p50-NF-kappaB complexes partially compensate for the absence of RelB: severely increased pathology in p50(-/-)relB(-/-) double-knockout mice.

RelB-deficient mice (relB(-/-)) have a complex phenotype including multiorgan inflammation and hematopoietic abnormalities. To examine whether other NF-kappaB/Rel family members are required for the development of this phenotype or have a compensatory role, we have initiated a program to generate double-mutant mice that are deficient in more than one family member. Here we report the phenotypic changes in relB(-/-) mice that also lack the p50 subunit of NF-kappaB (p50(-/-)). The inflammatory phenotype of p50(-/-)relB(-/-) double-mutant mice was markedly increased in both severity and extent of organ involvement, leading to premature death within three to four weeks after birth. Double-knockout mice also had strongly increased myeloid hyperplasia and thymic atrophy. Moreover, B cell development was impaired and, in contrast to relB(-/-) single knockouts, B cells were absent from inflammatory infiltrates. Both p50(-/-) and heterozygous relB(-/+) animals are disease-free. In the absence of the p50, however, relB(-/+) mice (p50(-/-)relB(-/+)) had a mild inflammatory phenotype and moderate myeloid hyperplasia. Neither elevated mRNA levels of other family members, nor increased kappaB-binding activities of NF-kappaB/Rel complexes could be detected in single- or double-mutant mice compared to control animals. These results indicate that the lack of RelB is, in part, compensated by other p50-containing complexes and that the "classical" p50-RelA-NF-kappaB activity is not required for the development of the inflammatory phenotype.

Nuclear factor (NF)-kappa B2 (p100/p52) is required for normal splenic microarchitecture and B cell-mediated immune responses.

The nfkb2 gene is a member of the Rel/NF-kappa B family of transcription factors. COOH-terminal deletions and rearrangements of this gene have been associated with the development of human cutaneous T cell lymphomas, chronic lymphocytic leukemias, and multiple myelomas. To further investigate the function of NF-kappa B2, we have generated mutant mice carrying a germline mutation of the nfkb2 gene by homologous recombination. NF-kappa B2-deficient mice showed a marked reduction in the B cell compartment in spleen, bone marrow, and lymph nodes. Moreover, spleen and lymph nodes of mutant mice presented an altered architecture, characterized by diffuse, irregular B cell areas and the absence of discrete perifollicular marginal and mantle zones; the formation of secondary germinal centers in spleen was also impaired. Proliferation of NF-kappa B2-deficient B cells was moderately reduced in response to lipopolysaccharide, anti-IgD-dextran, and CD40, but maturation and immunoglobulin switching were normal. However, nfkb2 (-/-) animals presented a deficient immunological response to T cell-dependent and -independent antigens. These findings indicate an important role of NF-kappa B2 in the maintenance of the peripheral B cell population, humoral responses, and normal spleen architecture.

Expression of the chemokine N51/KC in the thymus and epidermis of transgenic mice results in marked infiltration of a single class of inflammatory cells.

Transgenic mice expressing the chemokine N51/KC in thymus, skin, and tongue showed a marked infiltration of a single class of inflammatory cells (neutrophils) in the sites of transgene expression. In the thymus, neutrophils were most numerous in the cortex and juxta-medullary regions, often forming aggregates or clusters. A similar, but less intense, neutrophilic infiltrate occurred in close proximity to the epidermal basal layer of the tongue and skin. No morphologic evidence of injury was observed in the thymus, skin, or tongue of these transgenic mice, indicating that N51/KC expression induces recruitment but not inflammatory activation of neutrophils. The lack of activation in the thymus resulted in a large senescent neutrophilic population that was phagocytosed by thymic macrophages and epithelial-reticular cells. These results indicate that N51/KC is a neutrophil chemoattractant in vivo and establish these transgenic mice as effective models to study the phenomena of recruitment and clearance of neutrophils, events that are critical for the initiation and resolution of the inflammatory response.

High transverse momentum triggered correlations over a large pseudorapidity acceptance in Au + Au collisions at square root(s(NN)) = 200 GeV.

A measurement of two-particle correlations with a high transverse momentum trigger particle (p(T)(trig) > 2.5 GeV/c) is presented for Au+Au collisions at square root(s(NN)) = 200 GeV over the uniquely broad longitudinal acceptance of the PHOBOS detector (-4 < Delta eta < 2). A broadening of the away-side azimuthal correlation compared to elementary collisions is observed at all Delta eta. As in p+p collisions, the near side is characterized by a peak of correlated partners at small angle relative to the trigger particle. However, in central Au+Au collisions an additional correlation extended in Delta eta and known as the "ridge" is found to reach at least |Delta eta| approximately = 4. The ridge yield is largely independent of Delta eta over the measured range, and it decreases towards more peripheral collisions. For the chosen (p(T)(trig) cut, the ridge yield is consistent with zero for events with less than roughly 100 participating nucleons.

Event-by-event fluctuations of azimuthal particle anisotropy in Au+Au collisions at square root(sNN) = 200 GeV.

This Letter presents the first measurement of event-by-event fluctuations of the elliptic flow parameter v(2) in Au+Au collisions at square root(s(NN))=200 GeV as a function of collision centrality. The relative nonstatistical fluctuations of the v(2) parameter are found to be approximately 40%. The results, including contributions from event-by-event elliptic flow fluctuations and from azimuthal correlations that are unrelated to the reaction plane (nonflow correlations), establish an upper limit on the magnitude of underlying elliptic flow fluctuations. This limit is consistent with predictions based on spatial fluctuations of the participating nucleons in the initial nuclear overlap region. These results provide important constraints on models of the initial state and hydrodynamic evolution of relativistic heavy ion collisions.

Amelioration of ischemia/reperfusion injury in isolated rats hearts by the ATP-sensitive potassium channel opener BMS-180448.

OBJECTIVE: Aims of this study were: (1) Evaluate by morphology and specific physiological and biochemical parameters, the protective effects of the cardioselective ATP-sensitive potassium channel opener BMS-180448 on ischemic/reperfused isolated rat heart, and (2) Determine the earliest time point ischemia-induced myocardial injury is observed by light microscopy. METHODS: Hearts from Sprague-Dawley rats were perfused on a Langendorff apparatus. After equilibration, hearts were treated with BMS-180448 (10 micro M) or vehicle (0.04% DMSO) for 10 min before the onset of ischemia. Four hearts/group were collected following 10, 18, or 25 min of ischemia. A nonischemic control group was also evaluated. Following 25 min of ischemia, another set of hearts was reperfused with oxygenated Krebs-Hensleit solution and allowed to recover for 30 min. Light and electron microscopic changes of the myocardium were semi-quantitatively evaluated together with physiological (i.e., heart rate, left ventricular diastolic pressure, time to contracture formation) and biochemical (i.e., lactate dehydrogenase, LDH, release) endpoints. RESULTS: Cardioprotective effects of BMS-180448 following ischemia/reperfusion consisted of a reduced rate of contracture formation, reduced LDH release, and enhanced recovery of contractile function during reperfusion (P < 0.05). Light microscopic evidence of myocardial damage was detected following 18 min of ischemia. Morphological changes in ischemic/reperfused hearts included interstitial edema, myofiber degeneration, and hypercontraction band formation. Ultrastructurally, swollen myofibrils, swollen mitochondria with disrupted cristae and electron-dense deposits, myofibrillar lysis, and contraction bands, were observed. Light and electron microscopic severity scores were significantly less (P < 0.05) in BMS-180448-treated hearts at the 25 min ischemic time point and in reperfused hearts, as compared to similarly-treated vehicle hearts. CONCLUSIONS: BMS-180448 ameliorates morphological evidence of ischemia/reperfusion myocardial damage in the isolated rat heart model, in agreement with physiological and biochemical parameters.

System size, energy, and centrality dependence of pseudorapidity distributions of charged particles in relativistic heavy-ion collisions.

We present the first measurements of the pseudorapidity distribution of primary charged particles in Cu+Cu collisions as a function of collision centrality and energy, sqrt[s_{NN}]=22.4, 62.4, and 200 GeV, over a wide range of pseudorapidity, using the PHOBOS detector. A comparison of Cu+Cu and Au+Au results shows that the total number of produced charged particles and the rough shape (height and width) of the pseudorapidity distributions are determined by the number of nucleon participants. More detailed studies reveal that a more precise matching of the shape of the Cu+Cu and Au+Au pseudorapidity distributions over the full range of pseudorapidity occurs for the same N{part}/2A rather than the same N_{part}. In other words, it is the collision geometry rather than just the number of nucleon participants that drives the detailed shape of the pseudorapidity distribution and its centrality dependence at RHIC energies.

System size, energy, pseudorapidity, and centrality dependence of elliptic flow.

This Letter presents measurements of the elliptic flow of charged particles as a function of pseudorapidity and centrality from Cu-Cu collisions at 62.4 and 200 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider. The elliptic flow in Cu-Cu collisions is found to be significant even for the most central events. For comparison with the Au-Au results, it is found that the detailed way in which the collision geometry (eccentricity) is estimated is of critical importance when scaling out system-size effects. A new form of eccentricity, called the participant eccentricity, is introduced which yields a scaled elliptic flow in the Cu-Cu system that has the same relative magnitude and qualitative features as that in the Au-Au system.

Energy dependence of directed flow over a wide range of pseudorapidity in Au + Au collisions at the BNL Relativistic Heavy Ion Collider.

We report on measurements of directed flow as a function of pseudorapidity in Au + Au collisions at energies of square root of SNN = 19.6, 62.4, 130 and 200 GeV as measured by the PHOBOS detector at the BNL Relativistic Heavy Ion Collider. These results are particularly valuable because of the extensive, continuous pseudorapidity coverage of the PHOBOS detector. There is no significant indication of structure near midrapidity and the data surprisingly exhibit extended longitudinal scaling similar to that seen for elliptic flow and charged particle pseudorapidity density.

System size and centrality dependence of charged hadron transverse momentum spectra in Au + Au and Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV.

We present transverse momentum distributions of charged hadrons produced in Cu + Cu collisions at square root of SNN = 62.4 and 200 GeV. The spectra are measured for transverse momenta of 0.25 < pT < 5.0 GeV/c at square root of SNN = 62.4 GeV and 0.25 < pT < 7.0 GeV/c at square root of SNN = 200 GeV, in a pseudorapidity range of 0.2 < eta < 1.4. The nuclear modification factor R(AA) is calculated relative to p + p data at both collision energies as a function of collision centrality. At a given collision energy and fractional cross section, R(AA) is observed to be systematically larger in Cu + Cu collisions compared to Au + Au. However, for the same number of participating nucleons, R(AA) is essentially the same in both systems over the measured range of pT, in spite of the significantly different geometries of the Cu + Cu and Au + Au systems.

Centrality dependence of charged hadron transverse momentum spectra in Au+Au collisions from sqrt[s(NN)]=62.4 to 200 GeV.

We have measured transverse momentum distributions of charged hadrons produced in Au+Au collisions at sqrt[s(NN)]=62.4 GeV. The spectra are presented for transverse momenta 0.25

Energy dependence of elliptic flow over a large pseudorapidity range in Au+Au collisions at the BNL relativistic heavy ion collider.

This Letter describes the measurement of the energy dependence of elliptic flow for charged particles in Au+Au collisions using the PHOBOS detector at the Relativistic Heavy Ion Collider. Data taken at collision energies of square root of s(NN)=19.6, 62.4, 130, and 200 GeV are shown over a wide range in pseudorapidity. These results, when plotted as a function of eta(')=|eta|-y(beam), scale with approximate linearity throughout eta('), implying no sharp changes in the dynamics of particle production as a function of pseudorapidity or increasing beam energy.

Both multiorgan inflammation and myeloid hyperplasia in RelB-deficient mice are T cell dependent.

Mice with a targeted disruption of RelB, a member of the Rel/NF-kappaB family of transcription factors, have multifocal, mixed inflammatory cell infiltration in several organs, myeloid hyperplasia, and splenomegaly due to extramedullary hemopoiesis. To elucidate the cellular requirements for this complex phenotype, we have bred RelB-deficient (RelB(kappaO)) animals to two strains of immunodeficient mice, recombinase-activating gene-1-deficient (RAG-1(kappaO), lacking B and T cells), and Nur77/N10-transgenic mice (Nur77/N10(TG), lacking only T cells). We also generated mutant mice deficient in both RelB and the p50 subunit of NF-kappaB (p50(kappaO), multiple defects in B cell function). RelB(kappaO)RAG-1(kappaO) and RelB(kappaO)Nur77/N10(TG) mice are disease-free, while RelB(kappaO)p50(kappaO) double-mutant animals develop an even more severe phenotype despite the absence of B cells in the inflammatory infiltrates. Thus, both multiorgan inflammation and myeloid hyperplasia in RelB-deficient mice are T cell dependent, whereas B cells are not crucially involved.

Multiorgan inflammation and hematopoietic abnormalities in mice with a targeted disruption of RelB, a member of the NF-kappa B/Rel family.

RelB, a member of the NF-kappa B/Rel family of transcription factors, has been implicated in the constitutive expression of kappa B-regulated genes in lymphoid tissues. We have generated mice carrying a germline mutation of the relB gene, resulting in the absence of RelB protein and a dramatic reduction of constitutive kappa B-binding activity in thymus and spleen. Mice homozygous for the disrupted relB locus had phenotypic abnormalities including multifocal, mixed inflammatory cell infiltration in several organs, myeloid hyperplasia, splenomegaly due to extramedullary hematopoiesis, and a reduced population of thymic dendritic cells. RelB-deficient animals also had an impaired cellular immunity, as observed in contact sensitivity experiments. Thus, RelB plays a decisive role in the hematopoietic system, and its absence cannot be functionally compensated by any other member of the NF-kappa B/Rel family.

Controlled recruitment of monocytes and macrophages to specific organs through transgenic expression of monocyte chemoattractant protein-1.

Transgenic mice overexpressing the chemokine monocyte chemoattractant protein-1 (MCP-1) in the thymus and central nervous system have a higher number of mononuclear cells in those tissues than do control littermates. In the thymus, there is a modest increase in the number of Mac-1 and F4/80 positive cells, but no apparent change in the number of lymphoid cells. A more pronounced mononuclear infiltrate is detected in transgenic mice expressing MCP-1 in the brain. The vast majority of the recruited cells in the brain are monocytes and macrophages, as defined by light microscopy, and ultrastructural and immunohistochemical criteria. Such cells are found in a perivascular orientation with minimal parenchymal infiltration, possibly as a consequence of the accumulation of MCP-1 in the vessels, as shown by immunohistochemistry. The mononuclear cell infiltrate in the brain can be significantly amplified by LPS treatment, suggesting that the recruitment properties of MCP-1 can be potentiated by additional factors.

Inhibition of ozone-induced nitric oxide synthase expression in the lung by endotoxin.

Inhalation of the pulmonary irritant ozone is associated with an accumulation of macrophages in the lung. These cells, along with type II epithelial cells, are activated to release increased quantities of hydrogen peroxide and nitric oxide, two reactive mediators that have been implicated in tissue injury. In the present studies we determined whether pretreatment of rats with bacterially derived endotoxin, which modulates oxidant levels in tissues, could abrogate the effects of ozone on lung injury and nitric oxide production. Acute exposure of rats to ozone (2 parts per million, 3 h) resulted in nitric oxide production in the lung as measured by electron paramagnetic resonance spin trapping. This was correlated with expression of inducible nitric oxide synthase (iNOS) mRNA in the lung as determined by in situ hybridization. Particularly high levels of iNOS were evident in alveolar macrophages and type II cells. Alveolar macrophages isolated from ozone-treated rats also expressed increased iNOS mRNA and protein as measured by Northern and Western blotting, respectively, and produced more nitric oxide compared with cells from air-exposed animals. Treatment of rats with endotoxin (5 mg/kg, intravenously), 30 min prior to ozone, was found to abrogate ozone-induced increases in iNOS mRNA and protein expression, as well as nitric oxide production by alveolar macrophages. This was associated with a reduction in ozone-induced tissue injury as determined by levels of lung lavage fluid protein. Ozone inhalation also resulted in a reduction in intracellular glutathione in alveolar macrophages, an effect that was blocked by endotoxin administration. Taken together, these data provide evidence that the protective effects of endotoxin against ozone-induced injury are mediated, at least in part, by alterations in levels of lung oxidants and antioxidants.

Energy dependence of particle multiplicities in central Au+Au collisions.

We present the first measurement of the pseudorapidity density of primary charged particles in Au+Au collisions at root square[s(NN)] = 200 GeV. For the 6% most central collisions, we obtain dN(ch)/d(eta)/(/eta/<1) = 650+/-35(syst). Compared to collisions at root square[s(NN)] = 130 GeV, the highest energy studied previously, an increase by a factor of 1.14+/-0.05 at 90% confidence level, is found. The energy dependence of the pseudorapidity density is discussed in comparison with data from proton-induced collisions and theoretical predictions.

Pseudorapidity and centrality dependence of the collective flow of charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV.

This paper describes the measurement of collective flow for charged particles in Au+Au collisions at sqrt[s(NN)]=130 GeV using the PHOBOS detector at the Relativistic Heavy Ion Collider (RHIC). The measured azimuthal hit anisotropy is presented over a wide range of pseudorapidity (-5.0

Pseudorapidity distribution of charged particles in d+Au collisions at sqrt[sNN]=200 GeV.

The measured pseudorapidity distribution of primary charged particles in minimum-bias d+Au collisions at sqrt[s(NN)]=200 GeV is presented for the first time. This distribution falls off less rapidly in the gold direction as compared to the deuteron direction. The average value of the charged particle pseudorapidity density at midrapidity is |eta|< or =0.6)=9.4+/-0.7(syst) and the integrated primary charged particle multiplicity in the measured region is 82+/-6(syst). Estimates of the total charged particle production, based on extrapolations outside the measured pseudorapidity region, are also presented. The pseudorapidity distribution, normalized to the number of participants in d+Au collisions, is compared to those of Au+Au and p+(-)p systems at the same energy. The d+Au distribution is also compared to the predictions of the parton saturation model, as well as microscopic models.

Ratios of charged antiparticles-to-particles near mid-rapidity in Au + Au collisions at sqrt[s(NN)]=130 GeV.

We have measured the ratios of antiparticles to particles for charged pions, kaons, and protons near mid-rapidity in central Au+Au collisions at sqrt[s(NN)] = 130 GeV. We observe / = 1.00+/-0.01(stat)+/-0.02(syst), / = 0.91+/-0.07(stat)+/-0.06(syst), and

/

= 0.60+/-0.04(stat)+/-0.06(syst). The / and

/

ratios give a consistent estimate of the baryo-chemical potential mu(B) of 45 MeV, a factor of 5-6 smaller than in central Pb+Pb collisions at sqrt[s(NN)] = 17.2 GeV.