Large-Area Epitaxial Mott Insulating 1T-TaSe2 Monolayer on GaP(111)B

Two-dimensional Mott materials have recently been reported in the dichalcogenide family with high potential for Mottronic applications. Nevertheless, their widespread use as a single or few layers is hampered by their limited device integration resulting from their growth on graphene, a metallic substrate. Here, we report on the fabrication of 1T-TaSe2 monolayers grown by molecular beam epitaxy on semiconducting gallium phosphide substrates. At the nanoscale, the charge density wave reconstruction and a moiré pattern resulting from the monolayer interaction with the substrate are observed by scanning tunneling microscopy. The fully open gap unveiled by tunneling spectroscopy, which can be further manipulated by the proximity of a metal tip, is confirmed by transport measurements from micrometric to millimetric scales, demonstrating a robust Mott insulating phase at up to 400 K.

Outcomes of renal replacement therapy in the critically ill with COVID-19

Objective

To describe outcomes of critically ill patients with COVID-19, particularly the association of renal replacement therapy to mortality.

Design

A single-center prospective observational study was carried out.

Setting

ICU of a tertiary care center.

Patients

Consecutive adults with COVID-19 admitted to the ICU.

Intervention

Renal replacement therapy.

Main variables of interest

Demographic data, medical history, illness severity, type of oxygen therapy, laboratory data and use of renal replacement therapy to generate a logistic regression model describing independent risk factors for mortality.

Results

Of the total of 166 patients, 51% were mechanically ventilated and 26% required renal replacement therapy. The overall hospital mortality rate was 36%, versus 56% for those requiring renal replacement therapy, and 68% for those with both mechanical ventilation and renal replacement therapy. The logistic regression model identified four independent risk factors for mortality: age (adjusted OR 2.8 [95% CI 1.8–4.4] for every 10-year increase), mechanical ventilation (4.2 [1.7–10.6]), need for continuous venovenous hemofiltration (2.3 [1.3–4.0]) and C-reactive protein (1.1 [1.0–1.2] for every 10 mg/L increase).

Conclusions

In our cohort, acute kidney injury requiring renal replacement therapy was associated to a high mortality rate similar to that associated to the need for mechanical ventilation, while multiorgan failure necessitating both techniques implied an extremely high mortality risk.

Outcomes of renal replacement therapy in the critically ill with COVID-19

Objective

To describe outcomes of critically ill patients with COVID-19, particularly the association of renal replacement therapy to mortality.

Design

A single-center prospective observational study was carried out.

Setting

ICU of a tertiary care center.

Patients

Consecutive adults with COVID-19 admitted to the ICU.

Intervention

Renal replacement therapy.

Main variables of interest

Demographic data, medical history, illness severity, type of oxygen therapy, laboratory data and use of renal replacement therapy to generate a logistic regression model describing independent risk factors for mortality.

Results

Of the total of 166 patients, 51% were mechanically ventilated and 26% required renal replacement therapy. The overall hospital mortality rate was 36%, versus 56% for those requiring renal replacement therapy, and 68% for those with both mechanical ventilation and renal replacement therapy. The logistic regression model identified four independent risk factors for mortality: age (adjusted OR 2.8 [95% CI 1.8–4.4] for every 10-year increase), mechanical ventilation (4.2 [1.7–10.6]), need for continuous venovenous hemofiltration (2.3 [1.3–4.0]) and C-reactive protein (1.1 [1.0–1.2] for every 10 mg/L increase).

Conclusions

In our cohort, acute kidney injury requiring renal replacement therapy was associated to a high mortality rate similar to that associated to the need for mechanical ventilation, while multiorgan failure necessitating both techniques implied an extremely high mortality risk.

Route of administration-dependent anti-inflammatory effect of liposomal alendronate

Innate immunity and inflammation are of major importance in various pathological conditions. Intravenous (IV) and intraperitoneal (IP) liposomal alendronate (LA) treatments have been shown to deplete circulating monocytes and peritoneal macrophages resulting in the inhibition of restenosis and endometriosis (EM), respectively. Nevertheless, the correlation between the extent of circulating monocyte depletion and liposome biodistribution is unknown, and the route of administration-dependent bioactivity in restenosis and EM has not been determined. We found that, LA treatment resulted in a dose-response modified biodistribution following both IV and IP administrations. The biodistribution of high-dose LA (10mg/kg), but not that of the low-dose (1mg/kg), was similar in healthy and diseased animals. It is concluded that LA impedes its own elimination from the circulation by depleting circulating monocytes and/or inhibiting their endocytic activity, in a dose-dependent manner. Both IV and IP administration of LA mediated by the partial and transient depletion of circulating monocytes effected inhibition of restenosis. Inhibition of EM was effected only by IP administration, which depleted both intraperitoneal and circulating monocytes. Thus, EM should be considered as a local inflammatory condition with systemic manifestations as opposed to restenosis, a systemic inflammatory disease.

Midlife Women with Major Depressive Disorder: Effects of Quetiapine Extended-release on Mood, Sleep and Menopause-related Symptoms

Background:

Recent studies suggest that the menopausal transition may constitute a period of greater risk for the development of new onset/recurrent depressive episodes. In addition, the presence of vasomotor and other menopause-related complaints may adversely affect quality of life and overall functioning. With the long-term safety of hormone therapies being questioned, non-hormonal strategies are needed for the management of symptomatic midlife women. This report is a preliminary analysis of a study investigating the effects of quetiapine extended-release (Seroquel XR) in symptomatic perimenopausal and postmenopausal women with major depressive disorder (MDD).

Methods:

Peri and postmenopausal women, age 40 to 60 years, suffering from MDD and reporting menopause-related symptoms were recruited into a 2-week, placebo lead-in phase, followed by an open trial (8 weeks) with quetiapine extended-release, flexible dose, 150-300 mg/day. The primary outcome measure (i.e. changes in depressive symptoms) was assessed via Montgomery-Åsberg Depression Rating Scale (MADRS) scores. Other measures included: Hamilton Depression Rating Scale (HAM-D), menopause-related symptoms (Greene Climacteric Scale - GCS), Clinical Global Impression (CGI-S), sleep characteristics (Pittsburgh Sleep Quality Index - PSQI) and the impact of hot flashes on daily functioning (Hot Flash-Related Daily Interference Scale (HFRDIS).

Results:

Thirty-nine women (mean age 49.3±4.3 years) were enrolled in the placebo lead-in phase. Of those, 25 were considered eligible for the 8-week trial with quetiapine extended-release. This interim analysis (LOCF) included 18 women who completed 4 to 8 weeks of treatment with quetiapine extended-release (median MADRS total scores at baseline = 28 ±6.1; median final dose of quetiapine extended-release=200 mg/day). At the end of the study, 13 out of 18 (72.2%) participants achieved remission (total MADRS scores < 10). Overall, subjects showed significant reduction in total MADRS (p< 0.001) and HAM-D scores (p< 0.001). Treatment with quetiapine extended-release improved menopause-related symptoms, as shown by a decrease in Greene Climacteric Scale total scores (p< 0.001) and sub-scores for psychological (p< 0.001), vasomotor (p=0.001), and somatic (p=0.001) complaints (Wilcoxon tests). Quetiapine extended-release did affect menopause-related sexual dysfunction (changes in CGS sexual sub-scores, p=0.06). There was a substantial reduction in overall burden associated with vasomotor symptoms, i.e., decreased HFRDIS scores (p< 0.001). Lastly, sleep efficiency, perceived sleep quality, and daily sleep disturbances improved significantly after treatment with quetiapine extended-release (p< 0.001 for all PSQI sub-scores).

Discussion:

This is the first study examining the efficacy of Seroquel XR for the treatment of Major Depressive Disorder in a population of symptomatic peri and postmenopausal women. Treatment with Seroquel XR not only reduced depressive symptomatology but also improved vasomotor symptoms and sleep complaints. Larger randomized, placebo-controlled studies are warranted to better explore the efficacy and predictors of response with quetiapine extended-release for this specific population.

Peritoneal macrophage depletion by liposomal bisphosphonate attenuates endometriosis in the rat model

BACKGROUND

Activation of macrophages is central to the implantation of endometriosis (EM). We examined the hypothesis that macrophage depletion by intraperitoneal (IP) injection of liposomal alendronate (LA) could result in EM attenuation in a rat model, thus supporting the notion of the pivotal role of macrophages in EM pathology.

METHODS

In this study, 90 rats were subjected to an EM model and were divided randomly into seven groups: five groups were treated by 4x once-weekly IP injections of LA (0.02, 0.1, 1, 5 or 10 mg/kg) and the other two groups received saline injections (control) or empty liposomes. Sham-operated rats also received empty liposomes. Depletion of circulating monocytes was determined by flow cytometry analyzes of blood specimens. Four weeks after the initial surgery, the number, size and weight of implants were recorded, adhesions were graded, macrophage infiltration was assessed and the peritoneal fluid was analyzed for monocyte chemotactic protein 1 (MCP-1) and tumor necrosis factor alpha (TNFalpha).

RESULTS

Monocyte depletion following IP LA administration resulted in an inhibitory effect on the initiation and growth of EM implants, as expressed by implantation rate, adhesion scoring, implants' size and weight (>0.1 mg/kg LA, P < 0.05). Reduced numbers of infiltrating macrophages were observed in implants of the 1 mg/kg LA group. Peritoneal fluid MCP-1 levels were negatively correlated with LA dose (P < 0.001), whereas no significant correlation could be found for TNFalpha.

CONCLUSIONS

Macrophage depletion using IP LA has been shown to effectively inhibit the initiation and growth of EM implants, in a rat EM model. The clear dose-response effect may be viewed as a confirmation of the validity of the concept and encourages further study.

PKCepsilon mediates glucose-regulated insulin production in pancreatic beta-cells

Endocrine cells produce large amounts of one or more peptides. The post-translational control of selective production of a single protein is often unknown. We used 3 unrelated approaches to diminish PKCepsilon in rat islets to evaluate its role in preferential glucose-mediated insulin production. Transfection with siRNA (siR-PKCepsilon) or expression of inactive PKCepsilon (PKCepsilon-KD) resulted in a significant reduction in insulin response to glucose (16.7 mmol/l). Glucose stimulation resulted in concentration of PKCepsilon in the perinuclear region, an area known to be rich in ER-Golgi systems, associated with insulin-containing structures. ss'COP1 (RACK2) is the anchoring protein for PKCepsilon. Glucose-stimulated proinsulin production was diminished by 50% in islets expressing PKCepsilon-KD, and 60% in islets expressing RACK2 binding protein (epsilonV1-2); total protein biosynthesis was not affected. In islets expressing epsilonV1-2, a chase period following glucose stimulus resulted in a reduced proinsulin conversion to mature insulin. We propose that PKCepsilon plays a specific role in mediating the glucose-signal into insulin production: binding to ss'COP1 localizes the activated enzyme to the RER where it modulates the shuttling of proinsulin to the TGN. Subsequently the enzyme may be involved in anterograde trafficking of the prohormone or in its processing within the TGN.

Detection of early necrosis in a canine model of low flow myocardial ischemia using 125I-antimyosin (Fab')2

Low flow myocardial ischemia in the distribution of the left anterior descending coronary artery was established in 32 anesthetized dogs. The early development of irreversible myocardial injury was identified using 125I-antimyosin (Fab')2--a specific immunological marker of myocardial necrosis. The simultaneous injection of 131I-nonspecific (Fab')2 controlled for variables unrelated to specific antimyosin activity. It was also possible to calculate the relative uptake of 125I-antimyosin (Fab')2 in the ischemic area. In order to prevent recirculation of the (Fab')2, and to limit the time of exposure to the myocardium, the fragments were injected directly into the coronary circulation during diversion of the coronary sinus effluent. The antibody fragments were given either two, three or five hours after the onset of low flow in different groups of dogs and the animals were sacrificed 60 minutes later. Selective accumulation of 125I-antimyosin (Fab')2 in the ischemic area occurred between two and three hours after the onset of low flow ischemia indicating that necrosis was already established at this time. Macroautoradiographs of cross sections of the left ventricle and autoradiographs of microscopic sections of the ischemic myocardium independently confirmed selective accumulation of 125I-antimyosin (Fab')2 and hence necrosis, at three hours after the onset of low flow. In this study the use of 125I-antimyosin (Fab')2, in contrast to the use of histology, as a marker of necrosis avoided error due to sampling and also permitted the detection of cell death early during the ischemic process. The demonstration, within a narrow time frame, of early necrosis in this low flow preparation provides a potential model with which to evaluate agents for myocardial preservation in obstructive coronary disease.

Automated sample preparation and gas chromatographic-mass spectrometric analysis of urinary androgenic anabolic steroids

This paper presents an automated method for extracting anabolic agents from urine samples for their GC-MS analysis by selected-ion monitoring. The sample preparation was carried out in a Hewlett-Packard 7686 SPE PrepStation system. Each 0.6-ml aliquot was hydrolyzed, extracted, dried and trimethylsilyl (TMS) derivatized in a 2-ml vial without any hands-on labor. When sample preparation was finished 2 microl of the extract was injected into the gas chromatograph by split (1:10) mode. Due to the small amount of free space in the 2-ml vials for handling the sample, parameters like time of hydrolysis, type of shaking, number of extractions and some TMS derivatization parameters had to be adjusted to achieve the best recovery for all of the compounds in the screening. Manual and automated sample preparation schemes were compared in terms of linearity, precision, accuracy, limit of detection and recovery data. When large concentrations were analyzed using the automated method no carry-over effect was observed.

Characterization of the mUBC9-binding sites required for E2A protein degradation

Mammalian Ubc9 (mUbc9) is required for rapid degradation of the E2A proteins E12 and E47 by the ubiquitin-proteasome system. We have shown elsewhere that mUbc9 interacts with amino acids 477-530 of E12/E47. Here we test the hypothesis that this region, rich in proline, glutamic acid, serine, and threonine (PEST) residues, serves as the E2A protein degradation domain (DD). An E2A protein lacking this region, E47Delta(478-531), was significantly more stable than wild-type E47(half-life of more than 6 h versus 55 min). Deletion of the E2A DD had no effect on the E-box-binding and transcriptional activity of E47. We mapped two discreet mUbc9-interacting regions within the E2A DD: amino acids 476-494 and 505-513. E2A(505-513) interacted with mUbc9 but not with human Ubc5, MyoD, Id3, or the polymyositis-scleroderma autoantigen. Substitution of the E2A(505-513) central hydrophobic residues with basic residues abolished interaction with mUbc9. Also, full-length E47 lacking the second mUbc9-interacting region was significantly more stable than wild-type E47. Reintroduction of the E2A DD into the long-lived, naturally occurring chimeric oncoprotein E2A-HLF (hepatic leukemic factor) destabilized it, suggesting that this domain can transfer a degradation signal to a heterologous protein. E2A-HLF-DD chimeric protein was stabilized by the proteasome inhibitor LLNL, indicating the role of the ubiquitin-proteasome system mediating degradation through the E2A degradation domain. Our experiments indicate that the E2A DD mediates E2A protein interactions with the ubiquitin-proteasome system and that the E2A DD is required for metabolism of these widely expressed proteins.

Use of controlled vignettes in evaluation: does type of response method make a difference?

Two studies were performed using vignettes as a method in program evaluation. One study used a rating scale method. The second study used a forced choice decision method. The two studies were performed with students from the pre-Occupational Therapy (pre-OT) program, the Occupational Therapy (professional OT) program and the College of Business at Colorado State University. Students were asked to respond to a questionnaire about how a hypothetical job applicant with a cognitive disability would perform in one of three types of job settings: a segregated, sheltered workshop setting; an integrated supported employment setting; or an integrated competitive employment setting. The students in the Professional Occupational Therapy program had been part of a training grant, 'An integrated approach to personnel preparation for transition', which focused on the integration of transition competencies into an occupational therapy curriculum. The forced choice vignette method resulted in statistically significant positive outcomes toward supported employment and the influence of the training grant. The discussion focused on the different outcomes of the two studies relative to the methods applied and the use of vignettes as an evaluation tool to assess the impact of a modified curriculum. Attention was directed toward the problem of external validity when using vignettes (Gorman, C.D., Clover, W.H. & Doherty, M.E., (l978). Can we learn anything about interviewing real people from 'interviews' of paper people? Two studies of the external validity of a paradigm. Organizational Behavior and Human Performance, 22, 165-192.).

Plasminogen is not required for neointima formation in a mouse model of vein graft stenosis

Recent studies of mice that lack plasminogen have identified a critical role for this zymogen in arterial remodeling. To permit the use of these (and other) genetically modified mice in the analysis of venous injury, we developed a model in which a patch cut from the external jugular vein of a mouse is grafted to repair a surgically created defect in its carotid artery. In wild-type mice, the venous graft showed initial endothelial denudation and formation of a neointima that progressively and reproducibly expanded in a manner analogous to human vein graft disease, albeit at an accelerated pace. This neointima occupied 37+/-4.6% of the vessel lumen at day 7 and 66+/-5.7% at day 20. The proliferative index of neointimal cells assessed by proliferating cell nuclear antigen staining was 50.6+/-3. 6% at day 7 and 15.2+/-2.0% at day 20. CD45-positive leukocytes and alpha-actin-positive smooth muscle cells accounted for 9.5+/-1.0% and 9.9+/-1.1% of intimal area at day 7, respectively, with the latter increasing to 40.9+/-2.6% at day 20. Collagen accounted for 6.8+/-0.7% of intimal area at day 7 and 20.7+/-1.8% at day 20. Surprisingly, even though arterial neointima formation due to electrostatic and immune-mediated injury is impaired in plasminogen -/- mice, in our study vein graft neointima formation in these mice was not significantly different from that in controls (70.9+/-6.4 versus 65.6+/-4.4% luminal occlusion, P=NS). Thus, plasmin proteolysis, although critical in extracellular matrix degradation and cellular migration after arterial injury, does not appear to be so important in vein graft neointima formation, perhaps because of the relative lack of structural barriers to cellular migration in the normal vein wall. This novel model of vein graft injury should be useful for further studies of differences in the response to injury of arterial and venous tissues.

Interferon-gamma-mediated inhibition of cyclin A gene transcription is independent of individual cis-acting elements in the cyclin A promoter

Interferons (IFNs) affect cellular functions by altering gene expression. The eukaryotic cell cycle is governed in part by the periodic transcription of cyclin genes, whose protein products associate with and positively regulate the cyclin-dependent kinases. To understand better the growth inhibitory effect of IFN-gamma on vascular smooth muscle cells (VSMCs), we compared the expression and activity of G1 and S phase cyclins in control and IFN-gamma-treated VSMCs. IFN-gamma treatment did not inhibit the G1 cyclins but did decrease cyclin A protein, mRNA, and associated kinase activity by 85, 90, and 90%, respectively. Nuclear run-on and mRNA stability determinations indicated that this decrease was the result of transcriptional inhibition. To investigate the molecular basis of this inhibition, we examined protein-DNA interactions involving the cyclin A promoter. Electromobility shift assays showed little change with IFN-gamma treatment in the binding of nuclear proteins to isolated ATF, NF-Y, and CDE elements. In vivo genomic footprinting indicated that IFN-gamma treatment changed the occupancy of chromosomal NF-Y and CDE sites slightly and did not affect occupancy of the ATF site. In a previous study of transforming growth factor-beta1-mediated inhibition of the cyclin A promoter, we mapped the inhibitory effect to the ATF site; in the present study of IFN-gamma treatment, functional analysis by transient transfection showed that inhibition of the cyclin A promoter persisted despite mutation of the ATF, NF-Y, or CDE elements. We hypothesize that IFN-gamma inhibits cyclin A transcription by modifying co-activators or general transcription factors within the complex that drives transcription of the cyclin A gene.

Donor MHC and adhesion molecules in transplant arteriosclerosis

Transplant-associated arteriosclerosis remains an obstacle to long-term graft survival. To determine the contribution to transplant arteriosclerosis of MHC and adhesion molecules from cells of the donor vasculature, we allografted carotid artery loops from six mutant mouse strains into immunocompetent CBA/CaJ recipients. The donor mice were deficient in either MHC I molecules or MHC II molecules, both MHC I and MHC II molecules, the adhesion molecule P-selectin, intercellular adhesion molecule (ICAM)-1, or both P-selectin and ICAM-1. Donor arteries in which ICAM-1, MHC II, or both MHC I and MHC II were absent showed reductions in neointima formation of 52%, 33%, and 38%, respectively, due primarily to a reduction in smooth muscle cell (SMC) accumulation. In P-selectin-deficient donor arteries, neointima formation did not differ from that in controls. In donor arteries lacking both P-selectin and ICAM-1, the size of the neointima was similar to that in those lacking ICAM-1 alone. In contrast, neointima formation increased by 52% in MHC I-deficient donor arteries. The number of CD4-positive T cells increased by 2.8-fold in MHC I-deficient arteries, and that of alpha-actin-positive SMCs by twofold. These observations indicate that ICAM-1 and MHC II molecules expressed in the donor vessel wall may promote transplant-associated arteriosclerosis. MHC I molecules expressed in the donor may have a protective effect.

Embryonic expression suggests an important role for CRP2/SmLIM in the developing cardiovascular system

Proteins of the LIM family are critical regulators of development and differentiation in various cell types. We have described the cloning of cysteine-rich protein 2/smooth muscle LIM protein (CRP2/SmLIM), a LIM-only protein expressed in differentiated vascular smooth muscle cells. As a first step toward understanding the potential functions of CRP2/SmLIM, we analyzed its expression after gastrulation in developing mice and compared the expression of CRP2/SmLIM with that of the other 2 members of the CRP subclass, CRP1 and CRP3/MLP. In situ hybridization in whole-mount and sectioned embryos showed that CRP2/SmLIM was expressed in the sinus venosus and the 2 cardiac chambers at embryonic day 9. Vascular expression of CRP2/SmLIM was first seen at embryonic day 10. At subsequent time points, CRP2/SmLIM expression decreased in the heart but remained high in the vasculature. CRP1 was expressed both in vascular and nonvascular tissues containing smooth muscle cells, whereas CRP3/MLP was expressed only in tissues containing striated muscle. These patterns of expression were maintained in the adult animal and suggest an important role for this gene family in the development of smooth and striated muscle.

Reduced transplant arteriosclerosis in plasminogen-deficient mice

Recent gene targeting studies indicate that the plasminogen system is implicated in cell migration and matrix degradation during arterial neointima formation and atherosclerotic aneurysm formation. This study examined whether plasmin proteolysis is involved in accelerated posttransplant arteriosclerosis (graft arterial disease). Donor carotid arteries from wild-type B10.A2R mice were transplanted into either plasminogen wild-type (Plg+/+) or homozygous plasminogen-deficient (Plg-/-) recipient mice with a genetic background of 75% C57BL/6 and 25% 129. Within 15 d after allograft transplantation, leukocytes and macrophages infiltrated the graft intima in Plg+/+ and Plg-/- recipient mice to a similar extent. In Plg+/+ recipients, the elastic laminae in the transplant media exhibited breaks through which macrophages infiltrated before smooth muscle cell proliferation, whereas in Plg-/- recipients, macrophages failed to infiltrate the transplant media which remained structurally more intact. After 45 d of transplantation, a multilayered smooth muscle cell-rich transplant neointima developed in Plg+/+ hosts, in contrast to Plg-/- recipients, in which the transplants contained a smaller intima, predominantly consisting of leukocytes, macrophages, and thrombus. Media necrosis, fragmentation of the elastic laminae, and adventitial remodeling were more pronounced in Plg+/+ than in Plg-/- recipient mice. Expression of the plasminogen activators (PA), urokinase-type PA (u-PA) and tissue-type PA (t-PA), and expression of the matrix metalloproteinases (MMPs), MMP-3, MMP-9, MMP-12, and MMP-13, were significantly increased within 15 d of transplantation when cells actively migrate. These data indicate that plasmin proteolysis plays a major role in allograft arteriosclerosis by mediating elastin degradation, macrophage infiltration, media remodeling, medial smooth muscle cell migration, and formation of a neointima.

Regulation of CD44 gene expression by the proinflammatory cytokine interleukin-1beta in vascular smooth muscle cells

The CD44 gene codes for a family of alternatively spliced, multifunctional adhesion molecules that participate in extracellular matrix binding, lymphocyte activation, cell migration, and tumor metastasis. In a mouse model of transplant-associated arteriosclerosis, CD44 protein was induced in the neointima of allografted vessels and colocalized with a subset of proliferating vascular smooth muscle cells (SMC). To elucidate the molecular mechanisms regulating CD44 expression in this model, we investigated the regulation of CD44 gene expression by interleukin (IL)-1beta. Treatment of rat aortic SMC with IL-1beta resulted in a 5.3-fold increase in cell surface CD44 expression. Northern analysis showed that IL-1beta promoted a dose- and time-dependent induction of CD44 mRNA which reached 6.6-fold after 48 h, and nuclear run-on analysis showed that IL-1beta increased the rate of CD44 gene transcription within 8 h of stimulation. In transient reporter gene transfection experiments in rat aortic SMC, a 1.4-kilobase fragment of the mouse CD44 5'-flanking sequence mediated this response to IL-1beta. Regulation of CD44 gene expression by the proinflammatory cytokine IL-1beta may contribute to SMC phenotypic modulation in the pathogenesis of arteriosclerosis.

Aortic carboxypeptidase-like protein, a novel protein with discoidin and carboxypeptidase-like domains, is up-regulated during vascular smooth muscle cell differentiation

Phenotypic modulation of vascular smooth muscle cells plays an important role in the pathogenesis of arteriosclerosis. In a screen of proteins expressed in human aortic smooth muscle cells, we identified a novel gene product designated aortic carboxypeptidase-like protein (ACLP). The approximately 4-kilobase human cDNA and its mouse homologue encode 1158 and 1128 amino acid proteins, respectively, that are 85% identical. ACLP is a nonnuclear protein that contains a signal peptide, a lysine- and proline-rich 11-amino acid repeating motif, a discoidin-like domain, and a C-terminal domain with 39% identity to carboxypeptidase E. By Western blot analysis and in situ hybridization, we detected abundant ACLP expression in the adult aorta. ACLP was expressed predominantly in the smooth muscle cells of the adult mouse aorta but not in the adventitia or in several other tissues. In cultured mouse aortic smooth muscle cells, ACLP mRNA and protein were up-regulated 2-3-fold after serum starvation. Using a recently developed neural crest cell to smooth muscle cell in vitro differentiation system, we found that ACLP mRNA and protein were not expressed in neural crest cells but were up-regulated dramatically with the differentiation of these cells. These results indicate that ACLP may play a role in differentiated vascular smooth muscle cells.

Thy-1, a novel marker for angiogenesis upregulated by inflammatory cytokines

We identified the cell surface glycoprotein Thy-1 on the endothelium of newly formed blood vessels in four models of angiogenesis in adult rats. Anti-Thy-1 staining showed that Thy-1 was upregulated in adventitial blood vessels after balloon injury to the carotid artery. Preabsorption with a rat Thy-1-Ig fusion construct eliminated all immunoreactivity and thus confirmed the specificity of the Thy-1 staining. Thy-1 was also expressed in the endothelium of small blood vessels formed after tumor implantation in the cornea, in periureteral vessels formed after ligation of the renal artery, and in small blood vessels of the uterus formed during pregnancy. In contrast with its expression during adult angiogenesis, Thy-1 was not expressed in the endothelium of blood vessels during embryonic angiogenesis. In vitro, the inflammatory cytokines interleukin-1beta and tumor necrosis factor-alpha upregulated Thy-1 mRNA by 8- and 14-fold, respectively. Vascular endothelial growth factor, basic fibroblast growth factor, transforming growth factor-beta, and platelet-derived growth factor-BB had no effect on Thy-1 mRNA. Thus, Thy-1 appears to be a marker of adult but not embryonic angiogenesis. The upregulation of Thy-1 by cytokines but not growth factors indicates the importance of inflammation in the pathogenesis of adult angiogenesis.

Vascular endothelial growth factor induces heparin-binding epidermal growth factor-like growth factor in vascular endothelial cells

Although several cytokines and growth factors have been shown to regulate vascular endothelial growth factor (VEGF) production, little is known about how VEGF may regulate growth factors that have known mitogenic and chemotactic actions on mesenchymal cells (which are involved in the maturation of the angiogenic process). We investigated the effect of VEGF on heparin-binding epidermal growth factor-like growth factor (HB-EGF) expression in human umbilical vein endothelial cells. HB-EGF mRNA was induced by 8-fold after 2 h of VEGF stimulation, and it returned to base line within 6 h. VEGF did not alter the half-life of HB-EGF mRNA (55 min). Nuclear run-on experiments showed a 4.9-fold increase in HB-EGF gene transcription within 2 h of VEGF stimulation, and Western analysis demonstrated an associated increase in cellular HB-EGF protein. We found that platelet-derived growth factor-BB (PDGF-BB) mRNA was also induced 3-fold after 5 h of VEGF stimulation, whereas neither endothelin 1 nor transforming growth factor-beta1 was regulated by VEGF. Finally, conditioned medium from VEGF-stimulated endothelial cells produced an increase in DNA synthesis in vascular smooth muscle cells, and this effect was blocked by a neutralizing antibody to PDGF. The induction of HB-EGF and PDGF-BB expression in endothelial cells may represent the mechanism by which VEGF recruits mesenchymal cells to form the medial and adventitial layers of arterioles and venules during the course of angiogenesis.

Hypercholesterolemia exacerbates transplant arteriosclerosis via increased neointimal smooth muscle cell accumulation: studies in apolipoprotein E knockout mice

BACKGROUND

Hypercholesterolemia is thought to be a significant risk factor for coronary vasculopathy in cardiac transplant recipients.

METHODS AND RESULTS

We examined the development of arteriosclerosis in mouse carotid artery loops allografted from B.10A(2R) (H-2h2) donors to normocholesterolemic C57BL/6J (H-2h) recipients and hypercholesterolemic C57BL/6J recipients in which the apolipoprotein (apo) E gene had been knocked out. Luminal occlusion and cross-sectional neointimal area were greater in arteries allografted into hypercholesterolemic recipients at 15 and 30 days after transplantation. We also measured cellular and extracellular matrix components of the neointima by computerized planimetry of the fractional areas subtended by smooth muscle cells (anti-alpha-actin stain), collagen (Masson's trichrome), lipid (oil red O), and leukocytes (anti-CD45). The neointimal area stained for smooth muscle cells was significantly greater in hypercholesterolemic recipients than in normocholesterolemic recipients at 15 and 30 days after allografting. Lipid contributed to neointimal area to a lesser degree, and there was no significant increase in the contribution of collagen or leukocytes.

CONCLUSIONS

Smooth muscle cell accumulation appears to be the principal contributor to the increase in neointimal area observed in arteries allografted into hypercholesterolemic mice.

Inhibition of growth and p21ras methylation in vascular endothelial cells by homocysteine but not cysteine

Although hyperhomocysteinemia has been recognized recently as a prevalent risk factor for myocardial infarction and stroke, the mechanisms by which it accelerates arteriosclerosis have not been elucidated, mostly because the biological effects of homocysteine can only be demonstrated at very high concentrations and can be mimicked by cysteine, which indicates a lack of specificity. We found that 10-50 microM of homocysteine (a range that overlaps levels observed clinically) but not cysteine inhibited DNA synthesis in vascular endothelial cells (VEC) and arrested their growth at the G1 phase of the cell cycle. Homocysteine in this same range had no effect on the growth of vascular smooth muscle cells (VSMC) or fibroblasts. Homocysteine decreased carboxyl methylation of p21(ras) (a G1 regulator whose activity is regulated by prenylation and methylation in addition to GTP-GDP exchange) by 50% in VEC but not VSMC, a difference that may be explained by the ability of homocysteine to dramatically increase levels of S-adenosylhomocysteine, a potent inhibitor of methyltransferase, in VEC but not VSMC. Moreover, homocysteine-induced hypomethylation in VEC was associated with a 66% reduction in membrane-associated p21(ras) and a 67% reduction in extracellular signal-regulated kinase 1/2, which is a member of the mitogen-activated protein (MAP) kinase family. Because the MAP kinases have been implicated in cell growth, the p21(ras)-MAP kinase pathway may represent one of the mechanisms that mediates homocysteine's effect on VEC growth. VEC damage is a hallmark of arteriosclerosis. Homocysteine-induced inhibition of VEC growth may play an important role in this disease process.

Progesterone inhibits arterial smooth muscle cell proliferation

Mortality from atherosclerotic cardiovascular disease is lower in premenopausal women than in age-matched men. It is also lower in postmenopausal women who take estrogens and progestins together rather than estrogens alone. Progesterone receptors were detected in human and rat aortic smooth muscle cells in vivo and in vitro (in subculture). We examined the effect of progesterone on proliferation of smooth muscle cells, important constituents of atherosclerotic plaques. Progesterone at physiologic levels inhibited DNA synthesis and proliferation in these cells in a dose-dependent manner, and pretreatment with the progesterone receptor antagonist RU486 blocked inhibition. Cyclin A and E messenger RNA levels decreased after progesterone treatment but those of cyclin B and D1 did not change. This cell cycle-dependent inhibition of arterial smooth muscle cell proliferation by progesterone may represent a mechanism for the hormone's protective effect against atherosclerosis.

The polymyositis-scleroderma autoantigen interacts with the helix-loop-helix proteins E12 and E47

The basic helix-loop-helix (bHLH) transcription factors E12 and E47 regulate cellular differentiation and proliferation in diverse cell types. While looking for proteins that bind to E12 and E47 by the yeast interaction trap, we isolated the rat (r) homologue of the human (h) polymyositis-scleroderma autoantigen (PM-Scl), which has been localized to the granular layer of the nucleolus and to distinct nucleocytoplasmic foci. The rPM-Scl and hPM-Scl homologues are 96% similar and 91% identical. We found that rPM-Scl mRNA expression was regulated by growth factor stimulation in cultured rat aortic smooth muscle cells. rPM-Scl bound to E12 and E47 but not to Id3, Gax, Myb, OCT-1, or Max. The C terminus of rPM-Scl (amino acids 283-353) interacted specifically with a 54-amino acid domain in E12 that is distinct from the bHLH domain. Finally, cotransfection of rPM-Scl and E47 specifically increased the promoter activity of a luciferase reporter construct containing an E box and did not affect the basal activity of the reporter construct. rPM-Scl appears to be a novel non-HLH-interacting partner of E12/E47 that regulates E2A protein transcription.

Collagen VIII is expressed by vascular smooth muscle cells in response to vascular injury

To identify genes involved in vascular remodeling, we applied differential mRNA display analysis to the rat carotid artery balloon injury model. One polymerase chain reaction product showing increased expression at days 2 to 14 after vascular injury was nearly identical to the mouse alpha 1 chain of type VIII collagen, a heterotrimeric short-chain collagen of uncertain function expressed by a limited number of cell types. By Northern analysis, expression of both chains of the type VIII collagen heterotrimer increased: collagen alpha 1 (VIII) mRNA expression was almost 4-fold higher than control by 7 days after vascular injury, and collagen alpha 2 (VIII) mRNA expression reached a maximum of almost 6-fold above baseline by 3 days after injury. By immunohistochemical analysis, type VIII collagen expression increased in the media and neointima in a localized pattern consistent with the distribution of activated dedifferentiated vascular smooth muscle cells (VSMCs). Cultured VSMCs expressed higher levels of type VIII collagen in response to serum and growth factors, notably platelet-derived growth factor (PDGF)-BB. VSMCs adhered significantly less to type VIII collagen than to type I collagen substrata and showed greater PDGF-BB-stimulated migration (by 2.2-fold) on type VIII collagen than on type I collagen. We hypothesize that increased expression of type VIII collagen by VSMCs after arterial injury may contribute to vascular remodeling through the promotion of VSMC migration.

Nuclear protein interactions with the human KDR/flk-1 promoter in vivo. Regulation of Sp1 binding is associated with cell type-specific expression

The endothelial cell type-specific tyrosine kinase KDR/flk-1 is a receptor for vascular endothelial growth factor and a critical regulator of endothelial cell growth and development. To study mechanisms of endothelial cell differentiation and gene regulation, we have analyzed the topology of the proximal promoter of human KDR/flk-1. A protected sequence between base pairs -110 and -25 was defined by in vitro DNase I footprinting analysis in human umbilical vein endothelial cells (HUVECs). Purified Sp1 alone produced similar protection, and electrophoretic mobility shift assays demonstrated that Sp1 was indeed the major nuclear protein binding to this region. Despite the cell type specificity of KDR/flk-1 expression, no cell type differences were observed in DNA-protein interactions in vitro. In contrast, in vivo footprinting assays demonstrated marked differences in core promoter interactions between cell types. Protection of Sp1 binding sites was observed in HUVECs by in vivo DNase I footprinting, whereas in human fibroblasts and HeLa cells a pattern consistent with nucleosomal positioning was observed. In vivo dimethylsulfate footprinting confirmed that DNA-protein interactions occurred within Sp1 elements in HUVECs but not in nonendothelial cells. It is possible that distant elements coordinate Sp1 binding and chromatin structure to regulate cell type-specific expression of KDR/flk-1.

Antithrombotic potency of hirudin is increased in nonhuman primates by fibrin targeting

BACKGROUND

Inhibition of thrombin by either the indirect thrombin inhibitor heparin or by more potent direct thrombin inhibitors such as hirudin reduces thrombus formation after arterial injury. The present study was designed to determine if a fibrin-specific thrombin inhibitor could, by local thrombin inhibition, prevent thrombosis more effectively.

METHODS AND RESULTS

We first studied antithrombotic potency in vitro, comparing fibrin-targeted hirudin (recombinant hirudin covalently linked to the Fab' fragment of the anti-fibrin monoclonal antibody 59D8) to recombinant hirudin in baboon plasma. Fibrin-targeted hirudin was nine times more effective than recombinant hirudin in inhibiting fibrin deposition on experimental clot surfaces in baboon plasma (P < .01). The potency of fibrin-targeted hirudin was then compared with that of recombinant hirudin in a baboon model of thrombus formation. 111In-labeled platelet deposition was measured in a synthetic graft segment of an extracorporeal arteriovenous shunt in control animals and in animals receiving either fibrin-targeted hirudin or hirudin. In these experiments, fibrin-targeted hirudin was 10-fold more potent than hirudin in inhibiting platelet deposition and thrombus formation (P < .05).

CONCLUSIONS

These data indicate that targeting a thrombin inhibitors such as hirudin to an epitope present in thrombi results in increased antithrombotic potency.

Degradation of E2A proteins through a ubiquitin-conjugating enzyme, UbcE2A

The helix-loop-helix E2A proteins (E12 and E47) govern cellular growth and differentiation. To identify binding partners that regulate the function of these ubiquitous transcription factors, we screened for proteins that interacted with the C terminus of E12 by the yeast interaction trap. UbcE2A, a rat enzyme that is highly homologous to and functionally complements the yeast ubiquitin-conjugating enzyme UBC9, was identified and cloned. UbcE2A appears to be an E2A-selective ubiquitin-conjugating enzyme because it interacts specifically with a 54-amino acid region in E47-(477-530) distinct from the helix-loop-helix domain. In contrast, most of the UbcE2A protein is required for interaction with an E2A protein. The E2A proteins appear to be degraded by the ubiquitin-proteasome pathway because the E12 half-life of 60 min is extended by the proteasome inhibitor MG132, and E12 is multi-ubiquitinated in vivo. Finally, antisense UbcE2A reduces E12 degradation. By participating in the degradation of the E2A proteins, UbcE2A may regulate cell growth and differentiation.

Mitogen-activated protein kinase phosphatase-1 in rat arterial smooth muscle cell proliferation

Smooth muscle cell proliferation and migration is important in arteriosclerosis. In this process, cytokines and growth factors are upregulated and bind to their respective receptors, which in turn stimulate mitogen-activated protein (MAP) kinases. MAP kinases then relay signals to the nucleus that activate quiescent smooth muscle cells. Phosphatases downregulate MAP kinases. We investigated the role of a dual-specificity tyrosine phosphatase, MAP kinase phosphatase-1 (MKP-1), in smooth muscle cell proliferation. MKP-1 expression was high in arterial tissue by Northern analysis, and MKP-1 message was detected mainly in the arterial smooth muscle layer by in situ hybridization. After balloon injury of the rat carotid artery, expression of MKP-1 decreased greatly, whereas that of MAP kinases, especially p44 MAP kinase, increased. The time course of the reduction in MKP-1 message correlated with increased tyrosine phosphorylation and elevated p44 MAP kinase enzymatic activity. In rat arterial smooth muscle cells overexpressing MKP-1, growth was arrested in the G1 phase and entry into the S phase was blocked. A reduction in MKP-1 expression may contribute in part to proliferation of smooth muscle cells after vascular injury, possibly through a decrease in dephosphorylation of p44 MAP kinase.

Enhanced thrombolytic and antithrombotic potency of a fibrin-targeted plasminogen activator in baboons

BACKGROUND

Thrombolytic therapy reduces mortality in patients with acute myocardial infarction, but significant limitations exist with the use of currently available agents. In the present report, we describe the thrombolytic and antithrombotic potencies of a hybrid recombinant plasminogen activator consisting of an antifibrin antibody 59D8 (AFA) and low-molecular-weight single-chain urokinase-type plasminogen activator (scuPA).

METHODS AND RESULTS

A thrombolysis model in which thrombi are preformed in vivo in juvenile baboons was developed to compare the potencies of AFA-scuPA, recombinant tissue plasminogen activator (rTPA), and recombinant scuPA (rscuPA) in lysing nonocclusive 111In-labeled platelet-rich arterial-type thrombi and 125I-labeled fibrin-rich venous-type thrombi. Systemic infusion of 1.89 nmol/kg AFA-scuPA produced thrombolysis that was comparable to that obtained with much higher doses of TPA (14.2 nmol/kg) and rscuPA (28.5 nmol/kg). When steady-state plasma concentrations are normalized, AFA-scuPA lyses thrombi sixfold more rapidly than scuPA and TPA (P < .001) and reduces the rate of formation more than comparable doses of rscuPA (P < .0001). At equivalent thrombolytic doses, AFA-scuPA produced fewer antihemostatic effects than either rTPA or rscuPA. Template bleeding time measurements were shorter (3.5 +/- 0.12 minutes for AFA-scuPA versus 5.3 +/- 0.36 and 5.2 +/- 0.04 minutes for rTPA and rscuPA, respectively; P < .05), alpha 2-antiplasmin consumption was less (P < .05), and D-dimer generation was lower (P < .05).

CONCLUSIONS

We conclude that antibody targeting of scuPA to fibrin increases thrombolytic and antithrombotic potencies with less impairment of hemostasis compared with rTPA and rscuPA.

Diagnostic accuracy of antimyosin scintigraphy in suspected myocarditis

BACKGROUND

Radiolabeled antibody specific for cardiac myosin administered intravenously has been used to define noninvasively regions of myocardial necrosis. Inflammatory heart disorders such as myocarditis and heart transplant rejection demonstrate diffuse and often faint myocardial uptake of antimyosin antibody. This study was undertaken to evaluate the reproducibility and diagnostic accuracy of antimyosin antibody imaging for the detection of patients with suspected myocarditis.

METHODS AND RESULTS

Fifty antimyosin scans, performed consecutively in patients with suspected myocarditis, were evaluated by one independent observer and two panels of observers. Antimyosin scan interpretations were compared with endomyocardial biopsy results and also with serial changes in left ventricular function. An independent observer (A) and a panel of five observers (A through E) interpreted the antimyosin scans as positive or negative on the basis of both planar images and tomographic reconstructions. Three of the five observers (A through C) again interpreted the scans but based interpretation only on planar images. Blinded random sequence evaluation of antimyosin scans based on the planar and tomographic interpretations revealed moderate agreement between the independent observer (A) and the group of observers (A through E) (kappa = 0.58). There was also moderate agreement between interpretations based on planar images alone and interpretations based on both planar and tomographic images (kappa [A through E]/[A through C] = 0.57; kappa [A through C]/A = 0.48). Comparison of antimyosin scan results with histologic evidence of myocarditis in endomyocardial biopsy specimens demonstrated that all scan results obtained from the individual or the panels of observers had a very high sensitivity (91% to 100%) and a high negative predictive value (93% to 100%). The specificity (31% to 44%) and positive predictive value (28% to 33%) were less impressive. We also compared the scan and biopsy results with the composite clinical standard of significant left ventricular functional improvement. Endomyocardial biopsy demonstrated poor sensitivity (35%) compared with antimyosin scans (82% to 94%) but had superior specificity (endomyocardial biopsy, 79%; antimyosin scan, 25% to 42%). The specificity of interpretations based on planar and tomographic interpretations (38% to 42%) was better than the planar images alone (25%). If reversible left ventricular dysfunction is considered clinical evidence of myocarditis, this study suggests that a negative endomyocardial biopsy significantly misses the presence of the disease. On the other hand, a negative antimyosin scan almost invariably excludes myocarditis.

CONCLUSIONS

This study demonstrates a high degree of interobserver reproducibility of antimyosin interpretation. Comparison of the scintigraphic results with histologic and clinical standards indicates a high sensitivity of antimyosin scans for the detection of myocarditis. The antimyosin scan is also not likely to miss clinically or pathologically diagnosed myocarditis, in contrast to the endomyocardial biopsy, which missed clinically validated myocarditis 65% of time. The combination of high sensitivity and negative predictive value suggests that antimyosin scintigraphy may be an effective screening procedure for obviating biopsies in patients with suspected myocarditis.

Downregulation of vascular endothelial growth factor receptors by tumor necrosis factor-alpha in cultured human vascular endothelial cells

Vascular endothelial growth factor (VEGF) potently stimulates angiogenesis, whereas TNF-alpha has both pro- and anti-angiogenic activity. By measuring thymidine uptake, we found that TNF-alpha blocked a 2.3-fold increase in DNA synthesis induced by VEGF in human endothelial cells. To explore the possibility that the two interact to regulate endothelial cell proliferation, we examined the effect of TNF-alpha on VEGF receptor expression. In venous and arterial endothelial cells, TNF-alpha potently reduced mRNA transcripts of the two VEGF receptors (KDR/flk-1 and flt-1) in a dose- and time-dependent fashion. TNF-alpha at 1 ng/ml induced maximal inhibition of mRNA expression, which fell by approximately 70% after 24 h. TNF-alpha treatment did not significantly affect the KDR/flk-1 half-life but did decrease its rate of transcription to 40% of control. The decrease in KDR/flk-1 mRNA depended partially on new protein synthesis and was abolished by phorbol ester pretreatment. TNF-alpha decreased the amount of 35S-labeled KDR/flk-1 immunoprecipitated by an antibody specific for KDR/flk-1 to 18% of control. We conclude that TNF-alpha downregulates expression of both VEGF receptors in human endothelial cells and that this effect is transcriptional (at least for KDR/flk-1). These data support the hypothesis that TNF-alpha exerts its antiangiogenic effect in part by modulating the VEGF-specific angiogenic pathway.

Induction of apoptosis by pyrrolidinedithiocarbamate and N-acetylcysteine in vascular smooth muscle cells

Pyrrolidinedithiocarbamate (PDTC) and N-acetylcysteine (NAC) have been used as antioxidants to prevent apoptosis in lymphocytes, neurons, and vascular endothelial cells. We report here that PDTC and NAC induce apoptosis in rat and human smooth muscle cells. In rat aortic smooth muscle cells, PDTC induced cell shrinkage, chromatin condensation, and DNA strand breaks consistent with apoptosis. In addition, overexpression of Bcl-2 suppressed vascular smooth muscle cell death caused by PDTC and NAC. The viability of rat aortic smooth muscle cells decreased within 3 h of treatment with PDTC and was reduced to 30% at 12 h. The effect of PDTC and NAC on smooth muscle cells was not species specific because PDTC and NAC both caused dose-dependent reductions in viability in rat and human aortic smooth muscle cells. In contrast, neither PDTC nor NAC reduced viability in human aortic endothelial cells. The use of antioxidants to induce apoptosis in vascular smooth muscle cells may help prevent their proliferation in arteriosclerotic lesions.

Immunologic basis of transplant-associated arteriosclerosis

Although immunosuppressive therapy minimizes the risk of graft failure due to acute rejection, transplant-associated arteriosclerosis of the coronary arteries remains a significant obstacle to the long-term survival of heart transplant recipients. The participation of specific inflammatory cell types in the genesis of this lesion was examined in a mouse model in which carotid arteries were transplanted across multiple histocompatibility barriers into seven mutant strains with immunologic defects. An acquired immune response--with the participation of CD4+ (helper) T cells, humoral antibody, and macrophages--was essential to the development of the concentric neointimal proliferation and luminal narrowing characteristic of transplant arteriosclerosis. CD8+ (cytotoxic) T cells and natural killer cells were not involved in the process. Arteries allografted into mice deficient in both T-cell receptors and humoral antibody showed almost no neointimal proliferation, whereas those grafted into mice deficient only in helper T cells, humoral antibody, or macrophages developed small neointimas. These small neointimas and the large neointimas of arteries grafted into control animals contained a similar number of inflammatory cells; however, smooth muscle cell number and collagen deposition were diminished in the small neointimas. Also, the degree of inflammatory reaction in the adventitia did not correlate with the size of the neointima. Thus, the reduction in neointimal size in arteries allografted into mice deficient in helper T cells, humoral antibody, or macrophages may be accounted for by a decrease in smooth muscle cell migration or proliferation.

Molecular cloning and characterization of SmLIM, a developmentally regulated LIM protein preferentially expressed in aortic smooth muscle cells

Differentiated, quiescent vascular smooth muscle cells assume a dedifferentiated, proliferative phenotype in response to injury, one of the hallmarks of arteriosclerosis. Members of the LIM family of zinc-finger proteins are important in the differentiation of various cells including striated muscle. We describe here the molecular cloning and characterization of a developmentally regulated smooth muscle LIM protein, SmLIM, that is expressed preferentially in the rat aorta. This 194-amino acid protein has two LIM domains, and comparisons of rat SmLIM with its mouse and human homologues reveal high levels of amino acid sequence conservation (100 and 99%, respectively). SmLIM is a nuclear protein and maps to human chromosome 3. SmLIM mRNA expression was high in aorta but not in striated muscle and low in other smooth muscle tissues such as intestine and uterus. In contrast with arterial tissue, SmLIM mRNA was barely detectable in venous tissue. The presence of SmLIM expression within aortic smooth muscle cells was confirmed by in situ hybridization. In vitro, SmLIM mRNA levels decreased by 80% in response to platelet-derived growth factor-BB in rat aortic smooth muscle cells. In vivo, SmLIM mRNA decreased by 60% in response to vessel wall injury during periods of maximal smooth muscle cell proliferation. The down-regulation of SmLIM by phenotypic change in vascular smooth muscle cells suggests that it may be involved in their growth and differentiation.

Increased proteolytic processing of protein tyrosine phosphatase mu in confluent vascular endothelial cells: the role of PC5, a member of the subtilisin family

Cleavage and subsequent release of the extracellular domains of receptor protein tyrosine phosphatases (RPTP) occur at high cell density and may have an important role in regulating their activity. Because cleavage of RPTP occurs at a target motif (RXK/RR) recognized by a family of subtilisin/kexin-like endoproteases, we postulated that members of the subtilisin family may have an important role in this cleavage. We show in this report that the membrane-associated RPTPmu--both in its full 200-kDa form and as a 100-kDa cleavage product--is upregulated 4- and 7-fold, respectively, as human umbilical vein endothelial cells (HUVEC) approach confluence. To determine whether RPTPmu cleavage depended on PC5 (a subtilisin/kexin like endoprotease present in endothelial cells), we transfected COS cells with expression plasmids coding for RPTPmu and PC5 or the closely related protease PACE4. PC5, but not PACE4, cleaved RPTPmu, and RPTPmu cleavage was absent in COS cells transfected with an expression plasmid encoding a mutant PC5 whose active-site serine had been mutated to alanine. We also performed RNA blot analysis to determine whether PC5 expression was affected by confluence in HUVEC. PC5 mRNA levels were upregulated by more than 30-fold when confluence in HUVEC increased from 25% to 100%. These results indicate that PC5 may have an important role in mediating the cleavage of RPTPmu in response to contact inhibition in HUVEC.

Arrest of endotoxin-induced hypotension by transforming growth factor beta1

Septic shock is a cytokine-mediated process typically caused by a severe underlying infection. Toxins generated by the infecting organism trigger a cascade of events leading to hypotension, to multiple organ system failure, and frequently to death. Beyond supportive care, no effective therapy is available for the treatment of septic shock. Nitric oxide (NO) is a potent vasodilator generated late in the sepsis pathway leading to hypotension; therefore, NO represents a potential target for therapy. We have previously demonstrated that transforming growth factor (TGF) beta1 inhibits inducible NO synthase (iNOS) mRNA and NO production in vascular smooth muscle cells after its induction by cytokines critical in the sepsis cascade. Thus, we hypothesized that TGF-beta1 may inhibit iNOS gene expression in vivo and be beneficial in the treatment of septic shock. In a conscious rat model of septic shock produced by Salmonella typhosa lipopolysaccharide (LPS), TGF-beta1 markedly reduced iNOS mRNA and protein levels in several organs. In contrast, TGF-beta1 did not decrease endothelium-derived constitutive NOS mRNA in organs of rats receiving LPS. We also performed studies in anesthetized rats to evaluate the effect of TGF-beta1 on the hemodynamic compromise of septic shock; after an initial 25% decrease in mean arterial pressure, TGF-beta1 arrested LPS-induced hypotension and decreased mortality. A decrease in iNOS mRNA and protein levels in vascular smooth muscle cells was demonstrated by in situ hybridization and NADPH diaphorase staining in rats treated with TGF-beta1. Thus these studies suggest that TGF-beta1 inhibits iNOS in vivo and that TGF-beta1 may be of future benefit in the therapy of septic shock.

Role of CD44 in the reaction of vascular smooth muscle cells to arterial wall injury

CD44, the principal receptor for hyaluronic acid, is a widely distributed cell surface proteoglycan involved in cellular activation, proliferation, and migration. These processes are also central to the vascular smooth muscle cell's response to arterial wall injury. We evaluated the expression of CD44 and its isoform, CD44-V6, on vascular smooth muscle cells in vitro and in vivo and assessed the role of CD44 in DNA synthesis. Cultured vascular smooth muscle cells expressed CD44 and CD44-V6 at levels equal to or higher than those of the beta 1 and beta 2 integrins. In a rat carotid artery balloon injury model, CD44 and CD44-V6 mRNAs were unregulated in vascular smooth muscle cells after injury, and CD44 protein expression was greatest at the luminal edge of the growing neointima. CD44-expressing smooth muscle cells proliferated actively, and hyaluronic acid expression increased after injury in a temporal pattern similar to that of CD44. Through binding to hyaluronic acid, CD44 augmented DNA synthesis in cultured human and rat smooth muscle cells by 48 +/- 7.8 and 100 +/- 12.5%, respectively, an effect inhibited by an anti-CD44 antibody that blocked hyaluronate binding. These observations support a role for CD44 in the reaction of vascular smooth muscle cells to arterial wall injury.

Induction of cyclin A gene expression by homocysteine in vascular smooth muscle cells

Homocysteine is an important and independent risk factor for arteriosclerosis. We showed previously that homocysteine stimulates vascular smooth muscle cell proliferation, a hallmark of arteriosclerosis. We show here that homocysteine and serum increased DNA synthesis synergistically in both human and rat aortic smooth muscle cells (RASMCs). Treatment of quiescent RASMCs with 1 mM homocysteine or 2% calf serum for 36 h increased cyclin A mRNA levels by 8- and 14-fold, respectively, whereas homocysteine plus serum increased cyclin A mRNA levels by 40-fold, indicating a synergistic induction of cyclin A mRNA. Homocysteine did not increase the half-life of cyclin A mRNA (2.9 h), but it did increase the transcriptional rate of the cyclin A gene in nuclear run-on experiments. The positive effect of homocysteine on cyclin A gene transcription was confirmed by our finding that homocysteine increased cyclin A promoter activity and ATF-binding protein levels in RASMCs. Finally, 1 mM homocysteine increased cyclin A protein levels and cyclin A-associated kinase activity by threefold. This homocysteine-induced expression lesions by promoting proliferation of vascular smooth muscle cells.