bluuebunny/crossref_metadata_2025 huggingface dataset:
Proteasome Inhibitors Trigger NOXA-Mediated Apoptosis in Melanoma and Myeloma Cells
Authors: Qin Jian-Zhong , Ziffra Jeffrey , Stennett Lawrence , Bodner Barbara , Bonish Brian K. , Chaturvedi Vijaya , Bennett Frank , Pollock Pamela M. , Trent Jeffrey M. , Hendrix Mary J.C. , Rizzo Paola , Miele Lucio , Nickoloff Brian J.
Published: September 2005

Patients with metastatic melanoma or multiple myeloma have a dismal prognosis because these aggressive malignancies resist conventional treatment. A promising new oncologic approach uses molecularly targeted therapeutics that overcomes apoptotic resistance and, at the same time, achieves tumor selectivity. The unexpected selectivity of proteasome inhibition for inducing apoptosis in cancer cells, but not in normal cells, prompted us to define the mechanism of action for this class of drugs, including Food and Drug Administration–approved bortezomib. In this report, five melanoma cell lines and a myeloma cell line are treated with three different proteasome inhibitors (MG-132, lactacystin, and bortezomib), and the mechanism underlying the apoptotic pathway is defined. Following exposure to proteasome inhibitors, effective killing of human melanoma and myeloma cells, but not of normal proliferating melanocytes, was shown to involve p53-independent induction of the BH3-only protein NOXA. Induction of NOXA at the protein level was preceded by enhanced transcription of NOXA mRNA. Engagement of mitochondrial-based apoptotic pathway involved release of cytochrome c, second mitochondria-derived activator of caspases, and apoptosis-inducing factor, accompanied by a proteolytic cascade with processing of caspases 9, 3, and 8 and poly(ADP)-ribose polymerase. Blocking NOXA induction using an antisense (but not control) oligonucleotide reduced the apoptotic response by 30% to 50%, indicating a NOXA-dependent component in the overall killing of melanoma cells. These results provide a novel mechanism for overcoming the apoptotic resistance of tumor cells, and validate agents triggering NOXA induction as potential selective cancer therapeutics for life-threatening malignancies such as melanoma and multiple myeloma.
Dual Induction of Apoptosis and Senescence in Cancer Cells by Chk2 Activation: Checkpoint Activation as a Strategy against Cancer
Authors: Chen Chang-Rung , Wang Wenxian , Rogoff Harry A. , Li Xiaotong , Mang William , Li Chiang J.
Published: September 2005

The human checkpoint kinase 2 (Chk2) plays a central role in regulation of the cellular response to DNA damage, resulting in cell cycle arrest, DNA repair, or apoptosis depending on severity of DNA damage and the cellular context. Chk2 inhibitors are being developed as sensitizers for chemotherapeutic agents. In contrast, here we report that direct activation of Chk2 alone (without chemotherapeutic agents) led to potent inhibition of cancer cell proliferation. In the absence of de novo DNA damage, checkpoint activation was achieved by increased Chk2 expression, as evidenced by its phosphorylation at Thr68, resulting in senescence and apoptosis of cancer cells (DLD1 and HeLa). The Chk2-induced apoptosis was p53 independent and was mediated by caspase activation triggered by loss of mitochondrial potential. The Chk2-induced senescence was also p53 independent and was associated with induction of p21. These results suggest that direct activation of checkpoint kinases may be a novel approach for cancer therapy.
Differential Regulation of Noxa in Normal Melanocytes and Melanoma Cells by Proteasome Inhibition: Therapeutic Implications
Authors: Fernández Yolanda , Verhaegen Monique , Miller Thomas P. , Rush Jenny L. , Steiner Philipp , Opipari Anthony W. , Lowe Scott W. , Soengas María S.
Published: September 2005

Melanoma is the most aggressive form of skin cancer and advanced stages are invariably resistant to conventional therapeutic agents. Using bortezomib as a prototypic proteasome inhibitor, we have identified a novel and critical role of the proteasome in the maintenance of the malignant phenotype of melanoma cells that could have direct translational implications. Thus, melanoma cells from early, intermediate, and late stages of the disease could not sustain proteasome inhibition and underwent an effective activation of caspase-dependent and -independent death programs. This effect was tumor cell selective, because under similar conditions, normal melanocytes remained viable. Intriguingly, and despite of interfering with a cellular machinery in charge of controlling the half-life of the vast majority of cellular proteins, bortezomib did not promote a generalized disruption of melanoma-associated survival factors (including NF-κB, Bcl-2, Bcl-xL, XIAP, TRAF-2, or FLIP). Instead, we identified a dramatic induction in vitro and in vivo of the BH3-only protein Noxa in melanoma cells (but not in normal melanocytes) in response to proteasome inhibition. RNA interference validated a critical role of Noxa for the cytotoxic effect of bortezomib. Notably, the proteasome-dependent regulation of Noxa was found to extend to other tumor types, and it could not be recapitulated by standard chemotherapeutic drugs. In summary, our results revealed Noxa as a new biomarker to gauge the efficacy of bortezomib specifically in tumor cells, and provide a new strategy to overcome tumor chemoresistance.
A Single Nucleotide Polymorphism in the MDM2 Gene: From a Molecular and Cellular Explanation to Clinical Effect
Authors: Bond Gareth L. , Hu Wenwei , Levine Arnold
Published: September 2005

In a recent article, a candidate pathway approach was taken to try to identify single nucleotide polymorphisms (SNP) that make up the genetic variation, which underlies the phenotypic variation seen between individuals in their susceptibility to cancer and the progression of their disease. The p53 stress response pathway was chosen given its well-documented importance in tumor suppression. A SNP was found which associates with the attenuation of the p53 pathway and the acceleration of tumor formation in humans and data was presented which describe a molecular mechanism for these phenotypes.
It's About Time: Scheduling Alters Effect of Histone Deacetylase Inhibitors on Camptothecin-Treated Cells
Authors: Bevins Robert L. , Zimmer Stephen G.
Published: September 2005

Chemotherapeutic treatment with combinations of drugs is front-line therapy for many types of cancer. Combining drugs which target different signaling pathways often lessens adverse side effects while increasing the efficacy of treatment and reducing patient morbidity. A defined scheduling protocol is described by which histone deacetylase inhibitors (HDIs) facilitate the cytotoxic effectiveness of the topoisomerase I inhibitor camptothecin in the killing of tumor cells. Breast and lung cancer cell lines were treated with camptothecin and sodium butyrate (NaB) or suberoylanilide hydroxamic acid on the day of, the day before, or the day after camptothecin addition. Depending on the time of addition, NaB-treated cells displayed a spectrum of responses from protection to sensitization, indicating the critical nature of timing in the use of HDIs. The IC80 (72-hour assay) dose of 100 nmol/L camptothecin could be lowered to 15 nmol/L camptothecin while maintaining or surpassing cell killing of the single agent if combined with an HDI added 24 to 48 hours after camptothecin. Experiments determined that cells arrested in G2-M by camptothecin were most sensitive to subsequent HDI addition. Western blot analysis indicated that in camptothecin-arrested cells, NaB decreases cyclin B levels, as well as the levels of the antiapoptotic proteins XIAP and survivin. These findings suggest that reducing the levels of these critical antiapoptotic factors may increase the efficacy of topoisomerase I inhibitors in the clinical setting if given in a sequence that does not prevent or inhibit tumor cell progression through the S phase.
RLIP76 Is a Major Determinant of Radiation Sensitivity
Authors: Awasthi Sanjay , Singhal Sharad S. , Yadav Sushma , Singhal Jyotsana , Drake Kenneth , Nadkar Aalok , Zajac Ewa , Wickramarachchi Dilki , Rowe Nancy , Yacoub Adly , Boor Paul , Dwivedi Seema , Dent Paul , Jarman Wendy E. , John Berchmans , Awasthi Yogesh C.
Published: September 2005

RLIP76 (RALBP1) is a glutathione-conjugate transporter that is a critical component of clathrin-coated pit–mediated endocytosis, as well as in stress responses. In cultured cells, it provides protection from stressors including heat, oxidant chemicals, chemotherapeutic agents, UV irradiation, and X-irradiation. Here, we show marked reduction in glutathione conjugate transport capacity and stepwise increase in radiation sensitivity associated with heterozygous or homozygous loss of the RLIP76 gene in mice. Survival after radiation in homozygous knockout animals was significantly shorter than either the heterozygous knockouts or the wild type. Delivery of recombinant RLIP76 to mice lacking RLIP76 via a liposomal delivery system rescued radiation sensitivity. Furthermore, treatment of wild-type mice with RLIP76-containing liposomes conferred resistance to radiation. These findings suggest that inhibiting RLIP76 could be used for sensitization to radiation during cancer therapy and that RLIP76 liposomes could be radioprotective agents useful for treatment of iatrogenic or catastrophic radiation poisoning.
Nuclear-Cytoplasmic Partitioning of Phosphatase and Tensin Homologue Deleted on Chromosome 10 (PTEN) Differentially Regulates the Cell Cycle and Apoptosis
Authors: Chung Ji-Hyun , Eng Charis
Published: September 2005

Phosphatase and tensin homologue deleted on chromosome 10 (PTEN), a tumor suppressor phosphatase that dephosphorylates both protein and lipid substrates, is found to be mutated in both heritable and sporadic breast cancer. Cellular PTEN has been shown to regulate Akt phosphorylation, mitogen-activated protein kinase (MAPK) phosphorylation, p27kip1, and cyclin D1 protein levels. Additionally, we and others have shown that PTEN can regulate not only the cell cycle but also cellular apoptosis. Until recently, the functions of PTEN have been thought to occur through cytoplasmic PTEN. However, we have shown that PTEN localizes to the nucleus and that this localization coincides with the G0-G1 phases of the cell cycle. Furthermore, we have shown that PTEN has bipartite nuclear localization sequence (NLS)-like sequences that are required for major vault protein-mediated nuclear import. These findings suggest that subcellular localization of PTEN may regulate its function and that nuclear-localized PTEN may regulate unique cellular functions that have been attributed to cytoplasmic PTEN. To examine this possibility, we analyzed downstream PTEN readouts using MCF-7 Tet-Off breast cancer cell lines stably transfected with two different NLS mutant PTEN constructs, which do not localize to the nucleus, and compared these with cells transfected with wild-type PTEN and empty vector control cells. We found that cytoplasmic PTEN down-regulates phosphorylation of Akt and up-regulates p27kip1, whereas nuclear PTEN down-regulates cyclin D1 and prevents the phosphorylation of MAPK. Additionally, whereas we observe that nuclear PTEN is required for cell cycle arrest, we found that cytoplasmic PTEN is required for apoptosis. Our observations show that nuclear-cytoplasmic partitioning differentially regulates the cell cycle and apoptosis and, in this manner, provide further evidence that nuclear import of PTEN should play a role in carcinogenesis.
Histone Deacetylase Inhibition Down-Regulates Cyclin D1 Transcription by Inhibiting Nuclear Factor-κB/p65 DNA Binding
Authors: Hu Jing , Colburn Nancy H.
Published: September 2005

Histone deacetylase (HDAC) inhibitors are emerging as a promising new class of cancer therapeutic agents. HDAC inhibitors relieve the deacetylation of histone proteins. However, little is known about the nonhistone targets of HDAC inhibitors and their roles in gene regulation. In this study, we addressed the molecular basis of the down-regulation of the nuclear factor-κB (NF-κB)–responsive gene cyclin D1 by the HDAC inhibitor trichostatin A in mouse JB6 cells. Cyclin D1 plays a critical role in cell proliferation and tumor progression. Trichostatin A inhibits cyclin D1 expression in a NF-κB-dependent manner in JB6 cells. Electrophoretic mobility shift assay studies showed that trichostatin A treatment prevents p65 dimer binding to NF-κB sites on DNA. Moreover, a chromatin immunoprecipitation assay shows that trichostatin A treatment inhibits endogenous cyclin D1 gene transcription by preventing p65 binding to the cyclin D1 promoter. However, acetylation of p65 is not affected by trichostatin A treatment. Instead, trichostatin A enhances p52 acetylation and increases p52 protein level by enhancing p100 processing. This is the first report that trichostatin A, a HDAC inhibitor, activates p100 processing and relieves the repression of p52 acetylation. The enhanced acetylation of p52 in the nuclei may operate to cause nuclear retention of p65 by increasing the p52/p65 interaction and preventing IκBα-p65 binding. The enhanced p52 acetylation coincides with decreased p65 DNA binding, suggesting a potential role of p52 acetylation in NF-κB regulation. Together, the results provide the first demonstration that HDAC inhibitor trichostatin A inhibits cyclin D1 gene transcription through targeting transcription factor NF-κB/p65 DNA binding. NF-κB is therefore identified as a transcription factor target of trichostatin A treatment.
Phosphorylation of AML1/RUNX1 Regulates Its Degradation and Nuclear Matrix Association
Authors: Biggs Joseph R. , Zhang Youhong , Peterson Luke F. , Garcia Marileila , Zhang Dong-Er , Kraft Andrew S.
Published: September 2005

The acute myeloid leukemia 1 (AML1) transcription factors are key regulators of hematopoietic differentiation. Cellular AML1c protein is found in the nucleus and can be separated into two fractions, one soluble in buffers containing salt and nonionic detergent and the other insoluble and tightly bound to the nuclear matrix. We find that the AML1c protein is modified by both phosphorylation and ubiquitination. Our studies show that the majority of the ubiquitinated AML1c is associated with the insoluble nuclear matrix. Treatment of cells with the proteasome inhibitor PS341 (Velcade, Bortezomib) increases the levels of ubiquitinated AML1c. Mutation of the four phosphorylation sites necessary for transcriptional regulation (serine 276, serine 293, serine 303, and threonine 300) mimics the effects of the proteasome inhibitor, increasing the levels of ubiquitinated, matrix-bound AML1c. We find that the soluble and insoluble forms of AML1c are degraded at a similar rate. However, mutation of these four serine/threonine residues statistically increases the half-life of the matrix-associated AML1c. Thus, phosphorylation of AML1c on specific serine/threonine residues controls both transcriptional activity and rate of degradation.
The Loss of a Single Telomere Can Result in Instability of Multiple Chromosomes in a Human Tumor Cell Line
Authors: Sabatier Laure , Ricoul Michelle , Pottier Géraldine , Murnane John P.
Published: September 2005

Spontaneous telomere loss has been proposed as an important mechanism for initiating the chromosome instability commonly found in cancer cells. We have previously shown that spontaneous telomere loss in a human cancer cell line initiates breakage/fusion/bridge (B/F/B) cycles that continue for many cell generations, resulting in DNA amplification and translocations on the chromosome that lost its telomere. We have now extended these studies to determine the effect of the loss of a single telomere on the stability of other chromosomes. Our study showed that telomere acquisition during B/F/B cycles occurred mainly through translocations involving either the nonreciprocal transfer or duplication of the arms of other chromosomes. Telomere acquisition also occurred through small duplications involving the subtelomeric region of the other end of the same chromosome. Although all of these mechanisms stabilized the chromosome that lost its telomere, they differed in their consequences for the stability of the genome as a whole. Telomere acquisition involving nonreciprocal translocations resulted in the loss of a telomere on the donor chromosome, which consequently underwent additional translocations, isochromosome formation, or complete loss. In contrast, telomere acquisition involving duplications stabilized the genome, although the large duplications created substantial allelic imbalances. Thus, the loss of a single telomere can generate a variety of chromosome alterations commonly associated with human cancer, not only on a chromosome that loses its telomere but also on other chromosomes. Factors promoting telomere loss are therefore likely to have an important role in generating the karyotype evolution associated with human cancer.
Balloon-Floating Right Heart Catheter Monitoring for Acute Coronary Syndromes Complicated by Heart Failure – Discordance between Guidelines and Reality
Authors: Porter Avital , Iakobishvili Zaza , Haim Moti , Behar Solomon , Boyko Valentina , Battler Alexander , Hasdai David
Published: September 2005

Purpose: Current guidelines (class IIA recommendations) recommend balloon-floating right heart catheter monitoring (RHC) in particular for patients with ST elevation acute coronary syndromes (ACS) who have progressive heart failure (HF) or cardiogenic shock (CS), as well as for other ACS patients with hemodynamic instability. However, their implementation remains undetermined. The aim of the study was to analyze RHC use in ACS patients, in particular those with HF. Subjects and Methods: The Euro Heart ACS Survey enrolled 10,484 ACS patients (ST elevation, no ST elevation and undetermined ECG).We analyzed the general RHC use, in particular in HF patients. Results: Of the 10,234 patients with data regarding RHC use, RHC was used in 309 patients (3.0%). Patients with RHC presented more often with ST segment elevation ACS, symptoms other than angina, Killip class III/IV, lower systolic blood pressure and a higher heart rate. Of the 10,136 patients with documented HF status, 549 (5.4%) had CS, 2,529 (25.0%) had mild to moderate HF, and 7,058 (69.6%) had no HF. RHC was performed in 111 (20.2%) patients with CS, 87 (3.4%) patients with mild to moderate HF, and 109 (1.5%) patients without HF. In contrast, echocardiography was performed in 376 (68.4%) CS patients, 1,812 (71.6%) patients with mild to moderate HF, and 4,484 (63.5%) patients without HF. Conclusions: In contrast to the unequivocal recommendations to use RHC for hemodynamically unstable ACS patients, RHC is infrequently used in current clinical practice. Perhaps it has been supplanted by echocardiography, a noninvasive and readily available modality. Given the reserved use of RHC in ACS patients, and the reported complications associated with RHC, the guidelines regarding its use should be reconsidered.
Contributions of Intrinsic Renal Cells to Crescentic Glomerulonephritis
Authors: Tipping Peter G. , Timoshanko Jennifer
Published: September 2005

The pro-inflammatory contributions of leukocytes, particularly macrophages and T cells, to the immunopathogenesis of proliferative forms of glomerulonephritis (GN) have been clearly established by various techniques, including in vivo depletion studies in experimental models. The evidence for an active pro-inflammatory role for intrinsic renal cells in GN has relied on studies demonstrating their production of pro-inflammatory mediators in vitro and during the development of GN. Until recently,the specific in vivo contributions of mediators from intrinsic renal cells to inflammatory injury in GN have proven difficult to define. Utilising ‘chimeric’ mice as a tool, several studies have explored the involvement of intrinsic renal cells via their production of cytokines and other key pro-inflammatory molecules. These studies provide evidence of important functional contributions of intrinsic renal cells to inflammatory injury in GN via their expression of cytokines, cytokine receptors, MHC-II and co-stimulatory molecules. They suggest a sequence of interactions between cytokines from leukocytes and intrinsic renal cells and important contributions of glomerular epithelial cell proliferation to crescent formation.
Effects of Hyaluronan-Fortified Surfactant in Ventilated Premature Piglets with Respiratory Distress
Authors: Wang Xiaoning , Sun Zhonghou , Qian Liling , Guo Chunbao , Yu Wenliang , Wang Wei , Lu Karen W. , Taeusch H. William , Sun Bo
Published: September 2005

We hypothesized that enriching surfactant with hyaluronan would restore lung function when tested in a premature animal model. Newborn piglets (85% gestation, term 112–114 days) were delivered by cesarean section, subjected to mechanical ventilation (tidal volume 6– 8 ml/kg) and randomly assigned to treatment with 50 or 100 mg/kg Curosurf (C50 and C100), 50 or 100 mg/kg Curosurf mixed with 2.5% HA (w/w, CH50 and CH100). A ventilated and not treated group (Cont) and a not treated and not ventilated group (Non) were included as controls. Six hours after treatment the lungs were removed and biochemical, biophysical, cytological and histological analyses were carried out. The CH100, CH50, C100 and C50 groups had variable but significantly improved alveolar phospholipid content, minimal surface tension, alveolar aeration and wet/dry lung weight ratios, but little histological evidence of lung injury. CH100, CH50 and C100 groups had the best effects in terms of oxygenation, lung compliance and histology and evidence of decreased inflammation (IL-8 and TNF-α mRNA expression). We conclude that HA added to 50 mg/kg Curosurf or use of 100 mg/kg Curosurf with or without HA provides the best effects in terms of lung function and reduction of inflammation.
Relationship between Hyperglycemia and Retinopathy of Prematurity in Very Low Birth Weight Infants
Authors: Ertl Tibor , Gyarmati Judit , Gaál Valéria , Szabó Ilona
Published: September 2005

Retinopathy of prematurity (ROP) is a multifactorial vasoproliferative retinal disorder that increases in incidence with decreasing gestational age. Recently, an association between hyperglycemia and severe ROP was found in extremely low birth weight infants (ELBWI). The purpose of this study was to evaluate the possible relation between hyperglycemia and ROP at any stage in very low birth weight infants (VLBWI). We analyzed the data of 201 VLBWI. The incidence of ROP and hyperglycemia was detected and the χ2 test was applied to investigate the association between the two variables. The Clinical Risk Index for Babies (CRIB) score was attributed as a marker of illness severity. The incidence of ROP and hyperglycemia in VLBWI was 35.3 and 19.4%, respectively. ROP developed more frequently in hyperglycemic infants (p < 0.001). The gestational age, birth weight, and Apgar scores were significantly lower, the CRIB score was higher in ROP patients. In hyperglycemic ROP patients the CRIB score was significantly higher compared to euglycemic ROP patients (mean (SD) 8.1 (4.2) vs. 5.5 (3.3); p < 0.01). A logistic regression model revealed that gestational age (OR 0.59; 95% CI 0.46–0.76; p < 0.001) and hyperglycemia (OR 3.15; 95% CI 1.12–8.84; p < 0.05) are independent risk factors in ROP development. When ELBWI were analyzed separately, gestational age (OR 0.38; 95% CI 0.20–0.72; p < 0.01) and CRIB score (OR 1.58; 95% CI 1.02–2.45; p < 0.05) were found as significant contributors. Further studies are needed to elucidate the pathophysiological role of hyperglycemia in the development of vasoproliferative retinal disorder.
HERP1 Inhibits Myocardin-Induced Vascular Smooth Muscle Cell Differentiation by Interfering With SRF Binding to CArG Box
Authors: Doi Hiroshi , Iso Tatsuya , Yamazaki Miki , Akiyama Hideo , Kanai Hiroyoshi , Sato Hiroko , Kawai-Kowase Keiko , Tanaka Toru , Maeno Toshitaka , Okamoto Ei-ichi , Arai Masashi , Kedes Larry , Kurabayashi Masahiko
Published: September 2005

Objective—

Myocardin is a coactivator of serum response factor (SRF) required for vascular smooth muscle cell (VSMC) differentiation. HERP1 is a transcriptional repressor, which is abundantly expressed in vascular system and is known to function as a target gene of Notch. However, the role of HERP1 in the pathogenesis of vascular lesions remains unknown. The present study characterizes the expression of HERP1 in normal and diseased vessels, and tests the hypothesis that HERP1 inhibits SRF/myocardin-dependent SMC gene expression.

Methods and Results—

Immunohistochemistry revealed that HERP1 and myocardin expression was localized to SMC in the neointima of balloon-injured rat aorta and in human coronary atherosclerotic lesions. Expression of both HERP1 and myocardin was elevated in cultured VSMCs compared with medial SMC. Overexpressed HERP1 inhibited the myocardin-induced SMC marker gene expression in 10T1/2 cells. HERP1 protein interfered with the SRF/CArG–box interaction in vivo and in vitro. Immunoprecipitation assays showed that HERP1 physically interacts with SRF.

Conclusions—

HERP1 expression was associated with the SMC proliferation and dedifferentiation in vitro and in vivo. HERP1 may play a role in promoting the phenotypic modulation of VSMCs during vascular injury and atherosclerotic process by interfering with SRF binding to CArG-box through physical association between HERP1 and SRF.
Probucol Enhances the Expression of Human Hepatic Scavenger Receptor Class B Type I, Possibly Through a Species-Specific Mechanism
Authors: Hirano Ken-ichi , Ikegami Chiaki , Tsujii Ken-ichi , Zhang Zhongyan , Matsuura Fumihiko , Nakagawa-Toyama Yumiko , Koseki Masahiro , Masuda Daisaku , Maruyama Takao , Shimomura Iichiro , Ueda Yukihiko , Yamashita Shizuya
Published: September 2005

Objective—

Scavenger receptor class B type I (SR-BI) is a major receptor for high-density lipoproteins (HDL) in the liver, which is the terminus of reverse cholesterol transport. Overexpression of SR-BI attenuated experimental atherosclerosis in murine models, concomitant with a reduction in plasma HDL-cholesterol levels. Probucol is known to be a potent hypolipidemic drug to regress xanthoma formation and carotid atherosclerosis in conjunction with a marked reduction in HDL-cholesterol levels. The aim of the present study was to know the effect of probucol on the expression of SR-BI and the underlying mechanism.

Methods and Results—

We found that probucol increased the expression of SR-BI proteins in in vitro human liver cells and an in vivo rabbit model, but not in wild-type C57Bl6 mice. The decay curve of SR-BI protein was markedly retarded in probucol-treated HepG2 cells in the presence of cycloheximide, indicating that probucol may stabilize human SR-BI protein. To determine the underlying mechanism for the observed species-specific effect, we conducted the following host-swap experiments, in which SR-BI was transfected or expressed in heterologous cells or hosts. Probucol did not increase human SR-BI protein in the liver of transgenic mice carrying the entire human SR-BI genome. Although probucol could stabilize even murine SR-BI, when transfected into a human cell line, HepG2, human SR-BI was not stabilized in a mouse hepatoma cell line, Hepa 1-6, treated with probucol.

Conclusion—

Probucol enhances hepatic SR-BI protein expression, possibly through species-specific stabilization of the protein.
Transplantation of Blood-Derived Progenitor Cells After Recanalization of Chronic Coronary Artery Occlusion
Authors: Erbs Sandra , Linke Axel , Adams Volker , Lenk Karsten , Thiele Holger , Diederich Klaus-Werner , Emmrich Frank , Kluge Regine , Kendziorra Kai , Sabri Osama , Schuler Gerhard , Hambrecht Rainer
Published: September 2005

Transplantation of blood-derived circulating progenitor cells (CPC) has been shown to improve myocardial regeneration after myocardial infarction. It remains unclear whether CPC transplantation exerts beneficial effects also in patients with chronic myocardial ischemia. We initiated a randomized, double-blind, placebo-controlled study evaluating the impact of intracoronary infusion of CPCs on coronary vasomotion and left ventricular (LV) function in patients after recanalization of chronic coronary total occlusion (CTO). After recanalization of CTO, 26 patients (age, 63±2 years; LV ejection fraction, 53±2%) were randomly assigned to the treatment (intracoronary transplantation of CPCs) or control group. Coronary flow reserve in response to adenosine (2.4 mg/min) was measured in the target vessel at the beginning of the study and after 3 months. LV function and infarct size were assessed by MRI and metabolism by
18
F deoxyglucose positron emission tomography. CPC application resulted in an increase in coronary flow reserve by 43% from 2.3±0.3 to 3.3±0.5 (
P
<0.05 versus beginning and control). At 3 months, the number of hibernating segments in the target region (from 2.9±0.6 to 2.0±0.6 segments,
P
<0.05 versus beginning and control) had declined in the treatment group, whereas no significant changes were observed in the control group. MRI revealed a reduction in infarct size by 16% and an increase in LV ejection fraction by 14% in the treatment group (from 51.7±3.7 to 58.9±3.2%;
P
<0.05 versus beginning and control) because of an augmented wall motion in the target region. Hence, intracoronary transplantation of CPCs after recanalization of CTO results in an improvement of macro- and microvascular function and contributes to the recruitment of hibernating myocardium.
Adenosine Monophosphate-Activated Protein Kinase Suppresses Vascular Smooth Muscle Cell Proliferation Through the Inhibition of Cell Cycle Progression
Authors: Igata Motoyuki , Motoshima Hiroyuki , Tsuruzoe Kaku , Kojima Kanou , Matsumura Takeshi , Kondo Tatsuya , Taguchi Tetsuya , Nakamaru Kazuhiko , Yano Miyuki , Kukidome Daisuke , Matsumoto Kazuya , Toyonaga Tetsushi , Asano Tomoichiro , Nishikawa Takeshi , Araki Eiichi
Published: September 2005

Vascular smooth muscle cell (VSMC) proliferation is a critical event in the development and progression of vascular diseases, including atherosclerosis. We investigated whether the activation of adenosine monophosphate-activated protein kinase (AMPK) could suppress VSMC proliferation and inhibit cell cycle progression. Treatment of human aortic smooth muscle cells (HASMCs) or isolated rabbit aortas with the AMPK activator 5-Aminoimidazole-4-carboxamide ribonucleoside (AICAR) induced phosphorylation of AMPK and acetyl Co-A carboxylase. AICAR significantly inhibited HASMC proliferation induced by both platelet-derived growth factor-BB (PDGF-BB) and fetal calf serum (FCS). Treatment with AICAR inhibited the phosphorylation of retinoblastoma gene product (Rb) induced by PDGF-BB or FCS, and increased the expression of cyclin-dependent kinase inhibitor p21
CIP
but not that of p27
KIP
. Pharmacological inhibition of AMPK or overexpression of dominant negative-AMPK inhibited both the suppressive effect of AICAR on cell proliferation and the phosphorylation of Rb, suggesting that the effect of AICAR is mediated through the activation of AMPK. Cell cycle analysis in HASMCs showed that AICAR significantly increased cell population in G0/G1-phase and reduced that in S- and G2/M-phase, suggesting AICAR induced cell cycle arrest. AICAR increased both p53 protein and Ser-15 phosphorylated p53 in HASMCs, which were blocked by inhibition of AMPK. In isolated rabbit aortas, AICAR also increased Ser-15 phosphorylation and protein expression of p53 and inhibited Rb phosphorylation induced by FCS. These data suggest for the first time that AMPK suppresses VSMC proliferation via cell cycle regulation by p53 upregulation. Therefore, AMPK activation in VSMCs may be a therapoietic target for the prevention of vascular diseases.
Targeted Disruption of
Smad4
in Cardiomyocytes Results in Cardiac Hypertrophy and Heart Failure
Authors: Wang Jian , Xu Ning , Feng Xinheng , Hou Ning , Zhang JiShuai , Cheng Xuan , Chen Yeguang , Zhang Youyi , Yang Xiao
Published: September 2005

Transforming growth factor-βs (TGF-βs) are pleiotropic cytokines involved in many physiological and pathological processes, including heart development and heart disease. Smad4 is the central intracellular mediator of TGF-β signaling. To investigate the function of Smad4 in heart development further, we generated a strain of cardiomyocyte-specific
Smad4
knockout mice using the Cre–
lox
P system. Unexpectedly, the deletion of
Smad4
in cardiomyocytes resulted in cardiac hypertrophy characterized by an increase in the size of cardiac myocytes, age-associated fibrosis, and reexpression of certain fetal genes. Approximately 70% of the
Smad4
mutant mice died spontaneously between 5 and 12 months of age. Echocardiography and an invasive hemodynamic study of the left ventricle revealed markedly decreased cardiac contractility in
Smad4
mutant mice compared with littermate controls. Moreover, phosphorylated extracellular signal–regulated kinase (ERK) 1/2 and mitogen-activated protein kinase–ERK (MEK) 1 were increased in the
Smad4
mutants, suggesting that an upregulation of MEK1–ERK1/2 signaling as a consequence of deletion of
Smad4
underlies the impaired cardiac function. These results reveal an important function of Smad4 in cardiac remodeling and suggest that an altered cellular response to TGF-β could be a mechanism by which cardiac myocytes undergo hypertrophy.
The Existence and Evolution of Diffusion–Perfusion Mismatched Tissue in White and Gray Matter After Acute Stroke
Authors: Koga Masatoshi , Reutens David C. , Wright Peter , Phan Thanh , Markus Romesh , Pedreira Bruno , Fitt Greg , Lim Indra , Donnan Geoffrey A.
Published: September 2005

Background and Purpose—

Although white matter is a potential target of acute stroke therapy, there is uncertainty about its relative resistance to ischemia and whether it is capable of mounting a penumbral response. To explore these issues further, we examined the differential effects of ischemia on gray and white matter using magnetic resonance (MR) perfusion–diffusion mismatch after acute stroke.

Methods—

MR imaging studies were performed within 12 hours in patients with initial hemispheric ischemic stroke. “At-risk” tissue was defined as tissue with abnormal diffusion-weighted imaging/perfusion-weight imaging or infarction on follow-up image. Tissue was segmented using a probabilistic atlas generated from age-matched controls. The proportions of “at-risk” tissue, which was penumbral at the time of imaging, were compared between gray and white matter.

Results—

Thirty-two patients had diffusion–perfusion mismatched penumbral tissue present in both gray and white matter compartments. Although the absolute mismatch volumes were greater in gray (median 42 cm
3
, interquartile range 18 to 70 cm
3
) than in white matter (39 cm
3
, 17 to 49 cm
3
;
P
<0.001), the proportion of “at-risk” tissue, which was penumbral at the time of imaging (median 3.7 hours, range 1.5 to 9.9 hours) was greater in white (69%, 49% to 86%) than gray matter (62%, 52% to 75%;
P
=0.026). However, the proportions spontaneously salvaged by 3 months were similar in both compartments.

Conclusions—

These findings are consistent with white matter being able to mount an ischemic penumbral response in humans and being more resistant to cerebral ischemia than gray matter. They also raise the possibility that the therapeutic window is longer for white matter and may require alternative therapeutic strategies.
Trends in Stroke Incidence in Auckland, New Zealand, During 1981 to 2003
Authors: Anderson Craig S. , Carter Kristie N. , Hackett Maree L. , Feigin Valery , Barber P. Alan , Broad Joanna B. , Bonita Ruth
Published: September 2005

Background and Purpose—

Long-term trends in stroke incidence in different populations have not been well characterized, largely as a result of the complexities associated with population-based stroke surveillance.

Methods—

We assessed temporal trends in stroke incidence using standard diagnostic criteria and community-wide surveillance procedures in the population (≈1 million) of Auckland, New Zealand, over 12-month calendar periods in 1981–1982, 1991–1992, and 2002–2003. Age-adjusted first-ever (incident) and total (attack) rates, and temporal trends, were reported with 95% confidence intervals (CIs). Rates were analyzed by sex and major age groups.

Results—

From 1981 to 1982, stroke rates were stable in 1991–1992 and then declined in 2002–2003, to produce overall modest declines in standardized incidence (11%; 95% CI, 1 to 19%) and attack rates (9%; 95% CI, 0 to 16%) between the first and last study periods. Some favorable downward trends in vascular risk factors such as cigarette smoking were counterbalanced by increasing age and body mass index, and frequency of diabetes, in patients with stroke.

Conclusions—

There has been a modest decline in stroke incidence in Auckland over the last 2 decades, mainly during 1991 to 2003, in association with divergent trends in major risk factors.
Effects of Clopidogrel and Aspirin in Combination Versus Aspirin Alone on Platelet Activation and Major Receptor Expression in Patients After Recent Ischemic Stroke
Authors: Serebruany Victor L. , Malinin Alex I. , Ziai Wendy , Pokov Alex N. , Bhatt Deepak L. , Alberts Mark J. , Hanley Dan F.
Published: September 2005

Background and Purpose—

Clopidogrel is widely used in patients after recent ischemic stroke; however, its ability to yield additional antiplatelet protection on top of aspirin has never been explored in a controlled study. To determine whether clopidogrel with aspirin (C+ASA) will produce more potent platelet inhibition than aspirin alone (ASA) in patients after ischemic stroke, we conducted the Plavix Use for Treatment of Stroke trial.

Methods—

Seventy patients after ischemic stroke were randomly assigned to C+ASA or ASA groups. Platelet studies included aggregometry; cartridge-based analyzers; expression of PECAM-1, P-selectin, GP IIb/IIIa (antigen and activity), vitronectin receptor, and formation of platelet-leukocyte microparticles by flow cytometry. Platelet tests were performed at baseline and after 30 days after randomization.

Results—

There were no deaths, hospitalizations, or serious adverse events. There were no differences in the baseline platelet characteristics between C+ASA and ASA groups, or significant changes in platelet parameters in the ASA group, except diminished collagen-induced aggregation (
P
=0.001). In contrast, therapy with C+ASA resulted in a significant inhibition of platelet activity assessed by ADP- (
P
=0.00001) and collagen-induced (
P
=0.02) aggregation; closure time prolongation (
P
=0.03), and reduction of platelet activation units with Ultegra (
P
=0.00001); expression of PECAM-1 (
P
=0.01), and GP IIb/IIIa activity with PAC-1 (
P
=0.02) when compared with ASA group. Therapy with C+ASA also resulted in the reduced formation of platelet–leukocyte microparticles (
P
=0.02).

Conclusion—

Treatment with C+ASA for 1 month provides significantly greater inhibition of platelet activity than ASA alone in patients after recent ischemic stroke in the frame of the small randomized trial.
Matrix Detachable Coils for the Endovascular Treatment of Intracranial Aneurysms
Authors: Taschner Christian A. , Leclerc Xavier , Rachdi Henda , Barros Alexander Maia , Pruvo Jean-Pierre
Published: September 2005

Background and Purpose—

Endovascular coil embolization has become an accepted alternative for the treatment of intracranial aneurysms. The purpose of this study was to evaluate the clinical safety and the angiographic stability of aneurysm occlusion with a new class of biologically active platinum coils after a 6-month period.

Methods—

Twenty-five patients with 25 intracranial aneurysms were treated by selective embolization with a new coated bioactive coil (Matrix; Boston Scientific Neurovascular). Matrix coils were used alone in 6 patients and in combination with Guglielmi detachable coils (GDCs; Boston Scientific Neurovascular) in 19. Angiographic results, procedure-related complications, and adverse neurological events during the follow-up period were recorded. Magnetic resonance angiography was performed at 6 months in all patients.

Results—

Initial angiographies demonstrated complete occlusion in 17 patients, residual neck in 7, and a persisting aneurysm in 1. The clinical follow-up showed stable results in all patients. The grade of aneurysm occlusion at 6 months improved in 4 patients, remained stable in 15, and deteriorated in 6. Three patients needed retreatment because of a major aneurysm recanalization. Angiographic recurrences in cases of aneurysms treated with a combination of Matrix coils and GDCs occurred within the expected range for bare platinum coils. Two of 3 patients needing retreatment had been treated with Matrix coils alone.

Conclusion—

Stable results were obtained predominantly when Matrix coils were combined with bare platinum coils. A prospective, randomized study is necessary to assess the potential benefit of Matrix coils for patients treated by endovascular techniques.
Relationship Between Arterial Stiffness and Cognitive Function in Elderly Subjects With Complaints of Memory Loss
Authors: Hanon Olivier , Haulon Sylvie , Lenoir Hermine , Seux Marie-Laure , Rigaud Anne-Sophie , Safar Michel , Girerd Xavier , Forette Françoise
Published: September 2005

Background and Purpose—

To evaluate the relationship between arterial stiffness and cognitive function in a population of elderly subjects reporting memory loss.

Methods—

We studied the association between cognitive function and arterial stiffness in 308 consecutive elderly subjects attending a geriatric outpatient clinic reporting memory impairment. Subjects were classified into 4 categories according to neuropsychological evaluation: normal cognitive function, mild cognitive impairment (MCI), Alzheimer disease (AD), or vascular dementia (VaD). Arterial stiffness was evaluated by carotid-femoral pulse wave velocity (PWV) measurement using Complior.

Results—

In this population, 78±8 years of age (women 64%), AD was present in 41%, VaD in 6%, MCI in 27%, and 26% of subjects had normal cognitive function. After adjustment for age, gender, systolic blood pressure, education level, cardiovascular diseases, and antihypertensive therapy, a significant association was observed between PWV and cognitive status (
P
<0.0001). PWV appears significantly higher in subjects with VaD (15.2±3.9 m/s) or AD (13.3±2.9 m/s) than in those without cognitive impairment (11.5±2.0 m/s;
P
<0.001). Moreover, PWV was higher in subjects with MCI (12.6±2.6 m/s) than in those without cognitive impairment (11.5±2.0 m/s;
P
=0.01). For each 2 m/s increment in PWV, the adjusted odds ratio (95% CI) was 1.73 (1.27 to 2.47) for AD and 3.52 (1.87 to 8.05) for VaD.

Conclusion—

Our results showed a relationship between arterial stiffness and cognitive impairment, suggesting that functional changes of the arterial system could be involved in the onset of dementia (VaD or AD types).
Effects of Spatial Congruity on Audio-Visual Multimodal Integration
Authors: Teder-Sälejärvi W. A. , Russo F. Di , McDonald J. J. , Hillyard S. A.
Published: September 2005

Spatial constraints on multisensory integration of auditory (A) and visual (V) stimuli were investigated in humans using behavioral and electrophysiological measures. The aim was to find out whether cross-modal interactions between A and V stimuli depend on their spatial congruity, as has been found for multisensory neurons in animal studies (Stein & Meredith, 1993). Randomized sequences of unimodal (A or V) and simultaneous bimodal (AV) stimuli were presented to right-or left-field locations while subjects made speeded responses to infrequent targets of greater intensity that occurred in either or both modalities. Behavioral responses to the bimodal stimuli were faster and more accurate than to the uni-modal stimuli for both same-location and different-location AV pairings. The neural basis of this cross-modal facilitation was studied by comparing event-related potentials (ERPs) to the bimodal AV stimuli with the summed ERPs to the unimodal A and V stimuli. These comparisons revealed neural interactions localized to the ventral occipito-temporal cortex (at 190 msec) and to the superior temporal cortical areas (at 260 msec) for both same-and different-location AV pairings. In contrast, ERP interactions that differed according to spatial congruity included a phase and amplitude modulation of visual-evoked activity localized to the ventral occipito-temporal cortex at 100-400 msec and an amplitude modulation of activity localized to the superior temporal region at 260-280 msec. These results demonstrate overlapping but distinctive patterns of multisensory integration for spatially congruent and incongruent AV stimuli.
Cognitive Requirements for Vestibular and Ocular Motor Processing in Healthy Adults and Patients with Unilateral Vestibular Lesions
Authors: Talkowski M. E. , Redfern M. S. , Jennings J. R. , Furman J. M.
Published: September 2005

This study investigated the role of cognition in the vestibulo-ocular reflex (VOR) and ocular pursuit using a dual-task paradigm in patients with unilateral peripheral vestibular loss and healthy adults. We hypothesized that cognitive resources are involved in successful processing and integration of vestibular and ocular motor sensory information, and this requirement would be greater in patients with vestibular dys-function. Sixteen well-compensated patients with surgically confirmed absent unilateral peripheral vestibular function and 16 healthy age-and sex-matched controls underwent seven combinations of vestibular-only, visual-only, and visual-vestibular stimuli while performing three different information processing tasks. Visual-vestibular stimuli included a semi-circular canal and an otolith stimulus provided through seated chair rotations; fixation on a laser target and sinusoidal smooth pursuit while still; and fixation on a head-fixed laser target during chair rotations. The information processing tasks were three different auditory reaction time (RT) tasks: (1) simple RT (2) disjunctive RT, and (3) choice RT. Our results showed increases in RTs in both patients and controls under all vestibular-only stimulation conditions and during ocular pursuit. Patients showed greater increases in RTs during vestibular stimulation and the more complex disjunctive and choice RT tasks. No differences between the groups were found during the visual-only or visual-vestibular interaction conditions. These results reveal interference between vestibulo-ocular processing and a concurrent RT task, suggesting that the VOR and the ocular motor system are dependent upon cognitive resources to some extent, and thus, are not fully automatic systems. We speculate that this interference with cognition occurs as a result of the sensory integration required for resolving inputs from multiple sensory streams. The particularly large decrement in information processing task performance of the patients compared with controls during vestibular stimulation suggests that compensation for unilateral vestibular loss requires continued cognitive resources.