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Biomedical subjects

M Valentine

Publications and source records attributed to M Valentine.

At least 19 recordsLinked to original sources
PubMed2001

Rational testing of the HIV-exposed infant.

OBJECTIVES: The objectives of this study were 1) to evaluate testing regimens of human immunodeficiency virus (HIV)-exposed infants and 2) to determine optimal methods of follow-up by enzyme-linked immunosorbent assay (ELISA) testing. METHODS: We reviewed the results from 742 HIV-exposed infants in the state of North Carolina; 2474 samples were tested for HIV by DNA polymerase chain reaction (PCR) at the University of North Carolina Retrovirology Core Laboratory. We then reviewed the utility and costs of ELISA testing of all HIV-exposed infants who were seen at the Duke University Pediatric Infectious Disease Clinic between January 1, 1993, and May 5, 1998. We used likelihood ratios to model probability of HIV infection given 3 negative DNA (PCR) tests and to provide recommendations on the use of ELISA follow-up. RESULTS: The overall sensitivity of the DNA PCR was 87.1%, and its specificity was 99.9%. We evaluated 224 HIV-exposed infants who were seen at Duke University and who had at least 3 negative diagnostic tests using either DNA PCR tests or HIV blood cultures. All 178 infants who subsequently underwent ELISA testing ultimately demonstrated seroreversion. The Duke University Pediatric Infectious Disease Clinic transferred the care of 65 patients to primary care physicians before ELISA testing and retained the care of the remaining 159 patients. Children who remained in Duke's care were more likely to have documentation of seroreversion (158 of 159 vs 20 of 65). We reviewed costs of travel, physician appointment, and HIV antibody testing in a tertiary care setting. Given 3 negative PCR tests, the expected cost per case of HIV detected by a positive ELISA assay is $23.8 million. CONCLUSIONS: Documentation of seroreversion in this cohort was nearly complete in the multidisciplinary subspecialty clinic but not when such responsibility was left to the primary care physician. Given the low probability of disease in patients who have had 3 negative PCR tests, documentation of a negative ELISA may not be an appropriate use of medical resources.

Algorithms↗
PubMed2000

Characterization of atherosclerosis in LDL receptor knockout mice: macrophage accumulation correlates with rapid and sustained expression of aortic MCP-1/JE.

Atherosclerosis and the expression of monocyte chemoattractant protein-1 (MCP-1) were quantified in low density lipoprotein receptor knockout (LDLR KO) mice fed 1.25% cholesterol (study #1) or 0.2% cholesterol (study #2). In study #1 plasma total cholesterols leveled-off at 1800 mg/dl whereas plasma triglycerides remained low. In en face specimens of the aortic root and arch, intimal foam cells plus extracellular lipid particles accumulated and by 8 weeks the fatty streak surface area had rapidly expanded at both sites. In study #2, total cholesterols averaged 400 mg/dl and fatty streaks were 2-3-fold smaller compared to those in study #1. In study #3, LDLR KO mice were fed chow or 1.25% cholesterol, and immunostaining demonstrated a few Mac-2-positive intimal macrophages in mice fed chow, and during the first 10 weeks of hypercholesterolemia the number of intimal macrophages increased continuously. In chow-fed mice (0 weeks) there was little MCP-1 in the aorta. After 2 days of hypercholesterolemia intimal macrophages stained for MCP-1, and during the next 10 weeks recently recruited arterial macrophages also expressed MCP-1. Macrophage accumulation was highly correlated with MCP-1 expression. In study #4, feeding LDLR KO mice 1.25% cholesterol for 6 months produced atherosclerotic plaques at both sites and they contained a fibrous cap of smooth muscle cells, macrophage-foam cells, connective tissue and cholesterol crystals. In summary, LDLR KO mice fed cholesterol develop fatty streaks that transform into fibrous plaques. Hypercholesterolemia rapidly triggers MCP-1 expression in resident intimal macrophages, which is followed by the accumulation of more macrophages that also express MCP-1, suggesting that this chemokine may both initiate and amplify monocyte recruitment to the artery wall during early atherogenesis.

Animals↗
PubMed1999

Performance of individuals with severe long-term traumatic brain injury on time-, event-, and activity-based prospective memory tasks.

This study investigated the effect of traumatic brain injury (TBI) on time-, event-, and activity-based prospective memory using a laboratory paradigm developed in the literature on ageing (Einstein, McDaniel, Richardson, Guynn, & Cunfer, 1995). The participants were 12 individuals with severe long-term TBI and 12 community controls. Participants were asked to answer general-knowledge questions on a computer for two sessions. The time- and event-based tasks were embedded in this filler activity. Participants were also required to carry out activity-based actions at the end of the two sessions. Participants with TBI performed significantly worse than did controls on all three prospective-memory tasks, indicating that TBI affects not only retrospective but also prospective memory. Implications of these results for the assessment and rehabilitation of memory problems in individuals with TBI are discussed.

Adolescent↗
PubMed1998

Variations in HIV risk behaviors of incarcerated juveniles during a four-year period: 1989-1992.

OBJECTIVE: To retrospectively monitor over several years change in incarcerated juveniles' human immunodeficiency virus (HIV) risk behaviors. METHODS: From 1989 to 1992, detainees who volunteered after an HIV class or were referred by a health care provider were counseled individually and privately by health educators using a standardized questionnaire and counseling form developed from an instrument used to counsel prostitutes in Los Angeles, California. RESULTS: The number counseled each year was 1045, 1745, 2354 and 1428 from 1989 to 1992, respectively. Those agreeing to HIV testing rose from 72% of total participants in 1989 to 84% of total participants in 1992. Eight of those youth tested as HIV positive. Four blind seroprevalence studies during the same time yielded one case in 1000 for 1988, one case in 1005 for 1989, two cases in 751 in late 1989 (2.7/1000), and one case in 1214 for 1990 (1.25/1000). The number worrying about AIDS and considering themselves vulnerable to AIDS increased, but protective behaviors did not. Sexual partners per year were 2.1 regardless of the age of first sexual activity. Alcohol was associated with an increased number of sexual partners (2.6/year) and higher rates of sexually transmissible infections (STIs) and pregnancy. Although 96% of boys and girls were sexually active, only 4% used a condom consistently during the first 3 years, and only 7% in 1992. Those reporting having used condoms with the intention to prevent both STIs and pregnancy had a higher rate of use. Those carrying condoms all the time used condoms more often. Males having sex with both males and females rarely used condoms, and 45% had one or more STIs. CONCLUSIONS: Although the rate of HIV infection remains low in juveniles detained by the County of Los Angeles, their rates of risky behaviors place them at high risk for HIV acquisition.

Adolescent↗
PubMed1998

Enhanced reduction of atherosclerosis in hamsters treated with pravastatin and captopril: ACE in atheromas provides cellular targets for captopril.

Inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG CoA) reductase and angiotensin-converting enzyme (ACE) reduce experimental atherosclerosis by different mechanisms. To determine whether dual-drug therapy additively retards the progression of early lesions, control hyperlipidemic hamsters were compared with those treated with pravastatin, captopril, and pravastatin plus captopril. After 8 weeks of treatment, pravastatin (34 mg/kg/day) reduced plasma total cholesterol and triglycerides by 41 and 84%, respectively, whereas captopril (100 mg/kg/day) reduced normal blood pressure by 21%. The combination of pravastatin and captopril (33 and 100 mg/kg/day) decreased plasma total cholesterol and triglycerides by 44 and 84%, and blood pressure was decreased by 14%. In the aortic arch, pravastatin reduced macrophage-foam cell size and fatty streak area by 21 and 31%, respectively, whereas captopril decreased macrophage-foam cell number and fatty streak area by 34 and 35%. Pravastatin plus captopril decreased macrophage-foam cell number, foam cell size, and fatty streak area by 38, 24, and 67%. ACE inhibitors were previously reported to retard atherosclerosis without affecting blood pressure, suggesting that these agents acted on the artery wall. Therefore the expression of arterial ACE was determined in normal and atherosclerotic hamster aortas. ACE messenger RNA (mRNA) and protein were detected in endothelial cells, intimal macrophage-foam cells and medial smooth-muscle cells of atherosclerotic arteries indicating an upregulation of ACE expression with hyperlipidemia and atherosclerosis. In conclusion, dual-therapy with pravastatin and captopril produced an additive reduction in fatty streak area compared with either drug alone and suggested that atherogenesis can be retarded beyond the level achieved with monotherapy. The presence of ACE in endothelial cells and intimal macrophage-foam cells provides cellular targets for captopril to directly modify the formation of early atherosclerotic lesions.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1997

Stimulation of activin A expression in rat aortic smooth muscle cells by thrombin and angiotensin II correlates with neointimal formation in vivo.

Vasoactive GTP-binding protein-coupled receptor agonists (e.g., angiotensin II [AII] and alpha-thrombin) stimulate the production of mitogenic factors from vascular smooth muscle cells. In experiments to identify mitogens secreted from AII- or alpha-thrombin-stimulated rat aortic smooth muscle (RASM) cells, neutralizing antibodies directed against several growth factors (e.g., PDGF and basic fibroblast growth factor [basic FGF]) failed to inhibit the mitogenic activity of conditioned media samples derived from the cells. In this report, we found that polyclonal neutralizing antibodies directed against purified human placental basic FGF reduced the mitogenic activity of AII-stimulated RASM cell-conditioned media and in immunoblot experiments identified a 26-kD protein (14 kD under reducing conditions) that was distinct from basic FGF. After purification from RASM cell-conditioned medium, amino acid sequence analysis identified the protein as activin A, a member of the TGF-beta superfamily. Increased activin A expression was observed after treatment of the RASM cells with AII, alpha-thrombin, and the protein kinase C agonist PMA. In contrast, PDGF-BB or serum caused only a minor induction of this protein. Although activin A alone only weakly stimulated RASM cell DNA synthesis, it demonstrated a potent comitogenic effect in combination with either EGF or heparin-binding EGF-like growth factor in the RASM cells, increasing DNA synthesis by up to fourfold. Furthermore, in a rat carotid injury model, activin A mRNA was upregulated within 6 h after injury followed by increases in immunoreactive protein detected in the expanding neointima 7 and 14 d later. Taken together, these results indicate that activin A is a vascular smooth muscle cell-derived factor induced by vasoactive agonists that may, either alone or in combination with other vascular derived growth factors, have a role in neointimal formation after arterial injury.

Activins↗
PubMed1997

Developmental regulation of Zbu1, a DNA-binding member of the SWI2/SNF2 family.

The SWI2/SNF2 gene family has been implicated in a wide variety of processes, involving regulation of DNA structure and chromatin configuration, mitotic chromosome segregation, and DNA repair. Here we report the characterization of the Zbu1 gene, also known as HIP116, located on human chromosome band 3q25, which encodes a DNA-binding member of this superfamily. Zbu1 was isolated in this study by its affinity for a site in the myosin light chain 1/3 enhancer. The protein has single-stranded DNA-dependent ATPase activity, includes seven helicase motifs, and a RING finger motif that is shared exclusively by the RAD5, spRAD8, and RAD16 family members. During mouse embryogenesis, Zbu1 transcripts are detected relatively late in fetal development and increase in neonatal stages, whereas the protein accumulates asynchronously in heart, skeletal muscle, and brain. In adult human tissues, alternatively spliced Zbu1 transcripts are ubiquitous with highest expression in these tissues. Gene expression is also dramatically induced in human tumor lines and in Li-Fraumeni fibroblast cultures, suggesting that it is aberrantly regulated in malignant cells. The developmental profile of Zbu1 gene expression and the association of the protein with a tissue-specific transcriptional regulatory element distinguish it from other members of the SWI2/SNF2 family and suggest novel roles for the Zbu1 gene product.

Adenosine Triphosphatases↗
PubMed1997

Detection of the t(2;5)(p23;q35) and NPM-ALK fusion in non-Hodgkin's lymphoma by two-color fluorescence in situ hybridization.

The non-Hodgkin's lymphoma (NHL) subset commonly referred to as large cell lymphoma (LCL) has historically been characterized by it's marked cytological, immunological, and clinical heterogeneity. One potential defining feature of these lymphomas, the t(2;5)(p23;q35), occurs in 25% to 30% of anaplastic LCLs and is also found in cases with diffuse large cell or immunoblastic morphology. We recently identified nucleophosmin (NPM) and anaplastic lymphoma kinase (ALK) as the genes on chromosomes 5 and 2, respectively, that are juxtaposed by this translocation. To provide a complementary approach to the use of classical cytogenetics or polymerase chain reaction-based methods for the detection of this abnormality, we have developed a two-color fluorescent in situ hybridization (FISH) assay for the t(2;5) that may be used for the analysis of both interphase nuclei and metaphase chromosomes. Three overlapping chromosome 5 cosmid clones located immediately centromeric to the NPM gene locus and an ALK P1 clone located telomeric to the chromosome 2 breakpoint were labeled with digoxigenin or biotin, respectively, and used to visualize the derivative chromosome 5 produced by the t(2;5), evident as juxtaposed or overlapping red and green fluorescent signals. This NPM-ALK FISH assay was initially validated by analysis of a series of cytogenetically characterized cell lines, with the presence of the der(5) chromosome showed specifically only in those lines known to contain the t(2;5). The assay was then applied in a blinded fashion to a series of eight cytogenetically t(2;5)-positive clinical specimens and seven known t(2;5)-negative cases, including three NHL and four Hodgkin's disease biopsy samples. Whereas the t(2;5)-negative cases were negative by FISH, all eight t(2;5)-positive cases were positive. One additional case, initially thought to be positive for the translocation by cytogenetics, was proven to not be a classic t(2;5) by interphase and metaphase FISH. These data indicate that the FISH assay described is a highly specific and rapid test that should prove to be a useful adjunct to the currently available methods for detection of the t(2;5).

Anaplastic Lymphoma Kinase↗
PubMed1996

Identification of novel regions of deletion in familial Wilms' tumor by comparative genomic hybridization.

Wilms' tumor, an embryonic renal neoplasm diagnosed primarily in young children, can occur in either a noninheritable (sporadic) or a familial form, with the latter presenting earlier and more often at bilateral sites. Although familial Wilms' tumor is thought to develop through inherited and acquired mutational inactivation of the two alleles of predisposing tumor suppressor genes, only a small percentage of cases can be accounted for by mutations affecting the WT1 gene or linkage to the Beckwith-Weidemann syndrome of the BWS region on the short arm of chromosome 11. To find chromosomal regions that might contain genes important in the development of this disease, we used comparative genomic hybridization to analyze tumor specimens from familial cases for chromosomal regions that were consistently lost. Although inherited lesions of tumor suppressors are most often inactivating point mutations, accompanying somatic lesions in the malignant clones are often chromosomal deletions; therefore, consensus regions of loss in familial tumors are likely to harbor genes linked to familial predisposition. There were extensive genomic aberrations among the eight familial cases studied, with an average of 6.5 changes/tumor (range, 0-22). The most consistent findings with likely biological relevance were deletions of chromosomes 4 (consensus, 4q21-qter), 9 (consensus, 9p21-pter), 20p, and 3 (consensus, 3q12-q21). These regions have not been previously implicated in Wilms' tumor and may harbor novel genes that could aid attempts to understand the familial predisposition as well as the development and progression of these tumors.

Chromosome Deletion↗
PubMed1996

Molecular cloning and chromosomal localization of the human cyclin C (CCNC) and cyclin E (CCNE) genes: deletion of the CCNC gene in human tumors.

The human Gi-phase cyclins are important regulators of cell cycle progression that interact with various cyclin-dependent kinases and facilitate entry into S-phase. We have confirmed the localization of the human cyclin C (CCNC) gene to chromosome 6q21 and of human cyclin E (CCNE) to 19q12. The CCNC gene structure was also determined, and we have shown that it is deleted in a subset of acute lymphoblastic leukemias, including a patient sample containing a t(2;6)(p21;q15), with no apparent cytogenetic deletion. Single-strand conformational polymorphism analysis of the remaining CCNC allele from patients with a deletion of one allele established that there were no further mutations within the exons or the flanking intronic sequences. These results suggest either that haploinsufficiency of the cyclin C protein is sufficient to promote tumorigenesis or that the important tumor suppressor gene is linked to the CCNC locus.

Chromosome Mapping↗
PubMed1996

Localization of chi1-related helicase genes to human chromosome regions 12p11 and 12p13: similarity between parts of these genes and conserved human telomeric-associated DNA.

The helicase enzymes are essential components of a number of multi-protein complexes, including those that regulate transcription, splicing, translation, and DNA repair. These enzymes assist in the unwinding of double-stranded DNA and RNA as an essential part of their function. The yeast Chl1 gene encodes a putative helicase that appears to be essential for normal chromosome transmission. Human cDNAs related to this yeast gene, hCHLR1 and hCHLR2, were recently isolated and shown to encode products that localize to the nucleus. Two corresponding genes have now been partially characterized and localized to human chromosome regions 12p11 and 12p13, indicating that this gene is contained within a duplicated region localized to 12p. In addition, a comparison of the hCHLR gene sequences with available databases indicates that a large portion of these genes, including exons encoding two functional domains of the carboxyl-terminal region of these proteins, has been duplicated as part of a larger human telomeric repeat sequence found on many human chromosomes. Our results suggest that duplication of a relatively large region of chromosome 12p containing this putative helicase gene has resulted in the creation of numerous pseudogenes as part of a subtelomeric repeat. The presence of these helicase pseudogenes, as well as pseudogenes for other genes such as the interleukin-9 receptor, within many subtelomeric regions support the possibility that the spread of this region is subject to exchange between different chromosomes and may have implications for elucidation of the mechanism of intra- and interchromosomal duplication events.

Base Sequence↗
PubMed1996

Der(16)t(1;16)(q21;q13) in Wilms' tumor: friend or foe.

The der(16)t(1;16)(q21;q13) chromosomal abnormality has been reported rarely in Wilms' tumor. This abnormality has also been found in several other pediatric and adult neoplasms, and may imply a poor prognosis in at least some of these solid tumors. To investigate its clinical significance in Wilms' tumor, we examined the records of 65 consecutive children with Wilms' tumor whose tumor cells were successfully karyotyped. The t(1;16) was present in seven patients (10%) whose ages ranged from 2.5 to 4.7 years (median 3.5 years) at diagnosis. Six of the seven patients were female. All four stages of Wilms' tumor were represented (two patients had stage IV disease). No patient had bilateral disease. All tumors were of "favorable histology." All seven patients are alive and off therapy with a median follow-up of 3.2 years (range, 2 to 8.5 years). One patient with this abnormality developed brain metastases within 4 months of completion of therapy. Comparison of these patients with the remaining 58 Wilms' tumor patients revealed no significant differences with regard to disease stage, histology, survival, or relapse-free survival. Cytogenetic evidence of der(16)t(1;16)(q21;q13) in Wilms' tumor does not appear to portend an adverse clinical outcome, although only a larger study that includes molecular detection methods can provide more conclusive evidence.

Child↗
PubMed1996

Allelic imbalance on chromosome 5q predicts long-term survival in neuroblastoma.

Neuroblastoma is the most common extracranial solid tumour of childhood. Amplification of the proto-oncogene, N-myc, confers a poor prognosis in neuroblastoma, while hyperdiploidy is associated with a favourable outcome. Little is known about the contribution of tumour-suppressor genes to the development or progression of neuroblastoma. We examined allelic imbalance at the locus of the tumour-suppressor gene, APC (adenomatous polyposis coli), on chromosome 5q using a polymerase chain reaction (PCR)-based assay. Nine of 24 (37.5%) informative neuroblastoma tumours showed allelic imbalance (AI) at this locus. Clinical data concerning N-myc amplification and DNA content were correlated with these results in the same patients. Allelic imbalance was found only in tumours containing a single copy of the N-myc gene and exhibiting hyperdiploidy. All nine patients with AI of chromosome 5q were alive after a median follow-up period of 46 months, while 7 of 15 (47%) of those lacking AI at this locus had died (P = 0.018). Allelic imbalance at three additional loci on chromosome 5 was demonstrated in tumours that exhibited AI at the APC locus, suggesting that endoreduplication of chromosome 5 had occurred. Fluorescent in situ hybridisation (FISH) analysis of tumour tissue from one patient exhibiting AI demonstrated two, three, four or six copies of the APC gene per cell, consistent with this hypothesis. These data suggest that allelic imbalance of chromosome 5 is involved in at least a subset of neuroblastomas and influences survival in patients with neuroblastoma.

Alleles↗
PubMed1995

Chromosomal localization and catalytic properties of the recombinant alpha subunit of human lymphocyte methionine adenosyltransferase.

Human lymphocyte methionine adenosyltransferase (HuLy MAT) consists of heterologous subunits alpha and beta. The cDNA sequence of the alpha subunit of HuLy MAT from Jurkat leukemic T cells was identical to that of the human kidney alpha subunit and highly homologous to the sequence of the extrahepatic MAT from other sources. The 3'-untranslated sequence was found to be highly conserved, suggesting that it may be important in regulating the expression of MAT. The extrahepatic alpha subunit unit of MAT was found to be expressed also in human liver, and no differences were found in the sequence of the alpha subunit from normal and malignant T cells. The sequence of two unspliced introns found in the cDNA clones from the Jurkat library enabled us to isolate genomic clones harboring the human extrahepatic alpha subunit gene and to localize it to the centromere on chromosome arm 2p, an area that corresponds to band 2p11.2. Expression of the alpha subunit cDNA in Escherichia coli yielded two peptides with the immunoreactivity and mobilities of authentic alpha/alpha' subunits from HuLy. The Km of the recombinant alpha subunit was 80 microM, which is 20-fold higher than found for the (alpha alpha')x beta y holoenzyme purified from leukemic lymphocytes and 4-10-fold higher than found for the normal lymphocyte enzyme. The data suggest that the alpha/alpha' subunits mediate the enzyme catalytic activity and that the beta subunit may be a regulatory subunit of extrahepatic MAT.

Adult↗
PubMed1995

Structure and expression of chicken protein kinase PITSLRE-encoding genes.

The human PITSLRE protein kinases (PK), members of the p34cdc2 kinase family named according to the single amino acid (aa) code of an important (PSTAIRE) regulatory region [Meyerson et al., EMBO J. 11 (1992) 2909-2917], are candidate tumor suppressor gene(s) localized to human chromosome 1p36.2 and a syntenic region of mouse chromosome 4 [Lahti et al., Nature Genet. 7 (1994) 370-375; Mock et al., Mammal. Genome 5 (1994) 191-192]. At least ten isoforms of this PK family are expressed from three duplicated and tandemly linked genes in humans [Xiang et al., J. Biol. Chem. 269 (1994) 15786-15794]. We have now isolated two different species of PITSLRE PK cDNAs from chicken that encode identical polypeptides, but are clearly expressed from different genes, based on nucleotide (nt) differences. Isolation of one of the corresponding chicken PITSLRE PK genes confirms that only one of the two species of PITSLRE mRNA is expressed from this gene. Comparison of the predicted avian PITSLRE PK aa sequence to human and mouse sequences shows a high degree of sequence identity (> 91%). Like humans, the PITSLRE PK genes in chickens must be closely linked, based on fluorescent in situ hybridization (FISH) localization of these genes to a single chicken microchromosome. PITSLRE PK mRNAs are expressed in two avian B- and T-cell lines. These results suggest that the PITSLRE PK gene family has been well conserved evolutionarily, that the gene duplication observed in humans is not a recent event, and that expression of redundant PITSLRE mRNAs is observed in different vertebrate species.

Amino Acid Sequence↗
PubMed1995

Orally active endothelin receptor antagonist BMS-182874 suppresses neointimal development in balloon-injured rat carotid arteries.

Vascular smooth muscle cell (SMC) proliferation is an important component in the development of restenosis. Because endothelin (ET) has been reported to act as an SMC mitogen, we postulated that the orally active ETA receptor antagonist BMS-182874 would suppress the development of the intimal lesion that develops in rat carotid arteries after balloon injury. Using cultured rat aortic SMC, we noted that ET-1-stimulated increases in [3H]thymidine incorporation were blocked by BMS-182874. To determine the effect of the drug on intimal lesion formation, we treated rats with BMS-182874 (100 mg/kg orally, p.o.) or vehicle once daily for 3 weeks, beginning 1 week before balloon injury. Two weeks after injury, drug-treated rats had a 35% decrease in lesion area and a 34% decrease in the lesion/media ratio as compared with the vehicle-treated rats. In situ hybridization (ISH) analysis of balloon-injured rat carotid arteries showed an increase in ETA receptor mRNA. These data support the concept that ETA receptor activation contributes to intimal lesion formation by promotion of SMC proliferation and suggest a potential use for ETA receptor antagonists in the amelioration of hyperproliferative vascular diseases, including restenosis.

Administration, Oral↗
PubMed1995

Selective blockade of the endothelin subtype A receptor decreases early atherosclerosis in hamsters fed cholesterol.

Recent studies suggest that endothelin and its receptors may be involved in atherogenesis. To test this hypothesis, cholesterol-fed hamsters were treated with a selective endothelin subtype A (ETA) receptor antagonist BMS-182874. Characterization of hamster atherosclerotic plaques indicated that they contained a fibrous cap of smooth muscle cells, large macrophage-foam cells, and epitopes of oxidized low density lipoprotein. Messenger RNA for both ETA and ETB receptors was detected in aortic endothelial cells, in medial smooth muscle cells, and in macrophage-foam cells and smooth muscle cells of the fibro-fatty plaques. BMS-182874 inhibited the endothelin-1-induced pressor response whereas the depressor effect was unaltered, suggesting that vascular ETA receptors were selectively blocked in vivo. In hyperlipidemic hamsters, BMS-182874 decreased the area of the fatty streak by reducing the number and size of macrophage-foam cells. The results indicated that ETA receptors and thus endothelin promoted the early inflammatory phase of atherosclerosis.

Animals↗