Activating C-H Bonds by Tuning Fe Sites and an Interfacial Effect for Enhanced Methanol Oxidation

The interaction mechanism between the reacting species and the active site of α-Fe₂ O₃ -based photoanodes in photoelectrochemical methanol conversion reaction is still ambiguous. Herein, a simple two-step strategy is demonstrated to fabricate a porous α-Fe₂ O₃ /CoFe₂ O₄ heterojunction for the methanol conversion reaction. The influence of the electronic structure of active site and interfacial effect on the reaction are investigated by constructing two different FeO₆ octahedral configurations and heterogeneous structures. The optimal sample ZnFeCo-2 affords high photocurrent density of 1.17 mA cm^-2 at 0.5 V vs Ag/AgCl, which is 3.2 times than that of ZnFe (0.37 mA cm^-2 ). Meanwhile, the ZnFeCo-2 also exhibits 97.8% Faraday efficiency of CH₃ OH to HCHO, and long-term stability over 40 h. Furthermore, density functional theory calculations reveal that the heterostructured α-Fe₂ O₃ /CoFe₂ O₄ with favorable electron transfer effectively lowers methanol adsorption, C-H bond activation, and HCHO desorption energy relative to the pristine α-Fe₂ O₃ , resulting in excellent methanol conversion efficiency.

Involvement of annexin V in the entry of influenza viruses and role of phospholipids in infection

Influenza viruses bind to annexin V, a widely spread non-glycosylated phospholipid-binding protein. Externally added phospholipids as well as antiserum against this protein specifically inhibit infection of these viruses in cell cultures. We conclude that annexin V plays an important role in the entry of these viruses.

Intratumoral blood flow in uterine myoma correlated with a lower tumor size and volume, but not correlated with cell proliferation or angiogenesis

OBJECTIVE

To investigate the correlation of intratumoral blood flow in uterine myoma with cell proliferation, angiogenesis, tumor size, and tumor volume.

METHODS

Thirty-nine patients who had been scheduled for surgery because of symptomatic uterine myomas were evaluated by transvaginal sonography and color Doppler ultrasound before surgery. The largest dimension of each tumor and the volumes of myomas were determined ultrasonographically. Pulsatility index (PI) was determined by color Doppler ultrasound according to the maximum systolic, end-diastolic, and the mean flow velocities measured within the uterine nodules. After surgery, the paraffin-embedded slides containing representative leiomyoma tissues were stained with hematoxylin and eosin, proliferating cell nuclear antigen for measurement of cell proliferation, and factor VIII for quantitation of microvessel density. The ultrasonographic findings were correlated postoperatively with pathologic findings, and the data were analyzed by simple linear regression and Fisher r to z transformation.

RESULTS

Simple regression analysis of the intratumoral PI values on the sizes of myomas showed a negative correlation (r = -0.47, P = .003; n = 39), whereas a less significant correlation between PI values and tumor volumes was observed (r = -0.42, P = .008). In contrast, no statistically significant correlation was observed between the intratumoral PI values and the values of the proliferating cell nuclear antigen index (r = 0.10, P = .547) or microvessel density counts (r = 0.18, P = .282).

CONCLUSION

The intratumoral blood flow by transvaginal color Doppler ultrasound correlated with a reduced tumor size and tumor volume, but did not correlate with cell proliferation or angiogenesis.

Two new sphingomyelin analogues inhibit phosphatidylcholine biosynthesis by decreasing membrane-bound CTP: phosphocholine cytidylyltransferase levels in HaCaT cells

The effects of two newly synthesized sphingomyelin analogues on phosphatidylcholine biosynthesis were investigated in the immortalized human keratinocyte cell line HaCaT. N-Acetyl-erythro-sphingosine-1-phosphocholine (AcSM) and N-octanoyl-erythro-sphingosine-1-phosphocholine (OcSM) inhibited the incorporation of choline into phosphatidylcholine with half-inhibitory concentrations (IC50) of 6 micrograms/ml and 10 micrograms/ml respectively. Further experiments revealed that AcSM and OcSM interfered with the translocation of the rate-limiting enzyme of phosphatidylcholine biosynthesis, CTP:phosphocholine cytidylyltransferase (EC 2.7.7.15), in HaCaT cells and inhibited cytidylyltransferase activity in vitro. Despite the fact that OcSM was a potent inhibitor of cytidylyltransferase in vitro, its effects on phosphatidylcholine biosynthesis and translocation of cytidylyltransferase in HaCaT cells were less pronounced as compared with AcSM. Finally, we showed that the comparatively strong effects of AcSM in cell culture experiments were due to the uptake of large amounts of this sphingomyelin analogue into the cells. The results presented demonstrate that the activity of cytidylyltransferase may be negatively regulated by a high ratio of choline head group-containing sphingolipids.

Differentiation between adenomyoma and leiomyoma with transvaginal ultrasonography

The clinical utility of transvaginal ultrasonography in the differentiation of adenomyoma from leiomyoma was evaluated in 147 patients who had been scheduled for surgery due to symptomatic uterine masses. In all subjects, ultrasonographic images obtained preoperatively were correlated postoperatively with surgicopathological findings. Pathological findings showed that 110 patients proved to have fibroids, while 30 had adenomyomata. For the diagnosis of adenomyoma, transvaginal ultrasonography attained a sensitivity of 80%, a specificity of 94.3%, a positive predictive value of 85.7% and a negative predictive value of 90.9%, compared with a sensitivity of 94.3%, a specificity of 80%, a positive predictive value of 90.9% and a negative predictive value of 85.7% for leiomyoma diagnosis. Further to assess which characteristic used in ultrasonography was useful in the differential diagnosis, five characteristics were analyzed and compared by chi 2 test. These were position, number, margin and echogenicity of the uterine masses and the presence or absence of hypoechoic spaces (lacunae). Margin, echogenicity, mass number and lacunae were significantly different between both conditions. A stepwise logistic regression procedure revealed that margin, lacunae and echogenicity were good parameters for differentiating adenomyoma from leiomyoma. If we selected the features of distinct margin and absence of hypoechoic lacunae within the masses for analysis, leiomyoma could be correctly predicted in 97% of patients.

Identification of annexin 33 kDa in cultured cells as a binding protein of influenza viruses

The binding of three influenza A and one influenza B virus strains to proteins of three continuously cultured cell lines was studied using protein overlay and immunostaining methods. The results obtained indicated the presence of both sialic acid-dependent and -independent binding of the virus strains; virus binding to proteins in the molecular mass range from about 40 to 103 kDa was dependent on sialic acid, whereas binding to the 33 kDa protein was independent of sialic acid. The 33 kDa binding protein was identified as annexin, a widely distributed non-glycosylated calcium-dependent phospholipid-binding protein.

Successful management of a pregnancy with maternal phenylketonuria: report of a case

Maternal phenylketonuria (PKU) is associated with significant complications such as mental retardation, microcephaly and congenital heart defects in nonphenylketonuric offspring. Dietary control with a low phenylalanine diet during the gestation period is effective in improving perinatal outcome in these cases. We present the case of a 27-year-old woman with classical features of PKU who had previously given birth to three babies, all of whom died of congenital heart disease. A low phenylalanine diet was started one month prior to the pregnancy and satisfactory fetal outcome was achieved.

Isolation and identification of hepatitis E virus in Xinjiang, China

This paper describes isolation and identification of a virus (termed strain 87A) which has the cytopathic effect and haemagglutination properties of hepatitis E virus (HEV). This virus was isolated by tissue culture from the faeces of a patient with acute non-A, non-B enteric hepatitis in Xinjiang, China. The isolated virus was neutralized by acute phase sera obtained from other patients with acute non-A, non-B enteric hepatitis. The virus particles also could be specifically aggregated with acute phase sera from patients with known HEV hepatitis in China, Burma, India and the U.S.S.R., and with acute and convalescent sera from an HEV-infected chimpanzee. Crystalline arrangements of virus particles in the cytoplasm were observed by electron microscopy in ultrathin sections of infected cells. The sedimentation coefficient of the strain 87A virus particles in sucrose gradients was 176S. Purified virus particles revealed a protein band of about 76K on SDS-PAGE and Western blotting. The evidence indicates that the strain 87A virus is an HEV. Our ability to propagate HEV in cell culture should facilitate research on this hepatotropic virus.

On the penetration mechanism of influenza viruses

The envelopes of influenza viruses contain in addition to lipids also two glycoproteins, the hemagglutinin and the neuraminidase, that are responsible for the adsorption, receptor splitting, penetration and budding processes of these viruses. In this article, hypotheses presented in the past with regard to the virus penetration are reconsidered. Based on results obtained with the fowl plague virus (influenza A/FPV/Rostock/34, H7N1) and MDCK-cells, we conclude that a fusion between the viral envelope and the plasma membrane is the initial step of virus entry.

Cellular incorporation and localization of fluorescent derivatives of gangliosides, cerebroside and sphingomyelin

Fluorescent dansyl derivatives of 3 natural sphingolipids (gangliosides, cerebroside and sphingomyelin) were shown to be readily taken up by culture cells (HeLa-, MDCK- and primary rat brain cells). A part of the incorporated fluorescent sphingolipids remained associated with the cells after incubation in a culture medium containing serum, showing a cellular integration of these lipids. Microscopical studies indicated a localization of incorporated lipids in distinct subcellular regions; whereas dansyl cerebroside densely stained structures suggestive of the cytoskeleton and the actin filament, dansyl sphingomyelin and dansyl gangliosides were primarily associated with the plasma membrane. The findings are consistent with the current views on the arrangement of sphingolipids in animal cells.

[Radiological observation on the workers exposed to vanadium]

The roentgenologic findings of 76 workers exposed to vanadium were presented. The chest X-ray showed increase in lung markings in 58 cases, diffuse streaks and reticular shadows in 15 cases, interstitial pulmonary fibrosis. The clinical features of the 71 workers were as follows: 63 cases had coughs, 53 cases had coughs with expectorations, 27 cases showed difficulty in breathing, and 31 cases had wheezing or whistling sounds in the lungs. The workers were exposed to vanadium pentoxide fume at concentration ranging from 1.2 to 18 mg/m3 and dust from 1.27 to 27.7 mg/m3.

Isolation and characterization of ceramide glycanase from the leech, Macrobdella decora

We have devised a simple method for achieving 890-fold purification of ceramide glycanase with 17% recovery from a North American leech, Macrobdella decora. The method includes water extraction, ammonium sulfate fractionation, and chromatography on octyl-Sepharose, Matrex gel blue A, and Bio-Gel A-0.5m columns. The final preparation showed one major protein band at 54 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. By using Bio-Gel A-0.5m filtration, the native enzyme was found to have a molecular mass of 330 kDa. With GM1 as substrate, the optimum pH of this enzyme was determined to be 5.0; the enzyme was stable between pH 4.5 and 8.5. Zn2+ at 5 mM and Cu2+, Ag+, and Hg2+ at 1 mM strongly inhibited the hydrolysis of GM1 by ceramide glycanase. The ceramide glycanase released the intact glycan chain from various glycosphingolipids in which the glycan chain is linked to the ceramide through a beta-glucosyl linkage. This enzyme also cleaved lyso-glycosphingolipids such as lyso-GM1 and lyso-LacCer and synthetic alkyl beta-lactosides. Among seven alkyl beta-lactosides tested, the enzyme only hydrolyzed the ones with an alkyl chain length of four or more carbons. The enzyme also hydrolyzed 2-(octadecylthio)ethyl O-beta-lactoside and 2-(2-carbomethoxyethylthio)ethyl O-beta-lactoside. p-Nitrophenyl, benzyl, and phytyl beta-lactosides, on the other hand, were not hydrolyzed. These results suggest that the enzyme can recognize the hydrophobic portion of glycolipid substrates. The fact that 2-(2-carbomethoxyethylthio)ethyl O-beta-N-acetyllactosaminide and DiGalCer were refractory to the enzyme indicated that in the substrate the first sugar attached to the hydrophobic chain cannot be N-acetylglucosamine and galactose. Furthermore, dodecyl maltoside, Gal alpha 1----6Glc beta Cer, and the LacCer in which the --CH2OH of the galactose was converted into --CHO were also resistant to the enzyme, and Man beta 1----4 Glc beta Cer was hydrolyzed at a much slower rate than LacCer. These results indicate that the nature and the linkage of the sugar attached to the glucose have a profound effect on the action of this enzyme. The hydrolysis of glycosphingolipids by ceramide glycanase is stimulated by bile salts. Among various bile salts tested, sodium cholate at a concentration of 1 microgram/microliter was found to be most effective in stimulating the hydrolysis of various glycosphingolipids with the exception of LacCer. For LacCer, sodium taurodeoxycholate at a concentration of 2-3 micrograms/microliters was most effective. Tween 20, Nonidet P-40, and Triton X-100 did not stimulate the hydrolysis of GM1.(ABSTRACT TRUNCATED AT 400 WORDS)

Interplay between lipids and viral glycoproteins during hemolysis and fusion by influenza virus

Since mixtures of lipids alone are known to elicit membrane fusion without participation of fusion proteins, the role of viral lipids in the so-called virus-induced hemolysis and cell fusion has been investigated, using as a model the fowl plague virus (influenza A/FPV/Rostock/H7N1). The experiments were planned in a way that allowed quantitative modification of viral lipids without changing envelope glycoproteins. Under the conditions employed, cholesterol oxidase of Nocardia erythropolis and phospholipase C of Bacillus cereus were shown to completely modify their substrates in the virus without altering virus-associated hemagglutinating and neuraminidase activities. It was found with such enzyme treatment that virus-induced hemolysis and cell fusion are greatly influenced by cholesterol and phospholipids of the envelope. It became clear, that hemolysis and fusion are differently dependent on the nature of lipid components even though mediated by the same viral glycoproteins.

Cytotoxic T cell lysis of target cells fused with liposomes containing influenza virus haemagglutinin and neuraminidase

The lytic activity of secondary cytotoxic lymphocytes against influenza A virus was tested on cells which had been fused with liposomes containing the haemagglutinin and the neuraminidase of an avian influenza A virus (fowl plague virus, FPV). Fusion was obtained solely by the activity of the haemagglutinin and neuraminidase incorporated into the liposomes, without the need for any additional fusion factor. Highly reproducible lysis of these FPV-liposome target cells by influenza A-specific cytotoxic cells was found. In contrast, target cells containing the glycoproteins HN and F of Newcastle disease virus (NDV) were not lysed. In almost all experiments effector cell populations capable of lysing target cells also lysed the natural killer cell (NK)-sensitive cell line YAC-1. However, high NK activity alone was not sufficient to lyse target cells fused with liposomes containing the viral surface glycoproteins. To our knowledge this is the first report where after artificial introduction of viral surface components into cell membranes (either by fusion or by transfection) lysis of target cells was monitored also for non-specific lysis mediated by NK-like cells. Both the H-2 restriction and the virus specificity of lysis of FPV-liposome target cells indicate that influenza virus haemagglutinin and possibly neuraminidase do function as target antigens for influenza-specific T cells.

Further studies on the role of neuraminidase and the mechanism of low pH dependence in influenza virus-induced membrane fusion

The role of neuraminidase and the mechanism of low pH dependence in influenza virus-induced membrane fusion have been studied further using fowl plague virus (FPV, H7N1). Two specific anti-FPV neuraminidase antisera obtained from chickens immunized with recombinant virus strains inhibited viral neuraminidase activity without influencing its haemagglutinating activity. These sera totally inhibited the FPV-induced fusion of erythrocytes and partially reduced haemolysis. But both fusion and haemolysis activities could be restored by external addition of Vibrio cholerae neuraminidase, indicating participation of neuraminidase in FPV-induced membrane fusion. With regard to low pH-dependent fusion by influenza virus, it was found that erythrocytes of various species showed different pH optima for haemolysis by FPV and that erythrocytes could be sensitized for fusion and haemolysis by FPV at neutral pH if they had been pretreated with a low pH buffer. These results demonstrated that surface properties of erythrocytes rather than that of the virus are critical in the low pH-dependent fusion and haemolysis by influenza viruses.

Immunogenic properties of the small chain HA2 of the haemagglutinin of influenza viruses

The small chain of influenza virus haemagglutinin, HA2 was isolated by a selective enzymic removal of HA1 or by preparative SDS-polyacrylamide gel electrophoresis. Anti-HA2 specific antisera and monoclonal antibodies were subtype-specific in immunodiffusion tests and radioimmunoassays. These antibodies did not inhibit haemagglutination or haemolysis, did not prevent virus release, did not neutralize infectivity, and HA2 did not induce a protective immunity. HA2-specific antigenic determinants could not be demonstrated on the surface of infected cells. Lymphocytes from pre-immunized mice could not be stimulated by HA2 to exert a cytotoxic effect.

The role of neutral glycolipids and phospholipids in myxovirus-induced membrane fusion

Myxoviruses (influenza virus and paramyxovirus) enter host cells by two successive steps consisting of attachment and fusion between viral and cellular membranes. The initial attachment is known to occur through specific binding of the viruses with the neuraminic acid-containing receptors of cellular membranes. Evidence is presented here that, in the following step of membrane fusion, neutral glycolipids terminating in galactose and certain phospholipids (primarily lecithin and sphingomyelin) interact with the viral envelopes and that this interaction may be fundamental to the fusion process.

Aminocyclitol resistance in Staphylococcus aureus: presence of plasmids and aminocyclitol-modifying enzymes

Aminocyclitol resistance in Staphylococcus aureus has been investigated by the analysis of the plasmids and aminocyclitol-modifying enzymes present in several clinical staphylococcal isolates. All of the strains tested were resistant to a broad range of aminocyclitols and contained large plasmids which encoded a variety of aminocyclitol-modifying enzymes in addition to other antibiotic resistances. All strains expressed multiple aminocyclitol-modifying enzymes. The plasmids present in these strains appear to be related by virtue of their similar restriction endonuclease digestion patterns. The plasmids are related and differ by the gain or loss of small DNA segments, one of which encodes erythromycin and kanamycin resistance.

Involvement of glycolipids in myxovirus-induced membrane fusion (haemolysis)

Myxoviruses (influenza viruses and paramyxoviruses) penetrate their host cells by fusion of viral and cellular membranes. During this process, virus envelopes react with galactose-terminating glycolipids of cellular membranes. This was suggested by experiments showing the ability of these lipids to inhibit fusion (as measured by haemolysis) when reacted with the viruses, and to enhance it when added as enrichment to erythrocytes.

Productive infection of chick embryo cells by influenza viruses tightly bound on substratum

To test whether penetration of influenza viruses could occur at the plasma membrane of host cells, virus particles were tightly bound on Concanavalin A-coated substratum of plastic culture plates and then overlayed with embryo cells. Under these conditions, endocytosis of the viruses was prevented but the cells were found to be effectively infected. The results indicate, that infection by influenza viruses can occur through fusion between the viral membrane and the host cell plasma membrane.

Simple and rapid separation of ortho- and paramyxovirus glycoproteins

The hemagglutinin (HA) and neuraminidase (NA) of influenza viruses, as well as the fusion protein (F) and hemagglutinin-neuraminidase (HN) of paramyxoviruses, have been separated in native form using a two-step procedure. The glycoproteins are efficiently extracted from virions using the on-ionic detergent octyl-beta-D-glucoside and are then applied to a column of agarose beads coupled with tyrosine-sulfanilic acid. Pure HA and F are obtained in good yield in the flow-through from this column. NA and HN bind strongly and can be eluted, albeit somewhat contaminated with HA or F, by raising the pH of the column buffer. The separated non-denatured fractions can be used for structural, functional, and antigenic studies.

Artificial phospholipid and glycolipid particles, visualization of their structures by fluorescence markers and some biological properties expressed by these particles

Homogeneous large (5--30 micrometer) lipid particles comparable in size and shape to blood cells can be obtained when excess of cholesterol is homogenized with egg phospholipids or brain glycolipids in a Dounce apparatus. The particles contain distinct structures of membranes and lipid cores as visualized by the included fluorescence markers. When these particles were used as models in studying interactions between membranes, it was demonstrated that several properties normally pertaining to natural membranes could be exhibited by lipids alone. It could also be shown that particles containing phospholipids or glycolipids were very different in their adhesiveness to tissue culture cells and in their response to sera of various species.

Transfer of glycolipid between membranes of tissue culture cells, using dansylcerebroside as a model

Donor cells, which had incorporated dansylcerebroside in their membranes, could further transfer this glycolipid to monolayers of acceptor cells. The case of transfer varied among acceptor cells, BHK cells being the best and MDBK cells the poorest acceptors of the cells tested. The process of transfer seemed to be mediated by lipids rather than by proteins of the membranes. The mode of attachment between donors and acceptors, such as classified as loose contact, tight adhesion or binding by lectin, did not significantly influence the extent of glycolipid transfer. However, modification of plasma membranes by infection of acceptor cells with myxoviruses resulted in enhancement of glycolipid transfer in some cases. Various factors have been evaluated with respect to dynamics of cellular membranes.

On the structure of the carbohydrate chains of different strains of the influenza virus

Structural features of the glycosyl chains of the influenca virus have been determined. It was found that fucose was solely terminal, whereas mannose and galactose were present at the terminal as well as subterminal and core positions. Mannose and glucose molecules were shown to be branching points in the glycosyl chains. Furthermore, linkage positions of carbohydrates within the chains were characterized.

Labeling of animal cells with fluorescent dansyl cerebroside

A dansyl (diaminoaphthalenesulfonyl)-derivative of cerebroside was prepared which could be effectively incorporated into the plasma membranes of tissue culture cells and erythrocytes. The cells which had assimilated the glycolipid fluoreced intensely and could be observed under a fluorescent microscope. Cells were initially labeled rather homogeneously over the whole surface. With longer incubation time organization of the fluorescent glycolipid took place and patches of the lipid in the membrane were formed. The redistribution and organization of the membrane lipid could be demonstrated most clearly when cells labeled with this fluorescent glycolipid were infected with myxoviruses. After infection of MDBK and BHK cells with fowl plaque virus areas of dense fluorescence appeared at margines of neighboring cells. When BHK cells were infected with Newcastle disease virus fusion of the cells was accompanied by complete redistribution of the glycolipid. Erythrocytes could also easily incorporate dansyl cerebroside. Chicken erythrocytes which contain cytoplsmic and nuclear membranes incorporated the fluorescent glycolipid in both membranes.

Sphingolipids of influenza viruses

Total lipid of four egg grown influenza viruses (A2-Asia, A2-England, A2-Taiwan and fowl plague virus) were extracted with chloroform-methanol. After mild alkali treatment of the extracts, glycosphingolipids and sphingomyelin were separated by a silicic acid column, and finally purified by thin layer chromatography. Fatty acid, sphingosine and carbohydrate components of individual lipid classes were then analysed by gas-liquid chromatography. Nearly identical results were obtained with all viruses investigated. Approximately 20% of the total lipid was monohexosylceramide, distributed equally between glucosyl- and galactosyl- analogues. Lactosylceramide and oligohexosylceramides were found in much smaller concentrations (approx. 2%). About 15% of the total lipid was attributed to sphingomyelin. A large proportion of fatty acids (around 25% in sphingomyelin and 60% in glycolipids) belonged to the long chain (C19-C26) normal- and 2-hydroxy series. C18-sphingosine was found to be the only base present in all lipid classes investigated.