bluuebunny/crossref_metadata_2025 huggingface dataset:
Regional Clustering of Shared Neutralization Determinants on Primary Isolates of Clade C Human Immunodeficiency Virus Type 1 from South Africa
Authors: Bures Renata , Morris Lynn , Williamson Carolyn , Ramjee Gita , Deers Mark , Fiscus Susan A. , Abdool-Karim Salim , Montefiori David C.
Published: July 2002

Clade C is one of the most prevalent genetic subtypes of human immunodeficiency virus type 1 (HIV-1) in the world today and one of the least studied with respect to neutralizing antibodies. Most information on HIV-1 serology as it relates to neutralization is derived from clade B. Clade C primary isolates of HIV-1 from South Africa and Malawi were shown here to resemble clade B isolates in their resistance to inhibition by soluble CD4 and their sensitivity to neutralization by human monoclonal antibody immunoglobulin G1b12 and, to a lesser extent, 2F5. Unlike clade B isolates, however, all 16 clade C isolates examined resisted neutralization by 2G12. Infection with clade C HIV-1 in a cohort of female sex workers in South Africa generated antibodies that neutralized the autologous clade C isolate and T-cell-line-adapted (TCLA) strains of clade B. Neutralization of clade B TCLA strains was much more sensitive to the presence of autologous gp120 V3 loop peptides compared to the neutralization of clade C isolates in most cases. Thus, the native structure of gp120 on primary isolates of clade C will likely pose a challenge for neutralizing antibody induction by candidate HIV-1 vaccines much the same as it has for clade B. The autologous neutralizing antibody response following primary infection with clade C HIV-1 in South Africa matured slowly, requiring at least 4 to 5 months to become detectable. Once detectable, extensive cross-neutralization of heterologous clade C isolates from South Africa was observed, suggesting an unusual degree of shared neutralization determinants at a regional level. This high frequency of cross-neutralization differed significantly from the ability of South African clade C serum samples to neutralize clade B isolates but did not differ significantly from results of other combinations of clade B and C reagents tested in checkerboard assays. Notably, two clade C serum samples obtained after less than 2 years of infection neutralized a broad spectrum of clade B and C isolates. Other individual serum samples showed a significant clade preference in their neutralizing activity. Our results suggest that clades B and C are each comprised of multiple neutralization serotypes, some of which are more clade specific than others. The clustering of shared neutralization determinants on clade C primary HIV-1 isolates from South Africa suggests that neutralizing antibodies induced by vaccines will have less epitope diversity to overcome at a regional level.
Evolutionary History of
Cucumber Mosaic Virus
Deduced by Phylogenetic Analyses
Authors: Roossinck Marilyn J.
Published: July 2002

Cucumber mosaic virus
(CMV) is an RNA plant virus with a tripartite genome and an extremely broad host range. Previous evolutionary analyses with the coat protein (CP) and 5′ nontranslated region (NTR) of RNA 3 suggested subdivision of the virus into three groups, subgroups IA, IB, and II. In this study 15 strains of CMV whose nucleotide sequences have been determined were used for a complete phylogenetic analysis of the virus. The trees estimated for open reading frames (ORFs) located on the different RNAs were not congruent and did not completely support the subgrouping indicated by the CP ORF, indicating that different RNAs had independent evolutionary histories. This is consistent with a reassortment mechanism playing an important role in the evolution of the virus. The evolutionary trees of the 1a and 3a ORFs were more compact and displayed more branching than did those of the 2a and CP ORFs. This may reflect more rigid host-interactive constraints exerted on the 1a and 3a ORFs. In addition, analysis of the 3′ NTR that is conserved among all RNAs indicated that evolutionary constraints on this region are specific to the RNA component rather than the virus isolate. This indicates that functions other than replication are encoded in the 3′ NTR. Reassortment may have led to the genetic diversity found among CMV strains and contributed to its enormous evolutionary success.
Varied Persistent Life Cycles of Borna Disease Virus in a Human Oligodendroglioma Cell Line
Authors: Ibrahim Madiha S. , Watanabe Makiko , Palacios J. Alejandro , Kamitani Wataru , Komoto Satoshi , Kobayashi Takeshi , Tomonaga Keizo , Ikuta Kazuyoshi
Published: July 2002

Borna disease virus (BDV) establishes a persistent infection in the central nervous system of vertebrate animal species as well as in tissue cultures. In an attempt to characterize the life cycle of BDV in persistently infected cultured cells, we developed 30 clones by single-cell cloning from a human oligodendroglioma (OL) cell line after infection with BDV. According to the percentage of cells expressing the BDV major proteins, p40 (nucleoprotein) and p24 (phosphoprotein), the clones were classified into two types: type I (>20%) and type II (<20%). mRNAs corresponding to both proteins were detected by in situ hybridization (ISH) in a percentage of cells consistent with that for the protein expression in the two types. Surprisingly, ISH for the detection of the genomic RNA, mainly in type II, revealed a significantly larger cell population harboring the genomic RNA than that with the protein as well as the mRNA expression. By recloning from type II primary cell clones, the same phenotype was confirmed in the secondary cell clones obtained: i.e., low percentage of protein-positive cells and higher percentage of cells harboring the genomic RNA. After nerve growth factor treatment, the two types of clones showed increases in the percentage of cells expressing BDV-specific proteins that reached 80% in type II clones, in addition to increased expression levels per cell. Such enhancement might have been mediated by the activation of the mitogen-activated protein kinase in the clones as revealed by the detection of activated ERK1/2. Thus, our findings show that BDV may have established a persistent infection at low levels of viral expression in OL cells with the possibility of a latent infection.
Requirements for Budding of Paramyxovirus Simian Virus 5 Virus-Like Particles
Authors: Schmitt Anthony P. , Leser George P. , Waning David L. , Lamb Robert A.
Published: July 2002

Enveloped viruses are released from infected cells after coalescence of viral components at cellular membranes and budding of membranes to release particles. For some negative-strand RNA viruses (e.g., vesicular stomatitis virus and Ebola virus), the viral matrix (M) protein contains all of the information needed for budding, since virus-like particles (VLPs) are efficiently released from cells when the M protein is expressed from cDNA. To investigate the requirements for budding of the paramyxovirus simian virus 5 (SV5), its M protein was expressed in mammalian cells, and it was found that SV5 M protein alone could not induce vesicle budding and was not secreted from cells. Coexpression of M protein with the viral hemagglutinin-neuraminidase (HN) or fusion (F) glycoproteins also failed to result in significant VLP release. It was found that M protein in the form of VLPs was only secreted from cells, with an efficiency comparable to authentic virus budding, when M protein was coexpressed with one of the two glycoproteins, HN or F, together with the nucleocapsid (NP) protein. The VLPs appeared similar morphologically to authentic virions by electron microscopy. CsCl density gradient centrifugation indicated that almost all of the NP protein in the cells had assembled into nucleocapsid-like structures. Deletion of the F and HN cytoplasmic tails indicated an important role of these cytoplasmic tails in VLP budding. Furthermore, truncation of the HN cytoplasmic tail was found to be inhibitory toward budding, since it prevented coexpressed wild-type (wt) F protein from directing VLP budding. Conversely, truncation of the F protein cytoplasmic tail was not inhibitory and did not affect the ability of coexpressed wt HN protein to direct the budding of particles. Taken together, these data suggest that multiple viral components, including assembled nucleocapsids, have important roles in the paramyxovirus budding process.
Electrochemical and Spectrophotometric Study of the Reactions of L-Leucine with Pyridoxal and Pyridoxal Phosphate
Authors: Pineda T. , Blázquez M. , Domínguez M. , Garcia-Blanco F.
Published: July 2002

The reactions of L-leucine (Leu) with pyridoxal (PL) and pyridoxal-5'-phosphate (PLP) were studied over pH 6 - 13.5. Formation of the Schiff bases was indicated by UV-VIS absorption bands and reduction waves on a mercury electrode. A comparative electrochemical and spectrophotometric study on the reaction mixtures as a function of pH and the amino acid-to-aldehyde concentration ratio was carried out. Apparent formation constant, KpH and acid-base constants for the Schiff bases were obtained. Reduction mechanisms of the imines are proposed in different pH zones. The formation constant, KSo, of an unprotonated Schiff base from unprotonated species of aldehyde and amino acid was determined by voltammetry. The results are compared to those obtained in analog Schiff bases in order to improve the quantitative description of the enzymatic models.
An Analysis of Substituent Effects on the Proton and Carbon-13 Chemical Shifts of 2-Substituted 9-Isothiocyanatoacridines
Authors: Danihel Ivan , Imrich Ján , Kristian Pavol , Liptaj Tibor , Mazagová Dana
Published: July 2002

Proton and 13C NMR chemical shifts and coupling constants J(H,H) of a series of 2-substituted 9-isothiocyanatoacridines and their 4-methyl and 4-methoxy analogs were determined. The obtained values were utilized in analysis of substituent effects using empirical equations based on two- and three-parameter linear correlations. It was found that short-range interactions (positions ipso, ortho and meta) are well described by the three-parameter model of Reynolds whereas long-range effects are satisfactorily compatible with the two-parameter model. The dominant direction of conjugation in the acridine skeleton was derived from changes in chemical shifts due to substitution (SCS).
DieneN-(2,4,6-Tribromophenyl)maleimide Copolymer Membranes for Pervaporation of Ethanol-Water Mixtures
Authors: Lokaj Jan , Bleha Miroslav , Kovářová Jana
Published: July 2002

Alternating copolymers of butadiene or isoprene with N-(2,4,6-tribromophenyl)maleimide and the copolymer of chloroprene containing 42.7 mole % N-(2,4,6-tribromophenyl)maleimide structure units were synthesized by radical copolymerization. Along with copolymerization, the Diels-Alder addition of comonomers proceeded. DSC revealed some crosslinking of the copolymers occurring even at room temperature. Homogeneous membranes were prepared from the copolymers by solution casting and tested in pervaporation of variously concentrated aqueous ethanol. Separation factors of the membranes related to the preferentially transported water increased with increasing content of ethanol in solutions to be separated. In contrast to hydrophilic maleimide groups, the incorporated diene units lowered separation efficiency due to their affinity to ethanol.
Synthesis of Ethyl 1-Ethyl-6-fluoro-1,4-dihydro-8-hydroxy-4-oxoquinoline-3-carboxylate
Authors: Rádl Stanislav
Published: July 2002

In connection with our research into antibacterial fluoroquinolones we required ethyl 1-ethyl-6-fluoro-1,4-dihydro-8-hydroxy-4-oxoquinoline-3-carboxylate (IIc) as an intermediate. This paper describes synthesis of this compound and the corresponding carboxylic acid.
Solubility of Tris(ethylenediamine)chromium(III) and Hexaureachromium(III) Hexacyanoferrates(III) in Water and Mixed Water-Organic Solvents
Authors: Holba Vladislav , Hanková Marcela
Published: July 2002

The solubilities of tris(ethylenediamine)chromium(III) and hexa(urea)chromium(III) hexacyanoferrates(III) in aqueous solutions of different supporting electrolytes as well as in binary mixtures of water with methanol, tert-butyl alcohol and acetonitrile were measured at 25 °C. The experimental data have been used to evaluate the activity coefficients of the saturating salts in water and their Gibbs energies of transfer from water into the binary mixtures investigated.
Crystal Chemistry of the Hydrogen Selenites MH2n+1(SeO3)n+1
Authors: Loub Josef
Published: July 2002

Thirty six SeO3 formations in 17 crystal structures of selenites with formula MH2n+1(SeO3)n+1 , where M = H, Li, Na, K, Rb, Cs, NH4, Tl and n = 0-3 were analysed in this paper. There are found five types of selenites: SeO(OH)2 (n = 14), SeO2(OH)- (n = 17), SeO(OH0.5)2-(n = 1), Se(OH0.5)30.5-(n = 3) and SeO(OH)(OH0.5)0.5- (n = 1). All formations SeO3 have the point symmetry 1. The overall mean value of 108 individual Se-O distances is 1.70(5) Å, of 108 O-Se-O angles is 101(3) grad. and of 57 O...O distances in hydrogen bonds is 2.60(6) Å. A very significant correlation was found between the ionic radius r (Å) of the element M and the value V/Z (Å3).
Determination of Polyaromatic Hydrocarbons in the Gas Phase of Air
Authors: Vozňáková Zdenka , Popl Milan , Knapová Magda
Published: July 2002

Polyaromatic hydrocarbons (PAH) were isolated from the gas phase of air by sorption on the Separon CHN polymeric sorbent and quantitated by capillary gas chromatography using flame ionization detection. The conditions for PAH desorption from the sorbent were examined. Hexane, giving desorption recoveries of 90-100%, was the most efficient eluent. The recovery was found independent of the amount of PAH sorbed over a wide region. Analyte losses associated with the removal of eluent were investigated. Based on the experimental results, a procedure was developed for the determination of PAH in the gaseous phase of air and tested on field samples. When 5 m3 volumes of air are sampled, the limits of determination of the individual PAH are from 10 to 20 ng/m3.
Flow-Induced Crystallization of High-Density Polyethylene
Authors: Fortelný Ivan , Kovářová Jana , Kovář Josef
Published: July 2002

Crystallization induced by flow in the capillary viscometer was studied for four grades of linear polyethylene. From rheological and DSC measurements it follows that crystallization was induced in all samples under study at temperatures higher than melting temperatures of the same samples crystallized at rest. The maximum temperature of flow-induced crystallization increases with increasing molar mass of polyethylene. Flow-induced crystallization of injection moulding grades of polyethylene only takes place in a limited interval of shear rates. This effect is explained as a consequence of the shear rate distribution in the capillary.
A Simplified Model for Calculation of the Gibbs Energy of Mixing in Crystals: Thermodynamic Theory, Restrictions and Applicability
Authors: Christov Christomir
Published: July 2002

A simplified model has been set up for calculation of the molar Gibbs energy of mixing ∆mixGm(s) in crystals based on the assumption of a complete liquid-solid thermodynamic equilibrium in the water-salt systems. The procedure allows the ∆mixGm(s) values to be calculated from the experimental solubility data for the saturated binary and ternary solutions. The ∆mixGm(s) values and the excess Gibbs energy of mixing ∆mixGEm(s) were calculated for six alkali-halide systems (KCl-RbCl-H2O, KBr-RbBr-H2O, KI-RbI-H2O, NH4Cl-NH4Br-H2O, RbCl-RbBr-H2O and CsCl-CsBr-H2O). The results obtained were compared with experimental data taken from the literature and values calculated based on various theoretical approaches.
Promoted TiO2 (Anatase)-Supported Vanadium Oxide Catalysts. TPR Study and Activity in Oxidation of Toluene
Authors: Antol Marcel , Prandová Katarina , Hronec Milan
Published: July 2002

Vanadium oxide doped with K, Li, Bi, Sb, Te, U or Mo oxide, supported on TiO2 - anatase, was studied by temperature programmed reduction (TPR). The influence of the addition of promoters (up to molar ratio M : V = 0.5) to 5 wt.% V2O5/TiO2 catalyst on the TPR profile is presented in correlation with their catalytic activity in the vapor phase oxidation of toluene. All promoters, except Bi2O3, decrease the catalyst reducibility and decrease the rate of the toluene oxidation. A strong negative influence on the activity of the toluene oxidation have K, Li, and Te oxides. However, the presence of all tested promoters in the molar ratio M : V = 0.05 has a positive effect on the selectivity of benzoic acid formation. A further increase of this ratio leads to a decrease of the selectivity in the case of U, Mo and mainly K oxides, while with Li, Bi, Sb, and Te oxides, the selectivity remains almost unchanged. No correlation between TPR profiles of doped catalysts and their selectivity was found. The most effective promoter of vanadia catalysts for the benzoic acid production is Sb oxide, possessing a very high selectivity at high conversion of toluene.
Effectiveness of Catalyst Extrudate of Tetralobed Cross Section Under Conditions of Influence of Internal Diffusion
Authors: Martinec Jan , Hanika Jiří
Published: July 2002

The results are summarized of mathematical modelling of the effect of internal diffusion on the rate of m-th order reaction taking place under non-isothermal conditions in the catalyst particle with tetralobed cross section. The effectiveness of the tetralobe-shaped extrudate is compared with that of cylindrical extrudate. The results obtained on the basis of mathematical modelling are confronted with the experimental data obtained on studying the dehydration reaction of cyclohexanol on cylindrical and tetralobed extrudates of gama-alumina under the conditions of influence of internal diffusion. The experimental data are in a qualitative agreement with the theoretical ones and confirm the higher effectiveness of shaped catalyst in comparison with the cylindrical extrudate catalyst.
Dihydrotestosterone with an Ammonium Centre in the Position 16β
Authors: Slavíková Barbora , Kasal Alexander , Buděšínský Miloš
Published: July 2002

In an alternative synthesis of 17β-hydroxy-16β-(piperidin-1-yl)-5α-androstan-3-one (4), neighbouring group participation between a 17β-carbonyloxy group and the 16β-amino group was used and a high yield partial hydrolysis of 3β,17β-diacetoxy-16β-(piperidin-1-yl)-5α-androstane (11) was developed. Interference of the neighbouring group participation was also apparent in another 17β-acetoxy derivative - in oxidation of compound 12 to 13. Compound 4 was converted into water-soluble derivatives, i.e. quaternary ammonium derivatives 17 to 20.
Novel Intramolecular Induction of Axial Chirality by a Centrally Chiral Element in the Biphenyl Series
Authors: Tichý Miloš , Günterová Jana , Závada Jiří
Published: July 2002

The title induction has been observed in the reaction of achiral 2,2',6,6'-tetrakis(bromomethyl)biphenyl with centrally chiral (R)-1-phenylethylamine, (R)-1-(1-naphthyl)ethylamine and (R)-1-(2-naphthyl)ethylamine. The ratio of the arising diastereomeric doubly bridged diamines and their thermodynamic stability have been determined. The diastereomer excess in the kinetically controlled reaction is solvent-dependent. The absolute configuration of the biphenyl twist in the products has been assigned on the basis of CD spectra and comparison with singly bridged biphenyl models of known sense of the twist.
Preparation of Chloro and Sulfanyl Derivatives of 1-(2-Deoxy-4-C-hydroxymethyl-α-L-threo-Pentofuranosyl)uracil
Authors: Hřebabecký Hubert , Balzarini Jan , Holý Antonín
Published: July 2002

3'-Chloro and 3'-acetylsulfanyl derivatives of 1-(2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil were prepared by reaction of 2,3'-anhydro-1-{5'-O-benzoyl-4'-C-[(benzoyloxy)methyl]-2'-deoxy-α-L-erythro-pentofuranosyl}uracil (3) with hydrogen chloride and thioacetic acid, respectively. The reaction with hydrogen chloride gave a mixture of N-1 and N-3 substituted uracil derivatives 12 and 14. Reaction of 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-α-L-threo-pentofuranosyl}uracil (7) with thionyl chloride and subsequent debenzoylation afforded 1-(4-C-chloromethyl-2-deoxy-β-D-erythro-pentofuranosyl)uracil (19). Nucleophilic substitution with lithium thioacetate, followed by deacylation, converted 1-{3-O-benzoyl-4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (9) into 1-(2-deoxy-4-C-sulfanylmethyl-β-D-erythro-pentofuranosyl)uracil (21). The obtained thiols were oxidized with iodine or air to give 1,1'-[disulfandiylbis(2,3-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-3,1-diyl]di(pyrimidine-2,4-(1H,3H)-dione) (17) and 1,1'-[disulfandiylbis(2,5-dideoxy-4-hydroxymethyl-α-L-threo-pentofuranose-5,1-diyl]di(pyrimidine-2,4(1H,3H)-dione) (22). Reaction of 1-{3-acetylsulfanyl-5-O-methanesulfonyl-4-C-[(benzoyloxy)methyl]-2,3-dideoxy-α-L-threo-pentofuranosyl)}uracil (24) with methanolic sodium methoxide afforded 1-(3,5-anhydro-2,3-dideoxy-4-C-hydroxymethyl-3-sulfanyl-α-L-threo-pentofuranosyl)uracil (25). The same reagent was used in the preparation of 1-(3,5-anhydro-2-deoxy-4-C-hydroxymethyl-α-L-threo-pentofuranosyl)uracil (26) from 1-{4-C-[(benzoyloxy)methyl]-2-deoxy-5-O-p-toluenesulfonyl-α-L-threo-pentofuranosyl}uracil (8). From the series of 4'-substituted 2'-deoxyuridine derivatives, synthesized in this study, solely the 4'-chloromethyl derivative 19 and the oxetane derivative 26 exhibited an appreciable activity against HIV-1 and HIV-2.
The Effects of Processing Parameters on the Synthesis of Siliceous MCM-41 from Colloidal Silicas
Authors: Rathouský Jiří , Zukalová Markéta , Zukal Arnošt
Published: July 2002

Well-ordered as-synthesized siliceous MCM-41 mesoporous molecular sieves can be prepared from the sol of colloidal silica (Ludox HS-40 and AS-40) only under optimized conditions. Two processing parameters have a significant effect on the structure. First, the period of stirring the mixture of Ludox AS-40 or HS-40 and tetraethylammonium hydroxide should be extended to 22 h. Second, the following temperature regime should be used: the reaction mixture consisting of colloidal silica, tetraethylammonium hydroxide, hexadecyltrimethylammonium chloride and water is being first aged at ambient temperature for 20 h, then the temperature is gradually increased and finally the mixture is kept at 100 °C for 40 h. As-made MCM-41 prepared even by an optimized procedure contains after calcination some proportion of an amorphous phase. Extraction with water of the as-made material is a suitable procedure for the improvement of the phase purity as less well-ordered and amorphous particles are preferentially dissolved and thus removed. In this way, a substantial improvement in the quality of MCM-41 molecular sieves can be achieved.
A New Host Lattice Built of the Werner-Type Copper(I,II) Cyanide Complex Involving a Macrocyclic Ligand
Authors: Yuge Hidetaka , Soma Takayoshi , Miyamoto Takeshi Ken
Published: July 2002

Crystals of a new clathrate [CuII(hmtd)CuI(CN)3]·CH2Cl2 were afforded from a Me2CO-EtOH-CH2Cl2 solution of a macrocyclic complex CuII(hmtd)CuI(CN)3·2 H2O (hmtd = 5,7,7,12,14,14-hexamethyl- 1,4,8,11-tetraazacyclotetradeca- 4,11-diene). It crystallizes in the monoclinic space group P21/n, a = 7.936(5), b = 18.717(4), c = 17.783(6) Å, β = 98.55(4)°, Z = 4, R = 0.0558 for 1 870 reflections. Unprecedentedly, only one of the three nitrogen-ends of a CuI(CN)3 moiety is coordinated to the square-pyramidal Cu(II) center. The guest CH2Cl2 molecules are captured in the channel between the potlid-shaped [CuII(hmtd)CuI(CN)3] molecules.
Stabilization of Dominant Structures in an Ionic Reaction-Diffusion System
Authors: Krämer Roland , Münster Arno F.
Published: July 2002

We describe a method of stabilizing the dominant structure in a chaotic reaction-diffusion system, where the underlying nonlinear dynamics needs not to be known. The dominant mode is identified by the Karhunen-Loeve decomposition, also known as orthogonal decomposition. Using a ionic version of the Brusselator model in a spatially one-dimensional system, our control strategy is based on perturbations derived from the amplitude function of the dominant spatial mode. The perturbation is used in two different ways: A global perturbation is realized by forcing an electric current through the one-dimensional system, whereas the local perturbation is performed by modulating concentrations of the autocatalyst at the boundaries. Only the global method enhances the contribution of the dominant mode to the total fluctuation energy. On the other hand, the local method leads to simple bulk oscillation of the entire system.
Kinetic Study of the Reactions of Some 5-Nitro-2-(4-nitrophenoxy)-3-X-thiophenes with Aniline and 4-Methoxyaniline in Methanol
Authors: Frenna Vincenzo , Macaluso Gabriella , Consiglio Giovanni , Guernelli Susanna , Spinelli Domenico
Published: July 2002

The rate constants of the title reactions have been measured at various amine concentrations. The second-order kinetic constant for the amino substitution increases in a hyperbolic way as a function of the nucleophile concentration. The k3Am/k-1 ratio for each catalysed system is not a monotonic function of the X substituent. This result has been rationalized in the framework of the SB-GA (Specific Base-General Acid) mechanism of base catalysis.
Theoretical Analysis of Pulse and Differential Pulse Polarography of Reversible Redox Reaction Complicated by Reactant Adsorption
Authors: Lovrić Milivoj , Zelić Marina , Komorsky-Lovrić Šebojka
Published: July 2002

Pulse and differential pulse polarograms of redox reactions complicated by reactant adsorption with and without lateral attractions in the monolayer are analysed theoretically by using a stationary spherical diffusion model. The continuous shift of the post-peak potential to lower values and the decrease in its half-peak width with increasing bulk concentration of reactant indicate attractions between adsorbed ions or molecules.
Sulfur Adsorption and Reaction with a TiO2(110) Surface: O↔S Exchange and Sulfide Formation
Authors: Hrbek Jan , Rodriguez Jose A. , Dvorak Joseph , Jirsak Tomas
Published: July 2002

Upon sulfur adsorption on TiO2(110) at 600 K, all surface oxygen is replaced by sulfur. High-resolution photoemission data show a complete loss of oxygen from the surface layer, a large binding energy shift and attenuation of Ti core levels, and the presence of three different S species. The bonding of sulfur is examined using first-principles density-functional calculations and the periodic supercell approach. At saturation the top layer of the oxide surface is converted to sulfide, with the majority of sulfur buckled above the Ti lattice plane and the remaining sulfur bonded in bridging sites. A mechanism for this self-limiting thermodynamically unlikely surface reaction is proposed.
Congenital adrenal hyperplasia: management during critical illness
Authors: Charmandari E , Lichtarowicz-Krynska E J , Hindmarsh P C , Johnston A , Aynsley-Green A , Brook C G D
Published: July 2002

BACKGROUND

Little is known of the optimal dose and administration schedule of hydrocortisone in critically ill patients with congenital adrenal hyperplasia (CAH) caused by 21-hydroxylase deficiency.

AIM

To determine plasma cortisol concentrations after intravenous administration of hydrocortisone in children with CAH and to relate these to plasma cortisol concentrations achieved by endogenous secretion in the stress of critical illness in previously healthy children.

METHODS

Plasma cortisol concentrations were measured in 20 patients with classical CAH (median age 11.2 years, range 6.1–16.4) following intravenous administration of hydrocortisone 15 mg/m2; and in 60 critically ill mechanically ventilated children (median age 2.5 years, range 0.25–16.3) on admission to the paediatric intensive care unit and for 24 hours thereafter.

RESULTS

In the CAH patients, plasma cortisol reached a mean peak of 1648.3 nmol/l (SD 511.9) within 10 minutes of the intravenous bolus, and fell rapidly thereafter; levels remained greater than 450 nmol/l for 2.5 hours only. In critically ill children, mean plasma cortisol on admission to the intensive care unit was 727 nmol/l (SD 426.1). Cortisol concentrations remained raised during the first 24 hours.

CONCLUSIONS

Critically ill patients with classical CAH may be best managed with a single intravenous hydrocortisone bolus followed by a constant rate infusion of hydrocortisone.
State anxiety responses to 60 minutes of cross training: Figure 1
Authors: Hale B S , Koch K R , Raglin J S
Published: July 2002

Objectives: Significant reductions in state anxiety following bouts of aerobic exercise have been consistently noted, whereas changes are generally absent after acute resistance training. However, the influence of a single exercise session involving both modes on state anxiety has not been examined.

Methods: To address this, state anxiety responses to 60 minutes of cross training were examined in 16 collegiate athletes (12 women, four men). Each subject completed two cross training exercise sessions (30 minutes of resistance training, 30 minutes of bicycle ergometry) in which the order of the exercises was reversed, with a minimum of one week between sessions. Each exercise mode was completed at about 70% of maximum. State anxiety (SAI-Y1) was assessed five minutes before, and 0, 10, and 60 minutes after exercise.

Results: Repeated measures analysis of variance showed a significant (p<0.05) main effect for time. However, the main effect for order and the order by time interaction were not significant. Post hoc analysis showed that state anxiety was reduced (p<0.05) from baseline (mean (SD) = 34.8 (7.9)) at 10 minutes (32.1 (7.5)) and 60 minutes (30.4 (5.9)) after exercise, but not at 0 minutes (33.8 (6.9)).

Conclusions: The results indicate that combined sessions of aerobic and resistance exercise are associated with reductions in state anxiety, and that the order in which the exercise is completed does not influence this response.
Helicobacter pylori infection induces hyperammonaemia in Mongolian gerbils with liver cirrhosis
Authors: Suto H , Azuma T , Ito S , Ohtani M , Dojo M , Ito Y , Kohli Y , Kuriyama M
Published: July 2002

BACKGROUND AND AIMS

We previously reported the effect of Helicobacter pylori eradication on hyperammonaemia in patients with liver cirrhosis. However, the role of H pylori as a cause of hyperammonaemia is controversial. We developed an animal model with liver cirrhosis and investigated the effect ofH pylori infection on hyperammonaemia.

MATERIALS AND METHODS

Five week old male Mongolian gerbils were inoculated orally with broth culture of H pylori. Forty eight gerbils were divided into four groups. Gerbils not inoculated with H pylori were fed a commercial rodent diet (group A) or a choline deficient diet (group C). Gerbils inoculated with H pyloriwere fed the commercial rodent diet (group B) or the choline deficient diet (group D). Blood ammonia levels of the femoral vein and portal vein were measured 30 weeks later.

RESULTS

All gerbils fed the choline deficient diet developed liver cirrhosis with fatty metamorphosis. The survival rate of group D was significantly lower than that of the other groups. Systemic and portal blood ammonia levels in group D were significantly higher than those in the other groups.

CONCLUSIONS

H pylori infection induces hyperammonaemia in gerbils with liver cirrhosis.
Personal values and cancer treatment refusal
Authors: Huijer Marli , van Leeuwen Evert
Published: July 2002

This pilot study explores the reasons patients have for refusing chemotherapy, and the ways oncologists respond to them. Our hypothesis, generated from interviews with patients and oncologists, is that an ethical approach that views a refusal as an autonomous choice, in which patients are informed about the pros and cons of treatment and have to decide by weighing them, is not sufficient. A different ethical approach is needed to deal with the various evaluations that play a role in treatment refusal. If patients forgo further treatment, while curative or palliative methods are available, there is no perspective from which to integrate the weighing of pros and cons of treatment and the preferences and values of individual cancer patients. A discrepancy thus results as regards what “good reasons” are, evoking misunderstandings or even breaking off communication. Suggestions are given for follow up research.
Assessing the ethical weight of cultural, religious and spiritual claims in the clinical context
Authors: Buryska James F
Published: July 2002

The aim of this paper is to expand upon the conclusions reached by Orr and Genesen in their 1997 article (published in this journal), Requests for ‘inappropriate’ treatment based on religious beliefs.1Assuming, with Orr and Genesen, that claims made in the name of religion are not absolute, I will propose some principles for determining when claims based on religious beliefs or cultural sensibilities “trump” other considerations and when they do not.
Who is my brother's keeper?
Authors: Kottow M H
Published: July 2002

Clinical and research practices designed by developed countries are often implemented in host nations of the Third World. In recent years, a number of papers have presented a diversity of arguments to justify these practices which include the defence of research with placebos even though best proven treatments exist; the distribution of drugs unapproved in their country of origin; withholding of existing therapy in order to observe the natural course of infection and disease; redefinition of equipoise to a more bland version, and denial of post-trial benefits to research subjects.

These practices have all been prohibited in developed, sponsoring countries, even though they invariably have pockets of poverty where conditions comparable to the Third World prevail. Furthermore, the latest update of the Declaration of Helsinki clearly decries double ethical standards in research protocols. Under these circumstances, it does not seem appropriate that First World scholars should propose and defend research and clinical practices with less stringent ethical standards than those mandatory in their own countries.

Recent years have witnessed frequent reports of less stringent ethical standards being applied to both clinical and research medical practices, for the most part in the field of drug trials and drug marketing, initiated by developed countries in poorer nations. Still more unsettling, a number of articles have endorsed the policy of employing ethical norms in these host countries, which would be unacceptable to both the legislations and the moral standards of the sponsor nations. Also, these reformulations often contravene the Declaration of Helsinki or one of its updates. This paper is not so much concerned with the actual practices, which have been subjected to frequent scrutiny and publicly decried when gross misconduct occurred. Rather, my concern relates to the approval and support such practices have found in the literature on bioethics from authors who might be expected to use their energy and scholarship to explore and endorse the universalisability of ethics rather than to develop ad hoc arguments that would allow exceptions and variations from accepted moral standards. To this purpose, issue will be taken with arguments in three fields: medical and pharmaceutical practices, research strategies, and local application of research results.
Making room for medical humanities: Figure 1:
Authors: Grant V J
Published: July 2002

Should medical humanities become part of the core curriculum in medicine? This paper describes the experiences of one medical school that decided it should. The paper describes the professional and academic rationale for this decision, the process by which it was implemented, the structure of the course, the strategies for assessment of students' work and the results of a teacher evaluation.
Occupational exposure to formaldehyde and wood dust and nasopharyngeal carcinoma
Authors: Vaughan Thomas L , Stewart Patricia A , Teschke Kay , Lynch Charles F , Swanson G Marie , Lyon Joseph L , Berwick Marianne
Published: July 2002

OBJECTIVES

To investigate whether occupational exposures to formaldehyde and wood dust increase the risk of nasopharyngeal cancer (NPC).

METHODS

A multicentred, population based case-control study was carried out at five cancer registries in the United States participating in the National Cancer Institute's SEER program. Cases (n=196) with a newly diagnosed NPC between 1987 and 1993, and controls (n=244) selected over the same period from the general population through random digit dialing participated in structured telephone interviews which inquired about suspected risk factors for the disease, including a lifetime history of occupational and chemical exposure. Histological type of cancer was abstracted from clinical records of the registries. Potential exposure to formaldehyde and wood dust was assessed on a job by job basis by experienced industrial hygienists who were blinded as to case or control status.

RESULTS

For formaldehyde, after adjusting for cigarette use, race, and other risk factors, a trend of increasing risk of squamous and unspecified epithelial carcinomas was found for increasing duration (p=0.014) and cumulative exposure (p=0.033) but not for maximum exposure concentration. The odds ratio (OR) for people cumulatively exposed to >1.10 ppm-years was 3.0 (95% confidence interval (95% CI) 1.3 to 6.6) compared with those considered unexposed. In analyses limited to jobs considered definitely exposed, these trends became stronger. The associations were most evident among cigarette smokers. By contrast, there was no association between potential exposure to formaldehyde and undifferentiated and non-keratinising carcinomas. There was little evidence that exposure to wood dust increased risk of NPC, as modest crude associations essentially disappeared after control for potential exposure to formaldehyde.

CONCLUSIONS

These results support the hypothesis that occupational exposure to formaldehyde, but not wood dust, increases risk of NPC. This association seems to be specific to squamous cell carcinomas. Established cohorts of workers exposed to formaldehyde and wood dust should continue to be monitored for NPC and other respiratory cancers. Future studies of NPC should take into account histological type in assessing risk from environmental and host factors.
Occupational risk factors for shoulder pain: a systematic review
Authors: van der Windt Daniëlle A W M , Thomas Elaine , Pope Daniel P , de Winter Andrea F , Macfarlane Gary J , Bouter Lex M , Silman Alan J
Published: July 2002

OBJECTIVES

To systematically evaluate the available evidence on occupational risk factors of shoulder pain.

METHODS

Relevant reports were identified by a systematic search of Medline, Embase, Psychlit, Cinahl, and Current Contents. The quality of the methods of all selected publications was assessed by two independent reviewers using a standardised checklist. Details were extracted on the study population, exposures (physical load and psychosocial work environment), and results for the association between exposure variables and shoulder pain.

RESULTS

29 Studies were included in the review; three case-control studies and 26 cross sectional designs. The median method score was 60% of the maximum attainable score. Potential risk factors related to physical load and included heavy work load, awkward postures, repetitive movements, vibration, and duration of employment. Consistent findings were found for repetitive movements, vibration, and duration of employment (odds ratio (OR) 1.4–46 in studies with method scores ⩾ 60%). Nearly all studies that assessed psychosocial risk factors reported at least one positive association with shoulder pain, but the results were not consistent across studies for either high psychological demands, poor control at work, poor social support, or job dissatisfaction. Studies with a method score ⩾60% reported ORs between 1.3 and 4.0. Substantial heterogeneity across studies for methods used for exposure assessment and data analysis impeded statistical pooling of results.

CONCLUSIONS

It seems likely that shoulder pain is the result of many factors, including physical load and the psychosocial work environment. The available evidence was not consistent across studies, however, and the associations were generally not strong. Future longitudinal research should evaluate the relative importance of each individual risk factor and the role of potential confounding variables—such as exposure during leisure time—to set priorities for the prevention of shoulder pain in occupational settings.
Occupational risk of infection by varicella zoster virus in Belgian healthcare workers: a seroprevalence study
Authors: Vandersmissen Godelieve , Moens Guido , Vranckx Robert , de Schryver Antoon , Jacques Pierre
Published: July 2002

OBJECTIVES

To assess the prevalence of varicella zoster virus (VZV) antibodies in Flemish (Belgian) healthcare workers, to investigate the association between seronegativity and selected variables, and to assess the reliability of recall about disease as a predictor of immunity.

METHODS

A seroprevalence study of VZV antibodies (IgG) was conducted among a systematic sample of 4923 employees in various professional groups, employed in 22 hospitals in Flanders and Brussels (Belgium). Information about sex, age, department, job, and years of employment, the country of origin, and history of varicella was obtained. The presence of VZV antibodies was investigated with the enzyme linked immunosorbent assay (ELISA), Enzygnost anti VZV / IgG (Dade Behring, Marburg, Germany). Statistical analysis was performed by calculating prevalences and prevalence ratios (PRs) and their 95% confidence intervals (95% CIs). Sensitivity, specificity, and positive and negative predictive values (PPV and NPV) of the recalled history were determined.

RESULTS

The prevalence of VZV seropositivity in Flemish healthcare workers was 98.5% (95% CI 98.1 to 98.8). Seronegativity was significantly associated with age and job, increasing with both older and younger age. The prevalence of seronegative workers was significantly less in nursing staff than non-nursing staff. There was no significant difference for sex and years of employment. The PPV and NPV of recalled history were 98.9% and 3.4%. Sensitivity and specificity were 83% and 38.9%.

CONCLUSION

The prevalence of VZV seropositivity was very high in this sample of Flemish healthcare workers. Because of this low overall susceptibility, VZV infection seems not to be an important occupational risk among healthcare workers in Flanders. The increasing seronegativity above the age of 45 is possibly due to a loss of detectable antibodies. A positive history of varicella was a good predictor of immunity, but a negative history had no value as a predictor of susceptibility in adults.
Exposure assessment and lung function in pig and poultry farmers
Authors: Radon K , Weber C , Iversen M , Danuser B , Pedersen S , Nowak D
Published: July 2002

OBJECTIVES

To describe the relation between spirometric findings and farming characteristics and variables of exposure to organic dust measured during work in animal buildings. Farmers have traditionally been described as having one of the most dangerous occupations, so a large scale study on European farmers was carried out. This is the report of the second part of that study.

METHODS

40 pig farmers in Denmark and 36 poultry farmers in Switzerland were chosen randomly and were assessed over 1 working day.

RESULTS

Mean (SD) baseline spirometric results in pig farmers were higher than in poultry farmers (forced expiratory volume in 1 second (FEV1) (% of reference value) 108.3 (16.7)v100.2 (14.2); p=0.04). Baseline lung function results were significantly associated with ventilation of the animal houses. Furthermore, temperature was related to spirometric findings in pig farmers.

CONCLUSIONS

Ventilation of the animal house and temperature might influence respiratory morbidity in farmers.
Exposure to carbon monoxide and nitrogen dioxide in enclosed ice arenas
Authors: Pelham T W , Holt L E , Moss M A
Published: July 2002

This article summarises the latest information on the adverse cardiorespiratory effects of exposure to carbon monoxide (CO) and nitrogen dioxide (NO2) in enclosed ice rinks. Sources of CO and NO2emissions are identified, current standards for these agents, as well as methods of controlling the emissions, dispersion, and evacuation of these toxic gases are presented. A detailed literature search involving 72 references in English and French from research conducted in North America and Europe was used. Material was from peer reviewed journals and other appropriate sources. Air pollutants such as carbon monoxide (CO), and nitrogen dioxide (NO2) which are present in enclosed skating facilities, may exacerbate a pre-existing pathogenic condition in those people who spend considerable time in these environments. Considering the popularity of ice hockey, short track speed skating, and figure skating, and the hundreds of hours that a sensitive person may spend each year in these environments, it would seem appropriate to seek more definitive answers to this important health problem. From the findings and conclusions of the research reviewed in this paper, 10 recommendations are listed.
Hypersensitivity syndrome caused by amitriptyline administration
Authors: Milionis Haralampos J , Skopelitou Antigone , Elisaf Moses S
Published: July 2002

Adverse cutaneous manifestations are among the most common side effects associated with psychotropic drugs. Skin reactions due to amitriptyline (a tricyclic antidepressant agent) include rashes and hypersensitivity reactions (for example, urticaria and photosensitivity) as well as hyperpigmentation. Hypersensitivity syndrome is a specific severe idiosyncratic reaction causing skin, liver, joint, and haematological abnormalities, which usually resolve after the discontinuation of the implicated drug. A case of a 24 year old woman who experienced hypersensitivity syndrome three weeks after the initiation of amitriptyline is reported.
Human immunoglobulin for diabetic amyotrophy—a promising prospect?
Authors: Courtney A E , McDonnell G V , Patterson V H
Published: July 2002

Diabetic neuropathies are universally recognised and cause significant morbidity. At present improving glycaemic control is the only recognised treatment. A man with type 2 diabetes presented with disabling asymmetric lower limb proximal neuropathy. Rapid clinical, functional, and electrical improvement followed treatment with intravenous immunoglobulin. The aetiology of diabetic amyotrophy remains controversial but there is evidence for an immune mediated process and this case suggests a role for immunoglobulin in the management of this debilitating condition.
Rectal bleeding in a patient with portal hypertension
Authors: Sinha U K , Raha S K , Wilkins W E
Published: July 2002

A 77 year old woman presented for the first time in 1997 with severe haematemesis and melena. After initial resuscitation she underwent an emergency upper gastrointestinal endoscopy which showed bleeding oesophageal varices. She was treated with injection sclerotherapy.