bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of potassium ion as the endothelium‐derived hyperpolarizing factor (EDHF) in the bovine coronary artery
Authors: Nelli Silvia , Wilson William S , Laidlaw Hilary , Llano Andrea , Middleton Susan , Price Andrew G , Martin William 
Published: July 2003

This study explored the role of the potassium ion in endothelium‐derived hyperpolarizing factor (EDHF)‐mediated vasodilatation in the bovine coronary artery.
Bradykinin‐induced, EDHF‐mediated vasodilatation was blocked by the Na+–K+ ATPase inhibitor, ouabain (1 μM), in a time‐dependent manner, with maximal blockade seen after 90 min. In contrast, the KIR channel inhibitor, Ba2+ (30 μM), had no effect.
When the potassium content of the bathing solution was increased in a single step from 5.9 to 7–19 mM, powerful vasodilatation (max. 75.9±3.6%) was observed. Vasodilatation was transient and, consequently, cumulative addition of potassium produced little vasodilatation, with vasoconstriction predominating at the higher concentrations.
The magnitude of potassium‐induced vasodilatation was similar in endothelium‐containing and endothelium‐denuded rings, and was unaffected by Ba2+ (30 μM), but abolished by ouabain (1 μM).
Ouabain (1 μM, 90 min) powerfully blocked bradykinin‐induced, nitric oxide‐mediated vasodilatation as well as that induced by the nitrovasodilator, glyceryl trinitrate, but that induced by the KATP channel opener, levcromakalim, was hardly affected.
Thus, activation of Na+–K+ ATPase is likely to be involved in the vasodilator responses of the bovine coronary artery to both nitric oxide and EDHF. These findings, together with the ability of potassium to induce powerful, ouabain‐ but not Ba2+‐sensitive, endothelium‐independent vasodilatation, are consistent with this ion contributing to the EDHF response in this tissue.

British Journal of Pharmacology (2003) 139, 982–988. doi:10.1038/sj.bjp.0705329
Blockade of HERG potassium currents by fluvoxamine: incomplete attenuation by S6 mutations at F656 or Y652
Authors: Milnes James T , Crociani Olivia , Arcangeli Annarosa , Hancox Jules C , Witchel Harry J 
Published: July 2003

Pharmacological blockade of the Human ether‐a‐go‐go related gene (HERG) potassium channel is commonly linked with acquired long QT syndrome and associated proarrhythmia. The objectives of this study were (i) to identify and characterise any inhibitory action on HERG of the selective‐serotonin re‐uptake inhibitor fluvoxamine, (ii) to then determine whether fluvoxamine shared the consensus molecular determinants of HERG blockade of those drugs so far tested.
Heterologous HERG potassium current (IHERG) was measured at 37°C, using the whole‐cell patch‐clamp technique, from a mammalian cell line (Human embryonic kidney 293) expressing HERG channels. IHERG tails, following repolarisation from +20 to −40 mV, were blocked by fluvoxamine with an IC50 of 3.8 μM.
Blockade of wild‐type HERG was of extremely rapid onset (within 10 ms) and showed voltage dependence, with fluvoxamine also inducing a leftward shift in voltage‐dependent activation of IHERG. Characteristics of block were consistent with a component of closed channel (or extremely rapidly developing open channel) blockade and dependence on open and inactivated channel states. The attenuated‐inactivation mutation S631A partially reduced the blocking effect of fluvoxamine.
The S6 mutations, Y652A and F656A, and the pore helix mutant S631A only partially attenuated blockade by fluvoxamine at concentrations causing profound blockade of wild‐type HERG.
All HERG‐blocking pharmaceuticals studied to date have been shown to block F656 mutant channels with over 100‐fold reduced potency compared to their blockade of the wild‐type channel. Fluvoxamine is therefore quite distinct in this regard from previously studied agents.

British Journal of Pharmacology (2003) 139, 887–898. doi:10.1038/sj.bjp.0705335
Near‐field scanning optical microscopy probes: a comparison of pulled and double‐etched bent NSOM probes for fluorescence imaging of biological samples
Authors: Burgos P. , Lu Z. , Ianoul A. , Hnatovsky C. , Viriot M.‐L. , Johnston L. J. , Taylor R. S. 
Published: July 2003

SummaryBent near‐field optical probes for biological applications have been fabricated using a combination of a two‐step chemical etching method and focused ion beam milling to create a well‐defined aperture. The transmission efficiencies have been evaluated as a function of laser wavelength (λ) and aperture size (D) for both large and small core fibres. The probe transmission behaviour follows a (D/λ)3 relationship. The double‐etched probes are compared to pulled probes fabricated from highly GeO2‐doped dispersion compensating fibre and a standard single‐mode optical fibre. The transmission efficiencies of both types of pulled probes are approximately two orders of magnitude lower than double‐etched probes with similar aperture sizes. To demonstrate the utility of the various probes, their imaging performance has been evaluated for samples of polymer beads and phase‐separated phospholipid monolayers of dipalmitoylphosphatidylcholine or cholesterol/phosphatidylcholine/sphingomyelin mixtures. Both pulled and double‐etched probes are suitable for fluorescence imaging of polymer spheres. However, pulled probes are rapidly damaged at the higher input laser intensities required for fluorescence imaging of monolayer samples doped with < 1% of a fluorescent dye‐labelled lipid. The images obtained with the double‐etched probes show excellent spatial resolution and signal/noise, illustrating the potential of such probes for imaging of biological samples.
Polarization artefacts of an FTIR microscope and the consequences for intensity measurements on anisotropic materials
Authors: Coats A. M. , Hukins D. W. L. , Imrie C. T. , Aspden R. M. 
Published: July 2003

SummaryThe infrared beam on both the main Nicolet Nexus bench and the attached Spectra‐Tech Continuum microscope has been shown to be partially polarized. The degree of polarization is ≈ 30%. Although the state of polarization of the infrared beam is of no consequence when measuring the spectra of isotropic materials (gases, liquids), there is a potential problem when considering the spectra of anisotropic materials. Single band intensities are particularly prone to error as small changes in sample thickness or orientation directly affect the intensity. Thickness effects can be overcome by measuring intensity ratios. However, because of the partially polarized nature of the infrared beam, even intensity ratios, illustrated here by the ratio amide I/II of collagen fibres, vary with sample orientation. If overlooked, this effect can be problematic when measuring infrared spectra with an FTIR microscope from samples that are anisotropic or contain anisotropic domains, even though they may appear isotropic on a macroscopic scale. Because dichroic ratios remain unaffected, the intensity ratio from two bands with different transition moments may be used to give a strong indication of the orientation of the sample. This work is illustrated by reference to the FTIR spectra of orientated polyethylene, collagen tape and human trabecular bone.
Variable‐angle total internal reflection fluorescence microscopy (VA‐TIRFM): realization and application of a compact illumination device
Authors: Stock K. , Sailer R. , Strauss W. S. L. , Lyttek M. , Steiner R. , Schneckenburger H. 
Published: July 2003

SummaryA novel compact illumination device in variable‐angle total internal reflection fluorescence microscopy (VA‐TIRFM) is described. This device replaces the standard condensor of an upright microscope. Light from different laser sources is delivered via a monomode fibre and focused onto identical parts of a sample under variable angles of total internal reflection. Thus, fluorophores in close proximity to a cell–substrate interface are excited by an evanescent wave with variable penetration depth, and localized with high (nanometre) axial resolution. In addition to quantitative measurements in solution, fluorescence markers of the cytoplasm and the plasma membrane, i.e. calcein and laurdan, were examined using cultivated endothelial cells. Distances between the glass substrate and the plasma membrane were determined using the mathematical algorithm of a four‐layer model, as well as a Gaussian‐shaped intensity profile of the illumination spot on the samples. Distances between 0 and 30 nm in focal contacts and between 100 and 300 nm in other parts of the cell were thus determined. In addition to measurements of cell–substrate topology, the illumination device appears appropriate for numerous applications in which high axial resolution is required, e.g. experiments on endocytosis or exocytosis, as well as measurements of ion concentrations proximal to the plasma membrane. The compact illumination device is also suitable for combining TIRFM with further innovative techniques, e.g. time‐resolved fluorescence spectroscopy, fluorescence lifetime imaging (FLIM) or fluorescence resonance energy transfer (FRET).
Dermatophytes isolated from domestic animals in Iran
Authors: Khosravi A. R. , Mahmoudi M. 
Published: July 2003

SummaryBetween 1994 and 1998, a total of 790 feather, hair and skin specimens from a variety of animals with suspected dermatophytoses were studied, of which 248 (31.4%) yielded dermatophytes. The most frequent dermatophytes isolated were Microsporum canis (38.3%), Trichophyton verrucosum (31.8%), T. mentagrophytes (13.3%) and M. gypseum (7.7%). There was a significantly higher proportion of positive cultures from cats (54.8%) than dogs (8.2%), and M. canis was the most common species isolated (87.2 and 50% respectively). Trichophyton verrucosum was the most frequent causative agent of dermatophytoses in ruminants, M. equinum in horses, M. gypseum in rabbits, M. gallinae in chickens and T. mentagrophytes in pet squirrels.
Use of Punica granatum as an antifungal agent against candidosis associated with denture stomatitis
Authors: César de Souza Vasconcelos Laurylene , Sampaio Maria Carméli Correia , Sampaio Fábio Correia , Higino Jane Sheila 
Published: July 2003

SummaryThe aim of this study was to evaluate the use of a gel containing the extract of Punica granatum as an antifungal agent against candidosis associated with denture stomatitis. Sixty patients with denture stomatitis confirmed by clinical and mycologic examination were selected. The patients were randomly allocated in two groups of 30 individuals each according to the medication prescribed: group A used miconazole (Daktarin® gel oral) and group B used a gel of P. granatum Linné (pomegranate). Both groups used the medicines three times per day for 15 days. Forty‐eight hours after finishing the treatment the patients were re‐examined and a second set of samples was collected for mycologic examination. The medicines were evaluated for their clinical response and negativity for Candida. The clinical results showed a satisfactory and regular response in 27 and 21 subjects of groups A and B, respectively. Negativity of yeasts was observed in 25 subjects of group A and 23 of group B. It can be concluded that the extract of P. granatum may be used as a topical antifungal agent for the treatment of candidosis associated with denture stomatitis.
Biofilm-Specific Cross-Species Induction of Antimicrobial Compounds in Bacilli
Authors: Yan Liming , Boyd Kenneth G. , Adams David R. , Burgess J. Grant 
Published: July 2003

ABSTRACT

An air-membrane surface (AMS) bioreactor was designed to allow bacteria to grow attached to a surface as a biofilm in contact with air. When
Bacillus licheniformis
strain EI-34-6, isolated from the surface of a marine alga, was grown in this reactor, cells produced antimicrobial compounds which they did not produce when they were grown in shake flask cultures. An unidentified red pigment was also produced by surface-grown cells but not by planktonically grown cells. Glycerol and ferric iron were important for the production of antimicrobial compounds and the red pigment. Release of these secondary metabolites was not due to the onset of sporulation. Cell-free spent medium recovered from beneath the reactor membrane could induce production of antimicrobial compounds and red pigment in shake flask cultures. Neither glycerol nor ferric iron was required for production of these inducer compounds. Spent medium from beneath the membrane of an AMS bioreactor culture of
Bacillus subtilis
strain DSM10
T
and
Bacillus pumilus
strain EI-25-8 could also induce production of antimicrobial compounds and a red pigment in
B. licheniformis
isolate EI-34-6 grown in shake flask cultures; however, the corresponding spent medium from shake flask cultures of DSM10
T
and EI-25-8 could not. These results suggest that there is a biofilm-specific cross-species signaling system which can induce planktonically grown cells to behave as if they were in a biofilm by regulating the expression of pigments and antimicrobial compounds.
Metabolic Engineering of the Carotenoid Biosynthetic Pathway in the Yeast
Xanthophyllomyces dendrorhous
(
Phaffia rhodozyma
)
Authors: Verdoes Jan C. , Sandmann Gerhard , Visser Hans , Diaz Maria , van Mossel Minca , van Ooyen Albert J. J. 
Published: July 2003

ABSTRACT

The
crtYB
locus was used as an integrative platform for the construction of specific carotenoid biosynthetic mutants in the astaxanthin-producing yeast
Xanthophyllomyces dendrorhous.
The
crtYB
gene of
X. dendrorhous
, encoding a chimeric carotenoid biosynthetic enzyme, could be inactivated by both single and double crossover events, resulting in non-carotenoid-producing transformants. In addition, the
crtYB
gene, linked to either its homologous or a glyceraldehyde-3-phosphate dehydrogenase promoter, was overexpressed in the wild type and a β-carotene-accumulating mutant of
X. dendrorhous.
In several transformants containing multiple copies of the
crtYB
gene, the total carotenoid content was higher than in the control strain. This increase was mainly due to an increase of the β-carotene and echinone content, whereas the total content of astaxanthin was unaffected or even lower. Overexpression of the phytoene synthase-encoding gene (
crtI
) had a large impact on the ratio between mono- and bicyclic carotenoids. Furthermore, we showed that in metabolic engineered
X. dendrorhous
strains, the competition between the enzymes phytoene desaturase and lycopene cyclase for lycopene governs the metabolic flux either via β-carotene to astaxanthin or via 3,4-didehydrolycopene to 3-hydroxy-3′-4′-didehydro-β-ψ-caroten-4-one (HDCO). The monocylic carotenoid torulene and HDCO, normally produced as minority carotenoids, were the main carotenoids produced in these strains.
Prevalence of Pandemic Thermostable Direct Hemolysin-Producing
Vibrio parahaemolyticus
O3:K6 in Seafood and the Coastal Environment in Japan
Authors: Hara-Kudo Yukiko , Sugiyama Kanji , Nishibuchi Mitsuaki , Chowdhury Ashrafuzzaman , Yatsuyanagi Jun , Ohtomo Yoshimitsu , Saito Akinobu , Nagano Hidetoshi , Nishina Tokuhiro , Nakagawa Hiroshi , Konuma Hirotaka , Miyahara Michiko , Kumagai Susumu 
Published: July 2003

ABSTRACT

Although thermostable direct hemolysin (TDH)-producing
Vibrio parahaemolyticus
has caused many infections in Asian countries, the United States, and other countries, it has been difficult to detect the same pathogen in seafoods and other environmental samples. In this study, we detected and enumerated
tdh
gene-positive
V. parahaemolyticus
in Japanese seafoods with a
tdh-
specific PCR method, a chromogenic agar medium, and a most-probable-number method. The
tdh
gene was detected in 33 of 329 seafood samples (10.0%). The number of
tdh
-positive
V. parahaemolyticus
ranged from <3 to 93/10 g. The incidence of
tdh
-positive
V. parahaemolyticus
tended to be high in samples contaminated with relatively high levels of total
V. parahaemolyticus
. TDH-producing strains of
V. parahaemolyticus
were isolated from 11 of 33
tdh
-positive samples (short-necked clam, hen clam, and rock oyster). TDH-producing strains of
V. parahaemolyticus
were also isolated from the sediments of rivers near the coast in Japan. Representative strains of the seafood and sediment isolates were examined for the O:K serovar and by the PCR method specific to the pandemic clone and arbitrarily primed PCR and pulsed-field gel electrophoresis techniques. The results indicated that most O3:K6
tdh
-positive strains belonged to the pandemic O3:K6 clone and suggested that serovariation took place in the Japanese environment.
Formation of 4-Hydroxy-2,5-Dimethyl-3[2H]-Furanone by
Zygosaccharomyces rouxii
: Identification of an Intermediate
Authors: Hauck Tobias , Brühlmann Fredi , Schwab Wilfried 
Published: July 2003

ABSTRACT

The formation of the important flavor compound 4-hydroxy-2,5-dimethyl-3[2H]-furanone (HDMF; Furaneol) from
d
-fructose-1,6-bisphosphate by the yeast
Zygosaccharomyces rouxii
was studied with regard to the identification of intermediates present in the culture medium. Addition of
o
-phenylenediamine, a trapping reagent for α-dicarbonyls, to the culture medium and subsequent analysis by high-pressure liquid chromatography with diode array detection revealed the formation of three quinoxaline derivatives derived from
d
-fructose-1,6-bisphosphate under the applied growth conditions (30°C; pH 4 to 5). Isolation and characterization of these compounds by tandem mass spectrometry and nuclear magnetic resonance spectroscopy led to the identification of phosphoric acid mono-(2,3,4-trihydroxy-4-quinoxaline-2-yl-butyl) ester (Q1), phosphoric acid mono-[2,3-dihydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q2), and phosphoric acid mono-[2-hydroxy-3-(3-methyl-quinoxaline-2-yl)-propyl] ester (Q3). Q1 and Q2 were formed independently of
Z. rouxii
cells, whereas Q3 was detected only in incubation systems containing the yeast. Identification of Q2 demonstrated for the first time the chemical formation of 1-deoxy-2,3-hexodiulose-6-phosphate in the culture medium, a generally expected but never identified intermediate in the formation pathway of HDMF. Since HDMF was detected only in the presence of
Z. rouxii
cells, additional enzymatic steps were presumed. Incubation of periplasmic and cytosolic protein extracts obtained from yeast cells with
d
-fructose-1,6-bisphosphate led to the formation of HDMF, implying the presence of the required enzymes in both extracts.
Use of a Green Fluorescent Protein-Based Reporter Fusion for Detection of Nitric Oxide Produced by Denitrifiers
Authors: Yin Shixue , Fuangthong Mayuree , Laratta William P. , Shapleigh James P. 
Published: July 2003

ABSTRACT

To determine if green fluorescent protein could be used as a reporter for detecting nitric oxide production,
gfp
was fused to
nnrS
from
Rhodobacter sphaeroides
2.4.3.
nnrS
was chosen because its expression requires nitric oxide. The presence of the fusion in
R. sphaeroides
2.4.3 resulted in a significant increase in fluorescent intensity of the cells, but only when nitrite reductase was active. Cells lacking nitrite reductase activity and consequently the ability to generate nitric oxide were only weakly fluorescent when grown under denitrification-inducing conditions. One of the
R. sphaeroides
strains unable to generate nitric oxide endogenously was used as a reporter to detect exogenously produced nitric oxide. Incubation of this strain with sodium nitroprusside, a nitric oxide generator, significantly increased its fluorescence intensity. Mixing of known denitrifiers with the reporter strain also led to significant increases in fluorescence intensity, although the level varied depending on the denitrifier used. The reporter was tested on unknown isolates capable of growing anaerobically in the presence of nitrate, and one of these was able to induce expression of the fusion. Analysis of the 16S rRNA gene sequence of this isolate placed it within the
Thauera aromatica
subgroup, which is known to contain denitrifiers. These experiments demonstrate that this green fluorescent protein-based assay provides a useful method for assessing the ability of bacteria to produce nitric oxide.
Transfection of
Diaporthe perjuncta
with
Diaporthe RNA Virus
Authors: Moleleki Ntsane , van Heerden Schalk W. , Wingfield Michael J. , Wingfield Brenda D. , Preisig Oliver 
Published: July 2003

ABSTRACT

Diaporthe perjuncta
is a pathogen of grapevines worldwide. A positive-strand RNA virus,
Diaporthe RNA virus
(DaRV), occurs in hypovirulent isolates of this fungus. A virus-free isolate from a South African grapevine was transfected with in vitro
-
transcribed positive strands of DaRV. Based on reverse transcription-PCR and partial sequence analysis, the transfected virus was identified as DaRV. The in vitro-transcribed RNA transcripts used to transfect fungal spheroplasts contained parts of the vector at their distal ends. These vector sequences were separated from the DaRV genome during replication in the new host. The transfected isolate had morphological features that differed from those of the isogenic virus-free strain, including production of a yellow pigment, a decreased growth rate, and lack of sporulation. An apple-based pathogenicity test did not reveal any differences in virulence between the virus-free and DaRV-transfected isolates. This study showed that virus-free fungal hosts can be successfully transfected with viruses other than the
Cryphonectria parasitica
hypovirus.
Characterization of Genes Involved in the Metabolism of α-Galactosides by
Lactococcus raffinolactis
Authors: Boucher Isabelle , Vadeboncoeur Christian , Moineau Sylvain 
Published: July 2003

ABSTRACT

Lactococcus raffinolactis
, unlike most lactococci, is able to ferment α-galactosides, such as melibiose and raffinose. More than 12 kb of chromosomal DNA from
L. raffinolactis
ATCC 43920 was sequenced, including the α-galactosidase gene and genes involved in the Leloir pathway of galactose metabolism. These genes are organized into an operon containing
aga
(α-galactosidase),
galK
(galactokinase), and
galT
(galactose 1-phosphate uridylyltransferase). Northern blotting experiments revealed that this operon was induced by galactosides, such as lactose, melibiose, raffinose, and, to a lesser extent, galactose. Similarly, α-galactosidase activity was higher in lactose-, melibiose-, and raffinose-grown cells than in galactose-grown cells. No α-galactosidase activity was detected in glucose-grown cells. The expression of the
aga-galKT
operon was modulated by a regulator encoded by the upstream gene
galR
. The product of
galR
belongs to the LacI/GalR family of transcriptional regulators. In
L. lactis
,
L. raffinolactis
GalR acted as a repressor of
aga
and lowered the enzyme activity by more than 20-fold. We suggest that the expression of the
aga
operon in lactococci is negatively controlled by GalR and induced by a metabolite derived from the metabolism of galactosides.