c-myb affects intracellular calcium handling in vascular smooth muscle cells

RBBP6, a RING finger-domain E3 ubiquitin ligase, induces epithelial-mesenchymal transition and promotes metastasis of colorectal cancer

RBBP6 has been implicated in tumorigenesis but its role in tumor metastasis and progression has not been evaluated. Interestingly, here we show that RBBP6 is upregulated in colorectal cancer (CRC) where its expression level is positively correlated with distant metastasis. In this study, we identified RBBP6, a RING Finger-domain E3 ubiquitin ligase, served as an independent prognostic factor and predicted poor outcome for CRC patients. RBBP6 promoted cell proliferation, migration, and invasion in CRC cells and promoted tumor growth, lung metastasis, and liver metastasis in mouse models. Mechanistically, we revealed that RBBP6 bound and ubiquitylated IκBα, an inhibitor of the NF-κB-signaling pathway. RBBP6-mediated ubiquitination and degradation of IκBα significantly enhanced p65 nuclear translocation, which triggered the activation of NF-κB pathway and then induced the epithelial–mesenchymal transition (EMT) process and cell metastasis. Furthermore, by DNA methylation results and ChIP analysis, we demonstrated that the promoter of RBBP6 was hypomethylated, and was activated by multi-oncogenic transcription factors. In conclusion, our findings suggest that RBBP6 may be a potential prognostic biomarker and therapeutic target for CRC invasion and metastasis.

The interaction between different types of activated RAW 264.7 cells and macrophage inflammatory protein-1 alpha

Background

Two major ways of macrophage (MΦ) activation can occur in radiation-induced pulmonary injury (RPI): classical and alternative MΦ activation, which play important roles in the pathogenesis of RPI. MΦ can produce chemokine MΦ inflammatory protein-1α (MIP-1α), while MIP-1α can recruit MΦ. The difference in the chemotactic ability of MIP-1α toward distinct activated MΦ is unclear. We speculated that there has been important interaction of MIP-1α with different activated MΦ, which might contribute to the pathogenesis of RPI.

Methods

Classically and alternatively activated MΦ were produced by stimulating murine MΦ cell line RAW 264.7 cells with three different stimuli (LPS, IL-4 and IL-13); Then we used recombinant MIP-1α to attract two types of activated MΦ. In addition, we measured the ability of two types of activated MΦ to produce MIP-1α at the protein or mRNA level.

Results

Chemotactic ability of recombinant MIP-1α toward IL-13-treated MΦ was the strongest, was moderate for IL-4-treated MΦ, and was weakest for LPS-stimulated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to secrete MIP-1α was significantly stronger than that of IL-4-treated or IL-13-treated MΦ (p < 0.01). The ability of LPS-stimulated MΦ to express MIP-1α mRNA also was stronger than that of IL-4- or IL-13-stimulated MΦ (p < 0.01).

Conclusions

The chemotactic ability of MIP-1α toward alternatively activated MΦ (M2) was significantly greater than that for classically activated MΦ (M1). Meanwhile, both at the mRNA and protein level, the capacity of M1 to produce MIP-1α is better than that of M2. Thus, chemokine MIP-1α may play an important role in modulating the transition from radiation pneumonitis to pulmonary fibrosis in vivo, through the different chemotactic affinity for M1 and M2.

The intermediate-conductance calcium-activated potassium channel KCa3.1 contributes to atherogenesis in mice and humans

Atherosclerosis remains a major cause of death in the developed world despite the success of therapies that lower cholesterol and BP. The intermediate-conductance calcium-activated potassium channel KCa3.1 is expressed in multiple cell types implicated in atherogenesis, and pharmacological blockade of this channel inhibits VSMC and lymphocyte activation in rats and mice. We found that coronary vessels from patients with coronary artery disease expressed elevated levels of KCa3.1. In Apoe(-/-) mice, a genetic model of atherosclerosis, KCa3.1 expression was elevated in the VSMCs, macrophages, and T lymphocytes that infiltrated atherosclerotic lesions. Selective pharmacological blockade and gene silencing of KCa3.1 suppressed proliferation, migration, and oxidative stress of human VSMCs. Furthermore, VSMC proliferation and macrophage activation were reduced in KCa3.1(-/-) mice. In vivo therapy with 2 KCa3.1 blockers, TRAM-34 and clotrimazole, significantly reduced the development of atherosclerosis in aortas of Apoe(-/-) mice by suppressing VSMC proliferation and migration into plaques, decreasing infiltration of plaques by macrophages and T lymphocytes, and reducing oxidative stress. Therapeutic concentrations of TRAM-34 in mice caused no discernible toxicity after repeated dosing and did not compromise the immune response to influenza virus. These data suggest that KCa3.1 blockers represent a promising therapeutic strategy for atherosclerosis.

The role of chemokines as inflammatory mediators in chronic hepatitis C virus infection

Hepatitis C virus (HCV) is a leading cause of chronic liver disease that can progress to cirrhosis and/or hepatocellular carcinoma. Intrahepatic inflammation and liver cell injury are defining features of chronic HCV infection. Chemokines, chemotactic cytokines that attract leucocytes to inflammatory sites, may be important in the development of intrahepatic inflammation. As T-helper (Th)1 inflammatory cells, characterized by interferon (IFN)-gamma and interleukin (IL)-2 secretion, predominate in the liver during chronic HCV infection, chemokines that attract these cells might be particularly important in disease progression. In this review, we focus on the role of Th1 chemokines, which are all members of the CXC or CC subfamilies. Among the CXC chemokines, the non-ELR group comprised of IFN-gamma-inducible protein 10 (IP-10), monokine induced by IFN-gamma (Mig) and IFN-inducible T-cell-alpha chemoattractant (I-TAC), attract Th1 cells through the interaction with their receptor, CXCR3. Among the CC subfamily, Th1-associated chemokines include regulated upon activation, normal T-cell expressed and secreted (RANTES) and macrophage inflammatory proteins (MIP)1alpha and beta. These chemokines attract cells through an interaction with their receptor, CCR5. While peripheral blood and intrahepatic levels of all of these chemokines are elevated in chronic hepatitis C patients, only select chemokines have been found to be correlated with hepatic inflammation. Among the six chemokines, IP-10 has uniquely been shown to have prognostic utility as a marker of treatment outcome. In the future, chemokines might be used to monitor the natural course and progression of HCV-associated liver disease, to identify patients with a high likelihood of achieving a therapeutic response, and they may even have potential as therapeutic targets.

K-ras activation generates an inflammatory response in lung tumors

Activating mutations in K-ras are one of the most common genetic alterations in human lung cancer. To dissect the role of K-ras activation in bronchial epithelial cells during lung tumorigenesis, we created a model of lung adenocarcinoma by generating a conditional mutant mouse with both Clara cell secretory protein (CC10)-Cre recombinase and the Lox-Stop-Lox K-ras(G12D) alleles. The activation of K-ras mutant allele in CC10 positive cells resulted in a progressive phenotype characterized by cellular atypia, adenoma and ultimately adenocarcinoma. Surprisingly, K-ras activation in the bronchiolar epithelium is associated with a robust inflammatory response characterized by an abundant infiltration of alveolar macrophages and neutrophils. These mice displayed early mortality in the setting of this pulmonary inflammatory response with a median survival of 8 weeks. Bronchoalveolar lavage fluid from these mutant mice contained the MIP-2, KC, MCP-1 and LIX chemokines that increased significantly with age. Cell lines derived from these tumors directly produced MIP-2, LIX and KC. This model demonstrates that K-ras activation in the lung induces the elaboration of inflammatory chemokines and provides an excellent means to further study the complex interactions between inflammatory cells, chemokines and tumor progression.

State of the Art in Burn Treatment

Optimal treatment of burn victims requires deep understanding of the profound pathophysiological changes occurring locally and systemically after injury. Accurate estimation of burn size and depth, as well as early resuscitation, is essential. Good burn care includes also cleansing, debridement, and prevention of sepsis. Wound healing, is of major importance to the survival and clinical outcome of burn patients. An ideal therapy would not only promote rapid healing but would also act as an antiscarring therapy. The present article is a literature review of the most up-to-date modalities applied to burn treatment without overlooking the numerous controversies that still persist.

Insulin Receptor Substrate-1/SHP-2 Interaction, a Phenotype-dependent Switching Machinery of Insulin-like Growth Factor-I Signaling in Vascular Smooth Muscle Cells

Insulin-like growth factor-I (IGF-I) plays a role in mutually exclusive processes such as proliferation and differentiation in a variety of cell types. IGF-I is a potent mitogen and motogen for dedifferentiated vascular smooth muscle cells (VSMCs) in vivo and in vitro. However, in differentiated VSMCs, IGF-I is only required for maintaining the differentiated phenotype. Here we investigated the VSMC phenotype-dependent signaling and biological processes triggered by IGF-I. In differentiated VSMCs, IGF-I activated a protein-tyrosine phosphatase, SHP-2, recruited by insulin receptor substrate-1 (IRS-1). The activated SHP-2 then dephosphorylated IRS-1 Tyr(P)-895, resulting in blockade of the pathways from IRS-1/Grb2/Sos to the ERK and p38 MAPK. Conversely, such negative regulation was silent in dedifferentiated VSMCs, where IGF-I activated both MAPKs via IRS-1/Grb2/Sos interaction-linked Ras activation, leading to proliferation and migration. Thus, our present results demonstrate that the IRS-1/SHP-2 interaction acts as a switch controlling VSMC phenotype-dependent IGF-I-induced signaling pathways and biological processes, and this mechanism is likely to be applicable to other cells.

Synthesis of immune modulators by smooth muscles

The primary function of smooth muscle cells is to contract and alter the stiffness or diameter of hollow organs such as blood vessels, the airways and the gastrointestinal and urogenital tracts. In addition to purely structural functions, smooth muscle cells may play important metabolic roles, particularly in various inflammatory responses. In cell culture, these cells have been shown to be metabolically dynamic, synthesizing and secreting extracellular matrix proteins, glycosaminoglycans and a wide variety of cell-cell signaling proteins, such as interleukins, chemokines and peptide growth factors. Secreted cell signaling proteins participate in the inflammatory response of smooth muscle-containing organs, and some can also stimulate smooth muscle migration, proliferation and contraction. The cellular signaling pathways controlling synthesis of these signaling proteins are similar to those used by cells mediating innate immunity and may contribute to pathogenesis of diverse diseases including atherosclerosis, asthma, inflammatory bowel diseases and preterm labor. Appreciating the role of smooth muscle cells in these diseases may lead to better understanding of the beneficial effects of anti-inflammatory drugs as well as identification of new targets for anti-inflammatory therapy.

Long-term suppression of tumor growth by TNF requires a Stat1- and IFN regulatory factor 1-dependent IFN-gamma pathway but not IL-12 or IL-18

Tumor cells engineered to secrete TNF were used as a model to examine how persistently high local concentrations of TNF suppress tumor growth. TNF secretion had no effect on tumor cell proliferation in vitro but caused a very impressive growth arrest in vivo that was dependent on both bone marrow- and non-bone marrow-derived host cells expressing TNFR. Suppression also required an endogenous IFN-gamma pathway consisting minimally of IFN-gamma, IFN-gamma receptor, Stat1, and IFN regulatory factor 1 since mice with targeted disruption of any of the four genes failed to arrest tumor growth. The ability of these mice to suppress tumor growth was restored after they were reconstituted with bone marrow cells from Wt mice. Interestingly, mice lacking the major IFN-gamma-inducing cytokines IL-12 and IL-18 or T cells, B cells, and the majority of NK cells that are potential sources of IFN-gamma nevertheless inhibited tumor development. Moreover, multiple lines of evidence indicated that local release of IFN-gamma was not required to inhibit tumor formation. These results strongly suggest a novel function for the endogenous IFN-gamma pathway that without measurable IFN-gamma production or activity affects the ability of TNF to suppress tumor development.

Biopsy neutrophilia, neutrophil chemokine and receptor gene expression in severe exacerbations of chronic obstructive pulmonary disease

We have applied immunohistology and in situ hybridization to bronchial biopsies of patients with chronic obstructive pulmonary disease (COPD) to examine neutrophil recruitment and to determine neutrophil chemoattractant and CXC receptor (CXCR) 1 and CXCR2 gene expression associated with acute severe exacerbations. Cells were counted in endobronchial biopsies of (1) patients with COPD intubated for exacerbations (E-COPD; n = 15), (2) those with COPD in a stable phase of their disease (S-COPD; n = 7), and (3) nonsmoker surgical control subjects intubated for a nonrespiratory surgical procedure (n = 15). In comparison with the nonrespiratory surgical procedure and S-COPD groups, neutrophilia and gene expression for epithelial-derived neutrophil attractant-78 (CXCL5), interleukin-8 (CXCL8), CXCR1, and CXCR2 were each upregulated in the E-COPD group (p < 0.01); compared with the S-COPD group, by 97-, 6-, 6-, 3-, and 7-fold, respectively (p < 0.01). In E-COPD, there was a significant positive association between the number of neutrophils and CXCR2 mRNA-positive cells (r = 0.79; p < 0.01) but not between the number of neutrophils and CXCR1 mRNA-positive cells. At the time of sampling of the mucosa, there was no association between neutrophil number and either the length of intubation or viral infection. Thus, in COPD, in addition to CXCL8 and CXCR1, CXCL5 and CXCR2 appear to play important roles in the airway neutrophilia characteristic of severe exacerbations.

Induction of C-X-C chemokines, growth-related oncogene alpha expression, and epithelial cell-derived neutrophil-activating protein-78 by ML-1 (interleukin-17F) involves activation of Raf1-mitogen-activated protein kinase kinase-extracellular signal-regulated kinase 1/2 pathway

Neutrophil recruitment into the airway typifies pulmonary inflammation and is regulated through chemokine network, in which two C-X-C chemokines play a critical role. Airway epithelial cells and vein endothelial cells are major cell sources of chemokines. ML-1 (interleukin-17F) is a recently discovered cytokine and its function still remains elusive. In this report, we investigated the functional effect of ML-1 in the expression of growth-related oncogene (GRO)alpha and epithelial cell-derived neutrophil activating protein (ENA)-78. The results showed first that ML-1 induces, in time- and dose-dependent manners, the gene and protein expressions for both chemokines in normal human bronchial epithelial cells and human umbilical vein endothelial cells. Furthermore, selective mitogen-activated protein kinase kinase (MEK) inhibitors 2'-amino-3'-methoxyflavone (PD98059), 1,4-diamino-2,3-dicyano-1,4-bis(o-aminophenylmercapto) butadiene (U0126), and Raf1 kinase inhibitor I partially inhibited Ml-1-induced GROalpha and ENA-78 production. In contrast, the combination of PD98059 and Raf1 kinase inhibitor I completely abrogated the chemokine production, whereas a protein kinase C inhibitor, 2-(1-(3-aminopropyl) indol-3-yl)-3-(1-methylindol-3-yl) maleimide, acetate (Ro-31-7549), and a phosphatidylinositol 3-kinase inhibitor, 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one (LY294002), did not affect their production. Together, these data indicates a role for Raf1-MEK-extracellular signal-regulated kinase 1/2 pathway in ML-1 induced C-X-C chemokine expression, suggesting potential pharmacological targets for modulation.

Human alveolar wall fibroblasts directly link epithelial type 2 cells to capillary endothelium

Alveolar wall fibroblasts directly link type 2 (T2) pneumocytes to capillary endothelium through apertures in their respective basal laminae in rabbit lung. These fibroblasts provide a bridge from the capillary to the airway lumen along which leukocytes may migrate without disrupting extracellular matrix. Normal human lungs were examined by transmission electron microscopy and serial section 3D reconstruction. We found contacts between fibroblasts and T2 pneumocytes and between fibroblasts and type 1 pneumocytes that occur at holes in the epithelial basal lamina. The same fibroblast also made contact with pericytes and endothelial cells through similar apertures. A survey of 41 T2 pneumocytes revealed that 54% of T2 pneumocytes had at least one gap in their basal lamina. A morphometric analysis showed these gaps occupied approximately 5.58 +/- 1.51% (mean +/- SE) of the area underneath T2 pneumocytes. We conclude that a population of single fibroblasts link T2 pneumocytes to adjacent capillary endothelial cells in alveolar walls of human lung. We propose that fibroblasts are organized to maintain communication between epithelium and mesenchyme and to provide directional information to migrating leukocytes.

The CXC chemokine GCP-2/CXCL6 is predominantly induced in mesenchymal cells by interleukin-1beta and is down-regulated by interferon-gamma: comparison with interleukin-8/CXCL8

Human granulocyte chemotactic protein-2 (GCP-2)/CXCL6 is a CXC chemokine that functionally uses both of the IL-8/CXCL8 receptors to chemoattract neutrophils but that is structurally most related to epithelial cell-derived neutrophil attractant-78 (ENA-78)/CXCL5. This study provides the first evidence that GCP-2 protein is, compared with IL-8, weakly produced by some sarcoma, but less by carcinoma cells, and is tightly regulated in normal mesenchymal cells. IL-1beta was the predominant GCP-2 inducer in fibroblasts, chondrocytes, and endothelial cells, whereas IL-8 was equally well up-regulated in these cells by TNF-alpha, measles virus, or double-stranded RNA (dsRNA). In contrast, lipopolysaccharide (LPS) was a relatively better stimulus for GCP-2 versus IL-8 in fibroblasts. IFN-gamma down-regulated the GCP-2 production in fibroblasts induced by IL-1beta, TNF-alpha, LPS, or dsRNA. The kinetics of GCP-2 induction by IL-1beta, LPS, or dsRNA in fibroblasts differed from those of IL-8. Freshly isolated peripheral blood mononuclear leukocytes, which are a good source of IL-8 and ENA-78, failed to produce GCP-2. However, lung macrophages and blood monocyte-derived macrophages produced GCP-2 in response to LPS. Quantitatively, secretion of GCP-2 always remained inferior to that of IL-8, despite the fact that the ELISA recognized all posttranslationally modified GCP-2 isoforms. The expression of GCP-2 was confirmed in vivo by immunohistochemistry. The patterns of producer cell types, inducers and kinetics and the quantities of GCP-2 produced, suggest a unique role for GCP-2 in physiologic and pathologic processes.

The effects of repeated dosing with 7.5% sodium chloride/6% dextran following uncontrolled intra-abdominal hemorrhage

The use of hypertonic saline Dextran (HSD) for resuscitation following trauma has many potential benefits, especially for the treatment of military casualties, but there is very limited data on the responses following multiple dosing with this fluid. The effects of a second dose of hypertonic saline dextran for resuscitation of uncontrolled intra-abdominal haemorrhage were studied in an experimental model. Under general anaesthesia, 17 large white pigs (weight range, 48-67 kg) were subjected to uncontrolled hemorrhage produced by a tear in the common iliac artery. This resulted in a significant (P < 0.01) reduction of both mean arterial pressure (MAP) and cardiac index. One hour after injury, animals were assigned to one of three groups, receiving either no resuscitation (Group A), or two doses of HSD (at a dose rate of 4 mL/kg), administered either 1 and 4 h after injury (Group B) or 1 and 7 h after injury (Group C). Animals were monitored for 12 h post-injury. A second infusion of HSD caused a significant hypernatremia and diuresis (P< 0.01) in both Groups B and C. There was a non-significant rise in MAP in both treatment groups, and in Group B only, there was a significant increase in cardiac index (P= 0.014). It is concluded that repeat administration of HSD for the resuscitation of uncontrolled hemorrhage results in limited cardiovascular improvements, but that the metabolic sequelae are potentially detrimental to survival.

Interleukin-8 expression by fetal and neonatal pulmonary cells in hyaline membrane disease and amniotic infection

IL-8, a chemokine with striking neutrophil-activating properties, is important in the pathogenesis of various disorders of the adult lung. Little is known about its production and possible role in fetal and neonatal lung disorders. We therefore examined IL-8 expression by immunohistochemistry in lung tissue from neonates with hyaline membrane disease, from fetuses with amniotic infection, and from a fetal control group with noninflammatory diseases. In the majority of cases with hyaline membrane disease, intense IL-8 immunoreaction was seen in fetal and neonatal neutrophils and in almost half of these cases, in epithelial cells of the terminal airways as well as in the connective tissue cell compartment. In contrast, in the amniotic infection group, strong IL-8 immunostaining was almost exclusively seen in maternal aspirated neutrophils. Little or no IL-8 signal was seen in the control cases in all cell types examined. Also, no IL-8 production by fetal lung cells was detected in fetuses <18 wk of gestation. The marked presence of IL-8 in all cell types of the lung in hyaline membrane disease cases indicates a role for IL-8 in the pathobiology of hyaline membrane disease possibly similar to that in adult respiratory distress syndrome. It further suggests that the cytokine network of the fetal lung is already well developed by the second trimester of pregnancy.

Burn resuscitation with two doses of 4 mL/kg hypertonic saline dextran provides sustained fluid sparing: a 48-hour prospective study in conscious sheep

BACKGROUND

The large fluid volumes usually required for burn resuscitation can be suppressed for 8 to 12 hours by intravenous infusion of 4 mL x kg(-1) hypertonic saline dextran (HSD) 1 hour after burn. We hypothesized that a double (8 mL x kg(-1)) dose of HSD or two repeated doses of 4 mL x kg(-1) could enhance or prolong the volume sparing.

METHODS

We produced a full-thickness flame burn covering 40% of the body surface on 18 anesthetized sheep. One hour after the burn, the animals were awake and resuscitated with either (1) lactated Ringer's solution (LR) only, (2) 8 mL x kg(-1) HSD followed by LR, or (3) 4 mL x kg(-1) HSD followed by LR, with a second dose of 4 mL x kg(-1) HSD administered when net fluid accumulation increased to 20 mL x kg(-1). For all regimens, infusion rates were adjusted to produce a urine output of 1 to 2 mL x kg(-1) x h(-1).

RESULTS

Animals resuscitated with only LR required fluid volumes identical to that predicted by the Parkland formula for the first 12 hours. Infusion of 8 mL x kg(-1) HSD initially created a net fluid loss (urine output > infused volume), followed by a rebound fluid requirement eventually equaling that of animals treated with LR only. Animals treated with two separate doses of 4 mL x kg(-1) HSD generally did not experience a net fluid loss or a rebound fluid requirement. Also in the HSD x 2 group, peak and net fluid accumulation was less than that of the other two groups from 18 hours through 48 hours, although the difference was not significant.

CONCLUSION

An initial 4 mL x kg(-1) dose of HSD reduces fluid requirements early after burn, and a second dose administered after an appropriate interval may prolong volume sparing through 48 hours. An 8 mL x kg(-1) continuously infused initial dose was without prolonged fluid sparing effect. The volume-sparing effect of HSD is thus dependent on all of the following: dose, dosing interval, and infusion rate.

c-Myb-binding sites mediate G(1)/S-associated repression of the plasma membrane Ca(2+)-ATPase-1 promoter

We demonstrate that two Myb-binding sites of the mouse plasma membrane Ca(2+)-ATPase-1 (PMCA1) promoter are required for G(1)/S cell cycle stage-associated repression of PMCA1 promoter activity. Nuclear run-on experiments revealed G(1)/S-associated repression of PMCA1 transcription. Ribonuclease protection assays revealed two transcription initiation sites between two Myb-binding sites in the PMCA1 promoter. Gel shift assays showed that c-Myb can bind to wild-type but not point mutated Myb binding sequences of the PMCA1 promoter. Transient transfection assays using cell cycle-synchronized vascular smooth muscle cells (VSMC) and PMCA1 promoter-luciferase constructs showed a 2-fold decrease in reporter activity at G(1)/S as compared with G(0). Overexpression of wild-type c-Myb severely repressed PMCA1 promoter activity at both G(0) and G(1)/S while co-transfection of a dominant negative c-Myb, or a construct encoding an anti-c-Myb neutralizing antibody, completely abolished the repression seen at G(1)/S. Single nucleotide substitutions in the first, second, or both Myb-binding sites alleviated the G(1)/S-associated repression of PMCA1 promoter activity in transformed rat VSMC and primary mouse VSMC cultures. We conclude that c-Myb mediates G(1)/S-associated transcriptional repression of the PMCA1 Ca(2+) pump in rodent VSMC by direct binding to the PMCA1 promoter.

v-Myb can transform and regulate the differentiation of melanocyte precursors

The activity of the c-Myb transcription factor is essential for the development of definitive multi- and uni-lineage progenitors of the haemopoietic system. Reflecting this requirement, c-Myb has been oncogenically activated by transduction in the E26 avian retrovirus which elicits an acute leukaemia by transforming haemopoietic progenitors. Here, we report the novel finding that Myb in cooperation with EGF receptor signalling can be used to generate clonally expanded populations of transformed cells which have the phenotype of melanocyte precursors. Through the use of a conditional temperature sensitive mutant of Myb, we show that in the transformed cells Myb regulates commitment to melanocyte differentiation and possibly proliferation. These results add to our understanding of the roles of c-Myb beyond the haemopoietic system and to our knowledge and means of investigating the importance of transcription factors in the melanocyte lineage.

Comparison of the acute hemodynamic effects of hypertonic or colloid infusions immediately after mitral valve repair

OBJECTIVE

To determine the acute hemodynamic effect of hypertonic saline and/or colloid solutions as volume resuscitation in postoperative mitral valve repair patients.

DESIGN

Prospective, randomized trial.

SETTING

Postoperative cardiac intensive care unit of Broussais Hospital.

PATIENTS

Twenty-six patients who underwent mitral valve repair were prospectively studied. Two patients were excluded during the study.

INTERVENTIONS

During the immediate postoperative period, when wedge pressure decreases to <8 mm Hg, patients were randomly assigned to receive 250 mL of either hypertonic saline 7.2%-hydroxyethyl starch 6% (molecular weight, 200,000; hydroxyethylation ratio, 0.5) solution (HS-HES group), hypertonic saline 7.2% solution (HS group), or hydroxyethyl starch 6% solution (HES group). The infusion was completed within 15 mins. No additional volume was infused throughout the study.

MEASUREMENTS AND MAIN RESULTS

Standard hemodynamic measurements and echocardiographic data demonstrated that HS-HES and HS induced a higher increase in left ventricular end-diastolic area than HES. In the HS-HES and HS groups, systemic vascular resistances decreased significantly and end-systolic area tended to decrease. In the HES group, systemic vascular resistances did not change and end-systolic area tended to increase. Accordingly, ejection fraction increased significantly by 21% and 18% with HS-HES (from 50.5 +/- 5.5 to 61.2 +/- 4.8) and HS (from 49.7 +/- 3.6 to 58.8 +/- 3.3), respectively, and did not change with HES. A major increase in cardiac index was observed after hypertonic solutions infusion, from 2.9 +/- 0.3 to 4.1 +/- 0.4 L/min/m2 in the HS-HES group and from 2.7 +/- 0.3 to 3.8 +/- 0.4 L/min/m2 in the HS group. Then, cardiac index progressively returned to baseline values within the 3 hrs after the infusion. No significant difference was observed between HS-HES and HS. In these groups, plasma sodium increased significantly after the infusion and remained higher than baseline values throughout the study. Adverse events were observed only with hypertonic solution administration: hypotensive episodes, sudden increases in pulmonary capillary wedge pressure, and ventricular arrhythmias. These side effects are likely attributable to a too-high dose and/or rate of infusion. All patients included in the study were discharged from the hospital before the 10th postoperative day.

CONCLUSION

We conclude that in patients who have undergone mitral valve repair, postoperative infusion of hypertonic saline solutions increases left ventricular preload and left ventricular ejection fraction. The use of these hypertonic solutions may be of interest in patients with valvular cardiomyopathy. A titrated dose and a low rate of infusion may substantially improve the safety.

Myb targeted therapeutics for the treatment of human malignancies

For the past several years, we have been engaged in developing a therapeutically effective strategy for disrupting gene function with reverse complementary, or so called 'antisense', oligodeoxynucleotides (ODN). This pursuit has focused on finding appropriate diseases in which to apply this approach, and suitable gene targets. Of the genes that we have targeted for disruption using the antisense ODN strategy (Clevenger et al., 1995; Gewirtz and Calabretta, 1988; Ratajczak et al., 1992c; Small et al., 1994) one that has been of particular interest, and one where therapeutically motivated disruptions are now in clinical trial, is the myb gene (reviewed in Lyon et al., 1994). These trials involve treatment of human leukemias. These diseases are a logical choice for developing oncogene targeted therapies because of easy access to tissues, and the abundance of knowledge about the cell and molecular biology of these diseases. Nevertheless, as will be touched on below, other malignancies have also been examined as models for Myb targeted therapy with some surprisingly encouraging results. Finally, while we have focused our efforts on the ODN strategy, I will allude briefly to other strategies for disrupting Myb function with therapeutic intent.

Interleukin-4 (IL-4), but not IL-10, regulates the synthesis of IL-6, IL-8 and leukemia inhibitory factor by human bone marrow stromal cells

Leukemia inhibitory factor (LIF), interleukin 6 (IL-6) and IL-8 are important regulators of inflammation and hematopoiesis. Human bone marrow stromal cells regulate marrow hematopoiesis by secreting cytokines. By using reverse-transcriptase polymerase chain reaction (RT-PCR), we demonstrate that human bone marrow stromal cells constitutively express LIF, IL-6 and IL-8 transcripts. By using specific ELISAs, we found that their spontaneous productions of LIF, IL-6 and IL-8 are elevated in response to serum and after stimulation with the pro-inflammatory cytokines IL-1alpha and TNF-alpha. The anti-inflammatory cytokine IL-4 reduces their serum- and cytokine-induced LIF secretion. By contrast, IL-4 stimulates their serum- and IL-1alpha-induced IL-6 synthesis. IL-4 has no effect on the serum-induced IL-8 synthesis by marrow stromal cells, but stimulates their cytokine-induced IL-8 production. The anti-inflammatory cytokine IL-10 has no effect on the serum- and cytokine-induced LIF, IL-6 and IL-8 synthesis by bone marrow stromal cells. RT-PCR experiments reveal the presence of IL-4 receptor alpha-chain mRNA and IL-10 receptor mRNA in cultured bone marrow stromal cells. The differential regulation by IL-4 of two related cytokines, such as LIF and IL-6, and the enhanced effect of this 'anti-inflammatory' cytokine on IL-6 and IL-8 synthesis highlight the tightly controlled regulation and the complexity of the cytokine production within the human bone marrow.

Mucosal macrophage inflammatory protein-1alpha levels are increased in Helicobacter pylori infection

We examined the relationship between the levels of macrophage inflammatory protein 1alpha (MIP-1alpha) and interleukin-8 (IL-8) in organ cultures of antral mucosal tissues, background gastroduodenal diseases, and grades of histologic gastritis. Significantly higher levels of MIP-1alpha and IL-8 were detected in patients with H. pylori infection than in those without infection. In H. pylori-positive patients, mucosal specimens from patients with peptic ulcer disease showed higher levels of MIP-1alpha and IL-8 than the specimens obtained from patients with erosive gastritis or those from endoscopically normal mucosa, and this was particularly pronounced in patients with duodenal ulcer. There were positive correlations between MIP-1alpha and IL-8 levels and histologic grades of activity, inflammation, and H. pylori density as defined by the Sydney system. However, the degree of association with the inflammatory cell count was different between these two chemokines. MIP-1alpha levels had a stronger association with mononuclear cells than with neutrophils, whereas IL-8 levels showed an association with neutrophils and mononuclear cells to an almost equal degree. These results suggest that MIP-1alpha and IL-8 may play important roles as inflammatory mediators in the pathogenesis of histologically proven H. pylori-associated gastritis.

Myb-dependent regulation of thrombospondin 2 expression. Role of mRNA stability

The nuclear transcription factor c-Myb, which is highly expressed in hematopoietic cells, has been shown to be functional in NIH 3T3 cells: cells that do not possess detectable levels of c-Myb. To identify endogenous target genes of c-Myb in fibroblasts, RNA isolated from NIH 3T3 cells stably transfected with a full-length or a dominant negative c-myb construct (GREMyb and GREMEn, respectively) was subjected to differential display analysis. 5'-Rapid amplification of cDNA ends of a selected band, sequencing, and a nucleotide homology search led to the identification of thrombospondin 2 (TSP 2) as the gene product repressed in GREMyb and induced in GREMEn cells. The pattern of TSP 2 expression during the cell cycle was consistent with c-myb-dependent regulation. The possibility that the identified transcript was TSP 1, a homologous product known to be repressed by v-Src, c-Jun, and v-Myc, was ruled out by using a TSP 2-specific DNA probe and by showing a distinct pattern of regulation of TSP 1 and TSP 2 expression. Nuclear run-on and TSP 2 promoter-reporter (chloramphenicol acetyltransferase) assays showed similar transcriptional levels in GREMyb and NIH 3T3 cells. However, mRNA stability studies showed a much shorter TSP 2 mRNA half-life in GREMyb compared with wild type NIH 3T3 cells, suggesting that c-myb affects TSP 2 expression via a post-transcriptional mechanism. The implications of a protooncogene-mediated suppression of TSP expression are discussed.

Possible involvement of m-calpain in vascular smooth muscle cell proliferation

Vascular smooth muscle cell (VSMC) proliferation still remains a poorly understood process, although it is believed to play a critical role in pathological states, including atherosclerosis and hypertension. Several reports have suggested that proteases may be directly involved in this process; however, it was still unclear which protease is responsible for VSMC proliferation. In this study, by use of a cell-permeable calpain inhibitor (calpeptin; benzyloxycarbonyl-Leu-nLeu-H), its analogue (benzyloxycarbonyl-Leu-Met-H), the cell-impermeable serine protease inhibitor leupeptin, and antisense oligonucleotide against m-calpain to inhibit proliferation of primarily cultured human VSMCs, we investigated whether calcium-activated neutral protease (calpain) is involved in VSMC proliferation. Calpeptin and its analogue, more specific for m-calpain, equally inhibited the proliferation of VSMCs in a dose-related manner, whereas a more limited antiproliferative effect was observed in leupeptin-treated VSMCs. Antisense oligonucleotide against m-calpain, but not scrambled antisense, dose-dependently inhibited m-calpain expression and proliferation of VSMCs. Maximal inhibition was an approximately 50% reduction of cell number and m-calpain antigen observed at 50 micromol/L of antisense oligonucleotide. Calpeptin or antisense oligonucleotide against m-calpain increased the expression of the endogenous calpain substrate pp125FAK (focal adhesion kinase), whereas the expression of the endogenous calpain inhibitor calpastatin was not affected. These results suggest that the proliferation of VSMCs requires protease activity, some of which is due to m-calpain.

Chemokine receptor CXCR4 expression in endothelium

The expression of chemokine receptor and viral coreceptor CXCR4 is reported in cultured endothelial cells and in arterial endothelium. A 1.9 kb transcript was cloned from cultured bovine aortic (BAEC) and human umbilical vein endothelial cells (HUVEC). CXCR4 mRNA was expressed at high levels in BAEC and HUVEC but was not expressed by cultured bovine arterial smooth muscle cells (BASM) or human umbilical vein smooth muscle cells (HUVSM). Western blotting with polyclonal antibodies demonstrated an approximate 46KD protein in endothelial cells only. In situ hybridization and immunocytochemistry (anti-CXCR4 monoclonal antibody 12G5) revealed both transcript and protein expression in cultured endothelial cells, and in the endothelium of normal aorta but not in aortic smooth muscle. The ligand for CXCR4, stromal cell derived factor 1 (SDF-1) stimulated mobilization of intracellular calcium at a moderate level (37% of the peak response to thrombin), confirming the expression of functional receptor at the endothelial surface. The involvement of CXCR4 in chemokine signaling, chemoattraction (through SDF-1), and its potential viral coreceptor activity suggest a multifunctional role in vascular homeostasis and pathophysiology.

Effects of hypertonic saline and dextran 70 on cardiac contractility after hemorrhagic shock

OBJECTIVE

The effects of a bolus of 7.5% NaCl-6% dextran 70 (HSD) on cardiac contractility were evaluated in anesthetized sheep with hemorrhagic shock.

BACKGROUND

HSD has been shown to be effective at resuscitation in cases of hypovolemia caused by hemorrhage. Common hemodynamic findings after the injection of HSD in hemorrhagic shock are the restoration of cardiac output, increased blood pressure, and improvement of peripheral circulation. Some mechanisms by which HSD maintains circulation in hemorrhagic shock have been proposed: rapid shift of fluid from intracellular to extracellular space, improved peripheral perfusion, and increased cardiac contractility. Conflicting data exist, however, regarding the positive effect of HSD on cardiac contractility after hemorrhagic shock.

METHODS

Hemorrhagic shock was induced by shedding mean blood volume of 31.4 mL/kg, and mean blood pressure was maintained at 50 mm Hg for 30 minutes. The HSD group (n = 6) received HSD (4 mL/kg), and the saline group (n = 6) received normal saline (40 mL/kg) after shock. Cardiac functions were measured in both groups using the left ventricular end-systolic pressure-volume relationship and preload recruitable stroke work during the experimental period: before shock, immediately after the resuscitation, and 2 hours after resuscitation.

RESULTS

Hemodynamic parameters in both groups demonstrated similar changes throughout the experimental period without significant difference between the two groups. Not only the slopes of end-systolic pressure-volume relationship and preload recruitable stroke work but also their placements did not result in any significant differences between the groups.

CONCLUSION

HSD seems to be an effective resuscitation fluid after hemorrhagic shock because the volume required to maintain circulation is smaller than that of normal saline. Our data, however, show that HSD does not enhance cardiac contractility after hemorrhagic shock.

c-Myb function in fibroblasts

The protooncogene c-myb is a nuclear transcription factor that shares significant sequence homology with two other myb family members, A-myb and B-myb. Recent studies have suggested that c-myb is involved in regulation of the cell cycle via control of intracellular calcium [Ca2+]i concentration. Given the limited cell type expression of the c-myb gene, we set out to investigate whether myb-dependent cell cycle regulation occurs in cells not known to express the c-myb protein. NIH 3T3 fibroblasts were stably transfected with an inducible c-myb dominant negative construct composed of a myb DNA binding domain linked to the Drosophila engrailed transcription suppresser (pGREMEn) and a full-length murine c-myb cDNA sequence. Induced expression of the dominant negative construct was associated with a G1 cell cycle arrest and a failure to increase late G1 intracellular calcium levels. Similar expression studies in mouse embryonic fibroblasts derived from the c-myb knockout mouse have demonstrated lower baseline [Ca2+]i levels than in normal mice fibroblasts that were not further lowered by MEn expression. We conclude that regulation of calcium homeostasis and cell cycle progression via myb-dependent transcription may play an important role in cells not possessing detectable levels of c-myb protein.

Hypovolemic shock and cardiac contractility: assessment by end-systolic pressure-volume relations

The end-systolic pressure-volume relation (ESPVR) is accepted as a load-independent measure of cardiac contractility. Potential curvilinearity of the ESPVR, dependency on coronary perfusion pressure (CPP) and sensitivity to the type of loading intervention might limit its use in hemorrhagic shock. This study compared ESPVRs obtained by caval and aortic occlusion under physiological loading conditions at baseline with those obtained during hemorrhagic shock (mean arterial pressure 45 mmHg). The left ventricular (LV) pressure (tip manometer) and volume (conductance catheter) were measured in ten anesthetized pigs. ESPVRs were fitted to linear and quadratic models. Within end-systolic pressure (Pes) ranges obtained under baseline conditions, ESPVR displayed only minimal curvilinearity (second-order coefficient a < 0.007) and could be accurately described by a linear model. However, nonlinearity of ESPVRs obtained over wider load ranges is suggested by negative volume axis intercepts of the linear model. Steeper ESPVR with aortic than with caval occlusion (2.28 +/- 0.22 vs 3.41 +/- 0.51 mmHg/ml, ns) could not be proven owing to the large interindividual variance of ESPVR slopes with both loading interventions. During shock the Pes range obtained by caval occlusion decreased to very low levels (from 49 +/- 2 to 34 +/- 1 mmHg), ESPVR did not adequately fit either of the two models (mean R < 0.66), and critical reduction of CPP induced negative ESPVR slope in four of ten experiments. In contrast, aortic occlusion at shock resulted in linear ESPVR (R = 0.927 +/- 0.029), Pes ranges (92 +/- 3 to 58 +/- 4 mmHg) comparable to the ones obtained by caval occlusion at control (113 +/- 5 to 73 +/- 6 mmHg), and steeper ESPVR than at control (3.41 +/- 0.51 to 7.38 +/- 1.0 mmHg/ml, P < 0.05). Interpretation of the increased ESPVR slope obtained with aortic occlusion as due to increased contractility in shock is, however, complicated by different Pes ranges. It is concluded that within Pes ranges obtained with caval or aortic occlusion in situ the ESPVR can be adequately fitted to a linear model. For assessment of the inotropic response to shock the ESPVR is of limited value because (1) caval occlusion is not suitable to generate ESPVR during shock, and (2) Pes ranges obtained with identical loading interventions differ greatly between baseline and shock and, therefore, apparent ESPVR changes are influenced by the potential nonlinearity of the ESPVR. Combining caval occlusion at baseline with aortic occlusion at shock would result in comparable Pes ranges. Interpretation of results is, however, complicated by diverging effects of the different loading interventions on the shape and slope of the ESPVR.

Expression of the plasma membrane Ca2+-ATPase in myogenic cells

To study the physiological function of the plasma membrane calmodulin-dependent calcium ATPase (PMCA) in intact cells, L6 myogenic cell lines stably overexpressing the human PMCA isoform 4CI (= human PMCA isoform 4b) were generated. Several independent L6 clones and controls stably transfected with the empty expression vector were analyzed in detail. The resting cytosolic calcium level in hPMCA4CI-overexpressing muscle cells (measured by the Fura-2 method) was significantly reduced by 20-30% compared with controls. This was shown in a cytosolic window of 1322 single cells (p < 0.01). Furthermore, the differentiation process of these cells was remarkably accelerated compared with control myoblasts and parental nontransfected L6 cells as assessed by multinucleated myotube formation and creatine phosphokinase activity elevation. After 4 and 6 days of differentiation, PMCA-overexpressing L6 cells from four independent clones displayed a 3- and 4-fold higher creatine phosphokinase activity compared with controls (n = 5, p < 0.02). These results may extend the concept of the function of the PMCA from simple prevention of calcium overload to an active involvement in intracellular calcium regulation with potentially important consequences for cellular functions.

Interleukin-1 stimulates rapid release of cytokine-induced neutrophil chemoattractant (CINC) in rat lungs

We found that intratracheal insufflation of interleukin-1 alpha (IL-1) in rats rapidly increased lung lavage cytokine-induced neutrophil chemoattractant (CINC) concentrations, lung tissue myeloperoxidase (MPO) activity, and lung lavage neutrophil counts, and that CINC elevation preceded the migration of neutrophils into the lung. Further, we found that bolus CINC insufflation increased CINC concentrations in plasma, and we found that alveolar macrophages (AM) in lung tissue selections or AM recovered by lavage from rats given IL-1 intratracheally stained positively for CINC by immunohistochemistry. In addition, incubating rat AM with increasing doses of IL-1 in vitro progressively increased CINC concentrations in the culture medium. Our results suggest that the potent neutrophil chemoattractant CINC is rapidly produced and released by rat AM following challenge with IL-1 in vivo or in vitro, and support the hypothesis that CINC is an important mediator in the development of pulmonary inflammation in the rat.