First Examples of Stable Arenium Ions from Large Methylene-Bridged Polycyclic Aromatic Hydrocarbons (PAHs). Directive Effects and Charge Delocalization Mode

In connection to a growing interest in developing structure/activity trends in nonalternant polyarenes, we report on the generation and NMR studies of the first series of persistent arenium ions from large methylene-bridged PAHs (mostly 22pi six-fused ring systems). Low-temperature protonation (FSO(3)H/SO(2)ClF) and model nitration (with HNO(3)/HOAc or NO(2)(+) BF(4)(-)) were used as mimic reactions for generation of biological electrophiles. The site(s) of protonation (and nitration) were determined as a function of PAH structure. Charge delocalization mode in the resulting arenium ions of protonation are assessed based on detailed low-temperature NMR studies at 500 MHz. Systems studied were 1-methylcyclopenta[def]phenanthrene 2, 11H-benz[bc]aceanthrylene 8, 5H-benzo[b]cyclopenta[def]chrysene 9, 13H-dibenzo-[bc,l]aceanthrylene 10, 13H-cyclopenta[rst]pentaphene 11, 4H-benzo[b]cyclopenta[mno]chrysene 12, 6H-cyclopenta[ghi]picene 13, 4H-cyclopenta[pqr]picene 14, 4H-cyclopenta[def]dibenz[a,c]anthracene 15. For comparison, dibenzo[a,c]anthracene 16 and dibenzo[a,h]anthracene 17 were also included (Figures 1 and 2). It is shown that the methano-bridge exerts a strong directive effect which diminishes as the bridge moves from the more central "inner" positions to more peripheral "outer" positions. Charge delocalization mode in the resulting carbocations are discussed based on the magnitude of Deltadelta (13)C values. Possible relationships with biological electrophiles formed by epoxide ring opening in the putative metabolites are also considered.

Extent of intestinal damage in the developing chick embryo after repetitive hypoxia under normoxic or hyperoxic conditions

BACKGROUND

Episodes of hypoxia and reperfusion play an important role in the development of intestinal damage during perinatal development. The aim of this study was to investigate the histopathology of the intestine in the developing chick embryo after exposure to repetitive hypoxia and recovery under two different conditions: normoxic and hyperoxic (60% O2).

METHODS

Chick embryos were exposed to 5 minutes of hypoxia. This was repeated six times with a recovery period of 15 minutes under normoxic conditions (21% O2) for chick embryos in test group 1 (TG1) and under hyperoxic conditions (100% O2) for chick embryos in test group 2 (TG2), from day 11 until day 20. Chick embryos that recovered under hyperoxic conditions (100% O2) were previously incubated under hyperoxic conditions (60% O2 for 24 hours). Histologic evaluation of the ileum was performed at different times after the interventions (2, 4, 8, 16, and 24 hours).

RESULTS

In both test groups, only chick embryos older than 19 days showed intestinal damage. Intestinal histology on day 19 showed vasodilation of villus capillaries (10% in TG1 and 15% in TG2), necrosis in the top of the villi (29% in TG1 and 30% in TG2), and necrosis with preservation of base of the crypts (2% in TG1) and transmucosal necrosis (2% in TG2).

CONCLUSIONS

Significant histologic changes, compared with the control group, were only found in chick embryos that were studied 2 hours after the interventions. Furthermore, recovery under hyperoxic conditions did not cause more intestinal damage compared with recovery under normoxic conditions.

Antigen-specific T(h)1 cells as direct effectors of Propionibacterium acnes-primed lipopolysaccharide-induced hepatic injury

T(h)1 cells are cytotoxic effector cells that utilize Fas ligand (FasL) and tumor necrosis factor. The physiological roles of cytotoxic T(h)1 cells are considered to be immunoregulation by eliminating autoreactive lymphocytes or hyper-activated foreign antigen-specific lymphocytes. Their pathological roles, however, remain to be clarified. To investigate whether T(h)1 cells can destroy organs, we generated a Propionibacterium acnes-specific T(h)1 clone from C57BL/6 mice and tested whether the clone could serve as an effector in a P. acnes-primed lipopolysaccharide (LPS)-induced hepatic injury system, one of the septic shock models. B6SMN:C3H-FasL(gld) (B6-gld) mice, which were deficient in functional FasL, were resistant to P. acnes/LPS-induced hepatic shock. The T(h)1 clone rendered B6-gld mice sensitive to the hepatic shock after the i.v. transfer. The hepatic injury in the clone-transferred B6-gld mice, which was evaluated by both biochemical and histological examination, was inhibited by an anti-FasL mAb that we developed. These results suggested that bacterial antigen-specific T(h)1 cells like this clone can participate in organ destruction in vivo as one of the cytotoxic effectors and play a critical role in endotoxin-induced hepatic injury.

Gain-of-function mutation at the extracellular domain of KIT in gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the human gastrointestinal tract. Previous studies of GISTs found gain-of-function mutations of the c-kit gene, which encodes a receptor tyrosine kinase (KIT). All the mutations were confined to exon 11, which encodes the juxtamembrane domain. By further examination of the whole coding region of c-kit complementary DNA in 35 GISTs, two were found to show the identical mutation at exon 9, which encodes the extracellular domain. The aims of the present study were to examine the frequency of the extracellular domain mutation and to determine whether the mutation is a gain-of-function type or not. Genomic DNA was extracted from paraffin-embedded tissues of 133 GISTs and exon 9 of the c-kit gene was amplified by polymerase chain reaction. Screening of the mutation was carried out by single-strand conformation polymorphism analysis and direct sequencing was done. Mutant c-kit cDNA was transfected into 293T human embryonic kidney cells and the magnitude of autophosphorylation of the mutant KIT was examined with or without the ligand of KIT, stem cell factor (SCF). In total, seven GIST cases (approximately 5%) were found with the identical mutation at exon 9. The mutant KIT exhibited constitutive autophosphorylation without SCF stimulation. The prognosis of the patients with the extracellular domain mutation was comparable to that of the patients with the juxtamembrane domain mutation.

Measurement of B(0)(d)-B_(0)(d) mixing rate from the time evolution of dilepton events at the upsilon(4S)

We report a determination of the B(0)(d)-&B_(0)(d) mixing parameter Deltam(d) based on the time evolution of dilepton yields in Upsilon(4S) decays. The measurement is based on a 5.9 fb(-1) data sample collected by the Belle detector at KEKB. The proper-time difference distributions for same-sign and opposite-sign dilepton events are simultaneously fitted to an expression containing Deltam(d) as a free parameter. Using both muons and electrons, we obtain Deltam(d) = 0.463+/-0.008 (stat)+/-0.016 (syst) ps(-1). This is the first determination of Deltam(d) from time evolution measurements at the Upsilon(4S). We also place limits on possible CPT violations.

Gain-of-function mutation at the extracellular domain of KIT in gastrointestinal stromal tumours

Gastrointestinal stromal tumours (GISTs) are the most common mesenchymal tumours of the human gastrointestinal tract. Previous studies of GISTs found gain-of-function mutations of the c-kit gene, which encodes a receptor tyrosine kinase (KIT). All the mutations were confined to exon 11, which encodes the juxtamembrane domain. By further examination of the whole coding region of c-kit complementary DNA in 35 GISTs, two were found to show the identical mutation at exon 9, which encodes the extracellular domain. The aims of the present study were to examine the frequency of the extracellular domain mutation and to determine whether the mutation is a gain-of-function type or not. Genomic DNA was extracted from paraffin-embedded tissues of 133 GISTs and exon 9 of the c-kit gene was amplified by polymerase chain reaction. Screening of the mutation was carried out by single-strand conformation polymorphism analysis and direct sequencing was done. Mutant c-kit cDNA was transfected into 293T human embryonic kidney cells and the magnitude of autophosphorylation of the mutant KIT was examined with or without the ligand of KIT, stem cell factor (SCF). In total, seven GIST cases (approximately 5%) were found with the identical mutation at exon 9. The mutant KIT exhibited constitutive autophosphorylation without SCF stimulation. The prognosis of the patients with the extracellular domain mutation was comparable to that of the patients with the juxtamembrane domain mutation.

Influence of alkyl substitution on the gas-phase stability of 1-adamantyl cation and on the solvent effects in the solvolysis of 1-bromoadamantane

1-Adamantyl cations having three methyl groups or one, two, or three isopropyl groups on the 3-, 5-, and 7-positions were found by FT ICR to be more stable than the 1-adamantyl cation and that the stability increases with the number of isopropyl group. The relative stabilities calculated by PM3 were in good agreement with the experimental results. In contrast, the sequence of the rates for the solvolysis in nonaqueous solvents are 3,5,7-(Me)(3)-1-AdBr < 1-bromoadamantane (1-AdBr) < 3,5,7-(n-Pr)(3)-1-AdBr < 3,5,7-(i-Pr)(3)-1-AdBr. The rates of solvolysis of 3,5,7-(i-Pr)(3)-1-AdBr and 3,5,7-(n-Pr)(3)-1-AdBr relative to 1-AdBr at 25 degrees C are 15 and 3.8 in EtOH, respectively, but markedly decreases with the increase in the amount of added water, reaching 0.84 and 0.15, respectively, in 60% EtOH. Reflecting these effects of water, the Grunwald-Winstein (GW) relationship for 3,5,7-(i-Pr)(3)-1-AdBr and 3,5,7-(n-Pr)(3)-1-AdBr against Y(Br) is linear for nonaqueous alcohols (EtOH, MeOH, TFE-EtOH, TFE, 97% HFIP), but marked downward deviations are observed for aqueous organic solvents, in particular, aqueous ethanol and aqueous acetone. The effect of the alkyl substituents to diminish relative solvolytic reactivity in EtOH-H(2)O mixtures may be ascribed to a blend of steric hindrance to Betarphinsted base-type hydration to the beta-hydrogens and hydrophobic interaction of the alkyl groups with ethanol to make the primary solvation shell less ionizing. The introduction of one nonyl group to the 3-position showed much smaller deviations in the GW relationship than the case of 3,5,7-(n-Pr)(3)-1-AdBr. The markedly decelerated solvolysis of alkylated 1-bromoadamantanes in aqueous organic solvents is a kinetic version of anomalously diminished dissociation of alkylbenzoic acids in aqueous ethanol and aqueous tert-butyl alcohol that was demonstrated by Wepster and co-workers a decade ago and ascribed to hydrophobic effects.

Measurement of the CP violation parameter sin2 phi(1) in B(0)(d) meson decays

We present a measurement of the standard model CP violation parameter sin2 phi(1) (also known as sin2beta) based on a 10.5 fb(-1) data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric e(+)e(-) collider. One neutral B meson is reconstructed in the J/psiK(S), psi(2S)K(S), chi(c1)K(S), eta(c)K(S), J/psiK(L), or J/psipi(0) CP-eigenstate decay channel and the flavor of the accompanying B meson is identified from its charged particle decay products. From the asymmetry in the distribution of the time interval between the two B-meson decay points, we determine sin2 phi(1) = 0.58(+0.32)(-0.34)(stat)+0.09-0.10(syst).

PD-L2 is a second ligand for PD-1 and inhibits T cell activation

Programmed death I (PD-I)-deficient mice develop a variety of autoimmune-like diseases, which suggests that this immunoinhibitory receptor plays an important role in tolerance. We identify here PD-1 ligand 2 (PD-L2) as a second ligand for PD-1 and compare the function and expression of PD-L1 and PD-L2. Engagement of PD-1 by PD-L2 dramatically inhibits T cell receptor (TCR)-mediated proliferation and cytokine production by CD4+ T cells. At low antigen concentrations, PD-L2-PD-1 interactions inhibit strong B7-CD28 signals. In contrast, at high antigen concentrations, PD-L2-PD-1 interactions reduce cytokine production but do not inhibit T cell proliferation. PD-L-PD-1 interactions lead to cell cycle arrest in G0/G1 but do not increase cell death. In addition, ligation of PD-1 + TCR leads to rapid phosphorylation of SHP-2, as compared to TCR ligation alone. PD-L expression was up-regulated on antigen-presenting cells by interferon gamma treatment and was also present on some normal tissues and tumor cell lines. Taken together, these studies show overlapping functions of PD-L1 and PD-L2 and indicate a key role for the PD-L-PD-1 pathway in regulatingT cell responses.

[Disseminated atypical mycobacteriosis in a patient with chronic myelogenous leukemia]

A 61-year-old woman with a 6-year history of chronic myelogenous leukemia (CML) presented with recurrent fever in July 1996. Bone marrow aspiration, biopsy and chromosome analysis showed that CML was in the chronic phase. Bone marrow biopsy revealed nonspecific inflammatory lesions. Chest X-ray and computed tomography examinations demonstrated interstitial pneumonia. Cultures of gastric juice and bone marrow yielded colonies of Mycobacterium avium complex (MAC), and a diagnosis of disseminated atypical mycobacteriosis was made. Multidrug treatment including rifampicin, ethambutol, clarithromycin and ciprofloxacin was begun. The cultures subsequently became negative and the fever was resolved. However, fever eventually recurred and the patient died of multiple organ failure in October 1997. since disseminated atypical mycobacteriosis complicating hematological disorders worsens the prognosis, its early diagnosis and prompt treatment are important. Although it is often difficult to identify atypical mycobacterium as a causal agent, frequent culturing of atypical mycobacterium from various sources including bone marrow fluid can be helpful for early diagnosis whenever fever of undetermined origin occurs in patients with hematological disorders.

Role of osteopontin in the pathogenesis of bleomycin-induced pulmonary fibrosis

Pulmonary fibrosis is initiated by migration, adhesion, and proliferation of fibroblasts. Osteopontin (OPN) is one of the cytokines produced by activated macrophages and mediates various functions, including cell attachment and migration, by interacting with alphav integrin. In this study, we have investigated the role of OPN in the pathogenesis of pulmonary fibrosis. We developed a mouse model for pulmonary fibrosis by intratracheal instillation of bleomycin (BLM). OPN was strongly expressed in alveolar macrophages accumulating in the fibrotic area of the lung. OPN messenger RNA (mRNA) in the lung was notably induced by BLM instillation, and the development of the fibrotic process was associated with an increase in the expression of OPN mRNA and protein. In vitro, recombinant OPN enhanced migration, adhesion, and platelet-derived growth factor (PDGF)-mediated DNA synthesis of murine fibroblast cell line NIH3T3. These effects of OPN on fibroblasts were significantly suppressed by addition of antimouse alphav integrin monoclonal antibody (RMV-7). Furthermore, treatment of mice with RMV-7 repressed the extent of pulmonary fibrosis in this model. Conclusively, these data suggest that OPN produced by alveolar macrophages functions as a fibrogenic cytokine that promotes migration, adhesion, and proliferation of fibroblasts in the development of BLM-induced pulmonary fibrosis.

Evaluation of the effects of exercise and a mild hypocaloric diet on cardiovascular risk factors in obese subjects

A weight reduction program to improve cardiovascular risk factors was implemented in obese subjects. The program consisted of exercise training corresponding to the anaerobic threshold (AT) and a mild hypocaloric diet for 12 weeks. In this program, we evaluated the effects of a combination of exercise training and a diet on cardiovascular risk factors such as obesity, dyslipidemia, and poor exercise performance in obese subjects. In addition, we also evaluated the independent effects of exercise training and dietary modification. For this purpose, we adopted a relative training time and a diet score. A relative training time was calculated as the number of times that the subject performed exercises divided by all of the training sessions scheduled, and the diet score was calculated from information which each subject provided on a self-assessment questionnaire. Twenty three obese subjects (Age: 24-54 years old, 19 men and 4 women, body mass index (BMI) > 26 kg/m2) participated in this study. After the 12-week intervention, the mean reductions in body weight, body mass index and body fat were 4.7 kg, 1.7 kg/m2 and 2.9%, respectively (P < 0.0001). The % change in body weight was significantly associated with the diet score and with the relative training time. The mean reductions in total cholesterol, triglyceride and low density lipoprotein cholesterol were 21 mg/dl (P < 0.002), 34 mg/dl (P < 0.01) and 15.9 mg/dl (P < 0.01), respectively, and the % change in triglyceride was significantly associated with the diet score (P = 0.0056) and tended to correlate with the relative training time (P = 0.0596). Oxygen uptake at AT and at peak exercise were increased from 14.1 +/- 1.6 to 16.0 +/- 3.1 ml/min/kg (P < 0.005) and from 26.3 +/- 4.8 to 28.4 +/- 4.9 ml/min/kg (P < 0.002), respectively. A combination of aerobic exercise and a mild hypocaloric diet significantly contributed not only to weight loss but also to the improvement of dyslipidemia and exercise performance, but either hypocaloric diet or mild exercise independently did less. The diet score and the relative training time were useful for evaluating separately dietary modification and the quantity of exercise.

Determination of the local structure of the first and second shells in ordered and disordered Ni-Mn alloys

The coordination numbers and the interatomic distances for 50, 75 and 80 at.% Ni-Mn alloys in ordered and disordered states are presented. A new method for determining the first and second nearest neighbor coordination numbers in a binary alloy is applied. It is shown that magnetic properties of these alloys depend on short range order in atomic arrangement.

Gonadotropins stimulate growth of MCF-7 human breast cancer cells by promoting intracellular conversion of adrenal androgens to estrogens

Estrogen receptor (ER)-positive breast cancers initially respond well to estrogen ablation treatment but finally acquire refractoriness, the phenomenon that is a major clinical problem. Because some breast cancers synthesize estradiol (E(2)) and E(2) synthesis is regulated by gonadotropins in normal ovaries, and because circulating gonadotropins are elevated in postmenopausal women and during estrogen ablation treatment, we hypothesized that gonadotropins might modulate estrogen synthesis/metabolism in breast cancer tissue as well. To test this possibility, MCF-7 cells were treated with dehydroepiandrosterone (DHEA) or human chorionic gonadotropin (hCG; approximately LH), each alone or in combination. Cell growth (3-day treatment) was assayed by the MTT method and estrogen synthesis (24-hour treatment) was measured using the ERE-luciferase reporter system. First, MCF-7 cell growth was stimulated by DHEA in a concentration-dependent manner with a maximal effect at 10(-4) M. Although hCG alone did not have a significant proliferative effect, hCG significantly and dose dependently stimulated MCF-7 cell growth in the presence of a submaximal concentration of DHEA (10(-7 )M). This stimulatory effect of DHEA and hCG was blocked by a pure antiestrogen ICI182,780 and an aromatase inhibitor, arimidex. Using MCF-7 cells transfected with the ERE-luciferase reporter system, hCG treatment was shown to increase ERE-mediated transcription. These results indicate that MCF-7 cells intrinsically converted DHEA into E(2) upon hCG stimulation, then grew their own cells DHEA- and hCG-dependently. We conclude that gonadotropins can act on breast cancer cells and accelerate conversion of DHEA into estrogens, thereby stimulating growth of estrogen-dependent tumor cells. This phenomenon, at least in part, could explain: (1) an increased tissue concentration of E(2) in postmenopausal breast cancer; (2) acquisition of hormone refractoriness during estrogen ablation treatment, and (3) the effectiveness of GnRH antagonist/superagonist in some postmenopausal breast cancer patients.

Substituent effects and charge delocalization mode in chrysenium, benzo[c]phenanthrenium, and benzo[g]chrysenium cations: a stable ion and electrophilic substitution study

The first series of persistent carbocations derived from mono- and disubstituted chrysenes Ch (5- methyl- 3, 2-methoxy- 19, 2-methoxy-11-methyl- 20, 2-methoxy-5-methyl- 21, and 9-methyl-4H-cyclopenta[def]chrysene 22), monosubstituted benzo[c]phenanthrenes BcPh (3-methoxy- 23, 3-hydroxy- 24), and monosubstituted benzo[g]chrysenes BgCh (12-methoxy- 25; 12-hydroxy- 26) were generated in FSO3H/SO2ClF or FSO3H-SbF5 (4:1)/SO2ClF and studied by low-temperature NMR at 500 MHz. The methoxy and methyl substituents direct the protonation to their respective ortho positions. Whereas parent Ch 1 is protonated at C-6/C-12, 3 is protonated at C-6 (3aH+) and at C-12 (3bH+) with the latter being the thermodynamic cation. The 2-methoxy-Ch 19 is protonated at C-1 to give two conformationally distinct carboxonium ions (19aH+/19bH+). In the disubstituted Ch derivatives 20 and 21, the 2-methoxy overrides the 5-methyl and the predominant carbocations formed are via attack ortho to methoxy. For the methano derivative 22 (Me at C-9), a 3:1 mixture of 22aH+/22bH+ is formed. For parent BcPh 13, nitration and benzoylation are directed to C-5. With 3-methoxy-BcPh 23, the site of attack moves to C-4, thus producing two conformationally distinct carboxonium ions (23aH+/23bH+), whereas conventional nitration gave a 2:1 mixture of 23aNO2 and 23bNO2. In 3-hydroxy-BcPh 24, the carboxonium ion 24H+ is exclusively formed. For parent BgCh 16, protonation, nitration, and benzoylation are all directed to C-10 (16H+, 16NO2, 16COPh), but presence of OMe or OH substituent at C-12 changes the site of attack to C-11. Charge delocalization mode is probed based on magnitude of delta delta 13Cs and conformational aspects via NOED experiments. Complete NMR data are also reported for several benzoylation/nitration products. Using ab initio/GIAO (and NICS), the NMR chemical shifts (and aromaticity) in model carbocations A-D were evaluated. This work represents the first direct study of the carbocations derived from the methyl-, methoxy-/hydroxy-derivatives of three important classes of bay-region and fjord-region PAHs whose diol-epoxides extensively bind to DNA. It also extends the available data on electrophilic chemistry of BcPh and BgCh.

Fatty-acyl-CoA thioesters inhibit recruitment of steroid receptor co-activator 1 to alpha and gamma isoforms of peroxisome-proliferator-activated receptors by competing with agonists

Peroxisome-proliferator-activated receptors (PPARs) alpha and gamma are ligand-dependent transcription factors that are key regulators of lipid and carbohydrate homoeostasis. Fatty acids bind to the ligand-binding domains (LBDs) of PPARalpha and PPARgamma and activate these receptors. To clarify whether fatty-acyl-CoAs interact directly with the LBDs of PPARalpha and PPARgamma, we performed a competition binding assay with radiolabelled KRP-297, a known dual agonist for these receptors. We show here that fatty-acyl-CoAs bind directly to PPARalpha and PPARgamma. Interestingly, fatty-acyl-CoAs, unlike fatty acids, failed to recruit steroid receptor co-activator 1 (SRC-1), on the basis of conformational changes in the LBDs of PPARalpha and PPARgamma. Moreover, fatty-acyl-CoAs also markedly inhibited agonist-induced recruitment of SRC-1. These findings demonstrate that fatty-acyl-CoAs have a novel function in the signalling pathways of PPARalpha and PPARgamma.

Autoimmune dilated cardiomyopathy in PD-1 receptor-deficient mice

Dilated cardiomyopathy is a severe pathology of the heart with poorly understood etiology. Disruption of the gene encoding the negative immunoregulatory receptor PD-1 in BALB/c mice, but not in BALB/c RAG-2-/- mice, caused dilated cardiomyopathy with severely impaired contraction and sudden death by congestive heart failure. Affected hearts showed diffuse deposition of immunoglobulin G (IgG) on the surface of cardiomyocytes. All of the affected PD-1-/- mice exhibited high-titer circulating IgG autoantibodies reactive to a 33-kilodalton protein expressed specifically on the surface of cardiomyocytes. These results indicate that PD-1 may be an important factor contributing to the prevention of autoimmune diseases.

Element-selective single atom imaging

Electron energy-loss spectroscopy (EELS) is widely used to identify elemental compositions of materials studied by microscopy. We demonstrate that the sensitivity and spatial resolution of EELS can be extended to the single-atom limit. A chemical map for gadolinium (Gd) clearly reveals the distribution of Gd atoms inside a single chain of metallofullerene molecules (Gd@C82) generated within a single-wall carbon nanotube. This characterization technique thus provides the "eyes" to see and identify individual atoms in nanostructures. It is likely to find broad application in nanoscale science and technology research.

One-dimensional metallofullerene crystal generated inside single-walled carbon nanotubes

Electron microscope imaging for gadolinium metallofullerenes encapsulating in single-wall carbon nanotubes [(Gd@C82)n@SWNTs] identifies the single Gd atom encaged in each. The intermolecular distance between Gd@C82 is extremely regular, regarding the chains of Gd@C82 as novel one-dimensional crystals. Chemical state analysis of Gd atoms suggests evidence for charge transfer from Gd to either a fullerene cage or a nanotube. The slopes of the temperature dependence of electric resistance for the mat-like films of (Gd@C82)n@SWNTs and (C60)n@SWNTs are much steeper than that for empty SWNTs, suggesting the electron scattering due to the electrostatic potential from inside fullerenes playing an important role.

Differential interaction of Cbl with Grb2 and CrkL in CD2-mediated NK cell activation

Natural killer (NK) cells participate in both innate and adoptive immunity by their prompt secretion of cytokines and by their ability to lyse virally infected cells or tumor cells. CD2 is surface glycoprotein receptors and crucial for NK cell activation. However, molecular events involved in CD2-mediated NK cell activation have not been fully elucidated. Cbl-Grb2 and Cbl-CrkL interactions have been implicated in T cell and B cell receptor, and cytokine receptor signaling. Here we analyzed tyrosine phosphorylation and interactions of Cbl with adapter proteins, Grb2 and CrkL, in NK3.3 cells. CD2 crosslinking results in the marked tyrosine phosphorylation of Cbl in an antibody concentration- and time-dependent manner. Immunodepletion studies reveal that Grb2-associated tyrosine phosphorylated p120 kDa protein is Cbl. In vitro binding studies using GST-fusion proteins demonstrate that Cbl constitutively associates with the SH3 domains of Grb2, with a preference for the amino-terminal domain. In addition, we demonstrate that CrkL associates with a large portion of tyrosine phosphorylated Cbl after CD2 stimulation of NK3.3 cells. In contrast to constitutive Cbl association with Grb2, tyrosine phosphorylated Cbl interacts with CrkL via its SH2 domain only after CD2 stimulation. Although the precise roles of interactions of Cbl with Grb2 and CrkL in NK cell activation remains to be elucidated, their tyrosine phosphorylation, in addition to the multiple protein interactions described here, strongly suggest that interactions of Cbl with Grb2 and CrkL may play pivotal roles in CD2-mediated NK cell activation.

Genomic organization, chromosomal localization, and the complete 22 kb DNA sequence of the human GCMa/GCM1, a placenta-specific transcription factor gene

The genomic sequence of the human GCMa/GCM1 gene, a mammalian homologue of Drosophila melanogaster GCM, was determined. Drosophila GCM is a neural transcription factor that regulates glial cell fate. The mammalian homolog however, is a placenta-specific transcription factor that is necessary for placental development. The 22 kb DNA sequence spanning the GCMa gene contains six exons and five introns, encoding a 2.8 kb cDNA. Overall genomic organization is similar for the human and mouse. Several potential binding sites for transcription factors like GATA, Oct-1, and bHLH proteins were found in the 5'-flanking region of the human gene. A DNA motif for GCM protein binding exists in the 5'-flanking region that is highly homologous with that of the mouse gene. The location of this gene was mapped to chromosome 6 using fluorescence in situ hybridization.

Persistent carbocations from bay region methoxy-substituted cyclopenta[a]phenanthrene and its derivatives. A structure/reactivity study

Using 500 MHz NMR, we have carried out a stable ion protonation and model nitration study of the methoxy-substituted hydrocarbon 6, its 15-ol 7, and the dimer 10, in order to evaluate OMe substituent effects on directing electrophilic attack and on charge delocalization mode/conformational aspects in the resulting carbocations. It is found that the C-11 methoxy group directs the electrophilic attack to C-12 and C-14. Thus protonation of 6 with FSO(3)H/SO(2)ClF gives a 4:1 mixture of monoarenium ions 6H(+)()/6aH(+)(). Prolonged reaction times and increased temperature induced fluorosulfonylation at C-14 (6(+)-SO(2)()F), whereas ambient nitration with NO(2)(+)BF(4)(-) occurred at C-12. The 15-ol derivative 7 is cleanly ionized to 11(+)(), providing the first example of an alpha-phenanthrene-substituted carbocation from phenanthrene C-1 position. Contrasting behavior of the D-ring methyl-substituted 9 and the C-11 methoxy-substituted 10 dimers is remarkable in that unlike 9 which is readily cleaved to produce the monomeric arenium ion 3H(+)(), 10 is diprotonated at the two C-12 sites and at C-12/C-14 in each unit. The latter dication-dimer exists as a mixture of diastereomers. Reactivity of 7 underscores the importance of 11(+)(). Attack at the C-14 ring junction is in concert with the proposal that electrophilic oxygen would attack at C-14/C-15 (epoxidation) followed by ring opening to give the biologically active 15-ol as a major metabolite.

Engagement of the PD-1 immunoinhibitory receptor by a novel B7 family member leads to negative regulation of lymphocyte activation

PD-1 is an immunoinhibitory receptor expressed by activated T cells, B cells, and myeloid cells. Mice deficient in PD-1 exhibit a breakdown of peripheral tolerance and demonstrate multiple autoimmune features. We report here that the ligand of PD-1 (PD-L1) is a member of the B7 gene family. Engagement of PD-1 by PD-L1 leads to the inhibition of T cell receptor-mediated lymphocyte proliferation and cytokine secretion. In addition, PD-1 signaling can inhibit at least suboptimal levels of CD28-mediated costimulation. PD-L1 is expressed by antigen-presenting cells, including human peripheral blood monocytes stimulated with interferon gamma, and activated human and murine dendritic cells. In addition, PD-L1 is expressed in nonlymphoid tissues such as heart and lung. The relative levels of inhibitory PD-L1 and costimulatory B7-1/B7-2 signals on antigen-presenting cells may determine the extent of T cell activation and consequently the threshold between tolerance and autoimmunity. PD-L1 expression on nonlymphoid tissues and its potential interaction with PD-1 may subsequently determine the extent of immune responses at sites of inflammation.

Synthesis of NG-061 and its analogs, and their biological evaluation as an enhancer of nerve growth factor

A novel potentiator of nerve growth factor (NGF), NG-061, which had been isolated from the fermentation broth of Penicillium minioluteum F-4627, was synthesized from methoxybenzoquinone and phenylacetylhydrazine in a single step. A series of acyl hydrazone derivatives were also synthesized and their potentiator activity of neurotrophic effect of NGF on neurite outgrowth was evaluated by assay with a rat pheochromocytoma cell line PC12.