bluuebunny/crossref_metadata_2025 huggingface dataset:
Fuzzy symmetric threshold functions and applications
Authors: Lee Edward T.
Published: April 2003

A fuzzy symmetric threshold (ST) function is defined to be a fuzzy set over the set of functions. All ST functions have full memberships in this fuzzy set. For n variables, there are (2n+2) ST functions. A distance measure between a nonsymmetric threshold function and the set of all ST functions is defined and investigated. An explicit expression for the membership function of a fuzzy ST function is defined through the use of this distance measure. An algorithm for obtaining this distance measure is presented with illustrative examples. It is also shown that any function and its complement always have the same grade of membership in the class of fuzzy ST functions. Applications to concise function representation and simple function implementation are also presented with examples. In addition, most inseparable unsymmetric functions are defined and investigated. Fuzzy ST functions are relevant to the development of practical applications of fuzzy methods and might contribute to the state of the art in the implementations of fuzzy methods in the areas requiring utilization of ST functions.
Prevalence of Cytolethal Distending Toxin Production in Periodontopathogenic Bacteria
Authors: Yamano Ryousuke , Ohara Masaru , Nishikubo Shuichi , Fujiwara Tamaki , Kawamoto Toru , Ueno Yoko , Komatsuzawa Hitoshi , Okuda Katsuji , Kurihara Hidemi , Suginaka Hidekazu , Oswald Eric , Tanne Kazuo , Sugai Motoyuki
Published: April 2003

Cytolethal distending toxin (CDT) is a newly identified virulence factor produced by several pathogenic bacteria implicated in chronic infection. Seventy three strains of periodontopathogenic bacteria were examined for the production of CDT by a HeLa cell bioassay and for the presence of thecdtgene by PCR with degenerative oligonucleotide primers, which were designed based on various regions of theEscherichia coliandCampylobacter cdtBgenes, which have been successfully used for the identification and cloning ofcdtABCgenes fromActinobacillus actinomycetemcomitansY4 (M. Sugai et al., Infect. Immun.66:5008-5019, 1998). CDT activity was found in culture supernatants of 40 of 45 testedA. actinomycetemcomintansstrains, but the titer of the toxin varied considerably among these strains. PCR experiments indicated the presence of Y4-typecdtsequences in these strains, but the rest ofA. actinomycetemcomitanswere negative by PCR amplification and also by Southern blot analysis for thecdtABCgene. In the 40 CDT-positive strains, Southern hybridization withHindIII-digested genomic DNA revealed that there are at least 6 restriction fragment length polymorphism types. This suggests that thecdtABCflanking region is highly polymorphic, which may partly explain the variability of the CDT activity in the culture supernatants. The rest of tested strains of periodontopathogenic bacteria did not have detectable CDT production by the HeLa cell assay and forcdtBsequences by PCR analysis under our experimental conditions. These results strongly suggested that CDT is a unique toxin predominantly produced byA. actinomycetemcomitansamong periodontopathogenic bacteria.
Detection of
Sporothrix schenckii
in Clinical Samples by a Nested PCR Assay
Authors: Hu Sindy , Chung Wen-Hung , Hung Shuen-Iu , Ho Hsin-Chun , Wang Zen-Whe , Chen Chien-Hsun , Lu Shu-Chuan , Kuo Tseng-tong , Hong Hong-Shang
Published: April 2003

Cutaneous sporotrichosis is a chronic granulomatous fungal infection caused by
Sporothrix schenckii
with worldwide distribution. Its traditional diagnosis is time-consuming and difficult to differentiate from that of a clinical sporotrichoid lesion caused by various pathogens. In this study, a nested PCR assay for the detection of
S. schenckii
was evaluated by using a sequence of 18S rRNA gene as a target. For the examination of specificity and sensitivity, five clinical isolates with 1 ATCC 10213 strain of
S. schenckii
, 10 strains of clinical common fungi, 3 strains of
Mycobacterium
spp.,
Staphylococcus aureus
, and normal human skin tissue were used. The expected fragment was amplified from six
S. schenckii
isolates in the first round and nested PCR but not from other microorganisms and human DNA. Their sequences were 100% identical to the
S. schenckii
18S rRNA gene sequence deposited in GenBank. A detection limit of 40 fg of
S. schenckii
DNA extract was determined with ethidium bromide staining. Serial dilution studies demonstrated that the nested PCR could detect a DNA amount of 1 CFU of
S. schenckii
in tissue samples. We further investigated the nested PCR assay for the detection of
S. schenckii
from the tail tissues of 5 experimentally infected mice and from the clinical biopsy specimens of 12 patients with sporotrichosis confirmed by culture or histochemical staining. The nested PCR assay was positive in all 5 infected mice and in 11 of the 12 clinical specimens. The high sensitivity and specificity of this nested PCR indicate that the assay can provide rapid diagnosis with sufficient accuracy to be clinically useful for patients with sporotrichosis.
Prospective Value of PCR Amplification and Sequencing for Diagnosis and Typing of Old World
Leishmania
Infections in an Area of Nonendemicity
Authors: Gangneux Jean-Pierre , Menotti Jean , Lorenzo Frédéric , Sarfati Claudine , Blanche Hélène , Bui Hung , Pratlong Francine , Garin Yves-Jean-François , Derouin Francis
Published: April 2003

We assessed the prospective value of PCR amplification of a repetitive sequence from
Leishmania
nuclear DNA and sequencing for the diagnosis and typing of Old World
Leishmania
infection in an area of nonendemicity. During this 42-month study, 29 of 168 consecutive samples were examined and classified as positive for
Leishmania
by direct examination and/or in vitro culture. This molecular approach showed excellent sensitivity (97%) and specificity (100%) compared to direct examination (86 and 100%, respectively) and in vitro culture (72 and 100%, respectively). Isoenzymatic and molecular typing allowed similar identification for 12 samples. Besides, PCR and subsequent sequencing of DNA products permitted the species identification of 14 samples for which parasite culture remained negative or did not allow isoenzymatic characterization, indicating the complementarity of parasitological and molecular tools.
Distribution of
Chlamydia pneumoniae
DNA in Atherosclerotic Carotid Arteries: Significance for Sampling Procedures
Authors: Cochrane Melanie , Pospischil Andreas , Walker Philip , Gibbs Harry , Timms Peter
Published: April 2003

Despite extensive efforts to confirm a direct association between
Chlamydia pneumoniae
and atherosclerosis, different laboratories continue to report a large variability in detection rates. In this study, we analyzed multiple sections from atherosclerotic carotid arteries from 10 endartectomy patients to determine the location of
C. pneumoniae
DNA and the number of sections of the plaque required for analysis to obtain a 95% confidence of detecting the bacterium. A sensitive nested PCR assay detected
C. pneumoniae
DNA in all patients at one or more locations within the plaque. On average, 42% (ranging from 5 to 91%) of the sections from any single patient had
C. pneumoniae
DNA present. A patchy distribution of
C. pneumoniae
in the atherosclerotic lesions was observed, with no area of the carotid having significantly more
C. pneumoniae
DNA present. If a single random 30-μm-thick section was tested, there was only a 35.6 to 41.6% (95% confidence interval) chance of detecting
C. pneumoniae
DNA in a patient with carotid artery disease. A minimum of 15 sections would therefore be required to obtain a 95% chance of detecting all true positives. The low concentration and patchy distribution of
C. pneumoniae
DNA in atherosclerotic plaque appear to be among the reasons for inconsistency between laboratories in the results reported.
Influence of Transferable Genetic Determinants on the Outcome of Typing Methods Commonly Used for
Enterococcus faecium
Authors: Werner Guido , Willems Rob J. L. , Hildebrandt Bianca , Klare Ingo , Witte Wolfgang
Published: April 2003

A variety of methods is used for a molecular typing of
Enterococcus
spp. and related gram-positive bacteria including macrorestriction analysis using pulsed-field gel electrophoresis (PFGE), ribotyping, rapid amplification of polymorphic DNA (RAPD), and amplified fragment length polymorphism (AFLP). To test the influence of transferable determinants on the outcome of different typing methods commonly used for enterococci, we established a homogenous strain collection of 24 transconjugants resulting from filter matings with antibiotic-resistant
Enterococcus faecium
. As expected, AFLP, RAPD, and PFGE all identified our model bacteria as strongly related. However, distinct differences in the resolving and discriminatory power of the tested methods could be clearly addressed. In PFGE, 22 of 24 transconjugants possessed less than a three-band difference to the recipient pattern and would be regarded as strongly related. Three different RAPD PCRs were tested; in two reactions, identical patterns for all transconjugants and the recipient were produced. One RAPD PCR produced an identical pattern for 18 transconjugants and the recipient and a clearly different pattern for the remaining 6 transconjugants due to a newly appearing fragment resulting from acquisition of the
tetL
gene. AFLP clusters all transconjugants into a group of major relatedness. Percent similarities were highly dependent on the method used for calculating the similarity coefficient (curve-based versus band-based similarity coefficient). Fragment patterns of digested plasmids showed the possession of nonidentical plasmids in most transconjugants. PFGE still could be recommended as the method of choice. Nevertheless, the more-modern AFLP approach produces patterns of comparable discriminatory power while possessing some advantages over PFGE (less-time-consuming internal standards). Plasmid fingerprints can be included to subdifferentiate enterococcal isolates possessing identical macrorestriction and PCR typing patterns.
Broadly Reactive and Highly Sensitive Assay for Norwalk-Like Viruses Based on Real-Time Quantitative Reverse Transcription-PCR
Authors: Kageyama Tsutomu , Kojima Shigeyuki , Shinohara Michiyo , Uchida Kazue , Fukushi Shuetsu , Hoshino Fuminori B. , Takeda Naokazu , Katayama Kazuhiko
Published: April 2003

We have developed an assay for the detection of Norwalk-like viruses (NLVs) based on reverse transcription-PCR (RT-PCR) that is highly sensitive to a broad range of NLVs. We isolated virus from 71 NLV-positive stool specimens from 37 outbreaks of nonbacterial acute gastroenteritis and sequenced the open reading frame 1 (ORF1)-ORF2 junction region, the most conserved region of the NLV genome. The data were subjected to multiple-sequence alignment analysis and similarity plot analysis. We used the most conserved sequences that react with diverse NLVs to design primers and TaqMan probes for the respective genogroups of NLV, GI and GII, for use in a real-time quantitative RT-PCR assay. Our method detected NLV in 99% (80 of 81) of the stool specimens that were positive by electron microscopy, a better detection rate than with the two available RT-PCR methods. Furthermore, our new method also detected NLV in 20 of 28 stool specimens from the same NLV-related outbreaks that were negative for virus by electron microscopy. Our new assay is free from carryover DNA contamination and detects low copy numbers of NLV RNA. It can be used as a routine assay for diagnosis as well as for elucidation of the epidemiology of NLV infections.
PCR-Based Method To Differentiate the Subspecies of the
Mycobacterium tuberculosis
Complex on the Basis of Genomic Deletions
Authors: Huard Richard C. , de Oliveira Lazzarini Luiz Claudio , Butler W. Ray , van Soolingen Dick , Ho John L.
Published: April 2003

The classical
Mycobacterium tuberculosis
complex (MtbC) subspecies include
Mycobacterium tuberculosis
,
Mycobacterium africanum
(subtypes I and II),
Mycobacterium bovis
(along with the attenuated
M. bovis
bacillus Calmette-Guérin [BCG]), and
Mycobacterium microti
; increasingly recognized MtbC groupings include
Mycobacterium bovis
subsp.
caprae
and “
Mycobacterium tuberculosis
subsp.
canettii
.” Previous investigations have documented each MtbC subspecies as a source of animal and/or human tuberculosis. However, study of these organisms is hindered by the lack of a single protocol that quickly and easily differentiates all of the MtbC groupings. Towards this end we have developed a rapid, simple, and reliable PCR-based MtbC typing method that makes use of MtbC chromosomal region-of-difference deletion loci. Here, seven primer pairs (which amplify within the loci
16S rRNA
, Rv0577, IS
1561
′, Rv1510, Rv1970, Rv3877/8, and Rv3120) were run in separate but simultaneous reactions. Each primer pair either specifically amplified a DNA fragment of a unique size or failed, depending upon the source mycobacterial DNA. The pattern of amplification products from all of the reactions, visualized by agarose gel electrophoresis, allowed immediate identification either as MtbC composed of
M. tuberculosis
(or
M. africanum
subtype II),
M. africanum
subtype I,
M. bovis
,
M. bovis
BCG,
M. caprae, M. microti
, or “
M. canettii
” or as a
Mycobacterium
other than MtbC (MOTT). This MtbC PCR typing panel provides an advanced approach to determine the subspecies of MtbC isolates and to differentiate them from clinically important MOTT species. It has proven beneficial in the management of
Mycobacterium
collections and may be applied for practical clinical and epidemiological use.
New Pathogenicity Marker Found in the Plasticity Region of theHelicobacter pyloriGenome
Authors: Santos Adriana , Queiroz Dulciene Maria Magalhães , Ménard Armelle , Marais Armelle , Rocha Gifone Aguiar , Oliveira Celso Affonso , Nogueira Ana Margarida Miguel Ferreira , Uzeda Milton , Mégraud Francis
Published: April 2003

Comparison of gastric carcinoma and gastritis isolates showed the presence of genes, probably carcinoma associated (JHP947andJHP940), that are situated in aHelicobacter pylorigenome region (45 kb in J99 and 68 kb in 26695) called the “plasticity region.” This region presents a great variability of DNA sequences. We investigated, by PCR, the presence of theJHP940andJHP947genes, as well as the presence of a third gene which seems to be associated with gastritis (HP986), onH. pyloristrains isolated from 200 Brazilian patients, 79 of whom had gastric carcinomas and 53 of whom had duodenal ulcers, to confirm this association. Gastritis isolates (n= 68) were included as a control. We also evaluated if these genes were related to the virulence-associatedcagAgenotype. The present methodology did not permit definitive conclusions to be reached regarding the association between theJHP940gene and gastric carcinoma or between theHP986gene and gastritis. However, we showed that theJHP947gene might be implicated in the development of both duodenal ulcer and gastric carcinoma. The presence of theJHP947gene was associated with thecagA-positive genotype. TheJHP947gene is a novel virulence marker candidate ofH. pylori.
Heterogeneity of RNA Polymerase Gene (
rpoB
) Sequences of
Mycobacterium gordonae
Clinical Isolates Identified with a DNA Probe Kit and by Conventional Methods
Authors: Itoh Saotomo , Kazumi Yuko , Abe Chiyoji , Takahashi Mitsuyoshi
Published: April 2003

In a previous study, we have evaluated genetic identification by using the
rpoB
gene, which was recently introduced by Kim et al. (J. Clin. Microbiol. 39:2102-2109, 2001; J. Clin. Microbiol. 37:1714-1720, 1999). In this process, we examined the
rpoB
gene heterogeneity of clinical isolates identified as
Mycobacterium gordonae
with the conventional biological and biochemical tests and/or a commercially available DNA probe kit. Sequencing of the
rpoB
gene of 34 clinical isolates revealed that
M. gordonae
clinical isolates were classified into four major clusters (A, B, C, and D). Interestingly, organisms belonging to cluster D (15 isolates) did not hybridize with
M. gordonae
ATCC 14470 and specifically possessed urease activity. Therefore, it could be considered to be a novel mycobacterium. The identification of
M. gordonae
is known to have ambiguous results sometimes. On the other hand, identification of clinical isolates seems to be inconvenient and unsuitable because of a more than 99% 16S rRNA gene similarity value between clusters. These findings suggest that the existence of
M. gordonae
-like mycobacteria that share similar biochemical and biological characteristics with the 16S rRNA gene of an
M. gordonae
type strain but less similarity at the genomic DNA level may have complicated the identification of
M. gordonae
in many laboratories. Furthermore, compared with
hsp65
PCR restriction analysis (PRA),
rpoB
PRA would have the advantage of producing no ambiguous results because of the intracluster homogeneity of the
rpoB
gene. In this case,
rpoB
would provide clearer results than
hsp65
, even if PRA analysis was used. We demonstrated that these
M. gordonae
-like mycobacteria were easily distinguished by PRA of the
rpoB
sequence. Additionally, the significance of this
M. gordonae
-like cluster may help to establish the comparison between the
M. gordonae
isolates from a clinical specimen and an infectious process in a given patient and to determine the true incidence of infection with this microorganism.
Tandem Tetramer-Based Microsatellite Fingerprinting for Typing of
Proteus mirabilis
Strains
Authors: Cieślikowski Tomasz , Gradecka Dobrosława , Mielczarek Magdalena , Kaca Wiesław
Published: April 2003

Two microsatellite tandem repeated tetramers, (GACA)
4
and (CAAT)
4
, were used for
Proteus mirabilis
strain differentiation. The microsatellite-based PCR tests were applied for the examination of interstrain diversity for 87
P
.
mirabilis
strains. Forty-six of the investigated strains were clinical isolates (5 were hospital isolates and 39 were outpatient clinic isolates); 42 strains were derived from the Kauffmann-Perch collection of laboratory strains. Fingerprinting done with the tetramers had a high discrimination ability [0.992 and 0.940 for (GACA)
4
and (CAAT)
4
, respectively]. The distributions of clinical isolates among well-defined laboratory strains, determined by numerical analysis (unweighted pair-group method with arithmetic averages; Dice similarity coefficient), proved their genetic similarity to reference strains in the Kauffmann-Perch collection. This analysis also indicated that it is possible to estimate some phenotypic properties of
P
.
mirabilis
clinical isolates solely on the basis of microsatellite fingerprinting.
Detection of Hepatitis B Virus DNA in Sera from Patients with Chronic Hepatitis B Virus Infection by DNA Microarray Method
Authors: Kawaguchi Kazunori , Kaneko Shuichi , Honda Masao , Kawai Hiroshi F. , Shirota Yukihiro , Kobayashi Kenichi
Published: April 2003

We have developed a sensitive and quantitative assay using a DNA microarray for the detection of hepatitis B virus (HBV) DNA in serum. Fluorescently labeled target cDNA prepared from cloned HBV DNA or serum HBV DNA was hybridized to capture DNA on a slide. A linear relationship was obtained between the intensities of the array spot and the amount of the cloned or serum HBV DNA, indicating the quantitative accuracy of this assay system. In addition, there was a significant correlation between the number of molecules of serum HBV DNA determined by the DNA microarray and that determined by a branched-DNA assay (
n
= 21,
r
= 0.89). Given these results, we conclude that the DNA microarray assay system may be useful as a diagnostic technique in the clinical laboratory.
Distinctiveness of
Mycobacterium tuberculosis
Genotypes from Human Immunodeficiency Virus Type 1-Seropositive and -Seronegative Patients in Lima, Peru
Authors: Ahmed Niyaz , Caviedes Luz , Alam Mahfooz , Rao K. Rajender , Sangal Vartul , Sheen Patricia , Gilman Robert H. , Hasnain Seyed E.
Published: April 2003

Genotypic analysis of
Mycobacterium tuberculosis
isolates obtained from human immunodeficiency virus type 1 (HIV-1)-seropositive (
n
= 80) and -seronegative (
n
= 25) patients from Lima, Peru, revealed two distinct genotypes correlating with the host immune status. While the level of intrastrain diversity of DNA fingerprints of HIV-seropositive isolates was less pronounced, these isolates showed many clonal groupings.
Drug-Associated Resistance Mutations in Plasma and Peripheral Blood Mononuclear Cells of Human Immunodeficiency Virus Type 1-Infected Patients for Whom Highly Active Antiretroviral Therapy Is Failing
Authors: Sarmati Loredana , Nicastri Emanuele , Uccella Ilaria , d'Ettorre Gabriella , Parisi Saverio G. , Palmisano Lucia , Galluzzo Clementina , Concia Ercole , Vullo Vincenzo , Vella Stefano , Andreoni Massimo
Published: April 2003

In 32 patients for whom highly active antiretroviral therapy was failing, a good agreement between drug resistance-associated mutations in plasma and peripheral blood mononuclear cells (PBMCs) was found (
k
= 0.85). The mutations with the lowest agreement were 20R, 63P, and 84V in the protease gene and 184V in the reverse transcriptase gene. In eight patients, primary drug resistance mutations were detected only in PBMCs.
Evaluation of a Fluorescence-Based PCR Method for Identification of Serogroup A Meningococci
Authors: Diggle M. A. , Smith K. , Girvan E. K. , Clarke S. C.
Published: April 2003

Standard and fluorescence-based PCR assays were developed for the identification of serogroup A meningococci by detection of the
mynA
gene. This assay was evaluated using bacterial cultures but provides the sensitivity required for the detection of the
mynA
gene from bodily fluids during meningococcal disease.
Prenatal Diagnosis of Congenital Human Cytomegalovirus Infection in Amniotic Fluid by Nucleic Acid Sequence-Based Amplification Assay
Authors: Revello M. Grazia , Lilleri Daniele , Zavattoni Maurizio , Furione Milena , Middeldorp Jaap , Gerna Giuseppe
Published: April 2003

Nucleic acid sequence-based amplification assays for detection of human cytomegalovirus (HCMV) immediate-early and pp67 mRNA in 65 amniotic fluid samples tested for prenatal diagnosis of congenital HCMV infection showed sensitivity, specificity, and negative and positive predictive values >90%.
Use of Equivocal Zone in Interpretation of Results of the Amplified Mycobacterium Tuberculosis Direct Test for Diagnosis of Tuberculosis
Authors: Kerleguer A. , Koeck J.-L. , Fabre M. , Gérôme P. , Teyssou R. , Hervé V.
Published: April 2003

The sensitivity and specificity of the Amplified Mycobacterium Tuberculosis Direct (AMTD) test, evaluated with 1,363 respiratory samples (128 from tuberculous patients), were 92.97 and 98.7%, respectively. When an equivocal zone (30,000 to 1,000,000 relative light units [RLU]) was used instead of a 30,000-RLU cutoff, the sensitivity and specificity of the AMTD test were 92.97 and 100%, respectively.
BIBI, a Bioinformatics Bacterial Identification Tool
Authors: Devulder G. , Perrière G. , Baty F. , Flandrois J. P.
Published: April 2003

BIBI was designed to automate DNA sequence analysis for bacterial identification in the clinical field. BIBI relies on the use of BLAST and CLUSTAL W programs applied to different subsets of sequences extracted from GenBank. These sequences are filtered and stored in a new database, which is adapted to bacterial identification.
Effect of the π-Electron Ring Current on the 1H NMR Spectra of 1,1'-Binaphthol Derivatives
Authors: Marin-Puga Gustavo , Horák Václav , Svornos Paris
Published: April 2003

High resolution 1H NMR spectra of two 1,1'-binaphthols (I, II), two 1,1'-binaphthalenediols (III, IV) and four 1,1'- binaphthalenediols acetates (IIIa - IVa) were obtained and analyzed. The effect of the ring current was evaluated by comparing the chemical shifts of the compounds, assigned through H-H COSY NMR experiments, to those of the corresponding monomers. All experimental chemicals shifts are in close agreement with the theoretical values obtained via the Bovey model for the ring current effect of a benzene moiety.
Principal Component Analysis and Target Testing of Substituent Effect Using Carbonyl Stretching Frequency and 13C NMR Chemical Shift Data Matrices
Authors: Fadhil Ghazwan F.
Published: April 2003

Principal component analysis technique has been applied to analyse the substituent effect on carbonyl stretching frequency and 13C NMR chemical shifts. The general formula for the investigated molecules is X-G-Y, where X represents the set of substituent (OMe, Me, F, Cl, Br, CN and NO2), Y is the probe site and G is benzene ring. According to the indicator function two significant components are responsible for the substituent effect. The validity of several substituent parameters have been investigated by target testing technique. Invariabily substituent parameters derived by iterative multiple linear regression analysis viz. σR (Reynolds), σF (Reynolds) and σR (NMR) have lower SPOIL values when compared with other substituent parameters. Model designing f IR and 13C NMR data matrices separately have shown that models which incorporate σR (Reynolds) and σF (Reynolds) or σR (NMR) and a substituent field parameters have the lowest root mean square error RMSE. Substituent effect on several properties are better correlated with Reynolds' σR and σF than with other commonly used substituent parameter(s). The orthogonality of substituent parameters used in the model can be achieved by including the methyl group in the substituent set.
Colour-Monitored Solid-Phase Multiple Peptide Synthesis under Low-Pressure Continuous-Flow Conditions. Synthesis of Medium-Size Peptides: The Propart of Human Procathepsin D and the Growth-Hormone Releasing Factor
Authors: Vágner Josef , Krchňák Viktor , Pícha Josef , Píchová Drahomíra , Fusek Martin
Published: April 2003

The synthesis of two medium-size peptide amides, the propart of human procathepsin D (1-45) and the bovine growth-hormon releasing factor (1-44) has been accomplished by the solid-phase multiple peptide synthesis under low-pressure continuous-flow conditions on standard methylbenzhydrylamine polystyrene-based resin in concatenated flow reactors with adjustable volume. The completeness of acylation of resin-bound free amino groups was monitored by the acid-base indicator bromophenol blue. The efficiency of the coupling reaction was increased by exposure to elevated temperature in an ultrasonic bath. Crude peptides were purified on a mass-overloaded Vydac C18 reversed-phase semipreparative HPLC column. The synthetic propart of human procathepsin D (1-45) exhibited inhibition activity to bovine cathepsin D and four other aspartic proteases. Significantly increased plasma concentration in gilts was determined after application of synthetic bovine growth-hormone releasing factor (1-44).
Purification of Glycerol Kinase by "Dye-Ligand" Chromatography and Hydrophobic Interaction Chromatography on Bead-Cellulose Derivatives
Authors: Žúbor Vladimír , Breier Albert , Horváthová Marta , Hagarová Dagmar , Gemeiner Peter , Mislovičová Danica
Published: April 2003

The crude extract of cytosole enzymes was obtained from homogenized cells of Saccharomyces cerevisiae by partition. The enzyme was then isolated from the lower aqueous phase displaying higher glycerol kinase activity by dye-ligand chromatography on Cibacron Blue (CB) or Remazol Brilliant Blue R (RB)-derivatized bead-cellulose, ATP being the eluent. The specific activity of glycerol kinase rised more than 10 and 7-times after affinity dye-ligand chromatography and hydrophobic interaction chromatography, respectively. Glycerol kinase obtained by the latter method was purified by CB-bead cellulose. The final preparation maintained its enzymic activity without noticeable losses during a long-term storage at 4 °C in dark.
Preparation of Some 6-Substituted N-Pyrazinyl-2-pyrazinecarboxamides
Authors: Dlabal Karel , Doležal Martin , Macháček Miloš
Published: April 2003

In connection with our research into antimycobacterial pyrazine derivatives we were interested in binuclear analogues with -CONH- bridge. The prepared compounds were tested in the form of dimethylsulfoxide solutions for their activity against Mycobacterium tuberculosis, M. kansasii, M. avium and M. fortuitum on a liquid Sula medium (pH 5.4).
On the Electrochemical, Spectral and Photochemical Properties of Cyano-Nitrosyl Complexes. A Comparison between Iron and Ruthenium Analogues
Authors: Fiedler Jan
Published: April 2003

First order rate constant of cyanide splitting from one-electron product of the nitropruside ion reduction was determined using a.c. polarography (k = 350 s-1 in CH3CN). [Ru(CN)5(NO)]2- ion is reduced reversibly (E1/2 = -1.04 V, k0 = 4.86 . 10-3 m s -1 in CH3CN; E1/2 = -0.39 V in H2O) with one electron. IR and EPR study indicates dimerization of the reduction product in solution but no cyanide splitting from electrogenerated [Ru(CN)5(NO)]3- was detected. Further reduction of [Ru(CN)5(NO)]3-, with consumption of protons occurs in aqueous media. Efficient photochemical reactions of [Fe(CN)4(NO)]2- with O2, KMNO4 and pyridine take place when the complex is excited at the metal-to-nitrosyl charge transfer band.
Kinetics and Mechanism of Oxidation of Selenium(IV) by Permanganate Ion in Aqueous Perchlorate Solutions
Authors: Hassan Refat M. , El-Gaiar Sahr A. , El-Summan Abd El-Hady M.
Published: April 2003

The kinetics of permanganate oxidation of selenium dioxide in perchloric acid solutions at a constant ionic strength of 2.0 mol dm-3 has been investigated spectrophotometrically. A first-order reaction in [MnO4-] and fractional order with respect to selenium(IV) were observed. The reaction rate was found to be pH-independent at lower acid concentrations ([H+] < 0.5 mol dm-3) and was acid-catalyzed beyond this range. Addition of Mn2+ and F- ions leads to the prediction that MnO4- is the sole reactive species in the oxidation process. A tentative reaction mechanism consistent with the reaction kinetics has been proposed.
Analogs of Arginine-Vasopressin Substituted in Position 2 with L-4-Cl-Phenylalanine or D-Phenylglycine
Authors: Czaja Malgorzata , Konieczna Ewa , Lammek Bernard , Slaninová Jiřina , Barth Tomislav
Published: April 2003

Eight new compounds were designed, synthesized and bioassayed as a part of our studies on the structure-activity relationship of arginine-vasopresine (AVP) analogs. Tyrosine in position 2 of AVP, dAVP, [Cpp1]AVP and [Cpp1,Val4]AVP was substituted by L-4-chlorophenylalanine (4-Cl-Phe) or D-phenylglycine [D-Gly(Phe)] and the effect of these changes on agonistic/antagonistic activity in uterotonic and pressor test was followed. All but one of these analogs were found inhibitory in uterotonic test, however in most cases their potency was fairly low. As to the pressor activity the agonistic potency of the 4-Cl-Phe substituted analogs was essentially the same as having 4-F-Phe in position 2. As far as the potency of antagonists is concerned, 4-Cl-Phe peptides showed significantly higher potency than the 4-F-Phe analogs. All compounds containing D-phenylglycine in position 2 were inactive in the pressor test.
Biologically Important Physicochemical Properties of Kojic Acid Derivatives
Authors: Baláž Štefan , Šturdík Ernest , Ujhelyová Regina , Valigura Dušan , Uher Michal , Veverka Miroslav , Konečný Václav , Adamcová Jana , Michalík Peter , Brtko Július
Published: April 2003

Physicochemical properties (hydrophobicity, acidity, metal complexing ability), which are expected to play a role in biological activity of kojic acid derivatives, were determined for 35 compounds. The structure-property relationship were analysed with the aim to predict the properties of new derivatives and to obtain the data for formulation of quantitative structure-time-activity relationships. Linear correlations were found between hydrophobicity expressed as decadic logarithm of the 1-octanol/buffer partition coefficient and the sum of fragment constants and correlation factors according to Leo and Hansch as well as between acidity and a set of Hammett constants of the varying substituents.
Nucleophilic Addition in Transition Metal, Pseudohalide-4-nitropyrazole Systems
Authors: Hvastijová Mária , Kohout Jiří , Skirl Renate
Published: April 2003

The possibility of nucleophilic addition of 4-nitropyrazole (4-NO2-pz) to a pseudohalide group present in the coordination sphere of a central atom was investigated. Ten products were isolated from M(II)-X--4-nitropyrazole systems with M = Cu, Ni or Co and X = NCO, N(CN)2 or C(CN)3, and investigated by infrared and electronic spectroscopy. Four of these compounds were pseudohalide complexes, two were complexes with anionic chelate ligands formed by nucleophilic addition, and the remaining products were mixtures of pseudohalide and chelate complexes. The [Cu(NCO)2(4-NO2-pz)2] complex is rhombic octahedral or five-coordinate, the [Cu(NCO)2(4-NO2-pz)] complex is five-coordinate. The remaining compounds possess octahedral or pseudooctahedral structures which involve pseudohalide bridging in the [MX2(4-NO2-pz)2] type complexes, or bridging via free carbamoyl oxygens or cyanide nitrogens in the [M(4-NO2-pz.X)2] type complexes.
Sigmatropic Isomerization of Tetraphenylcyclopentadienes: Reaction Mechanism and Quantum Chemical Treatment
Authors: Šebek Pavel , Sedmera Petr , Böhm Stanislav , Kuthan Josef
Published: April 2003

Thermal isomerization of 2,3,5,5-tetraphenylcyclopenta-1,3-diene (Ia) or 1,2,4,5-tetraphenylcyclopenta-1,3-diene (IIa) in melts lead to identical equilibrium mixtures of hydrocarbon IIa with prevailing 1,2,3,4-tetraphenylcyclopenta-1,3-diene (IIIa). The isomerization of bis-tert-butyl cyclopentadienes Ib or Ic produces an equilibrium mixture with preponderant 1,2,3,4-tetrasubstituted cyclopentadienes IIIb, IIIc besides minority isomers IIb, IIc. On the contrary, the 1,2,4,5-tetrasubstituted phenanthrene hydrocarbon IXa having forced coplanarity of both benzene rings only partially isomerizes to IXb. Equilibrium constants of the isomerization IIa → IIIa in diphenyl ether at 323 to 433 K were measured (K = 5.8 -2.3). Relative stability of hydrocarbons Ia, IIa, IIIa and VIIa is interpreted on the basis of quantum chemical AM1 calculations. The time course of isomerization of the hydrocarbon IIc allowed us to propose two reaction mechanisms based on the [1,3]- and [1,5]-sigmatropic steps. The preparation of 2,3,5,5-tetrasubstituted cyclopentadienes Ia - Ic by dehydration of cis-1,2-diols IVa - IVc is described.
Dissociation of Hydroxamic Acids: Solvent Effects
Authors: Exner Otto , Hradil Martin , Mollin Jiří
Published: April 2003

The dissociation constants of benzohydroxamic, 4-chlorobenzohydroxamic, and 4-nitrobenzohydroxamic acids, and their N-methyl and O-methyl derivatives, were measured spectrophotometrically or potentiometrically in mixtures of 2-propanol and water. The results were extrapolated to zero ionic strength. The ratio of dissociation constants of the N-methyl and O-methyl derivatives can be taken to represent - with some approximation - the ratio of NH and OH acidities of the parent acid. This ratio increases with substitution by electron-attracting substituents, and decreases with solvent permittivity: some irregularities might be attributable to the effects of mixed solvents, It follows that 4-nitrobenzohydroxamic acid behaves essentially as N-acid in all solvents, 4-chlorobenzohydroxamic acid only in 90% 2-propanol or 80% methyl cellosolve. In benzohydroxamic acid the NH and OH acidities are comparable, the latter prevails slightly in water, the former in less polar solvents. Some apparent discrepancies in the literature can be explained in the same terms, only a few results have not yet been explained.
Study of Cyclization of 1-Benzoyl-3-methyl-3-(2-methoxycarbonylphenyl)thiourea to 1-Methyl-2-thioxo-4-quinazolone
Authors: Kaválek Jaromír , Macháček Vladimír , Sedlák Miloš , Štěrba Vojeslav
Published: April 2003

The reaction mechanism of the title reaction was proposed on the bases of the kinetic study. The reaction takes place in two stages considerably differing in rates. In the first, faster stage, the anion of initial substance cyclizes to 1-methyl-3-benzoyl-2-thioxo-4-quinazolone. The reaction is reversible, the concentration of 1-methyl-3-benzoyl-2-thioxo-4-quinazolone decreases with increasing concentration of methanolate. In the second stage, the benzoyl group rearrangement in the given substance from nitrogen to sulfur and subsequent methanolysis to 1-methyl-2-thioxo-4-quinazolone take place. The rate-determining step is the methanolysis for [CH3O(-)] < 4 . 10-3 mol l-1 and the benzoyl group rearrangement for higher methanolate concentrations.
New Heterocyclo-Substituted Pyrazolo[3,4-b]pyridine Derivatives
Authors: Abdel Hafez Ali A. , Awad Ibrahim M. A. , Ahmed Raga A.
Published: April 2003

In this investigation and in continuance with our previous work in the synthesis of some heterocyclic compounds fused with pyridine moiety, we used 3-amino-4,6-diphenyl-1H-pyrazolo[3,4-b]pyridine (II) as starting material to synthesize many heterocyclic compounds containing pyrazolopyridine moiety.
The Aerobic Riboflavin-Sensitized Photodecomposition of Tryptophan, Tryptamine and Indole Acetic Acid. Ground-State and Photopromoted Flavin-Indole Interactions
Authors: Martínez Gabriela , Zimerman Oscar E. , García Norman A.
Published: April 2003

The interaction between riboflavin (RF) and the indole derivatives tryptophan, tryptamine and indole-3-acetic acid at visible light irradiation was studied in water and water/ethanol mixed solvent. Besides a dark indole-RF association, important only at indole concentration higher than 10-3 mol dm-3, a complex picture of competitive reactions operate. Triplet excited RF is quenched by the indoles in concentrations ca 10-4 mol dm-3 (rate constants of the order of 109 mol-1 dm3 s -1) and by dissolved oxygen. Both, singlet molecular oxygen and superoxide anion (in a further reaction step) are produced. As a consequence the rate of indol photodecomposition decreases in order: indole-3-acetic acid > tryptophan >> tryptamine, and the rate of RF autofading suffers an important delay compared with that in the absence of indoles.
Synthesis and Biological Effects of N-(2-Phosphonomethoxyethyl) Derivatives of Deazapurine Bases
Authors: Dvořáková Hana , Holý Antonín
Published: April 2003

Analogs of antiviral 9-(2-phosphonomethoxyethyl)adenine (PMEA,II), containing modified purine bases 1-deazaadenine (VII, 3-deazapurine (XI), 7-deaza-7-cyanoadenine (XIIIb) and 3-deazaguanine (XXIb) were prepared by alkylation of the heterocyclic bases with bis(2-propyl) 2-chloroethoxymethylphosphonate (V) in dimethylformamide in the presence of sodium hydride or cesium carbonate. The obtained protected derivatives were deblocked with bromotrimethylsilane to give the phosphonic acids. 3-DeazaPMEG (XXIb) is active against DNA viruses and exhibits a marked cytostatic effect against L-1210 leukemia.
Some New Derivatives of 2-Pentenedioic Acid
Authors: Tolman Vladimír , Sedmera Petr
Published: April 2003

Michael addition of N-acylaminomalonates to propynoic esters led to the (E)-4-acylamino)-4-carboxy-2-pentenedioic triesters IIa - IIf. On deprotection and decarboxylation, these compounds afforded 2-(N-acylamino)-2-pentenedioic acid derivatives IIIa - IIIc. Dimethyl (E)-4-diazo-2-pentenedioate (IV) was prepared by direct transfer of the diazo group. On treatment of IV with 4-toluenesulfonic acid, 2-(4-toluenesulfonyloxy)-2-pentenedioate (V) was formed. Iodination of (E)-2-pentenedioic acid led directly to the 2,4-diododerivative VII. From dimethyl (E)-4-oxo-2-pentenedioate the oximino ester VIIIa and the free oximino acid VIIIb were prepared.
The Effect of Lithium Alkoxides on Deprotonizations by Superbases Made from Butyllithium and Potassium tert-Pentoxide
Authors: Lochmann Lubomír , Jakubův Hana , Brandsma Lambert
Published: April 2003

The presence or absence of lithium tert-pentoxide (t-PeOLi) in Superbases, prepared from butyllithium (BuLi) and potasium tert-pentoxide (t-PeOK), affects the metallation rate of toluene only slightly, the rate factors being between 1.0 and 0.3. Thus, lithium alkoxide is not essential for the high reactivity of Superbases. However, the ring-to-side chain metallation ratio is increased in the presence of t-PeOLi. On the other hand, an excess of t-PeOK (molar ratio t-PeOK/BuLi ≥ 3)considerably increases in the rate and yield of the side chain methallation of toluene and suppresses its ring mrtallation. In this way, alkoxides enable some control on regioselectivity in Superbase reactions.
Novel Dehydrogenation of 2,5-Diaryl Substituted ∆2-Oxazolines to Oxazoles
Authors: Klein Robert F. X. , Horák Václav , Baker Godfrey A. S.
Published: April 2003

The dehydrogenation of various 2,5-diaryl substituted ∆2-oxazolines with either Br2/LiBr/CaCO3 (molar ratio 1.05 : 2 : 3) or CuBr2/LiBr/CaCO3 (molar ratio 2 : 1 : 3) in refluxing o-dichlorobenzene gives the corresponding oxazole up to 87% yield. Free radical benzylic bromination followed by dehydrobromination is the expected dehydrogenation mechanism. The successful application of the reagent combination for this transformation is in contrast to standard dehydrogenation reagents, including N-bromosuccinimide, 2,3-dichloro-5,6-dicyano-1,4-benzoquinone, chloranil, NiO2 and active γ-MnO2.
The Behaviour of Some Long-Chain 3-Substituted Furans and Thiophenes under Electron Impact
Authors: Shabana Rashad , Atta Sanaa M. S.
Published: April 2003

The behaviour of 24 long-chain 3-substituted furans (I, II) and thiophenes (III, IV) under electron impact was studied. Different fragmentation pathways were outlined.
Preconcentration of Uranium(VI) on Modified and Unmodified Amberlite XAD 4 Sorbent
Authors: Vácha Jan , Sommer Lumír
Published: April 2003

The sorption of uranyl ions on columns with the macrophorus hydrophobic sorbent Amberlite XAD 4 modified with 1-(2-pyridylazo)-2-naphthol and sodium diethyldithiocarbamate was examined. Following elution of the uranyl ion with HNO3 (2 - 4 mol l-1) or of the diethyldithiocarbamate UO22+-chelate with a methanolic solution of HCl (0.1 mol l-1), uranium was determined spectrophotometrically with 4-(2-pyridylazo)resorcinol or with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. The preconcentration of uranium on Amberlite XAD 4 type sorbents is convenient for its spectrophotometric determination in waters.
Heats of Decomposition and Equilibrium Dissociation Pressures of the Magnesian and Calcareous Compounds in Desulfurization Technologies
Authors: Hartman Miloslav , Trnka Otakar , Veselý Václav
Published: April 2003

In processes for flue gas cleanup, several magnesian and calcareous compounds occur either as parent sorbent materials or as a reaction products. very simple predictive expressions are proposed for estimating the decomposition heats and dissociation pressures of hydroxide, carbonate, sulfite and sulfate of magnesium and calcium at different temperatures. The developed relationships are based on the thermochemical data and experimental results taken from the literature.
Synthesis of Luminophores Based on Thiazole Derivatives of PBD
Authors: Lhoták Pavel , Kurfürst Antonín
Published: April 2003

Organic luminophore 2-(biphenyl-4-yl)-5-phenyl-1,3,4-oxadiazole (PBD, III) was converted by series of reaction into thioamide VIII which cyclized with substituted bromoacetylarenes X to give the bifluorophore system XI. The thiazole analog XIII was obtained by analogous reaction of bromoacetyl derivative V with thiobenzamide. All the thus-prepared compounds exhibit pronounced fluorescence in solution as well as in the crystalline state.
Synthesis and Some Reactions of Thieno[2,3-d]pyrimidines and S-Substituted Mercaptopyridines
Authors: Abdel Hafez Ali A. , Ahmed Raga A. , Geies Ahmed A. , El-Kashef Hussein S.
Published: April 2003

Ethyl 3-cyano-4,6-diphenyl-2-pyridylthioacetate (II) yielded with hydrazine hydrate hydrazides III, IV that both proved to be versatile compounds for the synthesis of new heterocyclic derivatives. Thus the thieno[2,3-bpyridine derivatives Xa - Xd and XIIa - XIId were obtained.
Polarographic and Voltammetric Determination of 1-(2'-Nitrophenyl)-3,3-dimethyltriazene
Authors: Barek Jiří , Dřevínková Dana , Zima Jiří
Published: April 2003

The polarographic behaviour of 1-(2'-nitrophenyl)-3,3-dimethyltriazene in mixed aqueous-methanolic solvent was investigated by tast polarography, differential pulse polarography, and fast scan differential pulse voltammetry at a hanging mercury drop electrode. A mechanism is suggested for the reduction of the compound investigated. The optimum conditions were found for the determination of this analyte by tast polarography over the concentration region of 100 to 2 μmol l-1 and by differential pulse polarography or fast scan differential pulse voltammetry at a hanging mercury drop electrode over the region of 100 to 0.2 μmol l-1. Additional sensitivity increase in the last-mentioned technique was achieved by adsorptive accumulation of analyte on the hanging mercury drop surface, owing to which the concentration region was depressed to 0.1 - 0.02 μmol l-1.
Correlation of Density of Aqueous Solutions of NaOH, KOH, Na2CO3, and K2CO3
Authors: Palatý Zdeněk
Published: April 2003

The paper deals with correlation of density of aqueous solutions of NaOH, KOH, Na2CO3, and K2CO3 using an equation based on the additivity of molar volumes of components, the components being water and so-called basic electrolyte solution with precisely defined and measurable properties. The procedure mentioned has been tested at 20 °C using literature data. The procedure has been shown to give very precise results.
Eleven-Vertex Polyhedral Dicarbaplatinaborane Chemistry. Aspects of the Chemistry of Some closo-Structured {1,2,3-PtC2B8} Species and Some Related Compounds
Authors: Kennedy John D. , Štíbr Bohumil , Jelínek Tomáš , Fontaine Xavier L. R. , Thornton-Pett Mark
Published: April 2003

The reaction of the ten-vertex nido anions [6,9-C2B8H10]2-, [6-Me-6,9-C2B8H9]2- and [6-Ph-6,9-C2B8H9]2- with [cis-PtCl2(PMe2Ph)2] in CH2Cl2 yields the yellow crystalline closo-structured eleven-vertex compounds [2-X-1,1-(PMe2Ph)2-1,2,3-PtC2B8H9], where X = H (compound 1), Me (compound 2), or Ph (compound 3) in yields of 58 88%. These compounds have been characterized by multielement NMR spectroscopy and, in the case of compounds 1 and 2, by single-crystal X-ray diffraction analysis. Crystals of compound 1 were monoclinic, space group P21/n, with a = 947.6(1), b = 1 547.7(3), c = 1 804.0(3) pm, β = 104.78(1)°, and Z = 4, solved and refined to R (Rw) = 0.0216 (0.0234) with 4 200 unique reflections I > 2.0 σ(I). Crystals of compound 2 were monoclinic, space group I2/a (= C2/c), with a = 1 824.8(2), b = 1 016.8(2), c = 1 328.2(3) pm, β = 101.48(2)°, and Z = 4, solved and refined to R (Rw) = 0.0442 (0.0474) with 2 057 unique reflections I > 2.0 σ(I). The NMR and X-ray results reveal that the closed eleven-vertex compounds [2-X-1,1-(PR3)2-1,2,3-PtC2B8H9] exhibit a previously unsuspected but very free contrarotational fluxionality within the constrains of their η6-carborane-to-metal bonding that is accompanied by a marked flexing of the η6-{C2B8H9X} moiety between nido and arachno ten-vertex geometries and electronic characteristics. The structural and bonding implications are discussed and elucidated specifically with reference to the NMR and geometrical charcteristics of [closo-2,3- C2B9H11], [arachno-6,9- C2B8H14] and the [nido-6-X-6,9- C2B8H9]2- anions, together with other pertinent species such as [μ-6,9-(SnMe2)-nido-6,9-C2B8H10] and more generally with reference to other eleven-vertex metallaheteroborano species. The general behaviour patterns thus established are summarized.