bluuebunny/crossref_metadata_2025 huggingface dataset:
The Value of Magnetocardiography in Patients with and Without Relevant Stenoses of the Coronary Arteries Using an Unshielded System
Authors: HAILER BIRGIT , CHAIKOVSKY ILJA , AUTH‐EISERNITZ SABINE , SCHÄFER HARALD , VAN LEEUWEN PETER
Published: January 2005

Background: The diagnostic management of patients with chest pain remains a clinical challenge. Magnetocardiography (MCG) is a noninvasive method for the recording of cardiac electromagnetic signals at multiple sites above the chest cage. Contrary to electrocardiogram (ECG) the magnetic field is unaltered by surrounding tissues. The present study aimed to analyze the diagnostic value of an unshielded four‐channel MCG for the detection of coronary artery disease (CAD) in patients with chest pain.

Methods: The study included 417 subjects: 177 patients with angiographically documented CAD (stenoses ≥50%), 123 symptomatic patients without hemodynamically relevant stenosis (nCAD) and 117 healthy subjects. Twelve‐lead ECG was obtained in all subjects. The magnetocardiography recordings were taken from 36 positions at rest. From these current density vector maps were generated during the ST‐T interval. Each map was classified using a classification system with a scale from 0 (normal) to 4 (grossly abnormal).

Results: While the ECG was normal in all subjects the MCG revealed typical differences. In normals most maps were classified as category 0, 1 or 2, in nCAD and more so in CAD patients the categories 3 and 4 prevailed. Using a cut‐off value of 39.2% for the discrimination between normals and CAD patients sensitivity was 73.3%, specificity 70.1%.

Conclusion: Contrary to ECG, unshielded MCG reveals significant differences between normals and symptomatic patients with and without relevant stenoses using current density reconstruction during repolarization at rest. This method might be a suitable noninvasive tool for the management of patients with chest pain.
Coronary Sinus Lead Extraction in the Era of Cardiac Resynchronization Therapy:
Authors: KASRAVI BABAK , TOBIAS SERGE , BARNES MARY J. , MESSENGER JOHN C.
Published: January 2005

As the number of coronary sinus (CS) lead implantations for cardiac resynchronization therapy increases so will the need for extraction of these leads. The safety of extraction of leads from the branches of the CS has not been reported. We reviewed our database of patients undergoing pacemaker lead extraction from January 2002 through February 2004 at our institution. Of 149 patients referred for lead extraction, 14 (9%) had a biventricular device. The indications for lead extraction were infection, lead malfunction, and exit block. The duration of CS lead implants ranged between 2 and 43 months (mean 17 months). All 14 CS leads were removed successfully using nonsurgical lead extraction techniques. Three leads that were in place the longest (≥27 months) were removed via the femoral vein approach due to fibrous attachment of the CS lead body to the other pacemaker leads. The leads were structurally intact and without any significant fibrosis of their tips upon visual inspection. There were no major complications of CS laceration, hypotension, pericardial effusion, or excessive blood loss associated with any of the extraction procedures. CS leads were removed safely, successfully and with relative ease based on our experience in this small cohort of patients.
Individual Optimization of Pacing Sensors Improves Exercise Capacity without Influencing Quality of Life
Authors: EROL‐YILMAZ AYTEN , SCHRAMA TIM A. , TANKA JUTTA SCHROEDER , TIJSSEN JAN G. , WILDE ARTHUR A. , TUKKIE RAYMOND
Published: January 2005

Introduction: Programmable pacemaker sensor features are frequently used in default setting. Limited data are available about the effect of sensor optimization on exercise capacity and quality of life (QOL). Influence of individual optimization of sensors on QOL and exercise tolerance was investigated in a randomized, single blind study in patients with VVIR, DDDR, or AAIR pacemakers.,

Methods: Patients with ≥75% pacing were randomized to optimized sensor settings (OSS) or default sensor setting (DSS). Standardized optimization was performed using three different exercise tests. QOL questionnaires (QOL‐q: Hacettepe, Karolinska, and RAND‐36) were used for evaluation of the sensor optimization. One month before and after optimization, exercise capacity using chronotropic assessment exercise protocol and the three QOL‐q were assessed.

Results: Fifty‐four patients (26 male, 28 female) with a mean age of 65 ± 16 years were enrolled in the study. In each group (OSS and DSS) 27 patients were included. One month after sensor optimization, the achieved maximal heart rate (HR) and metabolic workload (METS) were significantly higher in OSS when compared with DSS (124 ± 28 bpm vs 108 ± 20 bpm, P = 0.036; 7.3 ± 4 METS vs 4.9 ± 4 METS, P = 0.045). Highest HR and METS were achieved in patients with pacemakers with accessible sensor algorithms. In patients with automatic slope settings (33%), exercise capacity did not improve after sensor optimization. QOL did not improve in OSS compared with DSS.

Conclusion: After 1 month of individual optimization of rate response pacemakers, exercise capacity was improved and maximum HR increased, although QOL remained unchanged. Accessible pacemaker sensor algorithms are mandatory for individual optimization.
Diagnostic Value of Nitrate Stimulated Tilt Testing Without Preceding Passive Tilt in Patients with Suspected Vasovagal Syncope and a Healthy Control Group
Authors: AERTS ARNAUD J. J. , DENDALE PAUL
Published: January 2005

Background: The contribution of the passive tilt phase, in a combined nitrate stimulated tilt protocol may be low yielding. In order to develop a shortened, and thus easier to perform test, we investigated the optimal duration of a nitrate tilt protocol without a preceding passive phase.

Methods: Thirty‐eight consecutive patients (18F/20M; mean age 46 ± 16) with clinically suspected vasovagal syncope and 31 control subjects (15F/16M; mean age 40 ± 18) were tested. The subjects were tilted to 70° for a maximum period of 30 minutes, and sublingual nitroglycerin 0.4 mg spray was administrated directly after attaining erect posture. Receiver operator characteristics (ROC) analysis was done to determine the optimal test duration.

Results: In the patient group 31 (82%) and in controls 5 (16%) had a positive test. Sensitivity, specificity, and accuracy at test end were 82, 84, and 83%, respectively. ROC analysis revealed that a maximum accuracy of 83% was attained at 14 minutes, with a sensitivity and specificity of 79 and 87%, respectively.

Conclusion: Nitrate stimulated tilt testing, without a preceding passive tilt phase, and limited to a test duration of 15 minutes, provides an accurate, sensitive, and specific method to provoke vasovagal reactions in subjects with clinically suspected vasovagal syncope.
Inhibition of Unnecessary RV Pacing with AV Search Hysteresis in ICDs (INTRINSIC RV):
Authors: OLSHANSKY BRIAN , DAY JOHN , McGUIRE MAUREEN , PRATT TIM
Published: January 2005

Implantable cardioverter defibrillators (ICDs) reduce sudden arrhythmic death risk but when these devices are programmed DDD and pace in the right ventricle (RV), they can be associated with increased mortality and heart failure morbidity compared to an ICD programmed to back‐up RV. An ideal ICD would provide effective treatment for life‐threatening tachyarrhythmias, reduce unnecessary RV pacing and maintain AV synchrony. The Inhibition of Unnecessary RV Pacing with AV Search Hysteresis (AVSH) in ICDs (INTRINSIC RV) study will assess whether an ICD programmed to DDDR with AVSH is equal to an ICD programmed to VVI with regard to mortality, heart failure hospitalizations, and several predefined secondary enpoints. AVSH allows intrinsic AV conduction beyond the programmed AV delay to help minimize ventricular pacing. INTRINSIC RV, a multi‐center, randomized, prospective trial will enroll >1,200 participants who receive a Guidant VITALITY AVT ICD. ICDs are programmed initially to DDDR AVSH 60–130. Then, after a week, if the %RV pacing <20%, patients are randomized to VVI‐40 or DDDR 60–130 with AVSH. Those with RV pacing ≥20% are placed in an obvservational arm and programmed ad libitum by the treating physician. Patients are followed for one year. This large, randomized, controlled, clinical trial will address whether DDDR with AVSH programming is equivalent to VVI programming in an ICD with regard to mortality and heart failure hospitalization.
Role of the transient outward current (Ito) in shaping canine ventricular action potential – a dynamic clamp study
Authors: Sun Xiaoyin , Wang Hong‐Sheng
Published: January 2005

Transmural electrical dispersion determines the repolarization sequence across the ventricular wall, and plays an important role in the development of arrhythmias under pathological conditions. While it is clear that the transmural gradient of the transient outward current (Ito) underlies the dramatic difference in phase 1 repolarization across the ventricle, its contribution to the transmural action potential duration (APD) dispersion is not clear. We investigated this problem using the dynamic clamp technique in canine ventricular myocytes. The dynamic clamp allows quantitative ‘insertion’ of simulated conductances in real, biological cells, bridging pure computer modelling and experimental electrophysiology. ‘Insertion’ of an epicardial level of Ito in endocardial cells produced a prominent phase 1 repolarization and a ‘spike‐and‐dome’ action potential morphology, but did not significantly affect the APD. Increasingly larger Ito densities prolonged, and then dramatically shortened the endocardial APD. We also used the dynamic clamp to subtract, or ‘block’ the native Ito in epicardial cells. Such ‘blockade’ eliminated the epicardial action potential notch, but had no significant effect on the APD. We conclude that Ito, while being a key regulator of phase 1 repolarization, does not significantly affect the APD of canine ventricular myocytes, and that the Ito gradient is not a significant contributor to the transmural APD dispersion in the canine ventricle. By allowing computer simulation on a biological background, the dynamic clamp is a new and effective tool to study the ionic basis of the electrical properties of cardiac cells.
Role of the N‐terminal negative charges of actin in force generation and cross‐bridge kinetics in reconstituted bovine cardiac muscle fibres
Authors: Lu Xiaoying , Bryant Mary K. , Bryan Keith E. , Rubenstein Peter A. , Kawai Masataka
Published: January 2005

Mutant yeast actins were used to determine the role of actin's N‐terminal negative charges in force generation. The thin filament was selectively removed from bovine cardiac skinned muscle fibres by gelsolin, and the actin filament was reconstituted from purified G‐actin. In this reconstitution, yeast wild‐type actin (2Ac: two N‐terminal negative charges), yeast mutant actins (3Ac and 4Ac), and rabbit skeletal muscle actin (MAc) were used. The effects of phosphate, ATP and ADP on force development were studied at 25°C. With MAc, isometric tension was 77% of the initial tension owing to the lack of a regulatory system. With 2Ac, isometric tension was 10% of the initial tension; with 3Ac, isometric tension was 23%; and with 4Ac, isometric tension was 44%. Stiffness followed a similar pattern (2Ac < 3Ac < 4Ac < MAc). A similar trend was observed during rigor induction and relaxation. Sinusoidal analysis was performed to obtain the kinetic constants of the cross‐bridge cycle. The results showed that the variability of the kinetic constants was ≤ 2.5‐fold among the 2Ac, 4Ac and MAc muscle models. When the cross‐bridge distribution was examined, there was no significant reapportionment among these three models examined. These results indicate that force supported by each cross‐bridge is modified by the N‐terminal negative charges of actin, presumably via the actomyosin interface. We conclude that two N‐terminal negative charges are not adequate, three negative charges are intermediate, and four negative charges are necessary to generate force.
Twenty-One Millisecond Pulsars in Terzan 5 Using the Green Bank Telescope
Authors: Ransom Scott M. , Hessels Jason W. T. , Stairs Ingrid H. , Freire Paulo C. C. , Camilo Fernando , Kaspi Victoria M. , Kaplan David L.
Published: January 2005

We have identified 21 millisecond pulsars (MSPs) in globular cluster Terzan 5 by using the Green Bank Telescope, bringing the total of known MSPs in Terzan 5 to 24. These discoveries confirm fundamental predictions of globular cluster and binary system evolution. Thirteen of the new MSPs are in binaries, of which two show eclipses and two have highly eccentric orbits. The relativistic periastron advance for the two eccentric systems indicates that at least one of these pulsars has a mass 1.68 times greater than the mass of the Sun at 95% confidence. Such large neutron star masses constrain the equation of state of matter at or beyond the nuclear equilibrium density.
Options for Field Diagnosis of Human African Trypanosomiasis
Authors: Chappuis François , Loutan Louis , Simarro Pere , Lejon Veerle , Büscher Philippe
Published: January 2005

Human African trypanosomiasis (HAT) due to
Trypanosoma brucei gambiense
or
T. b. rhodesiense
remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For
T. b. gambiense
HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for
T. b. rhodesiense
infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of
T. b. gambiense
HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years.
Bacterial Contamination of Blood Components
Authors: Brecher Mark E. , Hay Shauna N.
Published: January 2005

Blood for transfusion is a potential source of infection by a variety of known and unknown transmissible agents. Over the last 20 years, astounding reductions in the risk of viral infection via allogeneic blood have been achieved. As a result of this success, bacterial contamination of blood products has emerged as the greatest residual source of transfusion-transmitted disease. This paper summarizes the current status of detection, prevention, and elimination of bacteria in blood products for transfusion.
Update on Human Herpesvirus 6 Biology, Clinical Features, and Therapy
Authors: De Bolle Leen , Naesens Lieve , De Clercq Erik
Published: January 2005

Human herpesvirus 6 (HHV-6) is a betaherpesvirus that is closely related to human cytomegalovirus. It was discovered in 1986, and HHV-6 literature has expanded considerably in the past 10 years. We here present an up-to-date and complete overview of the recent developments concerning HHV-6 biological features, clinical associations, and therapeutic approaches. HHV-6 gene expression regulation and gene products have been systematically characterized, and the multiple interactions between HHV-6 and the host immune system have been explored. Moreover, the discovery of the cellular receptor for HHV-6, CD46, has shed a new light on HHV-6 cell tropism. Furthermore, the in vitro interactions between HHV-6 and other viruses, particularly human immunodeficiency virus, and their relevance for the in vivo situation are discussed, as well as the transactivating capacities of several HHV-6 proteins. The insight into the clinical spectrum of HHV-6 is still evolving and, apart from being recognized as a major pathogen in transplant recipients (as exemplified by the rising number of prospective clinical studies), its role in central nervous system disease has become increasingly apparent. Finally, we present an overview of therapeutic options for HHV-6 therapy (including modes of action and resistance mechanisms).
Pathway to Synthesis and Processing of Mycolic Acids in
Mycobacterium tuberculosis
Authors: Takayama Kuni , Wang Cindy , Besra Gurdyal S.
Published: January 2005

Mycobacterium tuberculosis
is known to synthesize α-, methoxy-, and keto-mycolic acids. We propose a detailed pathway to the biosynthesis of all mycolic acids in
M. tuberculosis
. Fatty acid synthetase I provides C
20
-S-coenzyme A to the fatty acid synthetase II system (FAS-IIA). Modules of FAS-IIA and FAS-IIB introduce
cis
unsaturation at two locations on a growing meroacid chain to yield three different forms of
cis
,
cis
-diunsaturated fatty acids (intermediates to α-, methoxy-, and keto-meroacids). These are methylated, and the mature meroacids and carboxylated C
26
-S-acyl carrier protein enter into the final Claisen-type condensation with polyketide synthase-13 (Pks13) to yield mycolyl-S-Pks13. We list candidate genes in the genome encoding the proposed dehydrase and isomerase in the FAS-IIA and FAS-IIB modules. We propose that the processing of mycolic acids begins by transfer of mycolic acids from mycolyl-S-Pks13 to
d
-mannopyranosyl-1-phosphoheptaprenol to yield 6-
O
-mycolyl-β-
d
-mannopyranosyl-1-phosphoheptaprenol and then to trehalose 6-phosphate to yield phosphorylated trehalose monomycolate (TMM-P). Phosphatase releases the phosphate group to yield TMM, which is immediately transported outside the cell by the ABC transporter. Antigen 85 then catalyzes the transfer of a mycolyl group from TMM to the cell wall arabinogalactan and to other TMMs to produce arabinogalactan-mycolate and trehalose dimycolate, respectively. We list candidate genes in the genome that encode the proposed mycolyltransferases I and II, phosphatase, and ABC transporter. The enzymes within this total pathway are targets for new drug discovery.
Characterization of Streptomyces scabies mutants deficient in melanin biosynthesis
Authors: Beauséjour Julie , Beaulieu Carole
Published: January 2005

Streptomyces scabies, a causal agent of common scab, produces both melanin and a secondary metabolite called thaxtomin A. To establish a possible relation between melanin and thaxtomin A production in S. scabies, we carried out N-methyl-N′-nitro-N-nitrosoguanidine (NTG) mutagenesis and isolated 11 melanin-negative mutants of S. scabies EF-35. These mutants were characterized for thaxtomin A production, pathogenicity, sporulation, and stress resistance. Nine of these mutants showed a significant reduction in thaxtomin A production when compared with the wild strain. However, only a few mutants exhibited a reduced level of virulence or a loss in their ability to induce common scab symptoms on potato tubers. Other pleiotrophic effects, such as higher sensitivity to heavy metals and incapacity to sporulate under certain stress conditions, were also associated with a deficiency in melanin production.Key words: common scab, potato, secondary metabolism, stress, thaxtomin.
Comparison of S-layer secretion genes in freshwater caulobacters
Authors: Iuga Mihai , Awram Peter , Nomellini John F , Smit John
Published: January 2005

Our freshwater caulobacter collection contains about 40 strains that are morphologically similar to Caulobacter crescentus. All elaborate a crystalline protein surface (S) layer made up of protein monomers 100–193 kDa in size. We conducted a comparative study of S-layer secretion in 6 strains representing 3 size groups of S-layer proteins: small (100–108 kDa), medium (122–151 kDa), and large (181–193 kDa). All contained genes predicted to encode ATP-binding cassette transporters and membrane fusion proteins highly similar to those of C. crescentus, indicating that the S-layer proteins were all secreted by a type I system. The S-layer proteins' C-termini showed unexpectedly low sequence similarity but contained conserved residues and predicted secondary structure features typical of type I secretion signals. Cross-expression studies showed that the 6 strains recognized secretion signals from C. crescentus and Pseudomonas aeruginosa and similarly that C. crescentus was able to secrete the S-layer protein C-terminus of 1 strain examined. Inactivation of the ATP-binding cassette transporter abolished S-layer protein secretion, indicating that the type I transporter is necessary for S-layer protein secretion. Finally, while all of the S-layer proteins of this subset of strains were secreted by type I mechanisms, there were significant differences in genome positions of the transporter genes that correlated with S-layer protein size.Key words: freshwater caulobacter, S-layer, type I secretion system, ABC transporter.
OmpD but not OmpC is involved in adherence ofSalmonella entericaserovar Typhimurium to human cells
Authors: Hara-Kaonga Bochiwe , Pistole Thomas G
Published: January 2005

Conflicting reports exist regarding the role of porins OmpC and OmpD in infections due to Salmonella enterica serovar Typhimurium. This study investigated the role of these porins in bacterial adherence to human macrophages and intestinal epithelial cells. ompC and ompD mutant strains were created by transposon mutagenesis using P22-mediated transduction of Tn10 and Tn5 insertions, respectively, into wild-type strain 14028. Fluorescein-labeled wild-type and mutant bacteria were incubated with host cells at various bacteria to cell ratios for 1 h at 37 °C and analyzed by flow cytometry. The mean fluorescence intensity of cells with associated wild-type and mutant bacteria was used to estimate the number of bacteria bound per host cell. Adherence was also measured by fluorescence microscopy. Neither assay showed a significant difference in binding of the ompC mutant and wild-type strains to the human cells. In contrast, the ompD mutant exhibited lowered binding to both cell types. Our findings suggest that OmpD but not OmpC is involved in the recognition of Salmonella serovar Typhimurium by human macrophages and intestinal epithelial cells.Key words: Salmonella, adherence, porins, intestinal epithelial cells, macrophage.
Optimization of casein-based semisynthetic medium for growing of toxigenicCorinebacterium diphtheriaein a fermenter
Authors: Tchorbanov Andrey I , Dimitrov Jordan D , Vassilev Tchavdar L
Published: January 2005

Diphtheria toxin is produced by growing Corinebacterium diphtheriae either in a semisynthetic casein-based medium or in the Pope–Lingood meat extract based medium. The World Health Organization advises the use of the semisynthetic one, as it has important advantages. Data on the composition of casein-based media and their ability to support high toxin production are not freely available. Important factors affecting toxin production during C. diphtheriae cultivation are the pH of the culture medium and the concentration of casein hydrolysate and of Fe2+. We established that the optimal pH for toxin production is 7.2. The highest yield of toxin was obtained using a casein hydrolysate concentration of 35.0 g/L and a Fe2+concentration of 0.05–0.41 µg/mL. Under these conditions, diphtheria toxin with higher purity and yield compared with the batches obtained using the meat-based medium of Pope–Lingood was produced.Key words: diphtheria toxin, diphtheria toxoid, cultivation, semisynthetic medium.
Influence of carbon and nitrogen sources on growth, nitrogenase activity, and carbon metabolism ofGluconacetobacter diazotrophicus
Authors: Tejera Noel A , Ortega Eduardo , Rodés Rosa , Lluch Carmen
Published: January 2005

The effects of different carbon and nitrogen sources on the growth, nitrogenase activity, and carbon metabolism of Gluconacetobacter diazotrophicus were investigated. The amino acids asparagine, aspartic acid, and glutamic acid affected microbial growth and nitrogenase activity. Several enzymatic activities involved in the tricarboxylic acid cycle were affected by the carbon source used. In addition, glucose and gluconate significantly increased the oxygen consumption (respiration rate) of whole cells of G. diazotrophicus grown under aerobic conditions. Enzymes responsible for direct oxidation of glucose and gluconate were especially active in cells grown with sucrose and gluconate. The presence of amino acids in the apoplastic and symplastic sap of sugarcane stems suggests that these compounds might be of importance in the regulation of growth and nitrogenase activity during the symbiotic association. The information obtained from the plant–bacterium association together with the results of other biochemical studies could contribute to the development of biotechnological applications of G. diazotrophicus.Key words: Gluconacetobacter diazotrophicus, endophyte, metabolism, nitrogen fixation.
Effect of foliar disease on the epiphytic yeast communities of creeping bentgrass and tall fescue
Authors: Allen Tom W , Quayyum Habib A , Burpee Leon L , Buck James W
Published: January 2005

The effect of mechanical wounding or foliar diseases caused by Sclerotinia homoeocarpa or Rhizoctonia solani on the epiphytic yeast communities on creeping bentgrass and tall fescue were determined by leaf washing and dilution plating. Total yeast communities on healthy bentgrass and tall fescue leaves ranged from 7.9 × 103 to 1.4 × 105 CFU·cm–2 and from 2.4 × 103 to 1.6 × 104 CFU·cm–2, respectively. Mechanically wounded leaves (1 of 2 trials) and leaves with disease lesions (11 of 12 trials) supported significantly larger communities of phylloplane yeasts. Total yeast communities on S. homoeocarpa infected or R. solani infected bentgrass leaves were 3.6–10.2 times and 6.2–6.4 times larger, respectively, than the communities on healthy leaves. In general, healthy and diseased bentgrass leaves supported larger yeast communities than healthy or diseased tall fescue leaves. We categorized the majority of yeasts as white-pigmented species, including Cryptococcus laurentii, Cryptococcus flavus, Pseudozyma antarctica, Pseudozyma aphidis, and Pseudozyma parantarctica. The percentage of pink yeasts in the total yeast community ranged from 2.6% to 9.9% on healthy leaves and increased to 32.0%–44.7% on S. homoeocarpa infected leaves. Pink-pigmented yeasts included Rhodotorula glutinis, Rhodotorula mucilaginosa, Sakaguchia dacryoidea, and Sporidiobolus pararoseus. Foliar disease significantly affected community size and composition of epiphytic yeasts on bentgrass and tall fescue.Key words: dollar spot, phylloplane, Rhizoctonia blight.
Morphology of Salmonella enterica serovar Heidelberg typing phages
Authors: Demczuk Walter , Ahmed Rafiq , Ackermann Hans-W
Published: January 2005

Eleven tailed phages are described. They belong to the Myoviridae, Siphoviridae, or Podoviridae families and represent the ViI, T1, T5, Jersey, N4, and P22 species of enterobacterial phages. Morphology is correlated with host range.Key words: Salmonella, phage morphology.
Role of glutamine synthetase in phenazine antibiotic production byPantoea agglomeransEh1087
Authors: Galbraith Matthew D , Giddens Stephen R , Mahanty H Khris , Clark Bruce
Published: January 2005

Pantoea agglomerans strain Eh1087 produces the phenazine antibiotic D-alanylgriseoluteic acid. A glutamine auxotroph harboring an insertion in a putative glnA gene was obtained by transposon-mutagenesis of Eh1087 that produced less D-alanylgriseoluteic acid than the parental strain (strain Eh7.1). Cosmids encoding the Eh1087 glnA were isolated by their ability to complement the mutant for prototrophy. The role of the Eh1087 glnA locus was functionally confirmed by complementation of an Escherichia coli glnA mutant. Analysis of the nucleotide and deduced amino acid sequences of the Eh1087 glnA gene indicated a high degree of similarity to the glnA genes and glutamine synthetase enzymes of other Enterobacteriaceae. Isotopic labelling experiments with15N-labelled ammonium sulfate demonstrated that wild-type Eh1087 incorporated15N into griseoluteic acid more readily than the glnA mutant Eh7.1. We conclude that the 2 nitrogens in the phenazine nucleus originate from glutamine and the intracellular glutamine synthesized by Eh1087 is a source of the phenazine nucleus nitrogens even in glutamine-rich environments.Key words: phenazine, Pantoea, Erwinia, glutamine synthetase, biosynthesis.
Purification and characterization ofThermobifida fuscaxylanase 10B
Authors: Kim Jeong H , Irwin Diana , Wilson David B
Published: January 2005

Thermobifida fusca grows well on cellulose and xylan, and produces a number of cellulases and xylanases. The gene encoding a previously unstudied endoxylanase, xyl10B, was overexpressed in E. coli, and the protein was purified and characterized. Mature Xyl10B is a 43-kDa glycohydrolase with a short basic domain at the C-terminus. It has moderate thermostability, maintaining 50% of its activity after incubation for 16 h at 62 °C, and is most active between pH 5 and 8. Xyl10B is produced by growth of T. fusca on xylan or Solka Floc but not on pure cellulose. Mass spectroscopic analysis showed that Xyl10B produces xylobiose as the major product from birchwood and oat spelts xylan and that its hydrolysis products differ from those of T. fusca Xyl11A. Xyl10B hydrolyzes various p-nitrophenyl-sugars, including p-nitrophenyl α-D-arabinofuranoside, p-nitrophenyl-β-D-xylobioside, p-nitrophenyl-β-D-xyloside, and p-nitrophenyl-β-D-cellobioside. Xyl11A has higher activity on xylan substrates, but Xyl10B produced more reducing sugars from corn fiber than did Xyl11A.Key words: xylanase, enzyme purification, Thermobifida fusca, family 10 hydrolase.
A review of conventional detection and enumeration methods for pathogenic bacteria in food
Authors: Gracias Kiev S , McKillip John L
Published: January 2005

With continued development of novel molecular-based technologies for rapid, high-throughput detection of foodborne pathogenic bacteria, the future of conventional microbiological methods such as viable cell enumeration, selective isolation of bacteria on commercial media, and immunoassays seems tenuous. In fact, a number of unique approaches and variations on existing techniques are currently on the market or are being implemented that offer ease of use, reliability, and low cost compared with molecular tools. Approaches that enhance recovery of sublethally injured bacteria, differentiation among species using fluorogenics or chromogenics, dry plate culturing, differentiation among bacteria of interest using biochemical profiling, enumeration using impedence technology, techniques to confirm the presence of target pathogens using immunological methods, and bioluminescence applications for hygiene monitoring are summarized here and discussed in relation to their specific advantages or disadvantages when implemented in a food microbiology setting.Key words: food pathogen, detection, enumeration methods, food safety.
Pheno and genotyping ofStaphylococcus aureus, isolated from bovine milk samples from São Paulo State, Brazil
Authors: Cabral K G , Lämmler C , Zschöck M , Langoni H , de Sá M E.P , Victória C , Da Silva A v
Published: January 2005

In the present study, 87 Staphylococcus aureus isolates obtained from milk samples of 87 cows with mastitis in 6 different municipal districts of 2 regions of São Paulo State, Brazil, were compared pheno and genotypically. Pulsed-field gel electrophoresis (PFGE) analysis of the strains was performed, and PCR was carried out to detect genes for a number of staphylococcal cell surface proteins, exoproteins, and 3 classes of agr genes. Nine distinct S. aureus lineages (LA–LI) were identified by PFGE. The lineages LA and LE, which accounted together for 63 strains (72.2%), were prevalent and had been collected from all of the 6 municipal districts, indicating a broad geographic distribution of these lineages; LB, LC, LD, LF, LG, LH, and LI, however, were isolated sporadically and accounted for 24 strains (27.8%). Some characteristics, like penicillin resistance and the presence of cap8 and agr class II genes, were associated with the prevalent lineages (LA and LE), and penicillin susceptibility and the presence of cna and cap5 genes were associated with sporadic lineages. According to the present results, some S. aureus lineages possess a combination of genes that confer the propensity to cause and disseminate infection, and only a limited number of clones are responsible for the cases of bovine mastitis on the various farms.Key words: S. aureus, mastitis, phenotyping, genotyping.
Degradation of acyl-homoserine lactone molecules by Acinetobacter sp. strain C1010
Authors: Kang Beom Ryong , Lee Jung Hoon , Ko Sug Ju , Lee Yong Hwan , Cha Jae Soon , Cho Baik Ho , Kim Young Cheol
Published: January 2005

A bacterium C1010, isolated from the rhizospheres of cucumbers in fields in Korea, degraded the microbial quorum-sensing molecules, hexanoyl homoserine lactone (HHSL), and octadecanoyl homoserine lactone (OHSL). Morphological characteristics and 16S rRNA sequence analysis identified C1010 as Acinetobacter sp. strain C1010. This strain was able to degrade the acyl-homoserine lactones (AHLs) produced by the biocontrol bacterium, Pseudomonas chlororaphis O6, and a phytopathogenic bacterium, Burkholderia glumae. Co-cultivation studies showed that the inactivation of AHLs by C1010 inhibited production of phenazines by P. chlororaphis O6. In virulence tests, the C1010 strain attenuated soft rot symptom caused by Erwinia carotovora ssp. carotovora. We suggest Acinetobacter sp. strain C1010 could be a useful bacterium to manipulate biological functions that are regulated by AHLs in various Gram-negative bacteria.Key words: quorum sensing, biological control, attenuation of bacterial diseases.
Selection of rhizobia for prairie legumes used in restoration and reconstruction programs in Minnesota
Authors: Tlusty Becki , Grossman Julie M , Graham Peter H
Published: January 2005

The inoculation of indigenous legumes used in revegetation and wetland reconstruction activities in Minnesota presents problems not found in more traditional seedings. Few studies have sought inoculant-quality rhizobia for the legumes involved or examined their interaction in an environment that involves a number of different legumes seeded simultaneously under initially adverse climatic conditions. In this note, we identify effective strains for Astragalus canadensis, Chamaecrista fasciculata, Dalea purpurea, Dalea candida, Desmodium canadense, and Lespedeza capitata. We are currently using these strains to examine the contribution of inoculated legumes to prairie productivity in Minnesota.Key words: prairie, restoration, inoculation, rhizobia, legumes.
Multiplex PCR detection of clinical and environmental strains ofVibrio vulnificusin shellfish
Authors: Panicker Gitika , Vickery Michael C.L , Bej Asim K
Published: January 2005

In this study, we developed a PCR-based rapid detection method for clinically important pathogenic strains of Vibrio vulnificus. Positive amplification of the 504-bp viuB fragment was seen in all 22 clinical isolates tested but only in 8 out of 33 environmental isolates. The combination of the species-specific 205-bp vvh fragment along with viuB in a multiplexed PCR enabled us to confirm the presence of potentially pathogenic strains of V. vulnificus. No amplification of other Vibrio spp. or non-Vibrio bacteria was evidenced, suggesting a high specificity of detection by this method. The sensitivity of detection for both targeted genes was 10 pg of purified DNA, which correlated with 103V. vulnificus CFU in 1 mL of pure culture or 1 g un-enriched seeded oyster tissue homogenate. This sensitivity was improved to 1 CFU per gram of oyster tissue homogenate in overnight-enriched samples. A SYBR Green I based real-time PCR method was also developed that was shown to produce results consistent with the conventional PCR method. Application of the multiplexed real-time PCR to natural oyster tissue homogenates exhibited positive detection of vvh in 51% of the samples collected primarily during the summer months; however, only 15% of vvh positive samples exhibited viuB amplicons. The rapid, sensitive, and specific detection of clinically important pathogenic V. vulnificus in shellfish would be beneficial in reducing illnesses and deaths caused by this pathogen.Key words: Vibrio, multiplex PCR, shellfish, SYBR Green I, real-time PCR.
Ecological study of the fungal populations of the acidic Tinto River in southwestern Spain
Authors: López-Archilla A I , González A E , Terrón M C , Amils R
Published: January 2005

The characterization of the microbial ecology of the Tinto River, an extreme habitat with an extremely low pH and a high concentration of heavy metals, revealed an unexpected level of microbial richness. A variety of microbial eukaryotes was isolated, among them several fungal strains that were identified and their physiological characteristics studied. Ninety strains of yeast were isolated from the Tinto River. Fifty-two percent of them were capable of growth in vitro using medium amended with river water. They belong to 6 genera of basidiomycetes (Rhodotorula, Cryptococcus, Tremella, Holtermannia, Leucosporidium, and Mrakia) and 2 of ascomycetes (Candida and Williopsis). In addition, 349 strains of hyphomycetes belonging to 17 genera (most of them ascomycetes) were isolated and studied. Forty-four percent of the isolated filamentous fungi (154 strains) were capable of growing in vitro using medium amended with Tinto River water. Of this percentage, 19% (29 strains) belonged to the genus Penicillium (16 species) and 66% (102 strains) were included in the genera Scytalidium, Bahusakala, Phoma, and Heteroconium or showed dark sterile mycelia, which probably are of dematiaceous hyphomycetes. In addition, we characterized strains of the ascomycete genera Lecythophora and Acremonium and of the zygomycete genus Mortierella, all of them capable of growing in medium amended with river water. Statistical correlation of biological and physicochemical variables suggested a positive relationship between the dematiaceous hyphomycetes and the most extreme physicochemical conditions found in the Tinto River. Principal components analysis confirmed this relationship and also showed that the Acremonium and Lecythophora groups had environmental preferences similar to those of dematiaceous fungi. The spatial positions of the sampling sites were grouped in 2 main clusters: (i) sampling sites in the mine zone in which most of the dematiaceous, Acremonium, and Lecythophora strains were isolated and (ii) sites that were not in the mine zone and sampling station 5 from which were isolated mainly strains of fungi that were not capable of growing in the medium amended with river water and species of the Penicillium genus.Key words: acidophilic fungi, hyphomycete fungi, acidophilic yeast, Tinto River, species richness.
Genetic relationships among Brazilian strains of Aspergillus ochraceus based on RAPD and ITS sequences
Authors: Fungaro Maria Helena Pelegrinelli , Magnani Marciane , Vilas-Boas Laurival Antônio , Vissotto Patrícia Cristina , Furlaneto Márcia Cristina , Vieira Maria Lúcia Carneiro , Taniwaki Marta Hiromi
Published: January 2005

Ochratoxin A (OA) is a mycotoxin that has been found in coffee beans and coffee beverages. Its toxicological profile includes carcinogenicity, nephrotoxicity, and immunotoxicity. Aspergillus ochraceus is the major species responsible for OA production in Brazilian coffee beans. The genetic relationships among 25 A. ochraceus strains collected from Brazilian coffee-bean samples were determined based on RAPD and internal transcribed spacer (ITS) sequence data. The isolates were resolved into 2 distinct groups, one with 4 strains (group A) and the other with 21 strains (group B). Specific nucleotide variations characterizing group A and B were found for both ITS1 and ITS2 regions. Group B is a new group proposed here to accommodate the majority of the Brazilian isolates. Each group was found to contain both toxigenic and nontoxigenic strains, indicating that there is no association between molecular genotypes and the ability to produce OA.Key words: Aspergillus ochraceus, ochratoxin A, ITS region (ITS1–5.8S–ITS2), RAPD.
Sex and species differences in plasma oxytocin using an enzyme immunoassay
Authors: Kramer Kristin M , Cushing Bruce S , Carter C Sue , Wu Julie , Ottinger Mary Ann
Published: January 2005

The neuropeptide hormone oxytocin (OT) is released peripherally and centrally and has been implicated in both physiology and behavior, especially sociosexual behaviors. Knowledge of OT levels in blood or other sources would be useful but these are rarely reported. Radioimmunoassay following extraction is the most commonly used method for measuring OT but is not ideal for use in small mammals in which blood volumes and concentrations of OT are low. Here we report a chemical and biological validation for a commercially available enzyme immunoassay for OT in unextracted plasma. In addition, comparisons of OT were made across species to allow comparison of the monogamous prairie vole (Microtus ochrogaster (Wagner, 1842)) to the polygynous Sprague Dawley rat. These species were chosen because OT plays a role in the formation of social bonds and we predicted that the highly social prairie vole would have higher plasma OT than the less social rat. Results of this comparison confirmed our hypothesis. Further, OT was significantly higher in females than in males in both species. Our results indicate that this enzyme immunoassay can be used to assay plasma OT in rodents and that the predicted correlations exist between plasma OT and gender as well as species-typical social behavior.
Thyroid function in growth-hormone-transgenic coho salmon (Oncorhynchus kisutch)
Authors: Eales J G , Devlin R , Higgs D A , McLeese J M , Oakes J D , Plohman J
Published: January 2005

We measured growth rate, plasma thyroxine (T4) and 3,5,3'-triiodothyronine (T3) concentrations, and liver and whole-brain T4 and T3 deiodination activities in yearling non-transgenic coho salmon, Oncorhynchus kisutch (Walbaum, 1792), fed a satiation ration (NTS) and in growth-hormone (GH)-transgenic salmon fed for 63 d with either a satiation ration (TS) or pair-fed the satiation ration consumed by NTS fish (TNT). Daily feed intake and specific growth rate for TS fish were significantly enhanced and approximately double those for TNT and NTS fish. There were no differences among groups in plasma T4 concentration or liver T4 outer-ring deiodination activity, but for both TS and TNT fish, plasma T3 concentrations were higher and liver T4 and T3 inner-ring deiodination activities were lower than for NTS fish. Whole-brain deiodination activities did not differ between TS and NTS fish. We conclude that the elevated plasma T3 concentrations of GH-transgenic salmon neither are driven by elevated plasma T4 concentrations nor are they the result of increased hepatic conversion of T4 to T3 by outer-ring deiodination. Instead they can be explained, at least in part, by reduced hepatic degradation of T3 to 3,3'-diiodothyronine by inner-ring deiodination. These changes in T4 and T3 metabolism are tightly linked to the GH-transgenic state and not to food intake or growth rate.
Gill morphometry and hematology of juvenile chinook salmon chronically exposed to treated (elemental chlorine-free) bleached kraft pulp mill effluent at low temperature to simulate winter exposure
Authors: Kruzynski G M , Farrell A P , Tierney K B , Sanders S M , Birtwell I K
Published: January 2005

We used an on-site mobile laboratory to assess the effects of pulp mill effluent on juvenile (~0.9 g) chinook salmon, Oncorhynchus tshawytscha (Walbaum in Artedi, 1792), that normally overwinter under ice in the upper Fraser River at Prince George, British Columbia. After a 28-day exposure at 0.4–2.7 °C to secondary-treated bleached kraft mill effluent (TBKME; 0%, 2%, 4%, 8%, or 16%) under both normoxic and hypoxic (~67% air saturation) conditions, hematocrit (Hct), leucocrit (Lct), and differential white blood cell counts were determined and gills were examined for gross and fine morphometry. TBKME had no effect on either Hct or Lct, but the highest TBKME concentration (16%) increased lymphocyte numbers, reduced secondary lamellae numbers, and increased the blood–water diffusion distance of secondary lamellae. Given the relatively high TBKME concentration, compared with actual discharges to the river, and the small physiological changes observed, it appears that chronic winter exposure of juvenile chinook salmon to TBKME under hypoxic winter conditions is unlikely to produce major disturbances to these aspects of the fish's physiology.
Pivotal range and thermosensitive period of the pig-nosed turtle, Carettochelys insculpta (Testudines: Carettochelydidae), from northern Australia
Authors: Young Jeanne E , Georges Arthur , Doody J Sean , West Peter B , Alderman Rachael L
Published: January 2005

Understanding temperature-dependent sex determination in nature often depends on knowledge of species-specific attributes that are integrated into the relationship between temperature and sex. We determined two such attributes for the pig-nosed turtle, Carettochelys insculpta Ramsay, 1886, in tropical Australia: the pivotal range in temperature that separates the male-producing domain from the female-producing domain, and the thermosensitive period during which the embryonic sex is influenced by temperature. The pivotal range for C. insculpta was very narrow, spanning only about 1 °C, and was centered on 32 °C, which is high but consistent with temperatures reported for other tropical species. The thermosensitive period spanned developmental stages 17–21 for temperature influence in the direction of maleness and 18–21 for temperature influence in the direction of femaleness. This period is slightly narrower than that for other reptile species but broadly consistent with the middle third of incubation.
Consequences of rainfall variation for breeding wetland blackbirds
Authors: Fletcher, Jr. Robert J , Koford Rolf R
Published: January 2005

Annual variability in abiotic factors can be pronounced, especially in systems that rely on precipitation, such as arid regions and prairie potholes. We report how annual variation in precipitation from 1999 to 2002 in the Prairie Pothole Region of Iowa, USA, affected both density and reproduction of two interspecific competitors: yellow-headed blackbirds, Xanthocephalus xanthocephalus (Bonaparte, 1826), and red-winged blackbirds, Agelaius phoeniceus (L., 1766). During dry years, yellow-headed blackbirds, an obligate wetland-breeding species, showed a marked reduction in density and a complete reproductive failure in which none of the nests we monitored fledged young. The reproductive failure was attributed primarily to nest predation, which was negatively correlated with water levels in wetlands. Conversely, red-winged blackbirds, a facultative wetland-breeding species, showed little variation in density and nest success. Both species exhibited similar patterns of reduced clutch size and later nest initiation dates in dry years, measures often tied to bottom-up effects of food availability and (or) age of individuals. Yet top-down effects of nest predation had a stronger influence, because lower clutch size did not result in fewer young fledged per successful nest. Incorporating how rainfall variation can affect wetland songbird demography will be critical for understanding population and community dynamics in changing environments.