bluuebunny/crossref_metadata_2025 huggingface dataset:
Interleukin-18 directly activates T-bet expression and function via p38 mitogen-activated protein kinase and nuclear factor-κB in acute myeloid leukemia–derived predendritic KG-1 cells
Authors: Bachmann Malte , Dragoi Cristina , Poleganov Marco A. , Pfeilschifter Josef , Mühl Heiko
Published: February 2007

The leukemic cell line KG-1 was isolated from a patient with acute myeloid leukemia and is regarded a cellular model of human dendritic cell progenitors. The T helper type 1 cytokine interleukin (IL)-18 has been shown to induce the maturation of these cells towards a dendritic phenotype and, moreover, is able to mediate IFNγ production in this model. Because T-box expressed in T cells (T-bet) is considered to be of paramount importance for dendritic cell function, the effects of IL-18 on this transcription factor have been investigated in the current study. Here, we show that activation of KG-1 cells by IL-18 induces T-bet mRNA and protein within 4 to 6 h of incubation. This hitherto unrecognized function of IL-18 was suppressed by the inhibition of p38 mitogen-activated protein kinase activity and nuclear factor-κB function. Blockage of translation by cycloheximide, usage of neutralizing antibodies, and the inability of IFNγ to mediate significant p38 mitogen-activated protein kinase activation in KG-1 cells clearly revealed that activation of T-bet was not via autocrine IFNγ. T-bet function was evaluated by short interfering RNA technology. Notably, specific suppression of T-bet induction impaired secretion of IFNγ by KG-1 cells under the influence of IL-18. Therapeutic application of IL-18 has the potential to profoundly affect the biology of acute myeloid leukemia predendritic cells such as KG-1 cells. Under these conditions, activation of T-bet may play a key role in processes that have the potential to correct the T helper type 1 deficiency associated with leukemia-mediated immunosuppression. [Mol Cancer Ther 2007;6(2):723–31]
Functional evaluation of novel soluble insulin-like growth factor (IGF)-II–specific ligand traps based on modified domain 11 of the human IGF2 receptor
Authors: Prince Stuart N. , Foulstone Emily J. , Zaccheo Oliver J. , Williams Christopher , Hassan Andrew Bassim
Published: February 2007

Ligands transported by the mannose 6-phosphate/insulin-like growth factor (IGF)-II receptor (IGF2R) include IGF-II– and mannose 6-phosphate–modified proteins. Increased extracellular supply of IGF-II, either secondary to loss of the clearance function of IGF2R, loss of IGF binding protein function, or increased IGF2 gene expression, can lead to embryonic overgrowth and cancer promotion. Reduced supply of IGF-II is detrimental to tumor growth, and this suggests that gain of function of IGF-II is a molecular target for human cancer therapy. Domain 11 of IGF2R binds IGF-II with high specificity and affinity. Mutagenesis studies have shown that substitution of glutamic acid for lysine at residue 1554 results in a 6-fold higher affinity for IGF-II (20.5 nmol/L) than native domain 11 (119 nmol/L). Here, we generate a novel high-affinity IGF-II ligand trap by fusion of mutated human 11E1554K to a COOH-terminal human IgG1 Fc domain (11E1554K-Fc). The resulting homodimer has a significantly increased affinity for IGF-II (1.79 nmol/L) when measured by surface plasmon resonance. IGF-II signaling via the IGF-I receptor and the proliferative effect of IGF-II were specifically inhibited by 11E1554K-Fc in both HaCaT and Igf2−/− mouse embryonic fibroblast cells. These data confirm that a novel engineered and soluble IGF2R-11E1554K-Fc protein functions as an IGF-II–specific and high-affinity ligand trap in vitro and that this protein has potential application as an IGF-II antagonist for cancer therapy following in vivo experimental evaluation. [Mol Cancer Ther 2007;6(2):607–17]
17-Allylamino-17-demethoxygeldanamycin enhances the lethality of deoxycholic acid in primary rodent hepatocytes and established cell lines
Authors: Mitchell Clint , Park Margaret A. , Zhang Guo , Han Song Iy , Harada Hisashi , Franklin Richard A. , Yacoub Adly , Li Pin-Lan , Hylemon Philip B. , Grant Steven , Dent Paul
Published: February 2007

Ansamycin antibiotics that target heat shock protein 90 function are being developed as anticancer agents but are also known to be dose limiting in patients due to hepatotoxicity. Herein, to better understand how the normal tissue toxicity of geldanamycins could be ameliorated to improve the therapeutic index of these agents, we examined the interactions of 17-allylamino-17-demethoxygeldanamycin (17AAG) and the secondary bile acid deoxycholic acid (DCA) in hepatocytes and fibroblasts. DCA and 17AAG interacted in a greater than additive fashion to cause hepatocyte cell death within 2 to 6 h of coadministration. As single agents DCA, but not 17AAG, enhanced the activity of extracellular signal-regulated kinase 1/2, AKT, c-Jun NH2-terminal kinase 1/2 (JNK1/2), and p38 mitogen-activated protein kinase (MAPK). Combined exposure of cells to DCA and 17AAG further enhanced JNK1/2 and p38 MAPK activity. Inhibition of JNK1/2 or p38 MAPK, but not activator protein-1, suppressed the lethality of 17AAG and of 17AAG and DCA. Constitutive activation of AKT, but not MAPK/extracellular signal-regulated kinase kinase 1/2, suppressed 17AAG- and DCA-induced cell killing and reduced activation of JNK1/2. DCA and 17AAG exposure promoted association of BAX with mitochondria, and functional inhibition of BAX or caspase-9, but not of BID and caspase-8, suppressed 17AAG and DCA lethality. DCA and 17AAG interacted in a greater than additive fashion to promote and prolong the generation of reactive oxygen species (ROS). ROS-quenching agents, inhibition of mitochondrial function, expression of dominant-negative thioredoxin reductase, or expression of dominant-negative apoptosis signaling kinase 1 suppressed JNK1/2 and p38 MAPK activation and reduced cell killing after 17AAG and DCA exposure. The potentiation of DCA-induced ROS production by 17AAG was abolished by Ca2+ chelation and ROS generation, and cell killing following 17AAG and DCA treatment was abolished in cells lacking expression of PKR-like endoplasmic reticulum kinase. Thus, DCA and 17AAG interact to stimulate Ca2+-dependent and PKR-like endoplasmic reticulum kinase–dependent ROS production; high levels of ROS promote intense activation of the p38 MAPK and JNK1/2 pathways that signal to activate the intrinsic apoptosis pathway. [Mol Cancer Ther 2007;6(2):618–32]
Disrupting Skp2-cyclin A interaction with a blocking peptide induces selective cancer cell killing
Authors: Ji Peng , Sun Daqian , Wang Hongbo , Bauzon Frederick , Zhu Liang
Published: February 2007

Skp2 fulfills the definition of an oncoprotein with its frequent overexpression in cancer cells and oncogenic activity in various laboratory assays and therefore is a potential cancer therapy target. The best-known function of Skp2 is that of an F-box protein of the SCFSkp2-Roc1 E3 ubiquitin ligase targeting the cyclin-dependent kinase inhibitor p27Kip1. Knockdown of Skp2 generally leads to accumulation of p27 but its effects on cancer cells are less certain. Another function of Skp2 is its stable interaction with cyclin A, which directly protects cyclin A from inhibition by p27 in in vitro kinase assays. Here, we report that an 18-residue blocking peptide of Skp2-cyclin A interaction can indirectly inhibit cyclin A/Cdk2 kinase activity dependent on the presence of p27 in in vitro kinase assays. Transmembrane delivery of this blocking peptide can induce cell death in a panel of four cancer cell lines in which Skp2 knockdown only have mild inhibitory effects. This Skp2-cyclin A interaction blocking peptide can synergize with a previously identified E2F1-derived LDL peptide, which blocks its access to cyclin A, in killing cancer cells. IC50 of the Skp2-cyclin A blocking peptide correlated with abundance of Skp2, its intended target, in cancer cells. These results suggest that Skp2-cyclin A interaction plays an important role in cancer cell survival and is an attractive target for cancer drug discovery. [Mol Cancer Ther 2007;6(2):684–91]
Role of human longevity assurance gene 1 and C18-ceramide in chemotherapy-induced cell death in human head and neck squamous cell carcinomas
Authors: Senkal Can E. , Ponnusamy Suriyan , Rossi Michael J. , Bialewski Jacek , Sinha Debijyati , Jiang James C. , Jazwinski S. Michal , Hannun Yusuf A. , Ogretmen Besim
Published: February 2007

In this study, quantitative isobologram studies showed that treatment with gemcitabine and doxorubicin, known inducers of ceramide generation, in combination, supra-additively inhibited the growth of human UM-SCC-22A cells in situ. Then, possible involvement of the human homologue of yeast longevity assurance gene 1 (LASS1)/C18-ceramide in chemotherapy-induced cell death in these cells was examined. Gemcitabine/doxorubicin combination treatment resulted in the elevation of mRNA and protein levels of LASS1 and not LASS2-6, which was consistent with a 3.5-fold increase in the endogenous (dihydro)ceramide synthase activity of LASS1 for the generation of C18-ceramide. Importantly, the overexpression of LASS1 (both human and mouse homologues) enhanced the growth-inhibitory effects of gemcitabine/doxorubicin with a concomitant induction of caspase-3 activation. In reciprocal experiments, partial inhibition of human LASS1 expression using small interfering RNA (siRNA) prevented cell death by about 50% in response to gemcitabine/doxorubicin. In addition, LASS1, and not LASS5, siRNA modulated the activation of caspase-3 and caspase-9, but not caspase-8, in response to this combination. Treatment with gemcitabine/doxorubicin in combination also resulted in a significant suppression of the head and neck squamous cell carcinoma (HNSCC) tumor growth in severe combined immunodeficiency mice bearing the UM-SCC-22A xenografts. More interestingly, analysis of endogenous ceramide levels in these tumors by liquid chromatography/mass spectroscopy showed that only the levels of C18-ceramide, the main product of LASS1, were elevated significantly (about 7-fold) in response to gemcitabine/doxorubicin when compared with controls. In conclusion, these data suggest an important role for LASS1/C18-ceramide in gemcitabine/doxorubicin-induced cell death via the activation of caspase-9/3 in HNSCC. [Mol Cancer Ther 2007;6(2):712–22]
R16, a novel amonafide analogue, induces apoptosis and G2-M arrest via poisoning topoisomerase II
Authors: Zhu Hong , Huang Min , Yang Fan , Chen Yi , Miao Ze-Hong , Qian Xu-Hong , Xu Yu-Fang , Qin Yu-Xin , Luo Hai-Bin , Shen Xu , Geng Mei-Yu , Cai Yu-Jun , Ding Jian
Published: February 2007

Amonafide, a naphthalimide derivative, although selected for exploratory clinical trials for its potent anticancer activity, has long been challenged by its unpredictable side effects. In the present study, a novel amonafide analogue, 2-(2-dimethylamino)-6-thia-2-aza-benzo-[def]-chrysene-1,3-diones (R16) was synthesized by substituting 5′-NH2 of the naphthyl with a heterocyclic group to amonafide, with additional introduction of a thiol group. In a panel of various human tumor cell lines, R16 was more cytotoxic than its parent compound amonafide. It was also effective against multidrug-resistant cells. Importantly, the i.p. administration of R16 inhibited tumor growth in mice implanted with S-180 sarcoma and H22 hepatoma. The molecular and cellular machinery studies showed that the R16 functions as a topoisomerase II (topo II) poison via binding to the ATPase domain of human topo IIα. The superior cytotoxicity of R16 to amonafide was ascribed to its potent effects on trapping topo II–DNA cleavage complexes. Moreover, using a topo II catalytic inhibitor aclarubicin, ataxia-telangiectasia-mutated (ATM)/ATM- and Rad3-related (ATR) kinase inhibitor caffeine and topo II–deficient HL-60/MX2 cells, we further showed that R16-triggered DNA double-strand breaks, tumor cell cycle arrest, and apoptosis were in a topo II–dependent manner. Taken together, R16 stood out by its improved anticancer activity, appreciable anti–multidrug resistance activities, and well-defined topo II poisoning mechanisms, as comparable with the parent compound amonafide. All these collectively promise the potential value of R16 as an anticancer drug candidate, which deserves further development. [Mol Cancer Ther 2007;6(2):484–95]
Ontogeny and Phylogeny of the Pelvis in Gorilla, Pongo, Pan, Australopithecus and Homo
Authors: Williams Frank L’Engle , Orban Rosine
Published: February 2007

To examine the evolutionary differences between hominoid locomotor systems, a number of observations concerning the growth of the pelvis among the great apes as compared to modern and fossil hominids are reported. We are interested in the size and shape of the coxal bones at different developmental stages across species that may elucidate the relationship between ontogeny and phylogeny (i.e., heterochrony) in the hominoid pelvis. Our hypotheses are: (1) do rates of absolute growth differ?, (2) do rates of relative growth differ?, and (3) does heterochrony explain these differences? Bivariate and multivariate analyses of pelvic dimensions demonstrate both the diversity of species-specific ontogenetic patterns among hominoids, and an unequivocal separation of hominids and the great apes. Heterochrony alone fails to account for the ontogenetic differences between hominids and the great apes. Compared to recent Homo, Australopithecus can be described as ‘hyper-human’ from the relative size of the ischium, and short but broad ilium. Australopithecus afarensis differs from Australopithecus africanus by its relatively long pubis. In multivariate analyses of ilium shape, the most complete coxal bone attributed to Homo erectus, KNM-ER 3228, falls within the range of juvenile and adult Australopithecus, whereas Broken Hill falls within the range of modern Homo, suggesting that the modern human ilium shape arose rather recently. Among the great apes, patterns of pelvic ontogeny do not exclusively separate the African apes from Pongo.
Growth Hormone and Insulin Resistance
Authors: Jørgensen Jens O.L. , Larsen Rune L. , Møller Louise , Krag Morten , Jessen Niels , Nørrelund Helene , Christiansen Jens S. , Møller Niels
Published: February 2007

Background: Experimental data in human subjects demonstrate that growth hormone (GH) acutely inhibits glucose disposal in skeletal muscle. The insulin-antagonistic effects are clinically relevant since active acromegaly is accompanied by glucose intolerance, whereas children with GH deficiency may develop fasting hypoglycemia. At the same time, GH stimulates the turnover and oxidation of free fatty acids (FFAs), and there is experimental evidence to suggest a causal link between elevated FFA levels and insulin resistance in skeletal muscle. During fasting, the induction of insulin resistance by GH is associated with enhanced lipid oxidation and protein conservation, which seems to constitute a favorable metabolic adaptation. Conclusions: Observational data in GH-deficient adults do not indicate that GH replacement is associated with significant impairment of glucose tolerance; however, care should be taken to avoid overdosing and to monitor glycemic control.
Isolated Growth Hormone Deficiency due to GH1 Gene Deletion: Central Nervous System Hypertension during Growth Hormone Treatment
Authors: Antonini Sonir R. , Faleiros Letícia , Machado Hélio R. , Carlos dos Santos Antonio , de Castro Margaret
Published: February 2007

Background: We report the case of a patient with an uncommon association of isolated growth hormone deficiency (IGHD) due to GH1 gene deletion and Chiari malformation type I. The patient presented with intracranial hypertension during recombinant human GH replacement therapy. Methods: GH deficiency (GHD) was diagnosed based on auxiological data and standard biochemical tests. Molecular analysis of the GH1 gene was performed using polymerase chain reaction amplification and SmaI enzyme restriction. The central nervous system (CNS) was evaluated by computed tomography (CT) and magnetic resonance imaging (MRI). Results: Molecular analysis showed that IGHD was due to homozygotic deletion of the 6.7-kb GH1 gene. After 28 months of GH treatment, CT and MRI scans showed enlargement of the third and lateral ventricles but a normal fourth ventricle, herniation of the cerebellar tonsils by the foramen magnum, presence of dysplastic cerebellar tonsils involving the medulla oblongata, absence of the cisterna magna and compression of the cerebellar tonsils and spinal cord by the posterior arch of the atlas. The patient underwent endoscopic third ventriculostomy, which resulted in complete symptom relief. Conclusions: This case illustrates the importance of CNS evaluation, including detailed examination of the posterior fossa, in patients with GHD.
PROP1 Gene Mutations and Pituitary Size: A Unique Case of Two Consecutive Cycles of Enlargement and Regression
Authors: Xekouki Paraskevi , Sertedaki Amalia , Livadas Sarantis , Argyropoulou Maria , Voutetakis Antonis
Published: February 2007

Background: Pituitary enlargement, which can regress with time, has been described in a number of PROP1-deficient patients. We report a PROP1-deficient patient with a unique variation in pituitary size. Case Description: A 4-year-old boy was first examined in 1989 for short stature (–2.3 standard deviation score). Growth hormone (GH) insufficiency was confirmed, and human GH (hGH) therapy was initiated and administered up to the age of 18.2 years. Levothyroxine was added 6 months after hGH initiation. Pituitary magnetic resonance imaging (MRI) obtained when the patient was 5 years old showed an enlarged pituitary gland, which grew larger by the age of 8.5 years and then regressed to normal size by the time the patient was 9.8 years old. MRI when the patient was 19 years old disclosed pituitary reenlargement, and another 3 years later indicated regression. On DNA analysis, the patient was found to be homozygous for the mutation 301–302ΔGA of the PROP1 gene. When the patient was 18.8 years old and asymptomatic, an impaired cortisol response to glucagon was detected. Conclusions: Regression of the pituitary enlargement in PROP1-deficient patients does not seem to constitute an end stage with respect to pituitary pathology. Further changes in pituitary morphology and size can be expected; therefore, long-term follow-up with pituitary MRI is advised.
Depression following Traumatic Brain Injury Associated with Isolated Growth Hormone Deficiency: Two Case Reports
Authors: Maric Nadja , Pekic Sandra , Doknic Mira , Jasovic-Gasic Miroslava , Zivkovic Vlada , Stojanovic Marko , Djurovic Branko , Popovic Vera
Published: February 2007

Background: Depression can be a sequela of a medical condition like traumatic brain injury (TBI), but the relationship between brain trauma and depression has not been recognized until recently. Eight to 15% of adults who sustain a TBI have severe and isolated growth hormone deficiency (GHD). It has been shown that GHD in adults is associated with changes in body composition, impairment of quality of life, and depression. Methods and Results: At the time of evaluation, two adult subjects who suffered TBI several years ago presented with isolated GHD together with depression. Prior to trauma, neither subject had psychiatric or endocrine morbidity. These case reports focus on opportunities and difficulties in deciding how best to treat them. Conclusions: Both depression and TBI are highly ranked in the list of burden of disease. The mechanism of depression in GH-deficient adults who have sustained a TBI should be clarified and the efficacy and tolerability of GH replacement therapy versus placebo versus antidepressant drugs should be assessed.
Hypodipsic Hypernatremia after Hypothalamic Infarct
Authors: Marazuela Mónica , López-Gallardo Gema , López-Iglesias María , Manzanares Rafael
Published: February 2007

Background: Hypothalamic hypodipsic syndrome is a rare condition, secondary to a defect in hypothalamic osmoreceptors that leads to impairment of water homeostasis and chronic hyperosmolality. It is frequently associated with defective osmoregulated vasopressin secretion and diabetes insipidus, and the combination results in a greater risk of hypernatremia. The principles of management consist of regulating vasopressin and water intake in relation to changes in daily body weight. Methods and Results: This case report concerns a patient who, after a postoperative cerebral infarction, developed an extensive hypothalamic syndrome including hypodipsic hypernatremia, diabetes insipidus, hyperthermia, profound short-term memory loss and initial severe anorexia, followed by hyperphagia with an inability to maintain body weight. Conclusion: The management of fluid balance proved extremely difficult in this amnesic patient, where weight alone was not sufficient to monitor water intake.
DCEBIO-Mediated Dilations Are Attenuated in the Female Rat Middle Cerebral Artery
Authors: Sokoya Elke M. , You Junping , Chen Jie
Published: February 2007

Background: Unlike in peripheral vessels, the endothelium-derived hyperpolarizing factor (EDHF)-mediated component to P2Y2 receptor-mediated dilations is significantly attenuated in the middle cerebral artery (MCA) of female rats compared to male rats. One aspect to the EDHF phenomenon is activation of the intermediate calcium-sensitive potassium (IKCa) channels located on the endothelium. In an attempt to pinpoint the site along the EDHF pathway that is compromised in females, we tested the hypothesis that direct activation of IKCa channels with DCEBIO would elicit attenuated hyperpolarization in the endothelium and smooth muscle of females compared to males. Methods: Inhibitors of nitric oxide synthase and cyclooxygenase were present throughout all experiments. Vessel diameter changes were assessed in pressurized and luminally perfused MCAs. Membrane potential changes in the endothelium and smooth muscle were measured using the perforated patch clamp method and sharp electrodes, respectively. Results and Conclusions: The maximum vasodilation to 3 × 10–4M DCEBIO was significantly reduced in females (37 ± 9%) compared to intact males (70 ± 4%). Endothelial cell hyperpolarization to DCEBIO was similar in both males and females. Smooth muscle cell hyperpolarization was attenuated in females (2 ± 1 mV) compared to males (15 ± 3 mV). Taken together, our data suggest that the transfer of hyperpolarization from the endothelium to the smooth muscle is impeded in the female rat MCA.
Does Periadventitial Fat-Derived Nitric Oxide Play a Role in Improved Saphenous Vein Graft Patency in Patients Undergoing Coronary Artery Bypass Surgery?
Authors: Dashwood Michael R. , Dooley Audrey , Shi-Wen Xu , Abraham David J. , Souza Domingos S.R.
Published: February 2007

Background/Aims: The saphenous vein is commonly used for coronary artery bypass surgery but its patency is poor. Vascular damage occurs during conventional surgery. However, patency improves when the graft is harvested with minimal surgical trauma, partly due to preservation of vascular endothelial nitric oxide synthase (eNOS) and tissue sources of nitric oxide (NO), a factor possessing both dilatory and anti-proliferative properties. Apart from these grafts exhibiting an intact luminal endothelium they are harvested complete with a surrounding cushion of tissue, much of which is fat. Methods: Immunostaining for eNOS was performed on vein graft sections and reverse-transcriptase polymerase chain reaction and Western blotting were used to identify eNOS mRNA and protein. NO synthase activity was measured using the citrulline assay. Results: Immunohistochemistry identified eNOS staining of vein graft segments, including dense staining of the cushion of perivascular fat and associated structures surrounding the vein. eNOS protein was confirmed in both the vein and surrounding fat by Western blot analysis. Using the citrulline assay, the perivascular fat and underlying vein possessed comparable NO synthase activity. Conclusions: Our observations suggest that perivascular fat-derived NO plays a beneficial role in saphenous veins harvested atraumatically and used as grafts in patients undergoing coronary artery bypass surgery.
Association between Dialysis Dose Improvement and Nutritional Status among Hemodialysis Patients
Authors: Azar Ahmad T. , Wahba Khaled , Mohamed Abdalla S.A. , Massoud Waleed A.
Published: February 2007

Background: Several studies suggest an association between improved survival and better nutritional status. It has been suggested that there is a correlation between dose of dialysis and nutritional status. However, in spite of the current practice, there are conflicting reports regarding the relationship between dose of dialysis or malnutrition, and biochemical outcome. In this article, we will discuss the impact of dose of dialysis on nutritional status and biochemical outcome in hemodialysis patients. We will also mention the interrelationships of dialysis dose, malnutrition, and biochemical outcome with respect to these patients. Methods: Data were processed on 134 dialysis patients (mean age 48.21 ± 13.38, 69 male, 65 female) on 3-times-per-week dialysis regimens. The overall study period was 3 months from June 1, 2005 to August 31, 2005. The patients were divided into two groups: the baseline group and the intervention group. The data of the baseline group were collected in June, 2005 and the data of the intervention group were collected in August, 2005 after applying the intervention or a protocol for dialysis adequacy improvement. Results: The statistical analysis demonstrated that there was a significant improvement in mean URR and Kt/V from the baseline to the intervention group. The intervention group had a considerably higher rate than the baseline group for all nutritional and biochemical outcome parameters. The study showed a strong positive correlation between nPCR and Kt/V (p = 0.0001) and also a strong positive correlation between serum albumin and Kt/V (p = 0.00001). No correlations were found between Kt/V and biochemical outcomes such as hemoglobin (p = 0.4922), calcium (p = 0.650), phosphate (p = 0.508), and phosphatase (p = 0.091). Conclusion: All the available evidence in hemodialysis patients confirms the close association between dialysis dose and biochemical outcome. A body of evidence also highlights the existence of relationship between malnutrition and outcome among these patients. Dose of dialysis and nutrition are considered to be interrelated.
Renoprotective Effects of a Selective Estrogen Receptor Modulator, Raloxifene, in an Animal Model of Diabetic Nephropathy
Authors: Dixon Alexis , Wells Corinne C. , Singh Sandhya , Babayan Regina , Maric Christine
Published: February 2007

Background/Aims: Our previous studies have shown that supplementation with 17β-estradiol (E2) from the onset of diabetes attenuates diabetic nephropathy. However, E2 is accompanied by feminizing effects as well as adverse side effects on other organs. The current study examined the renoprotective effects of a selective estrogen receptor modulator, raloxifene (RAL), in an experimental model of diabetic nephropathy. RAL activates estrogen receptors and estrogen-receptor-mediated cellular events without the side effects of E2. Methods: The study was performed in Sprague-Dawley nondiabetic (ND), streptozotocin-induced diabetic (D) and streptozotocin-induced D + RAL rats (n = 6/group). Results: After 12 weeks of treatment, D was associated with increased urine albumin excretion (ND: 4.2 ± 0.4; D: 41.3 ± 9.0 mg/day), glomerulosclerosis [glomerulosclerotic index; ND: 0.26 ± 0.04; D: 1.86 ± 0.80 arbitrary units (AU)], tubulointerstitial fibrosis (tubulointerstitial fibrosis index; ND: 0.37 ± 0.05; D: 2.12 ± 0.50 AU), increased collagen type I [ND: 1.31 ± 0.07; D: 4.65 ± 0.09 relative optical density (ROD)], collagen type IV (ND: 0.64 ± 0.03; D: 1.37 ± 0.11 ROD) and transforming growth factor beta (TGF-β) protein expression (ND: 0.65 ± 0.08; D: 1.25 ± 0.10 ROD), increased density of CD68-positive cells (ND: 1.37 ± 3.02; D: 29.2 ± 1.74 cells/mm2) and increased plasma levels of interleukin-6 (ND: 14.8 ± 5.0; D: 51.3 ± 14.0 pg/ml). Treatment with RAL partially or fully attenuated these processes (urine albumin excretion: 21.0 ± 5.0 mg/day; glomerulosclerotic index: 0.40 ± 0.06 AU; tubulointerstitial fibrosis index: 0.20 ± 0.04 AU; collagen type I: 2.55 ± 0.49 ROD; collagen type IV: 0.70 ± 0.09 ROD; TGF-β: 0.91 ± 0.08 ROD; CD68: 6.03 ± 2.38 cells/mm2; interleukin-6: 31.2 ± 5.0 pg/ml). Conclusions: Our data indicate that treatment with RAL attenuates albuminuria and renal structural changes associated with diabetes.
Pharyngeal Carriage and Antimicrobial Resistance of Haemophilus influenzae in Non-Type-b-Vaccinated Healthy Children Attending Day Care Centers in Turkey
Authors: Torun Müzeyyen Mamal , Namal Necmi , Demirci Mehmet , Bahar Hrisi , Kocazeybek Bekir
Published: February 2007

Background: The true prevalence of Haemophilus influenzae carriage rates in Turkey is unknown. As surveillance of pharyngeal carriage of resistant strains is important for initiating adequate empirical antimicrobial therapy, with the present study, we aimed to determine the carriage rates and antimicrobial resistance patterns of H. influenzae isolated from healthy children attending day care centers (DCCs) in Istanbul, Turkey. Methods: A total of 195 healthy children were included from two DCCs. Pharyngeal swabs were cultured for H. influenzae which were identified according to standard microbiologic procedures. Antimicrobial susceptibility tests were performed by the agar dilution method in accordance with the guidelines of the National Committee for Clinical Laboratory standards. β-Lactamase production was determined by the nitrocefin disc test. Results: The average pharyngeal carriage rate of H. influenzae was determined as 48.7%: 7.2% type b, 7.6% other capsulated strains, 33.9% noncapsulated strains, with a carriage peak between 0 and 11 months (68.1%). The ampicillin resistance observed in 7.3% of H. influenzae isolates was associated with a presence of β-lactamase, except for one isolate which was interpreted as β-lactamase-negative ampicillin-resistant strain. The resistance of H. influenzae to sulbactam/ampicillin, cefuroxime, azithromycin, tetracycline and cotrimoxazole was 0.5, 1.5, 0.5, 2.9 and 28.6%, respectively. Cefotaxime, ceftriaxone, ciprofloxacin and imipenem resistance was not detected. Conclusion: Our data show that the upper respiratory tract of about 48.7% of children was colonized with H. influenzae. This high colonization rate indicates that there is a need for surveillance of pharyngeal carriage of resistant strains in healthy Turkish children attending DCCs.
The Dihydrouracil/Uracil Ratios in Plasma and Toxicities of 5-Fluorouracil-Based Adjuvant Chemotherapy in Colorectal Cancer Patients
Authors: Zhou Zhi Wei , Wang Guo Qiang , Wan De Sen , Lu Zhen Hai , Chen Ying Bo , Li Su , Chen Gong , Pan Zhi Zhong
Published: February 2007

Background: This study was designed to measure the dihydrouracil (UH2)/uracil (U) ratio in plasma as a surrogate marker for dihydropyrimidine dehydrogenase (DPD) activity and to investigate the relationships of the UH2/U ratios in plasma with the toxicities of 5-fluorouracil (5-FU)-based adjuvant chemotherapy and 5-FU plasma concentrations in colorectal cancer patients. Methods: Thirty colorectal cancer patients received adjuvant chemotherapy of leucovorin plus 5-FU after operations. The concentrations of UH2, U and 5-FU were assayed by the high-performance liquid chromatography method. The relationships of the UH2/U ratios with the 5-FU toxicities and 5-FU plasma concentrations were analyzed.Results: There was a negative relationship between the UH2/U ratios and 5-FU plasma concentrations (p <0.001). 5-FU toxicities had a negative correlation with the UH2/U ratios and a positive correlation with 5-FU plasma concentrations (p < 0.05). Conclusion: The UH2/U ratio in plasma has close correlations with the 5-FU plasma concentration and 5-FU toxicity during chemotherapy, which may highlight the theoretical base of individual therapy for patients with colorectal cancer.
Use of the Collagen Gel Droplet Embedded Drug Sensitivity Test to Determine Drug Sensitivity against Ovarian Mature Cystic Teratoma with Malignant Transformation to Adenocarcinoma: A Case Report
Authors: Yamagami Wataru , Banno Kouji , Kawaguchi Makiko , Yanokura Megumi , Kuwabara Yoshiko , Hirao Nobumaru , Susumu Nobuyuki , Tsukazaki Katsumi , Aoki Daisuke
Published: February 2007

Background: The collagen gel droplet embedded drug sensitivity test (CD-DST) is a new anticancer drug sensitivity test that only requires a small number of cells. We report the use of this test in the choice of adjuvant chemotherapy for treatment of a rare case of ovarian cancer involving malignant transformation of ovarian mature cystic teratoma. Case Report: The patient was a 70-year-old female with an ovarian tumor, pleural effusion, carcinomatous ascites and a chest wall tumor. The histopathological diagnosis was adenocarcinoma, mature cystic teratoma with malignant transformation, stage IV. Paclitaxel/carboplatin therapy was selected as adjuvant chemotherapy based on CD-DST results. Upon completion of 6 courses, no increases in carcinomatous ascites or recurrent lesions were evident, and the chest wall tumor had disappeared completely. Conclusion: The CD-DST may be particularly useful for selecting preoperative chemotherapeutic drugs for patients with ovarian cancer in which the histological type of the primary tumor is unknown.
AMP-Activated Protein Kinase in Metabolic Control and Insulin Signaling
Authors: Towler Mhairi C. , Hardie D. Grahame
Published: February 2007

The AMP-activated protein kinase (AMPK) system acts as a sensor of cellular energy status that is conserved in all eukaryotic cells. It is activated by increases in the cellular AMP:ATP ratio caused by metabolic stresses that either interfere with ATP production (eg, deprivation for glucose or oxygen) or that accelerate ATP consumption (eg, muscle contraction). Activation in response to increases in AMP involves phosphorylation by an upstream kinase, the tumor suppressor LKB1. In certain cells (eg, neurones, endothelial cells, and lymphocytes), AMPK can also be activated by a Ca
2+
-dependent and AMP-independent process involving phosphorylation by an alternate upstream kinase, CaMKKβ. Once activated, AMPK switches on catabolic pathways that generate ATP, while switching off ATP-consuming processes such as biosynthesis and cell growth and proliferation. The AMPK complex contains 3 subunits, with the α subunit being catalytic, the β subunit containing a glycogen-sensing domain, and the γ subunits containing 2 regulatory sites that bind the activating and inhibitory nucleotides AMP and ATP. Although it may have evolved to respond to metabolic stress at the cellular level, hormones and cytokines such as insulin, leptin, and adiponectin can interact with the system, and it now appears to play a key role in maintaining energy balance at the whole body level. The AMPK system may be partly responsible for the health benefits of exercise and is the target for the antidiabetic drug metformin. It is a key player in the development of new treatments for obesity, type 2 diabetes, and the metabolic syndrome.
Ca2+Channel Subtypes and Pharmacology in the Kidney
Authors: Hayashi Koichi , Wakino Shu , Sugano Naoki , Ozawa Yuri , Homma Koichiro , Saruta Takao
Published: February 2007

A large body of evidence has accrued indicating that voltage-gated Ca2+channel subtypes, including L-, T-, N-, and P/Q-type, are present within renal vascular and tubular tissues, and the blockade of these Ca2+channels produces diverse actions on renal microcirculation. Because nifedipine acts exclusively on L-type Ca2+channels, the observation that nifedipine predominantly dilates afferent arterioles implicates intrarenal heterogeneity in the distribution of L-type Ca2+channels and suggests that it potentially causes glomerular hypertension. In contrast, recently developed Ca2+channel blockers (CCBs), including mibefradil and efonidipine, exert blocking action on L-type and T-type Ca2+channels and elicit vasodilation of afferent and efferent arterioles, which suggests the presence of T-type Ca2+channels in both arterioles and the distinct impact on intraglomerular pressure. Recently, aldosterone has been established as an aggravating factor in kidney disease, and T-type Ca2+channels mediate aldosterone release as well as its effect on renal efferent arteriolar tone. Furthermore, T-type CCBs are reported to exert inhibitory action on inflammatory process and renin secretion. Similarly, N-type Ca2+channels are present in nerve terminals, and the inhibition of neurotransmitter release by N-type CCBs (eg, cilnidipine) elicits dilation of afferent and efferent arterioles and reduces glomerular pressure. Collectively, the kidney is endowed with a variety of Ca2+channel subtypes, and the inhibition of these channels by their specific CCBs leads to variable impact on renal microcirculation. Furthermore, multifaceted activity of CCBs on T- and N-type Ca2+channels may offer additive benefits through nonhemodynamic mechanisms in the progression of chronic kidney disease.
Overview of PDEs and Their Regulation
Authors: Omori Kenji , Kotera Jun
Published: February 2007

Contraction and relaxation of vascular smooth muscle and cardiac myocytes are key physiological events in the cardiovascular system. These events are regulated by second messengers, cAMP and cGMP, in response to extracellular stimulants. The strength of signal transduction is controlled by intracellular cyclic nucleotide concentrations, which are determined by a balance in production and degradation of cAMP and cGMP. Degradation of cyclic nucleotides is catalyzed by 3′,5′-cyclic nucleotide phosphodiesterases (PDEs), and therefore regulation of PDEs hydrolytic activity is important for modulation of cellular functions. Mammalian PDEs are composed of 21 genes and are categorized into 11 families based on sequence homology, enzymatic properties, and sensitivity to inhibitors. PDE families contain many splice variants that mostly are unique in tissue-expression patterns, gene regulation, enzymatic regulation by phosphorylation and regulatory proteins, subcellular localization, and interaction with association proteins. Each unique variant is closely related to the regulation of a specific cellular signaling. Thus, multiple PDEs function as a particular modulator of each cardiovascular function and regulate physiological homeostasis.
A Role for Caspase-1 in Heart Failure
Authors: Merkle Sabine , Frantz Stefan , Schön Michael P. , Bauersachs Johann , Buitrago Monika , Frost Robert J.A. , Schmitteckert Eva M. , Lohse Martin J. , Engelhardt Stefan
Published: February 2007

Apoptosis of cardiomyocytes is increased in heart failure and has been implicated in disease progression. The activation of “proapoptotic” caspases represents a key step in cardiomyocyte apoptosis. In contrast, the role of “proinflammatory” caspases (caspases 1, 4, 5, 11, 12) is unclear. Here, we study the cardiac function of caspase-1. Gene array analysis in a murine heart failure model showed upregulation of myocardial caspase-1. In addition, we found increased expression of caspase-1 protein in murine and human heart failure. Mice with cardiomyocyte-specific overexpression of caspase-1 developed heart failure in the absence of detectable formation of interleukin (IL)-1β or IL-18 and inflammation. Transgenic caspase-1 induced primary cardiomyocyte apoptosis before structural and molecular signs of myocardial remodeling occurred. In contrast, deletion of endogenous caspase-1 was beneficial in the setting of myocardial infarction–induced heart failure. Furthermore, caspase-1–deficient mice were protected from ischemia/reperfusion-induced cardiomyocyte apoptosis. Studies in primary rat cardiomyocytes indicated that caspase-1 induces cardiomyocyte apoptosis primarily through activation of caspases-3 and -9. In contrast to previous findings, which imply a proinflammatory role of caspase-1, these data suggest a primary proapoptotic role for caspase-1 in cardiomyocytes. Our findings support a functional role for caspase-1–mediated myocardial apoptosis contributing to the progression of heart failure.
Deletion of Macrophage LDL Receptor–Related Protein Increases Atherogenesis in the Mouse
Authors: Overton Cheryl D. , Yancey Patricia G. , Major Amy S. , Linton MacRae F. , Fazio Sergio
Published: February 2007

Macrophage low-density lipoprotein receptor–related protein (LRP) mediates internalization of remnant lipoproteins, and it is generally thought that blocking lipoprotein internalization will reduce foam cell formation and atherogenesis. Therefore, our study examined the function of macrophage LRP in atherogenesis. We generated transgenic mice that specifically lack macrophage LRP through
Cre/lox
recombination. Transplantation of macrophage LRP
−/−
bone marrow into lethally irradiated female LDLR
−/−
recipient mice resulted in a 40% increase in atherosclerosis. The difference in atherosclerosis was not caused by altered serum lipoprotein levels. Furthermore, deletion of macrophage LRP decreased uptake of
125
I–very-low-density lipoprotein compared with wild-type cells in vitro. The increase in atherosclerosis was accompanied by increases in monocyte chemoattractant protein type-1, tumor necrosis factor-α, and proximal aorta macrophage cellularity. We also found that deletion of macrophage LRP increases matrix metalloproteinase-9. This increase in matrix metalloproteinase-9 was associated with a higher frequency of breaks in the elastic lamina. Contrary to what was found with other lipoprotein receptors, deletion of LRP increases atherogenesis in hypercholesterolemic mice. Our data support the hypothesis that macrophage LRP modulates atherogenesis through regulation of inflammatory responses.
Fusion of Human Hematopoietic Progenitor Cells and Murine Cardiomyocytes Is Mediated by α4β1 Integrin/Vascular Cell Adhesion Molecule-1 Interaction
Authors: Zhang Sui , Shpall Elizabeth , Willerson James T. , Yeh Edward T.H.
Published: February 2007

Fusion of transplanted stem cells and host cells has been proposed as a major mechanism for the generation of hepatocytes, Purkinje neurons, and cardiomyocytes. However, the mechanism of cell fusion has not been precisely defined. Furthermore, the consequence of cell fusion remains unclear. We have previously shown that adult peripheral blood CD34-positive cells injected into severe combined immune deficiency (SCID) mice can transform into cardiomyocytes, endothelial cells, and smooth muscle cells following experimentally induced myocardial infarction and that most of the newly formed cardiomyocytes result from cell fusion. We therefore undertook this study to define the mechanism and consequences of cell fusion. Here we show that hypoxia and cytokines increase fusion of human peripheral blood CD34-positive cells and murine cardiomyocytes in vitro by up to 7-fold, and this is blocked by anti-α4β1 or anti–vascular cell adhesion molecule (VCAM)-1. In vivo, fusion of progenitor cells and cardiomyocytes can also be blocked by anti-α4β1 or anti–VCAM-1, but not by anti–vascular endothelial growth factor. On the other hand, generation of human-derived endothelial cells is blocked by anti–vascular endothelial growth factor but not by anti-α4β1 antibodies. Two months following transplant, a high percentage of fused cells expressed cyclin B1 and incorporated bromodeoxyuridine. Thus, hematopoietic progenitor cell and cardiomyocyte fusion is mediated by α4β1/VCAM-1 interaction, leading to cell cycle reentry and cellular proliferation.
Peroxisome Proliferator-Activated Receptor-δ Upregulates 14-3-3ε in Human Endothelial Cells via CCAAT/Enhancer Binding Protein-β
Authors: Brunelli Luca , Cieslik Katarzyna A. , Alcorn Joseph L. , Vatta Matteo , Baldini Antonio
Published: February 2007

Peroxisome proliferator-activated receptor δ (PPARδ) agonists are promising new agents for treatment of the metabolic syndrome. Although they possess antiatherosclerotic properties in vivo and promote endothelial cell survival, their mechanism of action is incompletely understood. 14-3-3ε is a critical component of the endothelial cell antiapoptotic machinery, which is essential to maintain homeostasis of the vascular wall. To test the hypothesis that PPARδ targets 14-3-3ε in endothelial cells, we studied the response of the gene that encodes 14-3-3ε in humans,
YWHAE
, to PPARδ ligands (L-165,041 and GW501516). We found that PPARδ activates
YWHAE
promoter in a concentration and time-dependent manner. Consistent with these findings, L-165,041 increased 14-3-3ε mRNA and protein level, whereas PPARδ small interfering RNA suppressed both basal and L-165,041–dependent
YWHAE
transcription and 14-3-3ε protein expression. Surprisingly, PPAR response elements in
YWHAE
promoter were not required for upregulation by PPARδ, whereas a CCAAT/enhancer binding protein (C/EBP) site located at −160/−151 bp regulated both basal and PPARδ-dependent promoter activity. Intriguingly, activation or knock down of endogenous PPARδ regulated C/EBPβ protein expression. Chromatin immunoprecipitation assays demonstrated that L-165,041 determines the localization of C/EBPβ to the region spanning this C/EBP response element, whereas sequential chromatin immunoprecipitation analysis revealed that C/EBPβ and PPARδ form a transcriptional activating complex on this C/EBP site. Our work uncovers a novel role for C/EBPβ as a mediator of PPARδ-dependent 14-3-3ε gene regulation in human endothelial cells and provides insight into the mechanism by which PPARδ agonists may be beneficial in atherosclerosis.
Combined Loss of
Hey1
and
HeyL
Causes Congenital Heart Defects Because of Impaired Epithelial to Mesenchymal Transition
Authors: Fischer Andreas , Steidl Christian , Wagner Toni U. , Lang Esra , Jakob Peter M. , Friedl Peter , Knobeloch Klaus-Peter , Gessler Manfred
Published: February 2007

Congenital heart defects affect almost 1% of human newborns. Recently, mutations in Notch ligands and receptors have been found to cause a variety of heart defects in rodents and humans. However, the molecular effects downstream of Notch are still poorly understood. Here we report that combined inactivation of
Hey1
and
HeyL
, two primary target genes of Notch, causes severe heart malformations, including membranous ventricular septal defects and dysplastic atrioventricular and pulmonary valves. These defects lead to congestive cardiac failure with high lethality. We found both genes to be coexpressed with
Notch1
,
Notch2
and the Notch ligand
Jagged1
in the endocardium of the atrioventricular canal, representing the primary source of mesenchymal cells forming membraneous septum and valves. Atrioventricular explants from
Hey1
/
HeyL
deficient mice exhibited impaired epithelial to mesenchymal transition. Although epithelial to mesenchymal transition was initiated regularly, full transformation into mesenchymal cells failed. This was accompanied by reduced levels of
matrix metalloproteinase-2
expression and reduced cell density in endocardial cushions in vivo. We further show that loss of
Hey2
leads to very similar deficiencies, whereas a
Notch1
null mutation completely abolishes epithelial to mesenchymal transition. Thus, the
Hey
gene family shows overlap in controlling Notch induced endocardial epithelial to mesenchymal transition, a process critical for valve and septum formation.