bluuebunny/crossref_metadata_2025 huggingface dataset:
1141154113 Expression of natural cytotoxicity receptors in peripheral blood NK cell subsets of women with recurrent spontaneous abortions (RSA) or implantation failures
Authors: Fukui A , Ntrivalas EI , Gilman‐Sachs A , Kwak‐Kim J , Beaman KD
Published: May 2006

Problem:  Natural Cytotoxicity Receptors (NCRs) are unique markers of NK cells and regulate NK cell cytotoxicity and cytokine production. a2V‐ATPase is expressed in the cell membrane and can regulate the pH of the extracellular environment, which might facilitate NK cell killing or cytokine secretion. In this preliminary study we evaluated the expression of NCRs and a2V‐ATPase in peripheral blood NK cells of women with RSA or implantation (IVF‐ET) failures.

Method of Study:  Peripheral blood was obtained from women with RSA (n = 10), or IVF‐ET failures (n = 9). CD56dim and CD56bright NK cells were analyzed for the expression of NCRs (NKp46, NKp44 and NKp30) and a2V‐ATPase using flow cytometry.

Results:  For women with RSA, there were significant differences in the expression of NKp46 between CD56dim (36.9 ± 30.2) and CD56bright (76.0 ± 27.5) (P < 0.01), of NKp30 between CD56dim (30.9 ± 25.7) and CD56bright (55.8 ± 29.5) (P < 0.01), and of a2V‐ATPase between CD56dim (1.0 ± 0.9) and CD56bright (23.2 ± 15.1) (P < 0.01) NK cells. For women with IVF‐ET failures, there were significant differences in the expression of NKp46 between CD56dim (39.5 ± 21.5) and CD56bright (78.8 ± 26.0) (P < 0.01), of NKp30 between CD56dim (27.2 ± 17.9) and CD56bright (45.2 ± 29.8) (P < 0.05), and of a2V‐ATPase between CD56dim (1.6 ± 1.4) and CD56bright (21.2 ± 16.5) (P < 0.01) NK cells.

Conclusions:  The differential expression of NCRs and a2V‐ATPase in NK cell subsets of women with RSA and IVF‐ET failures may have an effect in cytotoxicity and cytokine production. Additional studies are currently in effect to evaluate these activities. We suggest that the analysis of NCRs and a2V‐ATPase expression in peripheral blood NK cell subsets may contribute to a better understanding in the biology of NK cells in women with RSA or IVF‐ET failures.
1141229409 Immunolocalization of IL‐10 in endometrium of habitual abortion: new diagnostic tool?
Authors: Scarpellini L , Scarpellini F , Sbracia M , Fimiani C , Patella A
Published: May 2006

Recently, the role of IL‐10, in controlling the response of the maternal immune system to the embryo has been highlighted. We studied the expression of IL‐10 by immunohistochemistry in human endometrium of patients with habitual abortions and in fertile controls. Endometria of 79 women affected by habitual abortion, without evidence of known abortive causes and sampled in the late secretory phase, were studied by immunohistochemistry for IL‐10 and CD‐56 expression. Monoclonal antibodies for these antigens were used on paraffin embedded tissues. Controls were endometria of 22 fertile women and 10 IVF pregnancies. HSCORE system was used for a semi‐quantitative assay. Stromal cells CD56 positive of secretory phase endometria and the decidua of pregnancies express IL‐10, whereas no expression was observed in proliferative phase samples. In the samples of habitual aborters, a statistical significant decrease of IL‐10 expression was shown. 29 of 79 patients showed a reduction in IL‐10 expression of more than 50%, relative to controls. IL‐10 is expressed in stromal cells of secretory phase and pregnancy, and markedly reduced in habitual aborters. Assessment of IL‐10 in secretory endometrium may be used in these patients to find Th2 impairment.
1141355494 Cytokine, chemokines and integrin levels in the severely preterm placenta distinguish between preeclampsia and other preinatal complications
Authors: McElrath TF , Allred EN , Hecht JL , Fichorova RN , Leviton A
Published: May 2006

Using a multiplex protein array, we tested the hypothesis that the concentrations of inflammatory proteins within placental chorionic stroma differ by perinatal complication. The chorionic plates of 30 singleton placentas were biopsied immediately after delivery for severe preeclampsia (PE), membrane rupture (pPROM) or preterm labor (PL) between 23–28 weeks and flash frozen after the amnion was removed. After thawing and homogenization, concentrations of select proteins were measured on the MesoScale Discovery platform. Analytes were grouped by the functional categories of: inflammation (IL1β, IL6, TNFα, IL18,), chemotaxis (IL8), endothelial effectors (P‐ and E‐selectin, VCAM1, ICAM1, ICAM3, VEGF) and inflammatory modulation (IL10, TGFβ, IL1ra, thrombomodulin). ANOVA and K‐means clustering examined differences between delivery indications. K‐means clustering distinguished PE placentas from the others, but did not discriminate PL from pPROM. Both PL and pPROM had distinct subsets of placentas with either increased inflammatory or increased modulatory activity. PE placentas tended to have low concentrations of one inflammation indicator (IL‐18 P = 0.04), two endothelial effectors (E‐selectin P = 0.02; ICAM1 P = 0.03), and one inflammation modulator (IL1ra P = 0.01). On the other hand, PE placentas also had elevated levels of 2 inflammation modulators (TGFβP = 0.04; thrombomodulin P < 0.001) and elevated levels of one endothelial effector (VEGF P < 0.001). The placental inflammatory response differs by perinatal complication. The PE response has limited inflammatory activation and elevated VEGF levels. The PL and pPROM placentas appeared similar in their distribution of subgroups with inflammatory or modulatory responses. This suggests possible common pathologic antecedents and progression.
1140406603 The immunoglobulin superfamily protein Izumo is required for sperm to fuse with eggs
Authors: Inoue N , Ikawa M , Isotani A , Okabe M
Published: May 2006

Representing the 60 trillion cells that build a human body, a sperm and an egg meet, recognize each other, and fuse to form a new generation of life. The factors involved in this important membrane fusion event, fertilization, have been sought for a long time. Recently, CD9 on the egg membrane was found to be essential for fusion, but sperm‐related fusion factors remain unknown. Here, by using a fusion‐inhibiting monoclonal antibody and gene cloning, we identify a mouse sperm fusion related antigen and show that the antigen is a novel immunoglobulin superfamily protein. We have termed the gene Izumo and produced a gene‐disrupted mouse line. Izumo ‐/‐ mice were healthy but males were sterile. They produced normal‐looking sperm that bound to and penetrated the zona pellucida but were incapable of fusing with eggs. Human sperm also contain Izumo and addition of the antibody against human Izumo left the sperm unable to fuse with zona‐free hamster eggs.
1141610241 Altered expression of HuR, an mRNA stabilizing protein, mediates aberrant Placenta Growth Factor (PlGF) expression in preeclampsia
Authors: Schaecher CP , Groesch KA
Published: May 2006

Background:  Control of mRNA stability is an essential regulatory process in eukaryotic gene expression. HuR, a 3’UTR mRNA binding protein, can protect AU‐rich mRNA from degradation in response to stresses. PlGF, an angiogenic growth factor, contains two consensus AU‐rich sites suggesting that under normal conditions HuR may protect PlGF mRNA from degradation. Trophoblast expression of PlGF is significantly decreased in preeclampsia and by hypoxia in vitro. We hypothesize that decreased levels of cytoplasmic HuR may contribute to decreased PlGF expression in hypoxic and preeclamptic trophoblast.

Methods:  Western blots were used to determine relative effects of in vitro hypoxia on HuR protein expression and subcellular localization in trophoblast. Immunohistochemistry was used to compare HuR expression patterns in trophoblast of preeclamptic and normal placentae.

Results:  Cytoplasmic expression of HuR was decreased 1.4 fold in the cytoplasm and 1.2 fold in the nucleus of JEG3 cells. A shift in HuR was more apparent in primary trophoblast with a greater than 2‐fold decrease in the cytoplasm and a 1.4 fold decrease in the nucleus following 24 hr of hypoxia. Immunohistochemical analyses detected HuR expression in near term trophoblast in situ. However, this technical approach did not detect a significant change in HuR expression between normal and preeclamptic trophoblast.

Conclusions:  HuR expression is decreased in hypoxic trophoblast, at least in vitro, which may provide a causal link to decreased PlGF mRNA expression. Down regulation of trophoblast PlGF expression is thought to contribute to the pathophysiology associated with preeclampsia including the relative lack of perfusion of the placenta and systemic renal effects.
1141634395 Analysis of protein profiles of amniotic fluid in a pregnant woman with a fetus of Down syndrome by SELDI‐TOF mass spectrometry
Authors: Nakanishi K , Sawai H , Komori S , Koyama K
Published: May 2006

Aim:  The identification of protein profiles of amniotic fluid in a pregnant woman with a normal fetus or fetus with down syndrome is a major issue in prenatal diagnosis.

Methods:  In this study, we analyzed protein profiles of amniotic fluids of pregnant women with a normal fetus (50 cases) and with a fetus of Down syndrome (7 cases) using SELDI‐TOF mass spectrometry. We used a weak cation exchange chip (CM10) under the condition of pH 4.5 for analyzing protein profiles.

Results:  We found 111 increased protein peaks in 3–10 kDa range, 111 peaks in 5–15 kDa and 53 peaks in 10–30 kDa, respectively. After comparing the protein profiles of normal to that of Down syndrome, we finally identified the increases in expression of a 5.4 kDa protein and a 13.4 kDa protein in pregnant women with a fetus of Down syndrome, whereas, 6.9 kDa, 12.5 kDa and 13.7 kDa proteins in pregnant women with a normal fetus.

Conclusion:  We first identified the protein profiles of amniotic fluid in normal pregnant women and specific protein profiles in pregnant women with a fetus of Down syndrome. These protein profiles in amniotic fluid might be important and useful information for prenatal diagnosis.
1141635158 IL‐10 deficiency and uterine NK cell cytotoxic activation link inflammation to preterm parturition
Authors: Murphy SP , Hanna NN , Fast LD , Shaw S , Padbury JF , Romero R , Sharma S
Published: May 2006

Preterm birth is a major cause of perinatal morbidity and mortality. Intrauterine infection/inflammation is associated with a majority of preterm labor and birth cases. Despite decades of studies recognizing a strong association between infection/inflammation and preterm birth, no effective method of preventing infection‐induced premature labor and delivery is yet available. Importantly, the mechanisms by which intrauterine infection/inflammation may contribute to preterm birth are not known. Based on our observations with human gestational tissue to highlight the role of IL‐10 in normal and comprimised pregnancy outcomes, we have performed experiments with syngeneic and allogeneic pregnant IL‐10‐/‐ mice or congenic wild type mice. Pregnancy outcomes were assessed in response to i.p. administration of low doses of lipopolysacchade (LPS) on gd 14. The mice were allowed to deliver or were sacrificed on gd 16 for isolation of uterine immune cells for functional studies or collected tissue for histological analysis. Attempts were made to prevent preterm parturition. LPS‐treated IL‐10‐/‐, but not wild type mice, displayed a significant acceleration in time of delivery, on gd 16.5 compared to gd 19.6 for wild type controls. The premature delivery observed in LPS‐treated IL‐10‐/‐ mice was associated with an increase in the number of uterine NK (uNK) cells. These cells also displayed a dramatic infiltration of the placenta with a perivascular localization. uNK cells appear to be responsible for the induction of preterm birth in these mice as depletion of NK cells completely restored normal length of gestation. Moreover, neutralization TNF‐α also rescued the premature delivery. Taken together, our results for the first time demonstrate that IL‐10 deficiency and uterine NK cell cytotoxic activation link intrauterine inflammation to preterm parturition.
RANS-Based Very Large
Eddy Simulation of Thermal and Magnetic Convection at Extreme
Conditions
Authors: Hanjalić K. , Kenjereš S.
Published: May 2006

For thermal and magnetic convection at very high Rayleigh and Hartman numbers, which are inaccessible to the conventional large eddy simulation, we propose a time-dependent Reynolds-average-Navier-Stokes (T-RANS) approach in which the large-scale deterministic motion is fully resolved by time and space solution, whereas the unresolved stochastic motion is modeled by a “subscale” model for which an one-point RANS closure is used. The resolved and modeled contributions to the turbulence moments are of the same order of magnitude and in the near-wall regions the modeled heat transport becomes dominant, emphasizing the role of the subscale model. This T-RANS approach, with an algebraic stress/flux subscale model, verified earlier in comparison with direct numerical simulation and experiments in classic Rayleigh-Bénard convection, is now expanded to simulate Rayleigh-Bénard (RB) convection at very high Ra numbers—at present up to O(1016)—and to magnetic convection in strong uniform magnetic fields. The simulations reproduce the convective cell structure and its reorganization caused by an increase in Ra number and effects of the magnetic field. The T-RANS simulations of classic RB indicate expected thinning of both the thermal and hydraulic wall boundary layer with an increase in the Ra number and an increase in the exponent of the Nu∝Ran correlation in accord with recent experimental findings and Kraichnan asymptotic theory.
Analysis of Spatiotemporal Variations and Flow Structures in a Periodically Driven Cavity
Authors: Sriram S. , Deshpande Abhijit P. , Pushpavanam S.
Published: May 2006

The time-dependent fluid flow in a square cavity was studied using model fluids of glycerol-water solution at different frequencies and amplitudes of motion of the top plate. The range of Reynolds numbers in our investigation varied from 5 to 3700. The experiments were carried out in a square cavity with a periodically driven lid, and planar velocity measurements were obtained using particle image velocimetry. The flow was driven by moving the top surface of the cavity in a simple harmonic motion. The aspect ratio, defined as the ratio of cavity length to the cavity height, is unity. The ratio of cavity spanwise width to the length of the cavity is 0.2. The temporal variation of velocity at fixed locations in the cavity exhibits a periodic variation. The basic frequency of the fluid motion at a point in the flow domain was observed to be the same as that of plate motion for low Reynolds number Re. However, existence of dominant secondary frequencies was observed along the central vertical plane. The velocity variation as a function of time at a fixed position and the velocity profiles along horizontal and vertical planes are also quantitatively described. These were compared to computational fluid dynamics (CFD) simulations based on the finite volume technique. Comprehensive details of the flow as a function of Reynolds number are analyzed. The evolution of secondary vortices at different plate positions as a function of Reynolds number is also presented. The planar velocity measurements acquired are indicative of the flow behavior in a periodically driven cavity with a narrow span width even at high Re. At very low Re, the flow throughout the periodically driven cavity qualitatively resembles the classical steady lid-driven cavity flow. At high Re, the entire cavity is occupied with multiple vortices. The qualitative features of the bulk flow observed are valid even for cavities with infinite span width.
Development of High Performance Micro DMFCS and a DMFC Stack
Authors: Lu G. Q. , Wang C. Y.
Published: May 2006

A silicon-based micro direct methanol fuel cell (μDMFC) for portable applications has been fabricated and its electrochemical characterization carried out. A membrane-electrode assembly (MEA) was specially fabricated to mitigate methanol crossover. The cell with active area of 1.625cm2 demonstrated a maximum power density of 50mW∕cm2 at 60°C. Since the silicon wafer is too fragile to compress for sealing, and a thicker layer of gold has to be coated on the silicon wafer to reduce contact resistance, further development of micro DMFCs for high power application was carried out using stainless steel as bipolar plate in which flow channels were fabricated by photochemical etching technology. The maximum power density of the micro DMFC reaches 62.5mW∕cm2 at 40°C and 100mW∕cm2 at 60°C with atmospheric pressure. An 8-cell air-breathing DMFC stack has been developed. Mass transport phenomena such as water transport and oxygen transport were investigated. By using a water management technique, cathode flooding was avoided in our air-breathing DMFC stack. Furthermore, it was found that oxygen transport in the air-breathing cathode is still very efficient. The DMFC stack produced a maximum output power of 1.33W at 2.21V at room temperature, corresponding to a power density of 33.3mW∕cm2. A passive DMFC using pure methanol was demonstrated with steady-state output power of 20-25mW∕cm2 over more than 10h without heat management.
Recovery, Bioaccumulation, and Inactivation of Human Waterborne Pathogens by the Chesapeake Bay Nonnative Oyster,
Crassostrea ariakensis
Authors: Graczyk Thaddeus K. , Girouard Autumn S. , Tamang Leena , Nappier Sharon P. , Schwab Kellogg J.
Published: May 2006

The introduction of nonnative oysters (i.e.,
Crassostrea ariakensis
) into the Chesapeake Bay has been proposed as necessary for the restoration of the oyster industry; however, nothing is known about the public health risks related to contamination of these oysters with human pathogens. Commercial market-size
C. ariakensis
triploids were maintained in large marine tanks with water of low (8-ppt), medium (12-ppt), and high (20-ppt) salinities spiked with 1.0 × 10
5
transmissive stages of the following human pathogens:
Cryptosporidium parvum
oocysts,
Giardia lamblia
cysts, and microsporidian spores (i.e.,
Encephalitozoon intestinalis
,
Encephalitozoon hellem
, and
Enterocytozoon bieneusi
). Viable oocysts and spores were still detected in oysters on day 33 post-water inoculation (pwi), and cysts were detected on day 14 pwi. The recovery, bioaccumulation, depuration, and inactivation rates of human waterborne pathogens by
C. ariakensis
triploids were driven by salinity and were optimal in medium- and high-salinity water. The concentration of human pathogens from ambient water by
C. ariakensis
and the retention of these pathogens without (or with minimal) inactivation and a very low depuration rate provide evidence that these oysters may present a public health threat upon entering the human food chain, if harvested from polluted water. This conclusion is reinforced by the concentration of waterborne pathogens used in the present study, which was representative of levels of infectious agents in surface waters, including the Chesapeake Bay. Aquacultures of nonnative oysters in the Chesapeake Bay will provide excellent ecological services in regard to efficient cleaning of human-infectious agents from the estuarine waters.
Rhizosphere Selection of Highly Motile Phenotypic Variants of
Pseudomonas fluorescens
with Enhanced Competitive Colonization Ability
Authors: Martínez-Granero Francisco , Rivilla Rafael , Martín Marta
Published: May 2006

Phenotypic variants of
Pseudomonas fluorescens
F113 showing a translucent and diffuse colony morphology show enhanced colonization of the alfalfa rhizosphere. We have previously shown that in the biocontrol agent
P. fluorescens
F113, phenotypic variation is mediated by the activity of two site-specific recombinases, Sss and XerD. By overexpressing the genes encoding either of the recombinases, we have now generated a large number of variants (mutants) after selection either by prolonged laboratory cultivation or by rhizosphere passage. All the isolated variants were more motile than the wild-type strain and appear to contain mutations in the
gacA
and/or
gacS
gene. By disrupting these genes and complementation analysis, we have observed that the Gac system regulates swimming motility by a repression pathway. Variants isolated after selection by prolonged cultivation formed a single population with a swimming motility that was equal to the motility of
gac
mutants, being 150% more motile than the wild type. The motility phenotype of these variants was complemented by the cloned
gac
genes. Variants isolated after rhizosphere selection belonged to two different populations: one identical to the population isolated after prolonged cultivation and the other comprising variants that besides a
gac
mutation harbored additional mutations conferring higher motility. Our results show that
gac
mutations are selected both in the stationary phase and during rhizosphere colonization. The enhanced motility phenotype is in turn selected during rhizosphere colonization. Several of these highly motile variants were more competitive than the wild-type strain, displacing it from the root tip within 2 weeks.
Combination of Multiplex PCR and PCR-Denaturing Gradient Gel Electrophoresis for Monitoring Common Sourdough-Associated
Lactobacillus
Species
Authors: Settanni Luca , Valmorri Sara , van Sinderen Douwe , Suzzi Giovanna , Paparella Antonello , Corsetti Aldo
Published: May 2006

A combination of denaturing gradient gel electrophoresis (DGGE) and a previously described multiplex PCR approach was employed to detect sourdough lactobacilli. Primers specific for certain groups of
Lactobacillus
spp. were used to amplify fragments, which were analyzed by DGGE. DGGE profiles obtained from
Lactobacillus
type strains acted as standards to analyze lactobacilli from four regional Abruzzo (central Italy) sourdoughs.
Spoligotyping of
Mycobacterium tuberculosis
Isolates from Pakistan Reveals Predominance of Central Asian Strain 1 and Beijing Isolates
Authors: Hasan Zahra , Tanveer Mahnaz , Kanji Akbar , Hasan Qaiser , Ghebremichael Solomon , Hasan Rumina
Published: May 2006

The estimated incidence of tuberculosis in Pakistan is 181 per 100,000; however, there is limited information on
Mycobacterium tuberculosis
genotypes circulating in the country. We studied 314
M. tuberculosis
clinical isolates; of these, 197 (63%) isolates grouped into 22 different clusters, while 119 (37%) had unique spoligotypes. Eighty-nine percent of the isolates were pulmonary (Pul), and 11% were extrapulmonary (E-Pul). We identified Central Asian Strain (CAS), Beijing, T1, Latin American-Mediterranean, and East African-Indian genogroups. Beijing strains, reportedly the most prevalent spoligotype worldwide, constituted 6% of our strain population. The CAS1 strain comprised 121 (39%) of the study isolates. No difference was observed between clustered isolates from cases of Pul and E-Pul tuberculosis. However, E-Pul isolates included a greater number of unique spoligotypes than Pul isolates (
P
= 0.005). The overall percentage of drug resistance was 54%, and that of MDR strains was 40%. While CAS1 strains were not associated with drug resistance, the relative risk of MDR was significant in Beijing strains compared to the non-Beijing groups (95% confidence interval, 1.2 to 8.9). The fact that the predominant strain, CAS1, is not associated with drug resistance is encouraging and suggests that an effective tuberculosis control program should be able to limit the high incidence of disease in this region.
Prospective Study of the Value of Quantitative Culture of Organisms from Blood Collected through Central Venous Catheters in Differentiating between Contamination and Bloodstream Infection
Authors: Chatzinikolaou Ioannis , Hanna Hend , Darouiche Rabih , Samonis George , Tarrand Jeffrey , Raad Issam
Published: May 2006

Collection of blood through a central venous catheter for the diagnosis of bacteremia is a debated topic. Quantitative cultures of organisms from blood collected through central venous catheters were found to be highly sensitive, specific, and predictive of bacteremia, especially when a cutoff point of 15 colonies of skin organisms was used.
Lack of Association between the Presence of the pVir Plasmid and Bloody Diarrhea in
Campylobacter jejuni
Enteritis
Authors: Louwen R. P. L. , van Belkum A. , Wagenaar J. A. , Doorduyn Y. , Achterberg R. , Endtz H. P.
Published: May 2006

The main mechanisms by which
Campylobacter jejuni
causes diarrhea are unknown. In contrast to a recent communication, we report here the absence of an association with the plasmid pVir in patients infected with
C. jejuni
who developed bloody diarrhea in The Netherlands, and we suggest a role for other virulence determinants.
Multiplex PCR-Based Reverse Line Blot Hybridization Assay To Identify 23
Streptococcus pneumoniae
Polysaccharide Vaccine Serotypes
Authors: Kong Fanrong , Brown Mitchell , Sabananthan Archcna , Zeng Xianyu , Gilbert Gwendolyn L.
Published: May 2006

We developed a multiplex PCR-based reverse line blot assay to identify 23 pneumococcal serotypes represented in the polysaccharide vaccine, using 334 well-characterized isolates, representing all 90 serotypes, and 268 “unknowns.” The assay identified all target serotypes, but 11, which cross-react with 1 to 4 nonvaccine serotypes, could be distinguished using serotype-specific antisera.
Early Diagnosis of
Acanthamoeba
Infection during Routine Cytological Examination of Cerebrospinal Fluid
Authors: Petry Franz , Torzewski Michael , Bohl Jürgen , Wilhelm-Schwenkmezger Thomas , Scheid Patrick , Walochnik Julia , Michel Rolf , Zöller Lothar , Werhahn Konrad J. , Bhakdi Sucharit , Lackner Karl J.
Published: May 2006

Early identification of
Acanthamoeba
in cerebrospinal fluid is mandatory to prevent fatal granulomatous amebic encephalitis. In the case presented here amebic trophozoites were detected in a routine cerebrospinal fluid sample. The antibiotic treatment and the apparently low virulence of this isolate were responsible for the benign progression of the infection.
Synthesis of 2,6-Di-O-methyl-D-mannose
Authors: Perry M. B. , Webb Ann C.
Published: May 2006

2,6-Di-O-methyl-D-mannose was synthesized using the following sequence of reactions: 1,3,4,6-tetra-O-acetyl-2-O-methyl-β-D-mannopyranose → methyl 2-O-methyl-α-D-mannopyranoside → methyl 2-O-methyl-6-O-trityl-α-D-mannopyranoside → methyl 3,4-di-O-acetyl-2-O-methyl-6-O-trityl-α-D-mannopyranoside → methyl 3,4-di-O-acetyl-2-O-methyl-α-D-mannopyranoside → methyl 3,4-di-O-acetyl-2,6-di-O-methyl-α-D-mannopyranoside → 2,6-di-O-methyl-D-mannose. The preparation and properties of derivatives of the 2,6-di-O-methyl-D-mannose are recorded.
Convenient C-alkylation of some acyloins
Authors: van de Sande Johan H. , Kopecky Karl R.
Published: May 2006

Acetoin, adipoin, and benzoin are conveniently alkylated by benzyl chloride and methyl iodide in 1,2-dimethoxyethane solution using sodium hydride as the base. Only alkylation at carbon is observed. Little or no alkylation occurs at oxygen.
Effect of temperature on "saturation currents" in gas phase radiolysis cells: the conductance of Pyrex and other cell materials
Authors: Byrtus R. M. , Freeman G. R.
Published: May 2006

When gas-filled Pyrex cells were heated above about 50°, the saturation currents obtained in a gamma radiation field apparently decreased. At temperatures above 100° good saturation currents were not obtained. At temperatures below 50° the conductance of Pyrex was negligible, and "true" saturation currents were measured. At temperatures greater than 50° the Pyrex conducted appreciably, so the total current flowing in the circuit was appreciably greater than the gas phase saturation current (absorbed dose rate 1010–1013 eV/ml s). If the outer surface of the cell was grounded, for example by ionized air, part of the current by-passed the measuring ammeter, thereby decreasing the "apparent" saturation current. The magnitude of the temperature effect was greatly decreased by wrapping the cell with teflon tape, thereby insulating it from the ionized air.The effect of temperature on apparent saturation currents measured in quartz cells was much smaller than that in Pyrex cells, because the conductance of quartz was much less than that of Pyrex at temperatures above 50°.When a metal cell that contains a Pyrex insulator between the electrodes is used, the temperature of the Pyrex should be kept below about 50°.
Isomerization of butene over a chromia–alumina catalyst
Authors: Chen H. C. , Hudgins R. R. , Silveston P. L.
Published: May 2006

Isomerization runs were performed in a micro-reactor at 325 °C over a range of butene partial pressure of 84 to 763 mm Hg and at a total pressure of approximately 1 atm. The isomerization rate of 1-butene passed through a maximum with increasing 1-butene partial pressure; the isomerization rate of cis- and trans-2-butene increased asymptotically with increasing cis- and trans-2-butene partial pressures respectively. Stereoselectivity was observed in the isomerization of each butene, and was found to be independent of pressure. Catalyst deactivation resulted in loss in stereoselectivity. Results suggest that surface reactions control isomerization and proceed simultaneously on different active sites.
Tris(ethylenediamine)ruthenium(III) iodide
Authors: Watt George W. , Senoff C. V.
Published: May 2006

The synthesis and electronic spectrum of [Ru(en)3]3+ have been described.
Electrolysis of low molecular weight carbohydrates in non-aqueous media. I. The products of electrolysis of monosaccharides
Authors: Hay G. W. , Smith F.
Published: May 2006

The electrolysis of monosaccharides in alkaline, non-aqueous media caused a sequential descent of the series as a result of the elimination of one-carbon units from the reducing end of the molecule, without the formation of chromatographically detectable quantities of oxidized derivatives.
Chemistry of the aminochromes. Part X. Some further observations on the reactions of aminochromes with thiols
Authors: Powell W. , Heacock R. A. , Mattok G. L. , Wilson D. L.
Published: May 2006

The reactions between aminochromes and thiols have been reinvestigated. In general aminochromes react with thiols to give mixtures of products including: 5,6-dihydroxyindoles; thio-substituted 5,6-dihydroxyindoles (the mercapto residue is now considered to be in the 4-position of the indole nucleus and not the 7-position as previously reported); and relatively unstable addition products formed between the aminochrome and the thiol. The mechanisms by which these compounds are formed are discussed. The characterization of three thio-substituted 5,6-dihydroxyindoles by nuclear magnetic resonance spectroscopy is described. The nuclear magnetic resonance spectra of a number of 5,6-diacetoxyindole derivatives are reported.
Molar excess Gibbs free energies of benzene – m-xylene mixtures
Authors: Boublík T. , Benson G. C.
Published: May 2006

Vapor–liquid equilibria for the system benzene – m-xylene were measured in a circulation still at 25, 37, and 50 °C. Excess free energy data were analyzed in terms of Flory's theory of non-polar mixtures.
Isomerization of methyl isocyanide sensitized by vibrationally excited ethane
Authors: Shaw D. H. , Dunning B. K. , Pritchard H. O.
Published: May 2006

The isomerization of methyl isocyanide in the presence of methyl radicals takes place by two mechanisms. One is the simple free-radical displacement reaction which has been described previously. The other is through a direct transfer of energy from vibrationally excited ethane molecules. The vibrationally sensitized component can be quenched by increasing the total pressure.
Calculation of the bond lengths in sulfur-containing heterocyclic systems
Authors: Živković T. , Trinajstić N.
Published: May 2006

The equations [Formula: see text] are proposed for use in the calculation of bond lengths in sulfur heterocycles.
Pyrrolidone hydrotribromide: a brominating agent with selectivity for ketones
Authors: Awang D. V. C. , Wolfe Saul
Published: May 2006

The relative reactivities of a ketone, an olefin, and an enol acetate towards bromination in tetrahydrofuran by "pyrrolidone–bromine complex", (pyrrolidone)3•HBr3 (PHT), are [Formula: see text] acetate. The conversion of benzalacetone to C6H5CH = CHCOCH2Br is given as an example. The selectivity of PHT is enhanced by dilution and is diminished upon addition of pyrrolidone to the reaction mixtures. The selectivity of phenyltrimethylammonium tribromide (PTAT) is not as great as that of PHT and is subject to acid catalysis.At a sufficiently low concentration in a nonpolar solvent, the enol of cyclohexanone reacts at least 1 000 000 times faster with molecular bromine than does cyclohexene. This observation suggests that the selectivity of perbromides may be due to their ability to furnish a low equilibrium concentration of bromine when dissolved in solvents of low polarity.
Reductions with sulfurated borohydrides. II. Reduction of typical aldehydes
Authors: Lalancette J. M. , Frêche A.
Published: May 2006

Aromatic and aliphatic aldehydes can be reduced by sulfurated sodium borohydride to the corresponding alcohols. The reduction gives a quantitative yield of alcohol, without secondary products, if the reaction is performed at 0–10 °C. At higher temperatures (60°), the reduction is accompanied by the formation of disulfide. A good selection of the two possible reactions is obtained by adjusting the operating temperature. A mechanism explaining the reduction and the formation of sulfurated product is presented.
Theoretical considerations bearing on the evaluation and interpretation of the dielectric behavior of physically adsorbed polar gases
Authors: McMullen T. , McIntosh R.
Published: May 2006

This paper consists of Part I and Part II. Part I contains a discussion of the evaluation of the dielectric constant of an adsorbed phase for a system which contains a small volume fraction of adsorbing solid. The method is similar to one employed earlier, but treats the case of spherical particles rather than spherical voids and employs the volume average macroscopic field of a phase rather than the volume average internal field. Part II contains the application of the correlation function method of Kubo to the assignment of the macroscopic dielectric properties of the adsorbed phase. The correlation function is developed for a system of rigid harmonic oscillators and used to establish the formulae for the static polarization and the resonance behavior of such a system. The results agree with earlier derivations by Kurbatov, by Benson, Channen, and McIntosh, and by Fröhlich.
Vibrational spectra of thiocarbonyl chlorofluoride and a normal coordinate analysis of thiocarbonyl chlorofluoride and thiocarbonyl difluoride
Authors: Moule D. C. , Subramaniam C. R.
Published: May 2006

The previously unreported infrared and Raman spectra of thiocarbonyl chlorofluoride have been obtained and analyzed. An assignment has been made for the in-plane fundamental frequencies. The frequency of the out-of-plane fundamental has been obtained from a partial analysis of the near ultra-violet (π*n) system. Normal coordinate analyses for thiocarbonyl fluoride and thiocarbonyl chlorofluoride have been carried out using the Urey–Bradley potential field. The value of the CS stretching force constant is found to show a marked change with the halogen substitution in contrast to the CO stretching constant in the carbonyl halides. This is attributed to the presence of ionic valence bond structures in the thiocarbonyl halides which are not significant in the carbonyl halides.
Reaction of dibromocarbene with aromatic ethers
Authors: Saraf S. D.
Published: May 2006

The reaction of dibromocarbene with 1-methoxynaphthalene, 2-methoxynaphthalene, and anisole is discussed. Bromotropones were isolated in good yields in the case of 1- and 2-methoxynaphthalenes. Anisole, on treatment with bromoform and potassium t-butoxide gave 4-bromotropone, whereas, on heating with phenyl(tribromomethyl)mercury, p-anisic acid and 4,4′-dimethoxybenzophenone were the main products.
Metallation of 5- and 6-membered ring sultones
Authors: Durst T. , Manoir J. du
Published: May 2006

Treatment of 1,3-propane and 1,4-butane sultone with n-butyllithium in tetrahydrofuran at −78° has been shown to result in metallation α to the sulfonyl group. This is in contrast to ring opening which has been observed when the reaction was carried out at room temperature (1,2). The products obtained from the interaction of the lithio derivatives 3 and 4 with carbonyl compounds and alkyl halides are described.
Reaction of dialkyl phosphorothioic acids with cyanogen bromide
Authors: Engel Robert R.
Published: May 2006

Dialkyl phosphorothioic acids (1) in benzene solution and in the presence of a tertiary amine react with cyanogen bromide to form the corresponding dialkyl phosphoroisothiocyanatidates (2). Under the reaction conditions these are partially decomposed to yield the alkylthiocyanates (3) and the alkylmetaphosphates (4).
Reactions of thiyl radicals. VI. Photolysis of ethanethiol
Authors: Steer R. P. , Knight A. R.
Published: May 2006

The photolysis of ethanethiol vapor in the pressure range 10 to 350 Torr and the effect of % decomposition, wavelength, and of added inert gas and ethylene on the rate of formation of the products has been determined. In addition, the effect of temperature on the photolysis of methanethiol–ethylene–inert gas and ethanethiol–ethylene–inert gas systems has been studied.For the pure substrate, the primary process is S—H bond cleavage and the hydrogen atom produced abstracts the sulfyhydryl hydrogen of the substrate. The quantum yield of molecular hydrogen formation is unity, independent of pressure. C2H5S radicals, formed either in the primary process or as a result of abstractive attack by H atoms or radicals on the substrate, combine to form an excited disulfide molecule. The major condensable product, C2H5SSC2H5, arises via collisional deactivation of this excited species which can also sensitize the decomposition of the substrate to give C2H4, C2H6, and H2S, the other products observed. With added inert gas the rates of formation of the minor products decrease whereas hydrogen and disulfide remain unchanged.With added ethylene, the major products are H2, C2H5SSC2H5, and C2H5SC2H5, the addition product. Diethyl sulfide is formed in a chain reaction by the attack of C2H5S on the olefinic double bond to form the composite radical, followed by H abstraction from the substrate. The hydrogen rate decreases due to the addition of H atoms to ethylene. The rate constant ratio, k22/k4, for the reactions [22] and [4], respectively,[Formula: see text]is pressure dependent, indicative of the formation of hot hydrogen atoms in the primary process of the photolysis of methanethiol and ethanethiol. The Arrhenius parameters A22/A4 and E22−E4 for the methanethiol–ethylene and ethanethiol–ethylene systems have been determined. Kinetic treatments of the proposed mechanisms have been undertaken.
Stereochemistry of hydrogenation of 19-substituted 5α-cholestan-3-ones
Authors: Watanabe Y. , Mizuhara Y. , Shiota M.
Published: May 2006

The effect of 19-substituents on the stereochemistry of hydrogenation of 19-substituted 5α-cholestan-3-ones was examined. It has been shown that hydroxyl, acetoxyl, and methoxyl groups have some effect in increasing 3α-alcohols on hydrogenation over platinum in ethanol compared with the case of the un-substituted ones.
Reduction of trichloromethylcarbinols. Hydrogenolysis of phenyl(trichloromethyl)carbinol and 1,1,1-trichloro-2-hydroxy-6-methyl-4- heptanone on metal surfaces
Authors: Kiehlmann Eberhard , Bianchi Robert J. , Reeve Wilkins
Published: May 2006

Reduction with zinc in neutral or acidic medium or catalytic hydrogenation of phenyl(trichloromethyl)-carbinol (1) gives β,β-dichlorostyrene (2), β-chlorostyrene (3), and phenyl(dichloromethyl)carbinol (4). β,β-Dichlorostyrene is the sole product of reduction of phenyl(trichloromethyl)carbinyl methyl ether with zinc and acetic acid. Lithium in liquid ammonia reduces the trichloromethyl group of 1 to give α-phenethyl alcohol (5) in low yield; acetophenone and β-phenethyl alcohol have been identified as byproducts of this reaction.Clemmensen reduction of 1,1,1-trichloro-2-hydroxy-6-methyl-4-heptanone (6) does not yield the expected 1,1,1-trichloro-6-methyl-2-heptanol; instead, 1,1-dichloro-6-methyl-1-hepten-4-one (7) and 1,1-dichloro-6-methyl-l-heptene (8) are formed as the main reaction products. Long reflux time, efficient stirring, and the employment of a large excess of amalgamated zinc and concentrated hydrochloric acid favor the formation of 8 while 7 is obtained in high yield when sulfuric acid is used instead of hydrochloric acid.A mechanism for the reduction of trichloromethylcarbinols (1 and 6) with zinc has been proposed, 7 being postulated as an intermediate in the formation of 8.
Liquid hydrogen chloride solvent system. XII. Reactions of some sulfur, selenium, and tellurium compounds
Authors: Peach M. E.
Published: May 2006

The ions Me2SCl+ and MeSCl2+ have been prepared in hydrogen chloride solution from the oxidation of dimethyl sulfide and methanesulfenyl chloride with chlorine, or from methyl sulfur trichloride (MeSCl2+), and characterized as their tetrachloroborates and hexafluorophosphates. Et2SCl+BCl4− and EtSCl2+BCl4− have been prepared analogously. Dimethyl selenium and dimethyl tellurium solutions were oxidized with chlorine to dimethyl selenium dichloride and dimethyl tellurium dichloride.Methanesulfenyl chloride solution was ionized due to the protonation of sulfur, and not to the loss of a chloride ion. Methylchlorosulfonium hexafluorophosphate has been characterized. Methane- and ethane-sulfenyl chloride solutions reacted with boron trichloride giving (RSCl)2BCl3.Sulfur tetrachloride, selenium tetrachloride, and tellurium tetrachloride were sparingly soluble and showed no acidic or basic properties in the solvent. Sulfur monochloride, sulfur dichloride, selenium monochloride, and tellurium dichloride were non-basic in solution.The new compounds, Me2S2.BCl3 and Me2Te.BCl3, have been prepared and characterized.
Hot molecules in radical combination
Authors: Bell T. N. , Zucker U. F.
Published: May 2006

1:1 Difluoroethylene is formed when CF3 radicals react with alkyl silanes. We propose that the olefin results from the rearrangement and decomposition of a hot molecule arising from radical recombination[Formula: see text]
Chemiluminescent reactions in the airglow
Authors: Young Robert A.
Published: May 2006

Laboratory experiments on chemiluminescent reactions involving atomic oxygen of pertinence to the earth's nightglow are reviewed. From simple consideration it is shown that the atomic oxygen concentration in the earth's upper atmosphere must be larger than the presently accepted value of 2 × 1011 atoms/cm3 at the peak in the atomic oxygen altitude profile. Rocket measurements of the volume emission intensity of 5577 Å radiation and laboratory measurements of the rate of its excitation by three-body atomic oxygen association indicate a peak upper atmospheric atomic oxygen concentration near 1012 atoms/cm3. The excitation of molecular oxygen emission in atomic association is a multistep process involving at least one quenchable precursor. Laboratory results are inadequate to define the excitation mechanism but a strongly temperature-dependent precursor deactivation process is required for laboratory observation to be consistent with the hypothesis that atomic association is the cause of nightglow O2 emission. Other processes are briefly discussed.
Quantitative aspects of base-catalyzed Michael addition: Mechanistic study of structural and medium effects on rate
Authors: Markisz John A. , Gettler Joseph D.
Published: May 2006

The quantitative kinetics of the reactions of acrylonitrile and methyl vinyl ketone with ethyl acetoacetate and 2,4-pentanedione, and those of acrylonitrile with ethanol and methanol in basic solution were studied as functions of base concentration, temperature, ionic strength, and solvent composition. An expression is obtained which relates the observed rates to the basicity of the solution for the 2,4-pentanedione reactions by the amount of anion in solution. For the other systems, reasonable values of ionization constants obtained empirically, similarly correlate observed rates with the concentration of base in the system. A quantitative correlation with activity coefficients as expressed by the expanded form of the Debye–Hückel equation gave good agreement for most of the experimental data with ionic strength. A derivation for the particular type of system employed indicated that the activity coefficient for the double-bonded compounds appears to have to be treated as an ion with partial ionic charge. On the basis of experimental data reported, the mechanism proposed involves, (i) anion attack on a polarized double bond, (ii) formation of a cyclic intermediate, severely restricted because of π orbital overlap, and (iii) protonation of this intermediate to form product.
Chloral–ketone condensations in acetic anhydride. Reaction of chloral with butanone, 3-pentanone, cyclohexanone, and 4-methyl-2-pentanone
Authors: Kiehlmann Eberhard , Loo Pui-Wah
Published: May 2006

In the presence of sodium acetate as catalyst, chloral hydrate undergoes a mixed aldol condensation with aliphatic and alicyclic ketones in acetic anhydride as solvent. Contrary to previous literature reports, reaction occurs at both the methyl and the methylene group in α-position to the carbonyl group of butanone, to give a mixture of 1,1,1-trichloro-2-hydroxy-4-hexanone (1) and 1,1,1-trichloro-2-hydroxy-3-methyl-4-pentanone (2a and 2b, diastereomers). 3-Pentanone, cyclohexanone, and 4-methyl-2-pentanoneyield 1,1,1-trichloro-2-hydroxy-3-methyl-4-hexanone (3a and 3b, diastereomers), 2-(1-hydroxy-2,2,2-trichloroethyl-) cyclohexanone (4a and 4b, diastereomers), and 1,1,1-trichloro-2-hydroxy-6-methyl-4- heptanone (5), respectively. Compound 5 is the exclusive product formed from chloral hydrate and 4-methyl-2-pentanone since attack at the methylene group is sterically hindered. The low-melting diastereomers 2a, 3a, and 4a which have not been characterized before, exhibit strong intramolecular hydrogen bonding and have been assigned the threo configuration on the basis of nuclear magnetic resonance and molecular model studies.
Polymerization behavior of 2,6-dimethoxystyrene
Authors: Lau W. Y. , Burns C. M.
Published: May 2006

Free radical, cationic, and anionic initiators were investigated as possible agents for the polymerization of 2,6-dimethoxystyrene. Polymerization was observed in all three cases, with rapid cross-linking apparently occurring with the cationic catalyst. Attempts at copolymerization with styrene and with methyl methacrylate resulted in the formation of homopolymers of 2,6-dimethoxystyrene, in the cationic cases, and of methyl methacrylate in the anionic cases. Random copolymers were obtained in the anionic case with styrene and in the free radical case with both comonomers. Monomer reactivity ratios were calculated, and the polymerization behavior was interpreted in terms of the molecular structure of 2,6-dimethoxystyrene.
Chemistry of the aminochromes. Part XIII. Some further observations on the reactions of the aminochromes with thioglycollic acid
Authors: Powell W. , Heacock R. A.
Published: May 2006

Thioglycollic acid reacts with adrenochrome in aqueous solution to give 5,6-dihydroxy-1-methylindole and 4-S-carboxymethylthio-5,6-dihydroxy-1-methylindole, together with smaller amounts of the lactone obtained by intramolecular cyclization of the latter compound. When the reaction is carried out in the absence of water the relative amount of 5,6-dihydroxy-1-methylindole formed is markedly reduced. At lower temperatures 4-S-carboxymethylthio-5,6-dihydroxy-1-methylindole is the main product obtained, whilst at higher temperatures the corresponding lactone predominates.The major products obtained by the action of thioglycollic acid on 4- and 7-methyladrenochrome in aqueous solution were 5,6-dihydroxy-1,4-dimethylindole and 4-S-carboxymethylthio-5,6-dihydroxy-1,7-dimethylindole respectively.