in the United States. That this relationship might exist has been proposed by Oster,1 who postulates the existence of a group of diseases caused by the depletion of plasmalogen in cell membranes. He includes arteriosclerosis, myocardial infarction, and angina pectoris as representative disorders with this possible origin.Plasmalogens are a type of phospholipid usually found as a component of cell membranes of muscle and of the myelin sheath of nerve fibers. The major plasmalogen of myocardium is a choline phosphatide containing an unsaturated fatty acid in a typical ester linkage and a second fatty acid as a vinyl ether,2 thereby differing from the more usual phospholipid exemplified by lecithin. Fatty aldehydes or plasmals can be released from this second

Triglyceride metabolism was studied in a 14-month-old cretin boy. Prior to therapy, the child was found to have hypertriglyceridemia, hypercholesterolemia, and increased plasma pre-beta lipoproteins. An abnormality in lipoprotein lipase was suggested by low postheparin lipase activity (PHLA) in the child's plasma.With 13 weeks of therapy, the triglyceride level fell and the lipoprotein distribution and PHLA in fasting plasma became normal. By 20 weeks, all lipid measures were normal. After only five weeks of thyroid replacement and improved oral intake, a paradoxical increase in plasma triglyceride and appearance of chylomicrons occurred despite a marked increase in PHLA.

Blood amylase and plasma non-esterified fatty acid concentrations responded in a correlated way to glucagon, glucose, fructose, epinephrine and orinase. Apparently these two components are associated in some common metabolic process, extrapancreatic in location.

Information about the highlights of the fifth annual Accent on Architecture of the American Institute of Architects (AIA) is presented. The event honored the institute's highest design awards for 1994 combining the Honor Awards for Architecture with Urban Design. Secretary of Housing and Urban Development Henry Cisneros underscores the role of architects in addressing problems in social problems. Norman Foster accepted the AIA Gold Medal from Jane Alexander.