The effect of orbital-lattice coupling on the electrical resistivity of YBaCuFeO5 investigated by X-ray absorption

Temperature-dependent X-ray absorption near-edge structures, X-ray linear dichroism (XLD) and extended X-ray absorption fine structure (EXAFS) spectroscopic techniques were used to investigate the valence state, preferred orbital and local atomic structure that significantly affect the electrical and magnetic properties of a single crystal of YBaCuFeO5 (YBCFO). An onset of increase of resistivity at ~180 K, followed by a rapid increase at/below 125 K, is observed. An antiferromagnetic (AFM)-like transition is close to the temperature at which the resistivity starts to increase in the ab-plane and is also observed with strong anisotropy between the ab-plane and the c-axis. The XLD spectra at the Fe L3,2-edge revealed a change in Fe 3d eg holes from the preferential [Formula: see text] orbital at high temperature (300-150 K) to the [Formula: see text] orbital at/below 125 K. The analysis of the Fe K-edge EXAFS data of YBCFO further revealed an unusual increase in the Debye-Waller factor of the nearest-neighbor Fe-O bond length at/below 125 K, suggesting phonon-softening behavior, resulting in the breaking of lattice symmetry, particularly in the ab-plane of Fe-related square pyramids. These findings demonstrate a close correlation between electrical resistivity and coupling of the preferred Fe 3d orbital with lattice distortion of a single crystal of YBCFO.

Polaronic effect in the x-ray absorption spectra of La1-x Ca x MnO3 manganites

X-ray absorption spectroscopy (XAS) is performed to study changes in the electronic structures of colossal magnetoresistance (CMR) and charged ordered (CO) La_1-x Ca _x MnO₃ manganites with respect to temperature. The pre-edge features in O and Mn K-edge XAS spectra, which are highly sensitive to the local distortion of MnO₆ octahedral, exhibit contrasting temperature dependence between CMR and CO samples. The seemingly counter-intuitive XAS temperature dependence can be reconciled in the context of polarons. These results help identify the most relevant orbital states associated with polarons and highlight the crucial role played by polarons in understanding the electronic structures of manganites.

Blood safety implications of donors using HIV pre-exposure prophylaxis

HIV pre-exposure prophylaxis (PrEP) is the use of one or more antiretroviral medications (in combination) to prevent HIV infection. The most commonly used PrEP medication (Truvada^® , Gilead Sciences, Inc.) acts by inhibiting HIV-1 reverse transcriptase. If someone who is using PrEP unknowingly becomes HIV infected (termed 'PrEP breakthrough infection'), there may be suppressed viral replication resulting in a virus level undetectable by the most sensitive HIV NAT. Failure to seroconvert and seroreversion (loss of previously detectable HIV antibodies) have also both been observed with 2nd, 3rd and 4th generation screening immunoassays, as well as Western blot assays. If such a person was tested in the course of donating blood, the results may therefore be difficult to interpret. The index of suspicion for possible PrEP 'interference' should be highest in the context of concomitant low-level positive or 'greyzone' reactivity on HIV NAT and serological tests, which is an unusual pattern in acutely HIV-infected blood donors. Another possibility is detectable HIV RNA with negative HIV serology (i.e. a potential 'NAT yield' case) but without subsequent HIV seroconversion (or disappearance of HIV RNA). Excluding antiretroviral therapy or PrEP use by the donor in such circumstances would be important. The current rarity of PrEP breakthrough infection indicates that any potential safety risk is likely very small. However, considering the increasing use of PrEP we feel it is prudent for those interpreting HIV donor screening test results to consider the potential for PrEP interference.

Unconventional interplay between heterovalent dopant elements: Switch-and-modulator band-gap engineering in (Y, Co)-Codoped CeO2 nanocrystals

We report the experimental observation and theoretical explanation of an unconventional interplay between divalent Co and trivalent Y dopants, both of which incur oxygen vacancies in the CeO₂ host that has predominantly tetravalent Ce cations. The Co dopant atoms were experimentally found to act as a switch that turns on the dormant effect of Y-modulated band-gap reduction. As revealed by density functional theory (DFT) calculations with structures verified by synchrotron-radiation x-ray measurements, a Co 3d band that hybridizes with Ce 4f band was lowered due to reduced O 2p repulsion arising from oxygen vacancies incurred by Y doping and therefore gave rise to the observed band-gap narrowing effect. Such switch-and-modulator scheme for band-gap engineering in nanocrystal materials can lead to important applications in environmental protection and solar energy harvesting technologies.

Synthesis and characterization of Pt nanoparticles with different morphologies in mesoporous silica SBA-15 for methanol oxidation reaction

Mesoporous SBA-15 silica materials functionalized with and without carboxylic acid groups were used to effectively control the morphology of Pt crystals, and the materials thus obtained were applied to methanol oxidation reactions. The Pt particles aggregated to form long spheroids inside the channels in pure SBA-15. When carboxylic acid groups were utilized, the SBA-15(-COOH) material facilitated the formation of higher Pt surface area, smaller Pt nanoparticles and nearly spherical shape due to the strong interaction between Pt(4+) ions and carboxylic acid on SBA-15. The Pt(4+) ions on the SBA-15(-COOH) material can be directly transformed to reduced Pt particles during calcination. The methanol oxidation activity on a Pt surface is strongly dependent on the shape of Pt particles. The near-spherical Pt nanoparticles on the SBA-15(-COOH) exhibited higher catalytic activity during methanol oxidation than Pt catalysts on unmodified SBA-15. The near-spherical Pt particles on the SBA-15(-COOH) contained large numbers of terrace sites on their surfaces, which led to high efficiency during methanol oxidation.

The protective effect of curcumin on ischemia-reperfusion-induced liver injury

OBJECTIVE

Reperfusion of the ischemic liver results in the generation of oxidative and nitrosative stresses and reaction product of peroxynitrite, which induce rapid cytotoxicity and liver injury. In this study we demonstrated that curcumin, an antioxidant, attenuated ischemia/reperfusion (I/R)-induced liver injury.

MATERIALS AND METHODS

Ischemia was induced by clamping the common hepatic artery and portal vein of rats for 30 minutes. Thereafter, flow was restored and the liver was reperfused for 80 minutes. Blood samples collected prior to ischemia and after reperfusion were analyzed for methyl guanidine (MG), nitric oxide (NO), tumor necrosis factor-alpha (TNF-α), and adenosphate triphosphate (ATP). Blood levels of serum glutamic oxaloacetic transaminase (sGOT), serum glutamate pyruvate transaminase (sGPT), and lactic dehydrogenase (LDH), which served as indexes of liver injury, were measured.

RESULTS

The protocol resulted in elevation of blood NO (P < .001), TNF-α (P < .001), and MG (P < .001). sGOT, sGPT, and LDH were elevated significantly (P < .001), whereas ATP was significantly diminished (P < .001). Pretreatment with curcumin (25 mg/kg) significantly attenuated the reperfusion liver injury, while the ATP content reversed. In addition, MG, TNF-α, and NO release were attenuated.

CONCLUSIONS

These results indicated that curcumin exerted potent anti-inflammatory effects in I/R-induced liver injury due to its antioxidant effects.

Attenuated relationship between cardiac output and oxygen uptake during high-intensity exercise

AIM

Recent findings have challenged the belief that the cardiac output (CO) and oxygen consumption (VO(2) ) relationship is linear from rest to maximal exercise. The purpose of this study was to determine the CO and stroke volume (SV) response to a range of exercise intensities, 40-100% of VO(2max), during cycling.

METHODS

Ten well-trained cyclists performed a series of discontinuous exercise bouts to determine the CO and SV vs. VO(2) responses.

RESULTS

The rate of increase in CO, relative to VO(2) , during exercise from 40 to 70% of VO(2max) was 4.4 ± 1.4 L L(-1). During exercise at 70-100% of VO(2max) , the rate of increase in CO was reduced to 2.1 ± 0.9 L L(-1) (P = 0.01). Stroke volume during exercise at 80-100% of VO(2max) was reduced by 7% when compared to exercise at 50-70% of VO(2max) (134 ± 5 vs. 143 ± 5 mL per beat, P = 0.02). Whole body arterial-venous O(2) difference increased significantly as intensity increased.

CONCLUSION

The observation that the rate of increase in CO is reduced as exercise intensity increases suggests that cardiovascular performance displays signs of compromised function before maximal VO(2) is reached.

X-Ray spectra and electronic correlations of FeSe(1-x)Te(x)

Critical issues concerning emerging Fe-based superconductors include the degree of electron correlation and the origin of the superconductivity. X-Ray absorption spectra (XAS) and resonant inelastic X-ray scattering spectra (RIXS) of FeSe(1-x)Te(x) (x = 0-1) single crystals were obtained to study their electronic properties that relate to electron correlation and superconductivity. The linewidth of Fe L(2,3)-edges XAS of FeSe(1-x)Te(x) is narrower than that of Fe-pnictides, revealing the difference between their hybridization effects and localization character and those of other Fe-pnictides. While no significant differences exist between the Fe L-edge XAS and RIXS of FeSe(1-x)Te(x) and those of Fe-pnictides, Se K-edge and Te K-edge XAS exhibit substantial edge shift, suggesting that the superconductivity in an Fe-Se superconductor is strongly associated with the ligand states. A comparison of the Se K-edge and Te K-edge spectra reveals that the charge transfer may occur between Se and Te. Given the Coulomb interaction and the bandwidth, the spectral results indicate that FeSe(1-x)Te(x) is unlikely to be a weakly correlated system unlike the Fe-pnictides of the "1111" and "122" families. The spectral results further demonstrate that superconductivity in this class of Fe-based compounds is strongly associated with the ligand 4p hole state.

Water extract of Zizyphus Jujube attenuates ischemia/reperfusion-induced liver injury in rats (PP106)

AIMS

Ischemia and reperfusion (I/R) injuries in the liver remain important clinical problems. Free oxygen radicals and nitrosative stress have been shown to be involved in the pathogenesis I/R-related liver injury. The purpose of this study was to characterize the effects of an extract of Zizyphus Jujube (ZJ), which has strong antioxidant effects, on I/R-induced liver injury.

MATERIALS AND METHODS

Ischemia (I) was induced in rat livers by clamping the common hepatic artery and portal vein for 40 minutes, after which flow was restored, and the liver was reperfused for 90 minutes. Blood samples were collected prior to I and after reperfusion to assay blood levels of alanine transaminase (ALT), lactic dehydrogenase (LDH), oxygen radical (OH), and nitric oxide (NO). In the pharmacologic intervention group a water extract of the fruit of ZJ was administered orally to rats (100 mg/mL for 7 days) that were subsequently exposed to the I/R liver injury.

RESULTS

The data showed that reperfusion (R) of the liver produced increases in blood concentrations of ALT (41.9+/-8.2 vs 338.0+/-89.6; P<.01; N=7) and LDH (317+/-129 vs 4073+/-950; P<.001; N=7). Oxygen radicals (55.1+/-14.3 vs 262.4+/-60.3; P<.001; N=7) and NO (69.3+/-14.9 vs 121.6+/-27.1; P<.01; N=7) also increased significantly in this R group. In the ZJ intervention group the liver injury, oxidative stress, and nitrosative stress were all significantly attenuated.

CONCLUSION

These results suggested that I/R-induced liver injury with white blood cell activation, oxidative stress, and nitrosative stress. Pretreatment with an extract of ZJ, which shows high antioxidant effects, significantly attenuated the I/R-induced liver injury.

Postischemia myocardial injury in coronary artery bypass patients (PP6)

PURPOSE

To investigate the reperfusion injury of the myocardium in patients undergoing elective coronary artery bypass surgery (CABG) with cardiopulmonary bypass (CPB), we monitored the blood levels of troponin I (TNI), white blood cells, oxygen radicals, malondialdehyde, and myeloperoxidase seeking to define the relationship between the CABG-induced systemic inflammation and myocardial injury.

MATERIALS AND METHODS

We selected 10 patients undergoing primary CABG with CPB at moderate hypothermia and cardioplegic arrest concomitant with intermittent warm blood cardioplegia. We compared all data with their own baseline values to study the reperfusion injury. After release of the aortic clamp, blood was drawn from the coronary sinus, via a catheter placed through the right atrium. We measured plasma levels of inflammatory mediators, such as malondialdehyde, myeloperoxidase, oxygen radicals, and the myocardium injury parameter of TNI.

RESULTS

Patients showed no difference concerning aortic clamp time. TNI increased significantly at 1, 15, and 30 minutes after the onset of reperfusion. Blood levels of white blood cells, oxygen radicals, malondialdehyde, and myeloperoxidase also increased significantly with reperfusion time.

CONCLUSIONS

Reperfusion of ischemic myocardium induced increased TNI, which may be related to the systemic inflammatory responses induced by ischemia and reperfusion of the myocardium among patients undergoing elective coronary bypass surgery.

A quasi-experimental retrospective evaluation of a prison policy change

Interrupted time-series design and quasi-experimental logic were employed to assess the behavioral effects of a prison disciplinary intervention on a population of approximately 2000 adult male inmates. The uncontrolled nature of the prison environment prevented experimental analysis of intervention effects. The quasi-experimental methodology applied in this study exemplifies how data, otherwise lost, can be retrieved. In addition, the process by which qualified conclusions can be drawn from the retrieved data is demonstrated.

A study of particulates and metallic element concentrations in temple

Concentrations of ambient suspended particulates were measured at Tzu Yun Yen temple in Taiwan (120 degrees , 34', 46.2''E, 24 degrees , 16', 17.1''N), where semi-open incense burning is characteristic. Many pilgrims from different areas with various beliefs visit the temple and burn incense. Samples were collected with a universal sampler used for measuring suspended particulate concentrations. Sampling period was from August 8, 2006, to October 6, 2006. The average PM(10) concentrations measured at the temple were 16% higher than 125 microg/m(3) (this value is the outdoor air quality standard according to Taiwan Environmental Protection Administration (EPA)). In coarse particulates (PM(2.5-10)), the mean metallic elements concentrations are in the order of Ca>Mg>Zn>Fe>Mn>Cr>Cu>Pb during weekend and weekday sampling. In addition, the fine particulates (PM(2.5)) mean metallic elements concentrations are in the order of Ca>Mg>Fe>Zn>Cr>Mn>Pb>Cu during weekend sampling and Ca>Fe>Mg>Zn>Cr>Mn>Pb>Cu during weekday sampling.

Correlation between magnetic properties and the electronic structures of soft magnetic ternary Fe(78-x)Y(x)B(22) (x = 4-9) bulk metallic glasses

Fe and Y K-edge extended x-ray absorption fine structure, Fe(Y) L(3,2)-edge (L(3)-edge) x-ray absorption near-edge structure (XANES) and valence-band photoemission spectroscopy (VB-PES) measurements have been carried out to study soft magnetic ternary Fe(78-x)Y(x)B(22) bulk metallic glasses (BMGs). The combined XANES and VB-PES results do not show broadening of the Fe 3d band to support the previous interpretation of the reduction of the magnetic moment in BMGs by Y-induced decrease of exchange splitting of Fe 3d orbitals. Instead, the density of delocalized/itinerant Fe 3d states in the vicinity of the Fermi level is found to be reduced by Y substitution, which reduces the strength of itinerant-states-mediated ferromagnetic coupling between local spins on the Fe ions and the total magnetic moment of the Fe-based BMGs.

Bacterial community changes with N'-N' dimethylforamide (DMF) additives during polycyclic aromatic hydrocarbons (PAH) biodegardation

This study examined the changes in the bacterial community during biodegradation of polycyclic aromatic hydrocarbon (PAH) substrate when N'-N' dimethylformamide (DMF) was added. The microbial populations that biodegrade the PAH substrate were assessed by Fluorescence in-situ hybridization (FISH) and changed from 49.45% Archaea and 49.15% Bacteria to 42.00% Archaea and 51.78% Bacteria when the PAH was supplemented with DMF. Nine microorganisms were classified as Gram-negative alpha-, beta- and gamma-Proteobacteria bacteria during biodegradation of PAH alone by the Biolog system. Incentive eleven microorganisms obtained from the PAH-DMF mixed substrate were found to be beta-, gamma-Proteobacteria bacteria, high G+C Gram-positive bacteria (HGC), low G+C Gram-positive bacteria (LGC) and there was even one Deinococcus-Thermus strain; this indicates greater biodiversity. The numbers in the Pseudomonad group were as high as 10(5)-10(6) CFU ml(-1), suggesting that this group plays an important role in PAH biodegradation. Community-Level Physiological Profiling (CLPP) and physiological characterization were different in the PAH biodegradation process with and without DMF. Utilization of the 95 carbon sources from the Biolog GN2 microtiter plate was greater during PAH biodegradation when PAH is present alone compared to that in the presence of DMF. The range of enzymatic activities during PAH biodegradation was lower in the presence of DMF. These results show that DMF should be used with caution when PAH is a substrate during laboratory or pilot biotreatability studies.

Fatal hepatic failure after emergence of the hepatitis B virus mutant during lamivudine therapy in a patient with liver cirrhosis

Lamivudine therapy for chronic hepatitis and decompensated liver cirrhosis related to the hepatitis B virus (HBV) resulted in improvement of liver function and inhibition of viral replication. Despite emergence of the HBV mutant, e-antigen seroconversion and improvement of liver function may be achieved with continuation of lamivudine therapy. Although hepatic decompensation has been reported in a few cases after the emergence of lamivudine-resistant mutants, fatal cases of non-transplant patients have only rarely been reported in the literature. Here, we describe a patient with HBV-related liver cirrhosis who died after a breakthrough infection with a lamivudine-resistant mutant. Hepatic failure and mortality developed after flare-up of severe hepatitis after 13 months of lamivudine treatment. Emergence of the HBV mutant with substitution of isoleucine for leucine at residue 426 (L4261) in combination with isoleucine for methionine at residue 550 (M5501) was observed at 10 and 13 months of treatment.

Structural investigation of catalyst deactivation of Pt/SDB for catalytic oxidation of VOC-containing wastewater

The stability of styrene-divinyl benzene copolymer (SDB)-supported Pt (Pt/SDB) catalysts for destruction of volatile-organic-compound (VOC) in wastewater was examined. The test reaction was wet oxidation of water-containing aliphatic alcohol and formaldehyde at 140 degrees C and 90 psig for 40 h. The catalytic performance tests indicated that activity of the Pt/SDB catalysts could be maintained for VOC concentration of 3 wt.%, whereas the catalysts deactivated rapidly for 10 wt.% VOC containing wastewater. In order to investigate the nature of catalyst deactivation, extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge (XANES) spectroscopy were used to characterize the fresh and used catalysts. After the reaction, there is no oxidation of Pt clusters observed in EXAFS and XANES spectroscopy suggesting that the oxidation reaction takes places via the adsorbed oxygen. The spectroscopy results further indicated that deactivation of the catalysts were mainly caused by the increase of Pd particle size. After the reaction, the Pt-Pt coordination number has no significant change for the 3 wt.% wastewater whereas increase from 5.6 to 6.2 for 10 wt.% wastewater. Combined with the fact that the catalysts fractured during the reactions, we suggested that Pt agglomeration was mainly caused by thermal migration of the metal clusters.

Sulfonic acid functionalized mesoporous MCM-41 silica as a convenient catalyst for Bisphenol-A synthesis

Sulfonic acid groups anchored to the surface of mesoporous MCM-41 silica have been identified with S K-edge XANES spectra and the material is an efficient catalyst for the liquid phase condensation of phenol with acetone to form Bisphenol-A with high selectivity.

Induction of Fas and Fas ligand expression on malignant glioma cells by Kupffer cells, a potential pathway of antiliver metastases

Kupffer cells play an important role in controlling the growth and development of liver metastases. However, the pathway of Kupffer cells against tumor metastases is not clear. In the present study, we set up an experimental model to investigate the mechanisms on how Kupffer cells kill tumor cells which metastasize to the liver. Malignant glioma cells were cocultured with Kupffer cells or treated with culture medium collected from lipopolysaccharide (LPS)-activated Kupffer cells. The results showed that the interaction between Kupffer cells and malignant glioma cells significantly stimulated the generation of tumor necrosis factoralpha (TNFalpha). TNFalpha was mainly produced by Kupffer cells, as its level in culture medium obtained from LPS-treated Kupffer cells was not significantly different from that of malignant glioma cells treated with the same medium. Both Kupffer cells and LPS/Kupffer cell-conditioned supernatants induced expression of Fas and Fas ligand on malignant glioma cells. Subsequently a significant proportion of malignant glioma cells became apoptotic, as evidenced by positive staining of annexin V and propidium iodine and an increase in cellular DNA fragmentation. Therefore, this study supports a novel pathway of Kupffer cells against liver metastases, in which tumor cells were apoptotic via the Fas-Fas ligand system induced by TNFalpha released from Kupffer cells.

Lack of age-associated LFA-1 up-regulation and impaired ICAM-1 binding in lymphocytes from patients with Down syndrome

To investigate the role of LFA-1 in the immune defects in DS patients, we analysed lymphocytes from DS patients in LFA-1 expression and LFA-1 mediated cell adhesion. DS patients less than 2 years of age expressed a higher level of LFA-1 when compared with age-matched controls. The difference in LFA-1 expression was much less significant in older DS patients when compared with age-matched children. Although older children (2-15-year-old groups) without DS tend to increase their expression of lymphocyte LFA-1 when compared with younger normal children (0-2 years old), DS patients showed no age-associated increase in lymphocyte LFA-1 expression. Two-colour analysis with CD4/CD8 and LFA-1 in patients and controls showed that proportions of CD4 + lymphocytes were comparable in DS patients and controls, while the proportion of CD8 + lymphocytes was higher in older DS patients. Expression levels of LFA-1 on both CD4 + and CD8 + lymphocytes in younger DS patients were higher when compared with age-matched controls and close to the expression levels in the older DS group. Proportions of memory lymphocytes expressing the CD45RO isoform were higher in both younger and older DS patients when compared with age-matched control groups. Noticeably, the LFA-1 expression levels on CD45RO lymphocytes from younger DS patients were higher than the levels of the controls and declined in the older DS group. We tested lymphocytes (EBV transformed B cells, resting and anti-CD3 stimulated T cells) for cellular adhesion to recombinant ICAM-1 and found that lymphocytes from DS patients were less adhesive, even though their beta2 integrin expression was comparable with that of normal controls. These results suggest that more generalized pathological processes, such as early senescence of the immune system or ineffective lymphocyte activation, and subsequent integrin dysfunction may underlie the immune defects in DS patients.

X-ray absorption spectroscopy investigations on oxidized Ni/Au contacts to p-GaN

X-ray absorption spectroscopy was used to investigate the electronic structure of as-deposited and oxidized Ni/Au contacts to p-GaN and to elucidate the mechanism responsible for low impedance. X-ray absorption near edge spectra of Ni K- and L3,2-edges clearly indicate formation of NiO on the sample surface after annealing. The reason for low impedance may be attributed to increase in hole concentration and existence of p-NiO layer on the surface.

X-ray absorption studies of carbon-related materials

X-ray absorption near-edge structure (XANES) measurements have been performed on nitrogen-doped diamond films with three different dopant concentrations and iron-layer-stabilized carbon nanotube (CNT) structures with various diameters at the C K-absorption edge using the sample drain current mode. The C K-edge XANES spectra of these N-doped diamond films resemble that of the undoped diamond regardless of the dopant concentration, which suggest that the overall bonding configuration of the C atom is unaltered. N dopants are found to reduce the intensities of both the sp2- and sp3-bond-derived resonance features in the XANES spectra. On the other hand, the C K-edge XANES spectra of CNTs indicate that the intensities of the pi* and sigma* bands and the interlayer-state features vary with the diameter of the CNT. This phenomenon may be caused by the Fe-layer-catalysed bending of the graphite sheet and the interaction between C and Fe atoms.

Chromium speciation in residues after sequential extraction of a thermally treated sludge analog

XANES fitting indicates that non-Cr2O3 form of Cr(III), transformed from CrO3 by four-hour heat application at 1100 degrees C, is the key species sorbed onto or lattice-diffused into kaolin matrices that exhibits strong leaching resistance to sequential extraction using various combined solutions including HNO3, H2O2, and HF. The EXAFS spectra are all in agreement with the XANES results. It is suggested that some Cr2O3 might have reacted with kaolin to form new compounds such as Cr2O3 x Al2O3 x 2SiO2 to account for the slight dissimilarity between the EXAFS spectra of samples and that of Cr2O3.

Polarization-dependent XANES study of Bi2Sr2Ca(1-x)Pr(x)Cu2O8-delta insulating single crystal

Pr doping has been extensively studied in cuprate superconductors to understand the mechanism of quenching of superconductivity in cuprate perovskites. Experience has revealed that it acts differently in different cuprate perovskites. We have made high resolution polarization XANES measurements on a Pr-doped single crystal within the ab-plane on the Cu K and Pr L III absorption edges to ascertain the valence state of Pr cation and thereby try learning how it is quenching superconductivity in the present case. Our results show that besides the Pr quenching holes the possibility of its localizing some holes through hybridization with O 2p and Cu 3d cannot be ruled out.

In situ EXAFS investigation of carbon-supported Pt clusters under potential control

The transformation of carbon supported Pt clusters under potential control in 1M HClO4 solution was investigated by in-situ X-ray absorption spectroscopy measurements. Both XANES and EXAFS data are used to show the structure evolution of the Pt clusters at various potentials. It showed that the white line area and the edge energy increase with the applied potential in the range 0.1-1.5V. The coordination number of oxygen and platinum on the Pt/C electrode increases and decreases, respectively, with the applied potential. It is found that the size of Pt cluster does not grow during the electrode fabrication. However, the crystallization of Pt cluster occurs during the potential cycling.

Synthesis of substituted 4(Z)-(methoxyimino)pentyl-1-piperidines as dual NK1/NK2 inhibitors

The NK1 and NK2 receptor activity of a series of 5-[(3,5-bis(trifluoromethyl)phenyl)methoxy]-3-(3,4-dichlorophenyl)-4(Z)-(methoxyimino)pentyl-1-piperidines was evaluated. Compounds 11d, 11e, 11f, 12a, and 12k were found to be our most potent inhibitors.

Dopamine D2 receptor gene (DRD2) is associated with alcoholism with conduct disorder

This study examined whether there is evidence for an association between alcoholism with conduct disorder and alleles of the TaqI A and TaqI B polymorphisms, both individually and as haplotypes, at the dopamine D2 receptor gene (DRD2). We studied 182 Han Chinese subjects, including 34 alcoholics with conduct disorder, 63 alcoholics without conduct disorder, and 85 nonalcoholics. Alcohol dependence and conduct disorder were defined according to DSM-III-R criteria. Significant associations were observed between TaqI A and TaqI B at the DRD2 locus, tested individually and as haplotypes, and alcoholism with conduct disorder. Our results suggested that DRD2 might be associated with conduct disorder or a predisposition to both conduct disorder and alcoholism. However, this needs to be further investigated by examining the differences among conduct disorder with alcoholism, conduct disorder only, and controls for the TaqI A and B system at DRD2.

Effects of hepatic blood inflow occlusion on liver regeneration following partial hepatectomy in an experimental model of cirrhosis

BACKGROUND

Hepatic blood inflow occlusion during hepatectomy may influence postoperative liver regeneration. The aim of this study was to investigate the influence of hepatic blood inflow occlusion on liver regeneration following partial hepatectomy in thioacetamide-induced cirrhotic rats.

METHODS

Forty-three cirrhotic Wistar-Furth rats were randomly assigned to three groups. Rats in group 1 underwent 64 per cent hepatectomy alone, those in group 2 were subjected to 15 min hepatic blood inflow occlusion followed by 64 per cent hepatectomy, and animals in group 3 were subjected to 30 min inflow occlusion followed by 64 per cent hepatectomy. Liver function, 5-bromo-2'-deoxyuridine (BrdU) labelling index and percentage of initial liver weight on days 1, 2 and 7 posthepatectomy were assessed.

RESULTS

Rats in groups 1 and 2 had a significantly higher serum albumin level and a markedly lower alanine aminotransferase level than animals in group 3 on day 1 posthepatectomy (P < 0.05). There was no significant difference in the serum level of total bilirubin of the three groups on days 1, 2 and 7. The BrdU labelling index was significantly higher in groups 1 and 2 than in group 3 animals on day 1 posthepatectomy (P < 0.01 and P < 0.05 respectively). Percentages of initial liver weight were similar in groups 1, 2 and 3 on days 1, 2 and 7 after hepatectomy.

CONCLUSION

Hepatic blood inflow occlusion for up to 30 min suppressed DNA synthesis and hepatocyte proliferation at an early posthepatectomy stage and consequently delayed recovery of liver function in cirrhotic rats. However, it did not affect restoration of liver mass or survival after 64 per cent hepatectomy.

Synthesis and NK1/NK2 receptor activity of substituted-4(Z)-(methoxyimino)pentyl-1-piperazines

A series of 5-[(3,5-bis(trifluoromethyl)phenyl)methoxy]-3-(3,4-dichlorophenyl)-4(Z)- (methoxyimino)pentyl-1-piperazines was prepared and their affinity for the NK1 and NK2 receptors investigated. Compounds 7f, 10o, 10r, and 10s were found to be our most potent inhibitors.

Influence of a Nonionic Surfactant (Triton X-100) on Contaminant Distribution between Water and Several Soil Solids

The influence of a nonionic surfactant (Triton X-100) on the contaminant distribution coefficients in solid-water mixtures was determined for a number of relatively nonpolar compounds (contaminants) on several natural solids. The studied compounds consisted of BTEX (benzene, toluene, ethylbenzene, and p-xylene) and chlorinated pesticides (lindane, alpha-BHC, and heptachlor epoxide), which span several orders of magnitude in water solubility (S(w)); the solid samples comprised a bentonite, a peat, and two other soils, which cover a wide range of solid organic matter (SOM) content. The applied surfactant concentrations (X) ranged from below the (nominal) CMC to 2-3 times the CMC. For relatively water-soluble BTEX compounds, the distribution coefficients with surfactant (K(d)*) all exceeded those without surfactant (K(d)); the K(d)*/K(d) ratios increased with increasing S(w) from p-xylene to benzene on each solid at a given X, with increasing X for each compound on a solid, and with decreasing solid SOM content for each compound over the range of X studied. For the less-soluble pesticides, the K(d)*/K(d) ratios exhibited a large increase with X for bentonite, a marginal change (increase or decrease) for a soil of 2.4% SOM, and a moderate-to-large decrease for two soils of 14.8% and 86.4% SOM. These unique observations were rationalized in terms of the properties of the compound, the amount of surfactant sorbed on the solid, the enhanced solubilization of the compound by surfactant in water, and the relative effects of the surfactant when adsorbed on minerals and when partitioned into SOM. Copyright 2000 Academic Press.

Appendicitis in the elderly

BACKGROUND

Acute appendicitis in the elderly (i.e. those over 60 years of age) is associated with high morbidity and mortality rates. The present retrospective study reviews 10 years ( 1986-1996) of experience and outcome in treating acute appendicitis in patients aged 60 or above.

METHODS

One hundred and thirty patients with acute appendicitis were identified and their case notes reviewed.

RESULTS

Acute appendicitis was diagnosed at admission in 84 patients (64.6%). The remaining patients were observed for a median duration of 9.4 h prior to diagnosis and treatment. Patients with an underlying perforated acute appendix had a significantly longer period of pain prior to admission (P = 0.029; Mann-Whitney U-test) but perforation per se was not associated with a significantly higher rate of morbidity and longer length of hospital stay. In contrast, the use of midline or paramedian incisions was associated with a higher wound infection rate (P=0.003; Pearson chi-squared test) and a longer hospital stay (P<0.001; Mann Whitney U-test). None of the patients were subsequently found to have an underlying colonic neoplasm. The overall morbidity rate was 28%. The mortality rate was 2.3% and all three patients who died had a severe comorbid medical condition prior to developing acute appendicitis.

CONCLUSIONS

Acute appendicitis in the elderly is still associated with significant morbidity. But once acute appendicitis is diagnosed, then expedient surgery, appropriate use of perioperative antibiotics and a right lower quadrant incision can help to minimize the morbidity. Pre-existing severe comorbid medical condition(s) is a major contributory factor to mortality in these patients.

Systemic cytokine response after laparoscopic-assisted resection of rectosigmoid carcinoma: A prospective randomized trial

OBJECTIVE

To compare the systemic cytokine response in patients after laparoscopic-assisted resection with those after open resection of rectosigmoid carcinoma.

SUMMARY BACKGROUND DATA

Laparoscopic resection of colorectal carcinoma is technically feasible, but objective evidence of its benefit is scarce. Systemic cytokines are accepted as markers of postoperative tissue trauma and mediators of the host immune response.

METHODS

Thirty-four patients with rectosigmoid carcinoma, without evidence of metastatic disease and suitable for laparoscopic resection, were randomized to undergo either laparoscopic (n = 17) or conventional open (n = 17) resection of the tumor. Clinical parameters were recorded. Sera were collected before surgery and at appropriate time points afterward and assayed for interleukin-1beta, tumor necrosis factor-alpha, interleukin-6, and C-reactive protein. The primary end points were the cytokine and C-reactive protein levels. Data were analyzed by intention to treat.

RESULTS

The demographic data of the two groups were comparable. The clinical outcome of both groups was satisfactory, with no surgical deaths and a reasonable complication rate. Both interleukin-1beta and interleukin-6 levels peaked 2 hours after surgery, with the responses in the laparoscopic group significantly less than those in the open group. C-reactive protein levels peaked at 48 hours, and the difference was also statistically significant. Levels of tumor necrosis factor-alpha were not elevated after surgery, and there was no difference between the groups.

CONCLUSIONS

Tissue trauma, as reflected by systemic cytokine response, was less after laparoscopic resection than after open resection of rectosigmoid carcinoma. The difference in the systemic cytokine response may have implications on the long-term survival.

Size Effects of Exchange Cation on the Pore Structure and Surface Fractality of Montmorillonite

Ca-montmorillonites were exchanged with both metal cations (manganese and copper) and organic cations (tetramethylammonium (TMA) and hexadecyltrimethylammonium (HDTMA)) to study the cation size effects on the pore structure and surface roughness of montmorillonite based on the classical and fractal analysis of their nitrogen adsorption isotherms. The surface fractal dimension D was calculated from their nitrogen isotherms with the aid of the recently proposed Neimark equation. The decrease of BET surface area of montmorillonite induced by the larger size of exchange cation was interpreted with both the coverture of some surface roughness (surface screening effect) and the inhibition of nitrogen molecule into some pores (pore blocking effect). The pore blocking effect was examined with the changes of mean pore size. Meanwhile, the D value was used to examine whether or not the surface screening effect existed. It was concluded that the combination of classical and fractal analyses of nitrogen isotherms may facilitate our understanding of the evolution of pore and surface structures of clay exchanged with different cations. Copyright 1999 Academic Press.

An unusual case of breast metastasis from an anorectal melanoma

An unusual case of solitary breast metastasis from a primary anorectal melanoma in a 59-year-old post-menopausal woman is reported. The course and management of melanotic breast metastases is discussed.

Laparoscopic-assisted resection of right-sided colonic carcinoma: a case-control study

BACKGROUND AND OBJECTIVES

Laparoscopic-assisted resection of colorectal carcinoma is technically feasible. Whether it is beneficial to patients is uncertain. This study reviewed the results of laparoscopic-assisted resection in patients with right-sided colonic adenocarcinoma.

METHODS

We attempted laparoscopic-assisted right to extended right hemicolectomy in 28 patients with right-sided colonic carcinoma (study group). The results were compared with 56 matched patients who underwent conventional open resection in the same period (comparative group).

RESULTS

The median follow-up times for the study and comparative groups were 21.4 and 23.5 months, respectively. The operating time was significantly longer (t-test, P < 0.001), whereas the time to resuming normal diet (Mann-Whitney U-test, P < 0.001) and the duration of hospital stay (Mann-Whitney U-test, P = 0.002) were significantly less in the study than in the comparative group. The oncological clearance, in terms of the number of lymph nodes removed and the resection margins, the complication rate, the disease-free rate, and the survival rate were comparable in the two groups.

CONCLUSIONS

We conclude that laparoscopic-assisted resection of right-sided colonic adenocarcinoma has the advantage over open surgery of allowing earlier recovery. However, this is at the expense of a longer operating time.

Laparoscopic-assisted resection of right-sided colonic carcinoma: a case-control study

BACKGROUND AND OBJECTIVES

Laparoscopic-assisted resection of colorectal carcinoma is technically feasible. Whether it is beneficial to patients is uncertain. This study reviewed the results of laparoscopic-assisted resection in patients with right-sided colonic adenocarcinoma.

METHODS

We attempted laparoscopic-assisted right to extended right hemicolectomy in 28 patients with right-sided colonic carcinoma (study group). The results were compared with 56 matched patients who underwent conventional open resection in the same period (comparative group).

RESULTS

The median follow-up times for the study and comparative groups were 21.4 and 23.5 months, respectively. The operating time was significantly longer (t-test, P < 0.001), whereas the time to resuming normal diet (Mann-Whitney U-test, P < 0.001) and the duration of hospital stay (Mann-Whitney U-test, P = 0.002) were significantly less in the study than in the comparative group. The oncological clearance, in terms of the number of lymph nodes removed and the resection margins, the complication rate, the disease-free rate, and the survival rate were comparable in the two groups.

CONCLUSIONS

We conclude that laparoscopic-assisted resection of right-sided colonic adenocarcinoma has the advantage over open surgery of allowing earlier recovery. However, this is at the expense of a longer operating time.