Magnetism and phase transitions in LaCoO3

Neutron scattering and magnetometry measurements have been used to study phase transitions in LaCoO3 (LCO). For H ≤ 100 Oe, evidence for a ferromagnetic (FM) transition is observed at Tc ≈ 87 K. For 1 kOe ≤ H ≤ 60 kOe, no transition is apparent. For all H, Curie-Weiss analysis shows predominantly antiferromagnetic (AFM) interactions for T > Tc, but the lack of long-range AFM order indicates magnetic frustration. We argue that the weak ferromagnetism in bulk LCO is induced by lattice strain, as is the case with thin films and nanoparticles. The lattice strain is present at the bulk surfaces and at the interfaces between the LCO and a trace cobalt oxide phase. The ferromagnetic ordering in the LCO bulk is strongly affected by the Co-O-Co angle (γ), in agreement with recent band calculations which predict that ferromagnetic long-range order can only take place above a critical value, γC. Consistent with recent thin film estimations, we find γC = 162.8°. For γ > γC, we observe power-law behavior in the structural parameters. γ decreases with T until the critical temperature, To ≈ 37 K; below To the rate of change becomes very small. For T < To, FM order appears to be confined to regions close to the surfaces, likely due to the lattice strain keeping the local Co-O-Co angle above γC.

Molecular cloning and characterization of an endogenous digestive β-glucosidase from the midgut of the fungus-growing termite Macrotermes barneyi

β-glucosidase from the midgut of the fungus-growing termite Macrotermes barneyi was first cloned and characterized to gain a better understanding of cellulolytic systems in fungus-growing termites. β-glucosidase activity was proven to present primarily in the midgut of M. barneyi and two β-glucosidases were partially purified from the midgut. Based on the N-terminus sequence of one of the β-glucosidases, a full-length cDNA fragment of 1708 bp was obtained. This sequence encodes a 493 amino acid protein belonging to glycoside hydrolase family 1. Quantitative real-time PCR analysis proved that the β-glucosidase gene was primarily expressed in the midgut. β-glucosidase was expressed heterologously and biochemically characterized. Results indicate that β-glucosidase is an endogenous, midgut-origin termite digestive enzyme. It may have applications in understanding the mechanism of lignocellulose degradation in fungus-growing termites.

Individual differences in locomotor activity are associated with levels of tyrosine hydroxylase and neurofilament proteins in the ventral tegmental area of sprague-dawley rats

We have demonstrated previously that chronic morphine and cocaine treatments increase levels of tyrosine hydroxylase (TH), and decrease levels of neurofilament (NF) proteins, in the ventral tegmental area (VTA), a major dopaminergic brain reward region, of outbred Sprague-Dawley rats. We have also found inherent differences in levels of these proteins in the VTA of inbred rat strains that differ in their behavioral responses to opiates, cocaine, and other drugs of abuse, with the Lewis rat showing higher levels of TH and lower levels of NFs in the VTA compared to the Fischer 344 rat. Based on recent reports that individual differences in drug responses among outbred Sprague-Dawley rats are highly correlated with the animals' locomotor response to novelty, we determined in the present study whether such within-strain differences in locomotor behavior are also associated with differences in levels of TH and NFs in the VTA. Groups of 42 Sprague-Dawley rats were assessed for locomotor activity in a novel environment. The four animals from each group with the lowest locomotor responses (designated L rats), and the four with the highest locomotor responses (designated H rats), were analyzed for TH and NF immunoreactivity by immunoblotting procedures. It was found that the VTA of L rats exhibited higher levels of TH and lower levels of three major NF proteins, NF-200, NF-160, and NF-68, compared to the VTA of H rats. A tendency for similar L versus H differences in TH and NF levels were observed when groups of rats with the second lowest and second highest locomotor responses were compared; no differences were seen in groups whose locomotor responses were closer to the median. These biochemical differences between H and L rats showed regional specificity, with no significant differences seen in several other regions of brain or spinal cord studied. Differences were also observed between L and H rats in their locomotor responses to acute and repeated cocaine exposure. The possible relationship between the individual differences in TH and NFs and individual differences in locomotor activity and other drug-related behaviors is discussed.

Double-Focusing Thermal Triple-Axis Spectrometer at the NCNR

The new thermal triple-axis spectrometer at the NIST Center for Neutron Research (NCNR) is located at the BT-7 beam port. The 165 mm diameter reactor beam is equipped with a selection of Söller collimators, beam-limiters, and a pyrolytic graphite (PG) filter to tailor the beam for the dual 20×20 cm(2) double-focusing monochromator system that provides monochromatic fluxes exceeding 10(8) n/cm(2)/s onto the sample. The two monochromators installed are PG(002) and Cu(220), which provide incident energies from 5 meV to above 500 meV. The computer controlled analyzer system offers six standard modes of operation, including a diffraction detector, a position-sensitive detector (PSD) in diffraction mode, horizontal energy focusing analyzer with detector, a Q-E mode employing a flat analyzer and PSD, a constant-E mode with the analyzer crystal system and PSD, and a conventional mode with a selection of Söller collimators and detector. Additional configurations for specific measurement needs are also available. This paper discusses the capabilities and performance for this new state-of-the-art neutron spectrometer.

Common crystalline and magnetic structure of superconducting A2Fe4Se5 (A=K,Rb,Cs,Tl) single crystals measured using neutron diffraction

Single-crystal neutron diffraction studies on superconductors A(2)Fe(4)Se(5), where A=Rb, Cs, (Tl, Rb), and (Tl, K) (T(c) ∼ 30 K), uncover the same Fe vacancy ordered crystal structure and the same block antiferromagnetic order as in K(2)Fe(4)Se(5). The Fe order-disorder transition occurs at T(S)=500-578 K, and the antiferromagnetic transition at T(N) = 471-559 K with an ordered magnetic moment ∼3.3μ(B)/Fe at 10 K. Thus, all recently discovered A intercalated iron selenide superconductors share the common crystalline and magnetic structure, which are very different from previous families of Fe-based superconductors, and constitute a distinct new 245 family.

Baifuzi reduces transient ischemic brain damage through an interaction with the STREX domain of BKCa channels

Stroke is a long-term disability and one of the leading causes of death. However, no successful therapeutic intervention is available for the majority of stroke patients. In this study, we explored a traditional Chinese medicine Baifuzi (Typhonium giganteum Engl.). We show, at first, that the ethanol extract of Baifuzi exerts neuroprotective effects against brain damage induced by transient global or focal cerebral ischemia in rats and mice. Second, the extract activated large-conductance Ca(2+)-activated K(+) channel (BK(Ca)) channels, and BK(Ca) channel blockade suppressed the neuroprotection of the extract, suggesting that the BK(Ca) is the molecular target of Baifuzi. Third, Baifuzi cerebroside (Baifuzi-CB), purified from its ethanol extract, activated BK(Ca) channels in a manner similar to that of the extract. Fourth, the stress axis hormone-regulated exon (STREX) domain of the BK(Ca) channel directly interacted with Baifuzi-CB, and its deletion suppressed channel activation by Baifuzi-CB. These results indicate that Baifuzi-CB activated the BK(Ca) channel through its direct interaction with the STREX domain of the channel and suggests that Baifuzi-CB merits exploration as a potential therapeutic agent for treating brain ischemia.

Analysis of the carrier-suppressed single-sideband modulators used to mitigate Rayleigh backscattering in carrier-distributed PON

By using the carrier-suppressed single-sideband (CS-SSB) modulation, the Rayleigh backscattering (RB) experienced by the uplink signal can be effectively mitigated due to the reduction of the spectral overlap between the uplink signal and the distributed optical carrier. In this work, we first introduce the theoretical analysis of the CS-SSB generation using the dual-drive MZM (DD-MZM)-based and a dual-parallel MZM (DP-MZM)-based optical networking units (ONUs). Due to the different modulation mechanisms of the two CS-SSB modulations, the frequency components of the generated CS-SSB signals are also different. The transmission performance and the dispersion tolerance of the uplink signals generated by the two CS-SSB modulators are also analyzed and discussed.

Slit-Robo signaling induces malignant transformation through Hakai-mediated E-cadherin degradation during colorectal epithelial cell carcinogenesis

The Slit family of guidance cues binds to Roundabout (Robo) receptors and modulates cell migration. We report here that ectopic expression of Slit2 and Robo1 or recombinant Slit2 treatment of Robo1-expressing colorectal epithelial carcinoma cells recruited an ubiquitin ligase Hakai for E-cadherin (E-cad) ubiquitination and lysosomal degradation, epithelial-mesenchymal transition (EMT), and tumor growth and liver metastasis, which were rescued by knockdown of Hakai. In contrast, knockdown of endogenous Robo1 or specific blockade of Slit2 binding to Robo1 prevented E-cad degradation and reversed EMT, resulting in diminished tumor growth and liver metastasis. Ectopic expression of Robo1 also triggered a malignant transformation in Slit2-positive human embryonic kidney 293 cells. Importantly, the expression of Slit2 and Robo1 was significantly associated with an increased metastatic risk and poorer overall survival in colorectal carcinoma patients. We conclude that engagement of Robo1 by Slit2 induces malignant transformation through Hakai-mediated E-cad ubiquitination and lysosomal degradation during colorectal epithelial cell carcinogenesis.

Application of five frozen human-pooled serum samples assigned by the International Federation of Clinical Chemistry and Laboratory Medicine reference procedure in a traceability investigation of γ-glutamyltransferase catalytic concentration measurements in China

Background

The in vitro directive of the European Union requires traceability to the international recommended reference procedures. The application of the reference procedures is necessary in order to evaluate the accuracy of γ-glutamyltransferase (GGT) assays of routine measurement systems in China.

Methods

Five frozen patient-pooled serum samples were assigned values by the International Federation of Clinical Chemistry and Laboratory Medicine (IFCC) reference procedure in order to evaluate the traceability of the results of GGT catalytic activity from six homogeneous systems. One of the serum samples was used to calibrate seven non-homogeneous systems.

Results

All of the homogeneous systems, except the Dade system (Dade Bering Inc, IL, USA), achieved traceability within the measurement range. The Roche and Hitachi systems were better than the other systems. After calibration, the variance of the non-homogeneous systems decreased dramatically from between 14.50% and 25.23% to between 1.25% and 3.09% and the bias decreased from between −11.4% and −4.1% to between 0.5% and 3.5%.

Conclusion

Manufacturers in China should ensure that their calibration systems correspond to the IFCC reference procedures. Fresh frozen pooled patient serum assigned by reference laboratories can be used to calibrate non-homogeneous systems in order to achieve traceability.

A self-protected colorless WDM-PON with 2.5 Gb/s upstream signal based on RSOA

In this investigation, we propose and demonstrate a colorless wavelength division multiplexed passive optical network (WDM-PON) at 2.5 Gb/s using reflective semiconductor optical amplifier (RSOA)-based optical networking units (ONUs); together with a self-protected architecture against fiber fault. In the optical line terminal (OLT), we use an array of self-seeding Fabry-Perot laser diodes (FP-LDs) to provide single-longitudinal-mode (SLM) continuous wave (CW) optical sources for the external injection to the RSOA-based ONUs. The self-survivable function for protecting the fiber fault in the distributed fibers and the proposed network performance are investigated and discussed.

Newly diagnosed high-risk malignant brain tumors with leptomeningeal dissemination in young children: A final update on Head Start II Regimen A2 intensified with high-dose methotrexate

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Background: The prognosis for young children with newly diagnosed malignant brain tumors with leptomeningeal dissemination remains poor. From Jan 1997 to Mar 2003, “Head Start II” Regimen A2, intensified with high-dose methotrexate, was offered to this high-risk population. Methods: Eligibility: patients < 10 yrs of age; confirmed diagnosis of medulloblastoma (MB), primitive neuroectodermal tumor (PNET), ependymoma and choroid plexus carcinoma (CPC); and high-risk status as determined by neuroaxis dissemination. Patients with atypical teratoid/rhabdoid tumor (ATRT), regardless of stage, were also eligible. Treatment: 5 cycles of vincristine (0.05 mg/kg/week × 3 doses), cisplatin (3.5 mg/kg), etoposide (4 mg/kg/day × 2 days), cyclophosphamide (65 mg/kg/day × 2 days), and methotrexate (400 mg/kg) with leucovorin. Children without progressive disease (PD) by the end of induction underwent a single consolidation cycle (carboplatin, etoposide, thiotepa) with autologous stem cell rescue. Reduced dose RT (2340cGy CSI and focal boost) was reserved for any with residual disease at the end of induction or for the older patient (>6 yrs of age). Results: 40 patients were enrolled (MB, 22; PNET, 6; ependymoma, 5; AT/RT, 6; CPC, 1), med age at diagnosis 38 mos (range 5 to 119 mos). Significant toxicities of this intensified regimen included GI toxicities and infections. Among the entire cohort, there were 26 CR, 6 PR, 2 with stable disease and 4 with PD (and 2 toxic deaths), for a CR +PR response rate of 82%. For disseminated MB (4 M1; 2 M2; 16 M3), the CR rate alone is 77% (17/22). The 5-year EFS and OS for disseminated MB are 45% (95% CI, 24 % to 64%) and 54% (95% CI, 31% to 72%), respectively. Of note, 6/12 MB survivors (all M3) did not receive RT and all are NED >5 years from diagnosis. In addition, there are 3 AT/RT survivors, 12, 54 and 66 mos post-diagnosis who did not receive RT. Conclusions: This intensified regimen is feasible and tolerable. For patients with disseminated MB, the majority of whom had M3 disease at diagnosis, the impressive response rate and outcomes suggest that the addition of methotrexate is justified for future studies. Long- term neuropsychological outcomes are being studied at this time.

No significant financial relationships to disclose.

Tunable S-band erbium-doped triple-ring laser with single-longitudinal-mode operation

We propose and demonstrate a tunable and stable single-longitudinal-mode (SLM) erbium fiber laser with a passive triple-ring cavity structure in S-band operation. The proposed laser is fundamentally structured by using three different lengths of ring cavities, which serve as the mode filters. When a mode-restricting intracavity fiber Fabry-Perot tunable filter (FFP-TF) is combined, the proposed resonator can guarantee a tunable and stable SLM laser oscillation. Moreover, the performances of the output power, wavelength stability, tuning range, and side-mode suppression ratio (SMSR) are studied.

Tunable slow light device using quantum dot semiconductor laser

This investigation experimentally demonstrates a tunable slow light device using a quantum dot (QD) semiconductor laser. The QD semiconductor laser at 1.3 mum fabricated on a GaAs substrate is grown by molecular beam epitaxy. Tunable slow light can be achieved by adjusting the bias current and wavelength detuning. The slow light device operated under probe signal from 5 to 10 GHz is presented. Moreover, we also demonstrate that the tunable slow light device can be used in a subcarrier multiplexed system.

Regulatory effect of sulphatides on BKCa channels

BACKGROUND AND PURPOSE

Sulphatides are sulphated glycosphingolipids expressed on the surface of many cell types, particularly neurones. Changes in sulphatide species or content have been associated with epilepsy and Alzheimer's disease. As the large conductance, calcium sensitive K(+) channel (BK(Ca)) are modulated by membrane lipids, the aim of the study was to explore possible effects of sulphatides on BK(Ca) channels.

EXPERIMENTAL APPROACH

Using patch-clamp techniques, we studied effects of exogenous sulphatides on BK(Ca) channels expressed in Chinese hamster ovary cells.

KEY RESULTS

Sulphatides reversibly increased the whole-cell current and the single channel open probability of BK(Ca) channels dose-dependently. The EC(50) value on the channel at +10 mV was 1.6 microM and the Hill coefficient was 2.5. In inside-out patches, sulphatides increased the single channel open probability from both intra- and extra-cellular faces of the membrane, but more effectively with external application. Furthermore, activation of the channels by sulphatides was independent of intracellular Ca(2+) concentration. Sulphatides also shifted the activation curve of the channels to less positive membrane potentials. Mutant BK(Ca) channels lacking a 59 aminoacid region important for amphipath activation (STREX) were less activated by the sulphatides.

CONCLUSIONS AND IMPLICATIONS

Sulphatides are novel activators of BK(Ca) channels, independent of intracellular Ca(2+) or other signalling molecules but partly dependent on the STREX sequence of the channel protein. As changes of sulphatide content are associated with neuronal dysfunction, as in epilepsy and Alzheimer's disease, our results imply that these effects of sulphatides may play important pathophysiological roles in regulation of BK(Ca) channels.

Dynamic characteristics of long-wavelength quantum dot vertical-cavity surface-emitting lasers with light injection

This investigation experimentally demonstrates the dynamic characteristics of quantum dot vertical-cavity surface-emitting lasers (QD VCSEL) without and with light injection. The QD VCSEL is fully doped structure on GaAs substrate and operates in the 1.3 mum optical communication wavelength. The eye diagram, frequency response, and intermodulation distortion are presented. We also demonstrate that the frequency response enhancement by light injection technique allows us to improve the performance of subcarrier multiplexed system.

Molecular weight of chitosan influences antimicrobial activity in oil-in-water emulsions

The objective of this study was to evaluate the antimicrobial efficiency of chitosans in oil-in-water emulsions. Model emulsions were prepared with 20% corn oil, 1.5% Tween 20, 1.5% Trypticase soy broth, 0.58% acetic acid, and chitosan polysaccharide or chitosan oligosaccharide in concentrations of 0, 0.1, 0.2, 0.5, and 0.7%. A control containing HCl was included to determine the role of acetic acid in the overall antibacterial activity. The pH of samples and controls was adjusted to 4.5. Emulsions were inoculated with Listeria monocytogenes (strains Scott A and 310) or Salmonella Typhimurium DT104 (strains 2486 and 2576) at a level of 10(7) CFU/ml. Inoculated emulsions were incubated at 10 and 25 degrees C for 4 days and analyzed for bacterial count every 24 h. Both tested Salmonella strains were more susceptible to acetic acid than Listeria. However, L. monocytogenes was more affected by chitosan than either Salmonella strain. During the storage at 25 degrees C, initial inoculum in the emulsions with 0.58% acetic acid and 0.1% chitosan polysaccharide was reduced to below the detection limits after 24, 48, 72, or 96 h for L. monocytogenes 310, Salmonella Typhimurium DT104 2576, Salmonella Typhimurium DT104 2486, or L. monocytogenes Scott A, respectively. Chitosan oligosaccharide was less effective against all tested bacteria and showed a concentration-dependent effect. The antimicrobial efficacy of chitosan was reduced at 10 degrees C, and reduction of microbial loads was delayed for approximately 24 h compared with 25 degrees C. Results suggest that addition of 0.1% chitosan polysaccharide would be sufficient to ensure the microbial safety of oil-in-water emulsions regardless of storage temperature.

The cellular matrix: a feature of tensile bearing dense soft connective tissues

The term connective tissue encompasses a diverse group of tissues that reside in different environments and must support a spectrum of mechanical functions. Although the extracellular matrix of these tissues is well described, the cellular architecture of these tissues and its relationship to tissue function has only recently become the focus of study. It now appears that tensile-bearing dense connective tissues may be a specific class of connective tissues that display a common cellular organization characterized by fusiform cells with cytoplasmic projections and gap junctions. These cells with their cellular projections are organised into a complex 3-dimensional network leading to a physically, chemically and electrically connected cellular matrix. The cellular matrix may play essential roles in extracellular matrix formation, maintenance and remodelling, mechanotransduction and during injury and healing. Thus, it is likely that it is the interaction of both the extracellular matrix and cellular matrix that provides the basis for tissue function. Restoration of both these matrices, as well as their interaction must be the goal of strategies to repair these connective tissues damaged by either injury or disease.

Neuroblastic and Schwannian stromal cells of neuroblastoma are derived from a tumoral progenitor cell

The coexistence of neuroblastic and Schwannian stromal (SS) cells in differentiating neuroblastoma (NB), and derivation of Schwannian-like cells from neuroblastic clones in vitro, were accepted previously as evidence of a common pluripotent tumor stem line. This paradigm was challenged when SS cells were suggested to be reactive in nature. The advent of microdissection techniques, PCR-based allelic analysis, and in situ fluorescent cytometry made possible the analysis of pure cell populations in fresh surgical specimens, allowing unequivocal determination of clonal origins of various cell subtypes. To overcome the complexity and heterogeneity of three-dimensional tissue structure, we used: (a) Laser-Capture Microdissection to obtain histologically homogeneous cell subtype populations for allelotype analysis at chromosomes 1p36, 11q23, 14q32, and 17q and study of MYCN copy number; (b) multiparametric analysis by Laser-Scanning Cytometry of morphology, DNA content, and immunophenotype of intact cells from touch imprints; and (c) bicolor fluorescence in situ hybridization on touch imprints from manually microdissected neuroblast and stroma-rich areas. Histologically distinct SS and neuroblastic cells isolated by Laser-Capture Microdissection had the same genetic composition in 27 of 28 NB analyzed by allelic imbalance and gene copy number. In all 20 cases studied by Laser-Scanning Cytometry, SS cells identified by morphology and S-100 immunostaining had identical DNA content and GD2-staining pattern as their neuroblastic counterparts. In 7 cases, fluorescence in situ hybridization demonstrated the same chromosomal makeup for SS and neuroblastic cells. These results provide unequivocal evidence that neuroblastic and SS cells in NB are derived from genetically identical neoplastic cells and support the classical paradigm that NB arises from tumoral cells capable of development along multiple lineages.

Single-longitudinal-mode operation of a grating-based fiber-ring laser using self-injection feedback

A fiber Bragg grating- (FBG-) based fiber-ring laser that utilizes the transmitted light of the FBG as self-injection feedback for single-longitudinal-mode (SLM) oscillation is proposed and demonstrated. This laser is simply constructed by means of feeding back the transmitted light of the FBG and is coupled into the main ring cavity through an optical coupler. The self-injection feedback is the key to ensuring SLM laser oscillation. The SLM operation principle is discussed in detail, and a SLM laser with output power of 6.6 dBm, an optical signal-to-noise ratio of 57 dB at 1549.19 nm, and a short-term linewidth of 3.5 kHz is reported.

Axially symmetric on-axis flat-top beam

A synthesis method for arbitrary on-axis intensity distributions from axially symmetric fields is developed in the paraxial approximation. As an important consequence, a new pseudo-nondiffracting beam, the axially symmetric on-axis flat-top beam (AFTB), is given by an integral transform form. This AFTB is completely determined by three simple parameters: the central spatial frequency S(c), the on-axis flat-top length L, and the on-axis central position z(c). When LS(c) >> 1, this AFTB can give a nearly flat-top intensity distribution on the propagation axis. In particular, this AFTB approaches the nondiffracting zero-order Bessel J0 beam when L--> infinity. It is revealed that the superposition of multiple AFTB fields can give multiple on-axis flat-top intensity regions when some appropriate conditions are satisfied.

Proteasome inhibitors induce cytochrome c-caspase-3-like protease-mediated apoptosis in cultured cortical neurons

The ubiquitin-proteasome protein degradation pathway is crucial in controlling intracellular levels of a variety of short-lived proteins and maintaining cellular growth and metabolism. In a previous study, we showed the accumulation of conjugated ubiquitin in CA1 neurons of the gerbil after 5 min of forebrain ischemia (; ). The accumulation of conjugated ubiquitin may reflect proteasome malfunction. In the present study, we investigated the effects of proteasome inhibitors on primary neuronal cultures to determine whether proteasomal malfunction induces neuronal death. When carbobenzoxy-Leu-Leu-Leu-aldehyde or lactacystin, two different types of proteasome inhibitors, were separately used to suppress proteasome activity, we observed induction of apoptotic neuronal cell death in both cases. During the apoptotic process, mitochondrial membrane potential was disrupted, cytochrome-c was released from mitochondria into the cytosol, and caspase-3-like proteases were activated. Apoptosis was inhibited by pretreatment with acetyl-aspartyl-glutamyl-valyl-aspart-1-aldehyde or overexpression of Bcl-x/(L). These results demonstrated that suppression of proteasome function induces neuronal apoptosis via the release of cytochrome c from mitochondria and activation of caspase-3-like proteases.

High level calcineurin activity predisposes neuronal cells to apoptosis

Calcineurin is a Ca(2+)/calmodulin-dependent protein phosphatase that is abundantly expressed in several specific areas of the brain, which are exceptionally vulnerable to stroke, epilepsy, and neurodegenerative diseases. In this study, we assessed the effects of high level activity of calcineurin on neuronal cells. Virus-mediated high level constitutive activity of calcineurin rendered neuronal cells susceptible to apoptosis induced by serum reduction or by a brief exposure to calcium ionophore. Adenovirus-mediated, high level forced activity of calcineurin induced cytochrome c/caspase-3-dependent apoptosis in neurons. Preincubation with the calcineurin inhibitors cyclosporin A and FK506 reduced susceptibility to apoptosis. High level constitutive expression of Bcl-2 or CrmA or incubation with a specific caspase-3 inhibitor inhibited the calcineurin-induced apoptosis. These data indicate that high level constitutive activity of calcineurin predisposes neuronal cells to cytochrome c/caspase-3 dependent apoptosis even under sublethal conditions.

Total syntheses of (+/-)-preussomerins G and I

[formula: see text] Preussomerins G and I (2 and 3) have been synthesized for the first time. The key reaction in the synthesis is a possibly biomimetic tautomerization reaction depicted in Scheme 3 and the foregoing graphic. The driving force for this interesting rearrangement is primarily derived from the increase in resonance energy associated with converting a naphthalene ring into two isolated benzene rings.

Total syntheses of (+/-)-preussomerins G and I

[formula: see text] Preussomerins G and I (2 and 3) have been synthesized for the first time. The key reaction in the synthesis is a possibly biomimetic tautomerization reaction depicted in Scheme 3 and the foregoing graphic. The driving force for this interesting rearrangement is primarily derived from the increase in resonance energy associated with converting a naphthalene ring into two isolated benzene rings.

Neuregulin stimulates myogenic differentiation in an autocrine manner

During myogenesis, mononucleated myoblasts form multinucleated myotubes by membrane fusion. Efficiency of this intercellular process can be maximized by a simultaneous progress, with a time window, of other neighboring myoblasts in the differentiation program. This phenomenon has been described as the community effect. It proposes the existence of a molecule that acts as a differentiation-inducing signal to a group of identical cells. Here, we show that neuregulin is a strong candidate for this molecule in myoblast differentiation. The expression of neuregulin increased rapidly but transiently at early stage of differentiation of rat L6 cells. Neuregulin showed a potent differentiation-promoting activity in membrane fusion and expression of myosin heavy chain. The antibodies raised against neuregulin and its cognate receptor ErbB3, which were capable of neutralizing the signal pathway, inhibited myotube formation and expression of myosin heavy chain in both L6 cells and primary rat myoblasts. The progress of differentiation was mostly halted after the expression of myogenin and cell cycle arrest. These results suggest that the activation of an autocrine signaling of neuregulin may provide a basic mechanism for the community effect observed in the differentiation of the embryonic muscle cells.

Oncogenic Ras triggers cell suicide through the activation of a caspase-independent cell death program in human cancer cells

To prevent neoplasia, cells of multicellular organisms activate cellular disposal programs such as apoptosis in response to deregulated oncogene expression, making the suppression of such programs an essential step for potentially neoplastic cells to become established as clinically relevant tumors. Since the mutation of ras proto-oncogenes, the most frequently mutated proto-oncogenes in human tumors, is very rare in some tumor types such as glioblastomas and gastric cancers, we hypothesized that mutated ras genes might activate a cell death program that cannot be overcome by these tumor types. Here we show that the expression of oncogenically mutated ras gene induces cellular degeneration accompanied by cytoplasmic vacuoles in human glioma and gastric cancer cell lines. Cells dying as a result of oncogenic Ras expression had relatively well-preserved nuclei that were negative for TUNEL staining. An immunocytochemical analysis demonstrated that the cytoplasmic vacuoles are derived mainly from lysosomes. This oncogenic Ras-induced cell death occurred in the absence of caspase activation, and was not inhibited by the overexpression of anti-apoptotic Bcl-2 protein. These observations suggested that oncogenic Ras-induced cell death is most consistent with a type of programmed cell death designated 'type 2 physiological cell death' or 'autophagic degeneration', and that this cell death is regulated by a molecular mechanism distinct from that of apoptosis. Our findings suggest a possible role for this non-apoptotic cell death in the prevention of neoplasia, and the activation of the non-apoptotic cell death program may become a potential cancer therapy complementing apoptosis-based therapies. In addition, the approach used in this study may be a valuable way to find genetically-regulated cell suicide programs that cannot be overcome by particular tumor types.

State-level variation in Medicare spending

Theoretically, Medicare provides one standard benefit package to all enrollees. But because of State-level variations in populations, service supply, and local practice patterns, national policy changes may have unequal impacts on access and service utilization. Across-the-board policy changes may create hardships in one area while appropriately discouraging use in another area. In this article, the authors describe State-level variations in Medicare enrollees, their insurance coverage, 1995 Medicare and beneficiary spending patterns in aggregate, per capita, and by service, and certain spending patterns for dually eligible beneficiaries. These data are useful for considering the State-level effects of payment reform.

Calbindin-D28k buffers intracellular calcium and promotes resistance to degeneration in PC12 cells

The calcium-binding protein calbindin-D28k (CB) has been hypothesized to function, in part, as a neuroprotective protein. CB is localized within nerve cells that are often less vulnerable to degeneration in patients with Alzheimer's disease and Parkinson's disease, and cells containing CB can buffer intracellular calcium concentrations ([Ca2+]i). The present study was designed to directly test the hypothesis that CB can protect cells from degeneration by reducing [Ca2+]i. PC12 cells, transfected to express different levels of CB, were found to be significantly less vulnerable to degeneration caused by serum withdrawal, glutamate, and the neurotoxin 1-methyl-4-phenylpyridinium (MPP+). However, CB did not protect cells from degeneration caused by the calcium ionophore A23187. CB-transfected cells exhibited reduced elevations in [Ca2+]i following treatment with bradykinin, or ATP compared to non-CB-containing cells. These data indicate that CB can protect cells from degeneration caused by certain conditions, and it reduces elevations in [Ca2+]i caused by influx from extracellular sources.

Four-wave mixing between a soliton and noise in a system with large amplifier spacing

Depletion of soliton energy by four-wave mixing between a soliton and amplifier noise in a system with 100-km amplifier spacing is studied. Dispersion exponentially decreasing fiber is used as transmission fiber. Improvement of the system by the use of a sliding-frequency filter to reduce noise power and the depletion of soliton energy is shown. The system can be further improved by compensation for depleted soliton energy.

Caspase-dependent apoptosis of COS-7 cells induced by Bax overexpression: differential effects of Bcl-2 and Bcl-xL on Bax-induced caspase activation and apoptosis

Bcl-2 family proteins and ICE/CED-3 family proteases (caspases) are regarded as the basic regulators of apoptotic cell death. They are evolutionarily conserved and implicated in a variety of apoptosis. However, the precise mechanism by which these two families interact to regulate cell death is not yet known. In this study, we found that the overexpression of the Bcl-2 family member Bax induced apoptotic cell death in COS-7 cells through the activation of CPP32 (caspase-3)-like proteases that cleaved the DEVD tetrapeptide. This apoptotic cell death was suppressed by the viral proteins CrmA and p35, as well as by the chemically synthesized caspase inhibitors Z-Asp-CH2-DCB and zVAD-fmk. We also found that the Bax-induced apoptosis of COS-7 cells was suppressed by Bcl-xL and Bcl-2, though both Bcl-xL and Bcl-2 similarly prevented etoposide-induced apoptosis in COS-7 cells. In addition, Bcl-xL inhibited the activation of caspase-3-like proteases accompanying Bax-induced COS-7 cell death but Bcl-2 did not. These results indicate that the caspase activation is essential for Bax-induced apoptosis, and that the ability of Bcl-2 and Bcl-xL to prevent the Bax-induced caspase activation and apoptosis in COS-7 cells could be differentially regulated. Our results also suggest that Bcl-2 family proteins function upstream of caspase activation and control apoptosis through the regulation of caspase activity.

Pim-1 kinase stimulates c-Myc-mediated death signaling upstream of caspase-3 (CPP32)-like protease activation

Pim-1 oncoprotein is a serine/threonine kinase that can closely cooperate with c-Myc in lymphomagenesis, as does Bcl-2. Although the molecular mechanism of this cooperative transformation remains unknown, it is speculated that, similar to Bcl-2, Pim-1 contributes to transformation by inhibiting apoptosis. In this study, therefore, we examined the effect of Pim-1 expression on c-Myc-mediated apoptosis of Rat-1 fibroblasts triggered by serum deprivation. Our results showed that, rather than inhibiting apoptosis, Pim-1 expression stimulated c-Myc-mediated apoptosis in Rat-1 fibroblasts. Pim-1 stimulated c-Myc-mediated apoptosis through an enhancement of the c-Myc-mediated activation of caspase-3 (CPP32)-like proteases, since the suppression of this activity by a specific caspase inhibitor abolished the apoptosis stimulation by Pim-1. A kinase-defective Pim-1 mutant failed to stimulate c-Myc-mediated apoptosis, and Pim-1 expression alone in the absence of c-Myc overexpression did not induce apoptosis of serum-deprived Rat-1 cells, indicating that the kinase activity of Pim-1 and the activated c-Myc signaling pathway were required for apoptosis stimulation by Pim-1. Together, these results suggest that Pim-1 oncoprotein stimulates as a serine/threonine kinase the death signaling elicited by c-Myc at a step upstream of caspase-3-like protease activation in Rat-1 fibroblasts. Our results also suggest that Pim-1 kinase might function cooperatively with c-Myc through the phosphorylation of a factor(s) which regulates the common signaling pathway involved in c-Myc-mediated apoptosis and transformation.

Risk of nodal metastases at laparoscopic pelvic lymphadenectomy using PSA, Gleason score, and clinical stage in men with localized prostate cancer

Laparoscopic pelvic lymph node dissection (LPLND) is a low-morbidity procedure used to stage prostate cancer accurately prior to definitive local therapy. To better select patients for LPLND, we reviewed the clinical features of 120 patients with clinically localized prostate cancer who underwent LPLND to define significant risk factors for nodal metastases. The age ranged from 43 to 79 years (mean 68). Serum prostate specific antigen (PSA) concentration ranged from 1.3 to 329 ng/mL, Gleason score ranged from 2 to 9, and clinical stage ranged from T1b to T3c. Nodal metastases were discovered in 15 patients (13%). Among men with a Gleason score > or = 7, 21% had nodal metastases (P = 0.004). A serum PSA > 20 ng/mL and clinical stage T1b, T2b, or greater also were statistically significant predictors of lymph node metastases (20% and 19%, respectively). In multivariate analysis, Gleason score significantly predicted nodal metastases when controlling for all other clinical measures. Therefore, LPLND is indicated for any patient with a Gleason score > or = 7, PSA > 20 ng/mL, and advanced clinical T stage, independently or in combination.

Calbindin-D28K in the nucleus of nerve growth factor-treated PC12 cells

Calbindin-D28K (CB) is a calcium-binding protein found within a subset of neurons, which has been proposed to buffer intracellular calcium and to protect cells from calcium-induced neurodegeneration. The rat pheochromocytoma PC12 cell line has been an invaluable tool for studying neuronal development and characterizing the molecular actions of nerve growth factor (NGF). Using Western and RNAse protection analyses and immunocytochemical and cell fractionation techniques, we now report that NGF induces the expression of CB not only in the cytoplasm and neurites, but also within the nuclei of PC12 cells. These data indicate that PC12 cells can serve as a useful model system in which to study the functions of CB and the role of nuclear CB.

Reduction of soliton interactions by sliding-frequency second-order Butterworth filters

The reduction of the soliton interaction by use of optical sliding-frequency second-order Butterworth filters is studied numerically. It is found that the second-order Butterworth filters can reduce the soliton interaction more effectively than Fabry-Perot filters or third-order Butterworth filters because the secondorder Butterworth filter induces larger frequency chirping on the soliton, compressing it as it propagates in the fiber after the filter.

Reduction of soliton interactions by zigzag-sliding-frequency guiding filters

Reductions of the soliton interactions and jitter by the upsliding-frequency filter, the downsliding-frequency filter, and the zigzag-sliding-frequency filter are numerically studied. It is shown that the most effective filter for reducing the soliton interactions is the zigzag-sliding-frequency filter.

Vector theory of self-focusing of an optical beam in Kerr media

The scalar theory of the self-focusing of an optical beam is not valid for a very narrow beam, and a correct description of the beam behavior requires a vector analysis in this case. A vector nonparaxial theory is developed from the vector Maxwell equations by application of an order-of-magnitude analysis method. For the same input beam, the numerical results of self-focusing from both scalar and vector theories are compared. It is found by the vector theory that a linearly polarized circular input beam becomes elliptical in the selffocusing process.