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C J Schwartz

Publications and source records attributed to C J Schwartz.

At least 19 recordsLinked to original sources
PubMed2001

IscR, an Fe-S cluster-containing transcription factor, represses expression of Escherichia coli genes encoding Fe-S cluster assembly proteins.

IscR (iron-sulfur cluster regulator) is encoded by an ORF located immediately upstream of genes coding for the Escherichia coli Fe-S cluster assembly proteins, IscS, IscU, and IscA. IscR shares amino acid similarity with MarA, a member of the MarA/SoxS/Rob family of transcription factors. In this study, we found that IscR functions as a repressor of the iscRSUA operon, because strains deleted for iscR have increased expression of this operon. In addition, in vitro transcription reactions established a direct role for IscR in repression of the iscR promoter. Analysis of IscR by electron paramagnetic resonance showed that the anaerobically isolated protein contains a [2Fe-2S](1+) cluster. The Fe-S cluster appears to be important for IscR function, because repression of iscR expression is significantly reduced in strains containing null mutations of the Fe-S cluster assembly genes iscS or hscA. The finding that IscR activity is decreased in strain backgrounds in which Fe-S cluster assembly is impaired suggests that this protein may be part of a novel autoregulatory mechanism that senses the Fe-S cluster assembly status of cells.

Amino Acid Sequence↗
PubMed2001

FTZ-Factor1 and Fushi tarazu interact via conserved nuclear receptor and coactivator motifs.

To activate transcription, most nuclear receptor proteins require coactivators that bind to their ligand-binding domains (LBDs). The Drosophila FTZ-Factor1 (FTZ-F1) protein is a conserved member of the nuclear receptor superfamily, but was previously thought to lack an AF2 motif, a motif that is required for ligand and coactivator binding. Here we show that FTZ-F1 does have an AF2 motif and that it is required to bind a coactivator, the homeodomain-containing protein Fushi tarazu (FTZ). We also show that FTZ contains an AF2-interacting nuclear receptor box, the first to be found in a homeodomain protein. Both interaction motifs are shown to be necessary for physical interactions in vitro and for functional interactions in developing embryos. These unexpected findings have important implications for the conserved homologs of the two proteins.

Amino Acid Motifs↗
PubMed2000

The cysteine desulfurase, IscS, has a major role in in vivo Fe-S cluster formation in Escherichia coli.

The cysteine desulfurase, IscS, provides sulfur for Fe-S cluster synthesis in vitro, but a role for IscS in in vivo Fe-S cluster formation has yet to be established. To study the in vivo function of IscS in Escherichia coli, a strain lacking IscS was constructed and characterized. Using this iscS deletion strain, we have observed decreased specific activities for proteins containing [4Fe-4S] clusters from soluble (aconitase B, 6-phosphogluconate dehydratase, glutamate synthase, fumarase A, and FNR) and membrane-bound proteins (NADH dehydrogenase I and succinate dehydrogenase). A specific role for IscS in in vivo Fe-S cluster assembly was demonstrated by showing that an Fe-S cluster independent mutant of FNR is unaffected by the lack of IscS. These data support the conclusion that, via its cysteine desulfurase activity, IscS provides the sulfur that subsequently becomes incorporated during in vivo Fe-S cluster synthesis. We also have characterized a growth phenotype associated with the loss of IscS. Under aerobic conditions the deletion of IscS caused an auxotrophy for thiamine and nicotinic acid, whereas under anaerobic conditions, only nicotinic acid was required. The lack of IscS also had a general effect on the growth of E. coli because the iscS deletion strain grew at half the rate of wild type in many types of media even when the auxotrophies were satisfied.

Carbon-Sulfur Lyases↗
PubMed1995

A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association.

This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesions progression. The initial (type I) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. Type III is the intermediate stage between type II and type IV (atheroma, a lesion that is potentially symptom-producing). In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc).

Aneurysm↗
PubMed1995

A definition of advanced types of atherosclerotic lesions and a histological classification of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association.

This report is the continuation of two earlier reports that defined human arterial intima and precursors of advanced atherosclerotic lesions in humans. This report describes the characteristic components and pathogenic mechanisms of the various advanced atherosclerotic lesions. These, with the earlier definitions of precursor lesions, led to the histological classification of human atherosclerotic lesions found in the second part of this report. The Committee on Vascular Lesions also attempted to correlate the appearance of lesions noted in clinical imaging studies with histological lesion types and corresponding clinical syndromes. In the histological classification, lesions are designated by Roman numerals, which indicate the usual sequence of lesion progression. The initial (type 1) lesion contains enough atherogenic lipoprotein to elicit an increase in macrophages and formation of scattered macrophage foam cells. As in subsequent lesion types, the changes are more marked in locations of arteries with adaptive intimal thickening. (Adaptive thickenings, which are present at constant locations in everyone from birth, do not obstruct the lumen and represent adaptations to local mechanical forces). Type II lesions consist primarily of layers of macrophage foam cells and lipid-laden smooth muscle cells and include lesions grossly designated as fatty streaks. Type III is the intermediate stage between type II and type IV (atheroma, a lesion that is potentially symptom-producing). In addition to the lipid-laden cells of type II, type III lesions contain scattered collections of extracellular lipid droplets and particles that disrupt the coherence of some intimal smooth muscle cells. This extracellular lipid is the immediate precursor of the larger, confluent, and more disruptive core of extracellular lipid that characterizes type IV lesions. Beginning around the fourth decade of life, lesions that usually have a lipid core may also contain thick layers of fibrous connective tissue (type V lesion) and/or fissure, hematoma, and thrombus (type VI lesion). Some type V lesions are largely calcified (type Vb), and some consist mainly of fibrous connective tissue and little or no accumulated lipid or calcium (type Vc).

Aneurysm↗
PubMed1994

A definition of initial, fatty streak, and intermediate lesions of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association.

The compositions of lesion types that precede and that may initiate the development of advanced atherosclerotic lesions are described and the possible mechanisms of their development are reviewed. While advanced lesions involve disorganization of the intima and deformity of the artery, such changes are absent or minimal in their precursors. Advanced lesions are either overtly clinical or they predispose to the complications that cause ischemic episodes; precursors are silent and do not lead directly to complications. The precursors are arranged in a temporal sequence of three characteristic lesion types. Types I and II are generally the only lesion types found in children, although they may also occur in adults. Type I lesions represent the very initial changes and are recognized as an increase in the number of intimal macrophages and the appearance of macrophages filled with lipid droplets (foam cells). Type II lesions include the fatty streak lesion, the first grossly visible lesion, and are characterized by layers of macrophage foam cells and lipid droplets within intimal smooth muscle cells and minimal coarse-grained particles and heterogeneous droplets of extracellular lipid. Type III (intermediate) lesions are the morphological and chemical bridge between type II and advanced lesions. Type III lesions appear in some adaptive intimal thickenings (progression-prone locations) in young adults and are characterized by pools of extracellular lipid in addition to all the components of type II lesions.

Animals↗
PubMed1994

A definition of initial, fatty streak, and intermediate lesions of atherosclerosis. A report from the Committee on Vascular Lesions of the Council on Arteriosclerosis, American Heart Association.

The compositions of lesion types that precede and that may initiate the development of advanced atherosclerotic lesions are described and the possible mechanisms of their development are reviewed. While advanced lesions involve disorganization of the intima and deformity of the artery, such changes are absent or minimal in their precursors. Advanced lesions are either overtly clinical or they predispose to the complications that cause ischemic episodes; precursors are silent and do not lead directly to complications. The precursors are arranged in a temporal sequence of three characteristic lesion types. Types I and II are generally the only lesion types found in children, although they may also occur in adults. Type I lesions represent the very initial changes and are recognized as an increase in the number of intimal macrophages and the appearance of macrophages filled with lipid droplets (foam cells). Type II lesions include the fatty streak lesion, the first grossly visible lesion, and are characterized by layers of macrophage foam cells and lipid droplets within intimal smooth muscle cells and minimal coarse-grained particles and heterogeneous droplets of extracellular lipid. Type III (intermediate) lesions are the morphological and chemical bridge between type II and advanced lesions. Type III lesions appear in some adaptive intimal thickenings (progression-prone locations) in young adults and are characterized by pools of extracellular lipid in addition to all the components of type II lesions.

Animals↗
PubMed1994

Prevention of atherosclerosis and end-organ damage: a basis for antihypertensive interventional strategies.

AIM: To review the nature of the complex relationships between essential hypertension and cardiovascular end-organ damage, with a particular focus on the pathogenesis and prevention of coronary heart disease, the major complication of untreated hypertension. RISK FACTORS FOR CORONARY HEART DISEASE: Both atherosclerosis and hypertension have their origins in childhood; in the second and third decades of life development of the more advanced fibrous plaques accelerates, emphasizing the need for early diagnosis and intervention. Perplexing and complex relationships have been found among the principal risk factors for coronary heart disease, hyperinsulinemia, insulin resistance, dyslipidemia and hypertension. In the pathogenesis of atherosclerosis at the cellular and molecular level, the important features are the effects of monocyte-macrophages, oxidant stress, lipoprotein modification, inflammatory mediators and the focal hemodynamic environment. Even brief periods of experimental hypertension can accentuate atherogenesis, the effects of which are greatest but not limited to the cervical and cerebral arteries. Further, acute hypertension lasting for even a few minutes causes a 'leakage' of plasma proteins and particulate probes into the artery wall, which has far-reaching implications for antihypertensive therapy. Recent work has shown that 24-h blood pressure variability is correlated with target-organ damage in hypertensive patients. THERAPY: Antihypertensive therapy should not only lower blood pressure but also prevent significant short-term blood pressure fluctuations. The trough: peak ratio has been used to assess the effect of antihypertensive treatment on blood pressure variability. CONCLUSION: More intensive research is required to clarify the nature of the interface between hypertension and atherogenesis.

Adolescent↗
PubMed1993

Inhibition of scavenger receptor-mediated modified low-density lipoprotein endocytosis in cultured bovine aortic endothelial cells by the glycoprotein processing inhibitor castanospermine.

Castanospermine (1,6,7,8-tetrahydroxyoctahydroindolizidine) is a plant alkaloid that inhibits alpha-glucosidases, including the glycoprotein processing glucosidase I. When endothelial cells were grown for 48 h, or longer, in the presence of this alkaloid, they produced scavenger receptors for modified low-density lipoproteins (LDL) that had mostly Glc3Man7-9(GlcNAc)2 structures rather than the usual complex types of oligosaccharides. Furthermore, growth in the presence of castanospermine resulted in a substantial inhibition in degradation of endocytosed 125I-acetylated LDL, as well as a dose-dependent inhibition of 125I-acetylated LDL binding to these cells. Scatchard analysis of binding curves indicated that the diminished binding was due to a decrease in the number of scavenger receptor molecules at the cell surface rather than to a change in the affinity of the receptors for their ligand. Since castanospermine-treated cells had the same total number of cellular receptor molecules as did controls cells, it seemed likely that castanospermine caused an alteration in receptor targeting, rather than an inhibition in receptor synthesis or a stimulation in receptor degradation. Density gradient fractionation of cell homogenates showed that castanospermine-treated cells did have a much greater percentage of scavenger LDL receptor molecules in the endoplasmic reticulum-Golgi fraction and fewer receptors in the plasma membrane fraction, whereas normal cells showed the opposite distribution.

Acetylation↗
PubMed1993

A modern view of atherogenesis.

Two key events in the atherogenic cascade are the focal influx and accumulation of low-density lipoprotein (LDL) cholesterol at arterial sites having a predilection for atherosclerotic lesion development and the recruitment of blood monocytes to these lesion-prone sites. Both processes are enhanced in the setting of hyperlipidemia and dyslipoproteinemia. The monocytes recruited to the endothelial surface subsequently migrate to the subendothelial space under the directed guidance of chemoattractants, such as monocyte chemotactic protein-1 and oxidatively modified LDL. These cells then undergo activation-differentiation to become macrophages. At the same time, LDL, and probably other lipoproteins such as the small dense LDL particles and lipoprotein (a), traverse the endothelium and undergo oxidative modification by reactive oxygen species. These oxidatively modified lipoproteins are recognizable by the non-down-regulating macrophage scavenger receptor. Their uptake by these receptors results in the formation of the foam cell characteristic of early-stage atherosclerosis. As monocyte recruitment and lipoprotein influx continue, the lesion grows and develops into the fatty streak. Subsequent foam cell necrosis due to the influence of cytotoxic oxidatively modified LDL and increased collagen synthesis by intimal smooth muscle cells lead to the established atherosclerotic lesion referred to as the fibrous plaque. As our understanding of the mechanisms involved in the pathogenesis of atherosclerosis has evolved over the past few years, novel strategies for intervention in the atherogenic process have emerged.

Animals↗
PubMed1993

Flow-related responses of intracellular inositol phosphate levels in cultured aortic endothelial cells.

In vitro and in vivo evidence indicates that hemodynamic wall shear stress evokes a diversity of biological responses in vascular endothelial cells, ranging from cell shape changes to alterations in low density lipoprotein receptor expression. The signal transduction mechanisms by which the level of fluid mechanical shear stress is recognized by the endothelial cell and translated into these diverse biological responses remain to be elucidated. The present study focuses on the association between the onset of elevated shear stress and activation of the phosphoinositide signal transduction pathway, as measured by the intracellular release of inositol phosphates, in cultured bovine aortic endothelial cells (BAECs). BAECs were seeded, grown to confluence on large polyester sheets, and preincubated with 0.3 microCi/ml [3H]inositol for 24 hours before insertion in parallel-plate flow chambers for exposure to high shear stress (HS) at 30 dynes/cm2 or low shear stress (LS) at < 0.5 dyne/cm2 for periods ranging from 15 seconds to 24 hours. The induction of HS was associated with an early, transient but significant increase (142%, HS/LS x 100%) in inositol trisphosphate (IP3) measured at 15 seconds of shear stress exposure followed by a major peak in IP3 (189%) observed at 5 minutes after HS onset. After these initial increases, IP3 levels returned to near resting levels within 30 minutes of continued HS exposure and then continued to decline to significantly lower (75%) levels relative to LS-treated cells within 4 hours and remained lower throughout the remainder of the 24-hour HS exposure. LS-treated cells exhibited no significant changes in inositol phosphate levels throughout the 24-hour exposure periods. Exposure of BAECs to shear stress of 60 dynes/cm2 resulted in an approximately fourfold increase in IP3 levels (396%) measured at 5 minutes, almost double the levels measured in cells exposed to 30 dynes/cm2 for 5 minutes. Pretreatment of BAECs for 30 minutes with 5 mM neomycin, an inhibitor of phosphoinositide metabolism, before HS exposure inhibited both the early increases in inositol phosphates and subsequent cell elongation and alignment observed in untreated BAECs simultaneously exposed to HS without inhibiting protein synthesis. These results indicate that the exposure of cultured BAECs to elevated wall shear stress is associated with an early biphasic IP3 increase followed by a resetting of intracellular inositol phosphate concentrations to levels below that observed in static cultured BAECs. Furthermore, neomycin inhibition of this IP3 response to shear stress is associated with an inhibition of one of the major endothelial biological responses to shear stress, i.e., cell shape change and orientation.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1993

Randomized controlled trial of three interventions in the management of persistent crying of infancy.

OBJECTIVES: The objective of this study was to evaluate the effectiveness of three methods in the management of infantile colic. METHODS: Healthy infants with persistent crying were randomly assigned to one of three groups for a 2-week period. All groups received an assessment and reassurance from a pediatrician and support from a public health nurse. Group 1 also received counseling regarding specific management techniques. Group 2 also received a car-ride simulation device. Group 3 acted as a control. Mothers completed crying diaries and preintervention and postintervention anxiety questionnaires. RESULTS: Thirty-eight mother-infant pairs were enrolled. Combining all three groups, there was a 24% reduction in daily hours of crying (P = .01) and a 18% improvement in maternal anxiety (P < .001), but no significant difference among groups. CONCLUSIONS: The natural history of persistent crying of infancy is improvement over time. These specific interventions proved no better than reassurance and support alone in decreasing daily hours of crying and maternal anxiety.

Anxiety↗
PubMed1992

Elevated expression of monocyte chemoattractant protein 1 by vascular smooth muscle cells in hypercholesterolemic primates.

Atherosclerosis is marked by an overt inflammatory infiltrate, with enhanced recruitment of monocytes/macrophages observed in both human and experimental atherosclerosis. We previously determined that monocyte chemoattractant protein 1 (MCP-1) accounts for virtually all of the chemotactic activity produced by vascular (aortic) smooth muscle cells in culture. We now report that arteries from a primate model of atherosclerosis with dietary-induced hypercholesterolemia exhibit increased levels of MCP-1 mRNA expression in vivo, whereas their normal counterparts demonstrate minimal MCP-1 expression. Furthermore, immunohistochemistry and in situ hybridization clearly indicate that the expression of MCP-1 protein and mRNA is in the smooth muscle cells of the medial layer of the artery and in monocyte-like and smooth muscle-like cells found in the overlying intimal lesion. These studies indicate that one of the responses to dietary hypercholesterolemia is the expression of MCP-1 by vascular smooth muscle cells. This expression, when augmented with other cellular and molecular factors, could significantly contribute to the recruitment of monocytes/macrophages to the vessel wall.

Animals↗
PubMed1992

Pathogenesis of the atherosclerotic lesion. Implications for diabetes mellitus.

In this review, we have highlighted pivotal cellular and molecular events in the initiation and progression of atherosclerosis. Key components of lesion initiation are an enhanced focal intimal influx and accumulation of lipoproteins, including LDL in hemodynamically determined lesion-prone areas, focal monocyte-macrophage recruitment, intimal generation of ROS, and oxidative modification of lipoproteins (including LDL [Ox-LDL]). Modified lipoproteins are taken up by the non-downregulating macrophage scavenger receptor, with foam cell formation and the development of the so-called fatty streak. One transitional event in lesion progression is foam cell necrosis, likely attributable to the cytotoxicity of both intimal free radicals and Ox-LDL, with development of an extracellular metabolically inert lipid core. Another is the migration to and proliferation within the intima of medial SMCs, leading to the synthesis of plaque collagens, elastin, and proteoglycans. Mural thrombosis plays a significant role in the late-stage progression of lesions. Regression of lesions is considered a function of the dynamic balance among components of initiation, progression, plaque stabilization, and removal of plaque constituents--the so-called regression quartet. Here, we critically examine how components of diabetes mellitus might impact not only lesion development, but also lesion regression. It is concluded that some components of diabetes mellitus augment key mechanisms in lesion initiation and progression and will likely retard the processes of plaque regression. Specifically, we focus on the various influences of diabetes mellitus on lipoprotein influx and accumulation, free radical generation and Ox-LDL, monocyte-macrophage recruitment, thrombosis and impaired fibrinolysis, and the reverse cholesterol transport system. The importance of nonenzymatic protein glycosylation in modifying a number of these processes is emphasized.

Arteriosclerosis↗
PubMed1992

Atherosclerosis. Potential targets for stabilization and regression.

Reviewed are various aspects of atherosclerotic plaque stabilization and regression in humans and experimental animals. Plaque regression is a function of the dynamic balance among initiation, progression, stabilization, and removal of plaque constituents. Pseudoregression, the result of the triad thrombolysis, age- or lesion-dependent arterial dilatation, and relaxation of vasospasm, may readily give rise to angiographic misinterpretation. Although lowering of plasma cholesterol and low density lipoprotein-cholesterol has demonstrated significant clinical benefits in a number of clinical trials, the magnitude of angiographic regressive changes is relatively small despite aggressive lipid-lowering regimens. The emerging need for alternative or complementary therapeutic interventions has been emphasized. In particular, they should be targeted to pivotal cellular or molecular mechanisms in initiation, progression, or stabilization. Potentially important therapeutic targets include the use of antioxidants or free radical scavengers such as Probucol or its analogues, butylated hydroxytoluene, tocopherols, and possibly the tocotrienols. Other therapeutic targets include intimal monocyte-macrophage recruitment, macrophage cholesterol acyltransferase inhibition, stimulation of the high density lipoprotein-mediated reverse cholesterol transport system, smooth muscle cell migration to and proliferation in the arterial intima, and intimal connective tissue synthesis. Whether the isoprenylated proteins associated with the cholesterol biosynthetic pathway will give rise to compounds regulating smooth muscle cell growth has yet to be determined. Because of the importance of thrombosis in the pathogenesis and progression of lesions, the need to develop interventional strategies targeted at endothelial cell thromboresistance and thromboregulation must assume a high priority in future research and development. Other areas of therapeutic promise include the calcium channel blockers and angiotensin converting enzyme inhibitors.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗