bluuebunny/crossref_metadata_2025 huggingface dataset:
Escherichia coli
Isolates Causing Asymptomatic Bacteriuria in Catheterized and Noncatheterized Individuals Possess Similar Virulence Properties
Authors: Watts Rebecca E. , Hancock Viktoria , Ong Cheryl-Lynn Y. , Vejborg Rebecca Munk , Mabbett Amanda N. , Totsika Makrina , Looke David F. , Nimmo Graeme R. , Klemm Per , Schembri Mark A.
Published: May 2010

Urinary tract infections (UTIs) are among the most common infectious diseases of humans, with
Escherichia coli
being responsible for >80% of all cases. Asymptomatic bacteriuria (ABU) occurs when bacteria colonize the urinary tract without causing clinical symptoms and can affect both catheterized patients (catheter-associated ABU [CA-ABU]) and noncatheterized patients. Here, we compared the virulence properties of a collection of ABU and CA-ABU nosocomial
E. coli
isolates in terms of antibiotic resistance, phylogenetic grouping, specific UTI-associated virulence genes, hemagglutination characteristics, and biofilm formation. CA-ABU isolates were similar to ABU isolates with regard to the majority of these characteristics; exceptions were that CA-ABU isolates had a higher prevalence of the polysaccharide capsule marker genes
kpsMT
II and
kpsMT
K1, while more ABU strains were capable of mannose-resistant hemagglutination. To examine biofilm growth in detail, we performed a global gene expression analysis with two CA-ABU strains that formed a strong biofilm and that possessed a limited adhesin repertoire. The gene expression profile of the CA-ABU strains during biofilm growth showed considerable overlap with that previously described for the prototype ABU
E. coli
strain, 83972. This is the first global gene expression analysis of
E. coli
CA-ABU strains. Overall, our data suggest that nosocomial ABU and CA-ABU
E. coli
isolates possess similar virulence profiles.
Proteomics of the
Autographa californica
Nucleopolyhedrovirus Budded Virions
Authors: Wang RanRan , Deng Fei , Hou Dianhai , Zhao Yong , Guo Lin , Wang Hualin , Hu Zhihong
Published: May 2010

Baculoviruses produce two progeny phenotypes during their replication cycles. The occlusion-derived virus (ODV) is responsible for initiating primary infection in the larval midgut, and the budded virus (BV) phenotype is responsible for the secondary infection. The proteomics of several baculovirus ODVs have been revealed, but so far, no extensive analysis of BV-associated proteins has been conducted. In this study, the protein composition of the BV of
Autographa californica
nucleopolyhedrovirus (AcMNPV), the type species of baculoviruses, was analyzed by various mass spectrometry (MS) techniques, including liquid chromatography-triple quadrupole linear ion trap (LC-Qtrap), liquid chromatography-quadrupole time of flight (LC-Q-TOF), and matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). SDS-PAGE and MALDI-TOF analyses showed that the three most abundant proteins of the AcMNPV BV were GP64, VP39, and P6.9. A total of 34 viral proteins associated with the AcMNPV BV were identified by the indicated methods. Thirteen of these proteins, PP31, AC58/59, AC66, IAP-2, AC73, AC74, AC114, AC124, chitinase, polyhedron envelope protein (PEP), AC132, ODV-E18, and ODV-E56, were identified for the first time to be BV-associated proteins. Western blot analyses showed that ODV-E18 and ODV-E25, which were previously thought to be ODV-specific proteins, were also present in the envelop fraction of BV. In addition, 11 cellular proteins were found to be associated with the AcMNPV BV by both LC-Qtrap and LC-Q-TOF analyses. Interestingly, seven of these proteins were also identified in other enveloped viruses, suggesting that many enveloped viruses may commonly utilize certain conserved cellular pathways.
Adenovirus Late-Phase Infection Is Controlled by a Novel L4 Promoter
Authors: Morris Susan J. , Scott Gillian E. , Leppard Keith N.
Published: May 2010

During human adenovirus 5 infection, a temporal cascade of gene expression leads ultimately to the production of large amounts of the proteins needed to construct progeny virions. However, the mechanism for the activation of the major late gene that encodes these viral structural proteins has not been well understood. We show here that two key positive regulators of the major late gene, L4-22K and L4-33K, previously thought to be expressed under the control of the major late promoter itself, initially are expressed from a novel promoter that is embedded within the major late gene and dedicated to their expression. This L4 promoter is required for late gene expression and is activated by a combination of viral protein activators produced during the infection, including E1A, E4 Orf3, and the intermediate-phase protein IVa2, and also by viral genome replication. This new understanding redraws the long-established view of how adenoviral gene expression patterns are controlled and offers new ways to manipulate that gene expression cascade for adenovirus vector applications.
Intra- and Interhost Evolutionary Dynamics of Equine Influenza Virus
Authors: Murcia Pablo R. , Baillie Gregory J. , Daly Janet , Elton Debra , Jervis Carley , Mumford Jennifer A. , Newton Richard , Parrish Colin R. , Hoelzer Karin , Dougan Gordon , Parkhill Julian , Lennard Nicola , Ormond Doug , Moule Sharon , Whitwham Andrew , McCauley John W. , McKinley Trevelyan J. , Holmes Edward C. , Grenfell Bryan T. , Wood James L. N.
Published: May 2010

Determining the evolutionary basis of cross-species transmission and immune evasion is key to understanding the mechanisms that control the emergence of either new viruses or novel antigenic variants with pandemic potential. The hemagglutinin glycoprotein of influenza A viruses is a critical host range determinant and a major target of neutralizing antibodies. Equine influenza virus (EIV) is a significant pathogen of the horse that causes periodical outbreaks of disease even in populations with high vaccination coverage. EIV has also jumped the species barrier and emerged as a novel respiratory pathogen in dogs, canine influenza virus. We studied the dynamics of equine influenza virus evolution in horses at the intrahost level and how this evolutionary process is affected by interhost transmission in a natural setting. To this end, we performed clonal sequencing of the hemagglutinin 1 gene derived from individual animals at different times postinfection. Our results show that despite the population consensus sequence remaining invariant, genetically distinct subpopulations persist during the course of infection and are also transmitted, with some variants likely to change antigenicity. We also detected a natural case of mixed infection in an animal infected during an outbreak of equine influenza, raising the possibility of reassortment between different strains of virus. In sum, our data suggest that transmission bottlenecks may not be as narrow as originally perceived and that the genetic diversity required to adapt to new host species may be partially present in the donor host and potentially transmitted to the recipient host.
Murine Gammaherpesvirus 68 LANA Is Essential for Virus Reactivation from Splenocytes but Not Long-Term Carriage of Viral Genome
Authors: Paden Clinton R. , Forrest J. Craig , Moorman Nathaniel J. , Speck Samuel H.
Published: May 2010

ORF73, which encodes the latency-associated nuclear antigen (LANA), is a conserved gamma-2-herpesvirus gene. The murine gammaherpesvirus 68 (MHV68) LANA (mLANA) is critical for efficient virus replication and the establishment of latent infection following intranasal inoculation. To test whether the initial host immune response limits the capacity of mLANA-null virus to traffic to and establish latency in the spleen, we infected type I interferon receptor knockout (IFN-α/βR
−/−
) mice via intranasal inoculation and observed the presence of viral genome-positive splenocytes at day 18 postinfection at approximately 10-fold-lower levels than in the genetically repaired marker rescue-infected mice. However, no mLANA-null virus reactivation from infected IFN-α/βR
−/−
splenocytes was observed. To more thoroughly define a role of mLANA in MHV68 infection, we evaluated the capacity of an mLANA-null virus to establish and maintain infection apart from restriction in the lungs of immunocompetent mice. At day 18 following intraperitoneal infection of C57BL/6 mice, the mLANA-null virus was able to establish a chronic infection in the spleen albeit at a 5-fold-reduced level. However, as in IFN-α/βR
−/−
mice, little or no virus reactivation could be detected from mLANA-null virus-infected splenocytes upon explant. An examination of peritoneal exudate cells (PECs) following intraperitoneal inoculation revealed nearly equivalent frequencies of PECs harboring the mLANA-null virus relative to the marker rescue virus. Furthermore, although significantly compromised, mLANA-null virus reactivation from PECs was detected upon explant. Notably, at later times postinfection, the frequency of mLANA-null genome-positive splenocytes was indistinguishable from that of marker rescue virus-infected animals. Analyses of viral genome-positive splenocytes revealed the absence of viral episomes in mLANA-null infected mice, suggesting that the viral genome is integrated or maintained in a linear state. Thus, these data provide the first evidence that a LANA homolog is directly involved in the formation and/or maintenance of an extrachromosomal viral episome
in vivo
, which is likely required for the reactivation of MHV68.
Functional and Genetic Studies of the Substrate Specificity of Coronavirus Infectious Bronchitis Virus 3C-Like Proteinase
Authors: Fang Shouguo , Shen Hongyuan , Wang Jibin , Tay Felicia P. L. , Liu Ding Xiang
Published: May 2010

Coronavirus (CoV) 3C-like proteinase (3CLpro), located in nonstructural protein 5 (nsp5), processes the replicase polyproteins 1a and 1ab (pp1a and pp1ab) at 11 specific sites to produce 12 mature nonstructural proteins (nsp5 to nsp16). Structural and biochemical studies suggest that a conserved Gln residue at the P1 position is absolutely required for efficient cleavage. Here, we investigate the effects of amino acid substitution at the P1 position of 3CLpro cleavage sites of infectious bronchitis virus (IBV) on the cleavage efficiency and viral replication by
in vitro
cleavage assays and reverse genetic approaches. Our results demonstrated that a P1-Asn substitution at the nsp4-5/Q2779, nsp5-6/Q3086, nsp7-8/Q3462, nsp8-9/Q3672, and nsp9-10/Q3783 sites, a P1-Glu substitution at the nsp8-9/Q3672 site, and a P1-His substitution at the nsp15-16/Q6327 site were tolerated and allowed recovery of infectious mutant viruses, albeit with variable degrees of growth defects. In contrast, a P1-Asn substitution at the nsp6-7/Q3379, nsp12-13/Q4868, nsp13-14/Q5468, and nsp14-15/Q5989 sites, as well as a P1-Pro substitution at the nsp15-16/Q6327 site, abolished 3CLpro-mediated cleavage at the corresponding position and blocked the recovery of infectious viruses. Analysis of the effects of these lethal mutations on RNA synthesis suggested that processing intermediates, such as the nsp6-7, nsp12-13, nsp13-14, nsp14-15, and nsp15-16 precursors, may function in negative-stranded genomic RNA replication, whereas mature proteins may be required for subgenomic RNA (sgRNA) transcription. More interestingly, a mutant 3CLpro with either a P166S or P166L mutation was selected when an IBV infectious cDNA clone carrying the Q6327N mutation at the nsp15-16 site was introduced into cells. Either of the two mutations was proved to enhance significantly the 3CLpro-mediated cleavage efficiency at the nsp15-16 site with a P1-Asn substitution and compensate for the detrimental effects on recovery of infectious virus.
Selling orthodontic need: innocent business decision or guilty pleasure?
Authors: Ackerman Marc Bernard
Published: May 2010

The principal objective for most patients seeking orthodontic services is a detectable improvement in their dentofacial appearance. Orthodontic treatment, in the mind of the patient, is something that makes you look better, feel better about yourself, and perhaps enhances your social possibilities, ie, to find a companion or make a positive impression during a job interview. Orthodontics, as a speciality, has collectively advanced the idea that enhanced occlusion (bite) improves the health and longevity of the dentition, and as a result many patients seeking orthodontic services affirm that their secondary goal of treatment is an oral health benefit. It would appear that there is some disparity between the end-user of orthodontic services and the orthodontic provider's perception of what constitutes orthodontic need. The aim of this paper is to examine two contrasting models that characterise how dentists ‘sell’ orthodontic services to patients and to discuss the conflict between professional ethics, practice management and evidence-based decision-making in orthodontic practice.
Moral distress related to ethical dilemmas among Spanish podiatrists
Authors: Losa Iglesias Marta Elena , Becerro de Bengoa Vallejo Ricardo , Salvadores Fuentes Paloma
Published: May 2010

Objectives

To describe the distress experienced by Spanish podiatrists related to ethical dilemmas, organisational matters, and lack of resources.

Design

A 2008 email survey of a representative sample of 485 Spanish podiatrists presenting statements about different ethical dilemmas, values and goals at the workplace.

Results

The response rate was 44.8%. Of all the respondents, 57% described sometimes having to act against their own conscience as distressing. Time constraints is the main cause of moral distress (67%) and 58% of respondents said that they found it distressing that patients have long waits for treatment. Distress related to inadequate treatment due to economical constraints or ineffectiveness was described by 60% of the podiatrists. Another 51% reported that time spent on administration and documentation is distressing. Female doctors experienced more distress than their male colleagues. Last, 36% of respondents reported that their workplace lacked strategies for dealing with ethical dilemmas.

Conclusion

These study results identify moral distress among Spanish podiatrists mainly related to time constraints, patient demands and lack of resources. Moral distress varies with sex and age. Organisational strategies such as moral deliberation and responsive evaluation offer the potential to address moral distress.
Failure to discount for conflict of interest when evaluating medical literature: a randomised trial of physicians
Authors: Silverman Gabriel K , Loewenstein George F , Anderson Britta L , Ubel Peter A , Zinberg Stanley , Schulkin Jay
Published: May 2010

Context

Physicians are regularly confronted with research that is funded or presented by industry.

Objective

To assess whether physicians discount for conflicts of interest when weighing evidence for prescribing a new drug.

Design and setting

Participants were presented with an abstract from a single clinical trial finding positive results for a fictitious new drug. Physicians were randomly assigned one version of a hypothetical scenario, which varied on conflict of interest: ‘presenter conflict’, ‘researcher conflict’ and ‘no conflict’.

Participants

515 randomly selected Fellows in the American College of Obstetricians and Gynecologists' Collaborative Ambulatory Research Network; 253 surveys (49%) were returned.

Main object measures

The self-reported likelihood that physicians would prescribe the new drug as a first-line therapy.

Results

Physicians do not significantly discount for conflicts of interest in their self-reported likelihood of prescribing the new drug after reading the single abstract and scenario. However, when asked explicitly to compare conflict and no conflict, 69% report that they would discount for researcher conflict and 57% report that they would discount for presenter conflict. When asked to guess how favourable the results of this study were towards the new drug, compared with the other trials published so far, their perceptions were not significantly influenced by conflict of interest information.

Conclusion

While physicians believe that they should discount the value of information from conflicted sources, they did not do so in the absence of a direct comparison between two studies. This brings into question the effectiveness of merely disclosing the funding sources of published studies.
Bladder cancer among hairdressers: a meta-analysis
Authors: Harling Melanie , Schablon Anja , Schedlbauer Grita , Dulon Madeleine , Nienhaus Albert
Published: May 2010

Background

Occupational risks for bladder cancer in hairdressers by using hair products have been examined in many epidemiological studies. But owing to small sample sizes of the studies and the resulting lack of statistical power, the results of these studies have been inconsistent and significant associations have rarely been found.

Methods

We conducted a meta-analysis to determine summary risk ratios (SRRs) for the risk of bladder cancer among hairdressers. Studies were identified by a MEDLINE, EMBASE, CENTRAL search and by the reference lists of articles/relevant reviews. Statistical tests for publication bias and for heterogeneity as well as sensitivity analysis were applied. In addition, the study quality and the risk of bias were assessed using six criteria.

Results

42 studies were included and statistically significantly increased risks around 1.3–1.7 were found for all but one analysis. The SRR increased with duration of employment from 1.30 (95% CI 1.15 to 1.48) for ‘ever registered as hairdresser’ to 1.70 (95% CI 1.01 to 2.88) for ‘job held ≥10 years’. No difference was found between the risk for smoking-adjusted data (SRR 1.35, 95% CI 1.13 to 1.61) and no adjustment (SRR 1.33, 95% CI 1.18 to 1.50). Studies assessed as being of high quality (n=11) and of moderate quality (n=31) showed similar SRRs. There was no evidence of publication bias or heterogeneity in all analyses.

Conclusion

In summary, our results showed an increased and statistically significant risk for bladder cancer among hairdressers, in particular for hairdressers in jobs held ≥10 years. Residual confounding by smoking cannot be totally ruled out. Because of the long latency times of bladder cancer it remains an open question whether hairdressers working prior to 1980 and after 1980, when some aromatic amines were banned as hair dye ingredients, have the same risk for bladder cancer.
Focused assessment with sonography in trauma (FAST): should its role be reconsidered?
Authors: Smith Jane
Published: May 2010

Focused assessment with sonography in trauma (FAST) is a limited ultrasound scan performed in the emergency department to assess patients admitted with blunt abdominal trauma (BAT). It is normally undertaken by emergency physicians in order to identify the presence of free fluid, which may represent haemoperitoneum. This potentially allows prompt referral to further imaging, such as a computed tomography (CT) scan, and/or surgery. FAST has been adopted worldwide, and most major trauma centres now have access to an ultrasound machine. Despite the popularity of FAST, there remains a lack of clarity and evidence around any actual contribution to patient survival. An ability to evaluate the true impact of FAST is complicated by factors such as the operator dependence of ultrasound, the improved access, speed and subsequent use of CT (which has reduced the value of FAST in some centres), a lack of standardisation around education and the most effective methods to ensure competence, and variations in the practice, quality and audit of FAST. Enthusiasm for FAST is undiminished among emergency physicians, and in general, point of care ultrasound is escalating in a range of areas, including the emergency department. Small portable and hand held ultrasound machines improve the accessibility of FAST and its benefits are frequently perceived to be an established and essential part of the emergency department service despite its limitations. Since the introduction of FAST, trauma patients are increasingly managed by non-surgical means if haemodynamically stable, and the presence of intraperitoneal fluid does not necessarily influence this decision. Recent developments in multi-detector CT, and in the use of contrast enhanced ultrasound, have broadened the management options for trauma patients, and can support a faster diagnostic pathway than was previously possible. FAST is a limited triage tool, whose actual value in the diagnostic and treatment pathway of patients with BAT remains questionable, and more data are needed to justify its use in the light of these recent developments.
Iron deficiency anaemia can be improved after eradication of Helicobacter pylori
Authors: Huang Xiaolu , Qu Xinhua , Yan Weili , Huang Youliang , Cai Mingci , Hu Bing , Wu Lianming , Lin Hai , Chen Zhiwei , Zhu Cuiying , Lu Lungen , Sun Xu , Rong Lan , Jiang Yibin , Sun Dayu , Zhong Liang , Xiong Ping
Published: May 2010

Background

Recent guidelines on iron deficiency anaemia (IDA) have confirmed the aetiological role of Helicobacter pylori (H pylori), but the relationship still remains controversial.

Methods

Starting in May 2009, searches of the following databases were undertaken: Medline (1966 to April 2009), Embase (1980 to April 2009), the Cochrane library (1800 to June 2008), Cochrane Central Register of Controlled Trials, Premedline, Healthstar, CBMdisc and the Chinese National Knowledge Infrastructure Database (January 1970 to April 2009). Changes in haemoglobin (Hb) concentrations and serum ferritin (SF) concentrations were recorded for intervention and control groups. The meta-analysis used random effect models and subgroup analyses were performed to explain heterogeneity.

Results

Eight studies met the inclusion criteria. All studies were performed in Asia, an area with a high incidence of IDA and H pylori. The pooled analysis of eight studies showed that H pylori eradication therapy can improve IDA, since changes in Hb and SF concentrations in the intervention groups were higher than in controls. The weighted mean difference (WMD) of Hb was 12.88 g/l (95% CI 6.03 to 19.74 g/l, p<0.00001); the WMD of SF was 10.05 μg/l (95% CI 5.48 to 14.63 μg/l, p<0.00001).

Conclusions

H pylori eradication therapy combined with iron administration is more effective than iron administration alone for the treatment of IDA. Eradication therapy has different effects on adults and children. Bismuth based triple therapy has a better response in terms of increased Hb and SF concentrations than proton pump inhibitor (PPI) based triple therapy.
Cold-sensitive mutant with defective growth at 5 °C from a psychrotrophic bacterium
Authors: Murray W. D. , Inniss W. E.
Published: May 2010

A cold-sensitive (CS) mutant of the psychrotroph, Bacillus psychrophilus, was obtained by N-methyl-N′-nitro-N-nitrosoguanidine mutagenization and penicillin counterselection. In the presence of citrate, the wild type grew well at both 5 and 20 °C whereas the CS mutant grew well at 20 °C (the permissive temperature) but, at 5 °C (the restrictive temperature), grew at a reduced rate for two to three generations followed by a complete plateau in growth. Upon return of the CS mutant to 20 °C, after a delay of about 40 h, growth resumed at the appropriate rate. The CS mutant exhibited growth rates similar to parental rates on a wide variety of carbon sources at 5 °C, but when Krebs cycle intermediates were used as substrates and in the presence of an equimolar amount of citrate, the typical cold-sensitive growth pattern occurred. Comparison of oxidative phosphorylation in the parent and CS mutant indicated that no phosphorylation occurred at 5 °C in the CS mutant during the plateau in growth. Examination of the effect of temperature on ATPase activity showed that at 5 °C the specific activity of ATPase isolated from the CS mutant grown at 5 °C was 15-fold less than the ATPases isolated from wild-type cells grown at either 5 or 20 °C and 10.5-fold lower than ATPase from CS mutant cells grown at 20 °C. The large reduction in CS mutant ATPase activity at 5 °C appears to be at least partly due to an effect on synthesis since citrate did not inhibit preformed ATPase.
Etude expérimentale de l'élimination des bactériophages en bassin de lagunage
Authors: Walker J. , Leclerc H. , Foliguet J. M.
Published: May 2010

Polluted river water was studied in an experimental lagoon to determine efficiency of removal of bacteriophages injected at the inlet of the lagoon. The bacteriophages were not significantly affected by the purification process and were found to migrate to the outlet in 4 to 5 days. They were detected 143 days after injection although about 80% of the added virus was removed by the lagoon treatment. These results contrast with those obtained with Salmonella, 99.9% of which were removed.
Some properties of the NADP-specific malic enzyme from the moderate Halophile Vibrio Costicola
Authors: Salvarrey Marcela S. , Cazzulo Juan José
Published: May 2010

NADP-specific malic enzyme (EC 1.1.1.40) has been purified about 160-fold from the moderate halophile Vibrio costicola. The enzyme has a molecular weight of about 120 000. The purified enzyme was unstable in dilute solutions but could be stabilised by NaCl or glycerol. NH4Cl or KCl caused maximal activation at 0.1 M, but higher concentrations were inhibitory. NaCl did not activate and was instead a mixed-type inhibitor towards NH4Cl or KCl. The salt concentration affected the kinetic parameters of the reaction. The apparent Km for L-malate reached a minimal value at about 0.1 M salt; the value for NADP, on the other hand, increased continuously with the salt concentration. The reaction also required a divalent cation activator, Mn2+ being better than Co2+ or Mg2+. NADH was a mixed-type inhibitor towards both substrates, whereas oxaloacetate was strictly competitive towards L-malate and non-competitive towards NADP. The inhibition kinetics were sigmoidal for NADH and hyperbolic for oxaloacetate. The malic enzyme from V. costicola was similar to those of a marine Pseudomonas and Halobacterium cutirubrum in kinetic and regulatory properties but showed a response to salts intermediate between those of the latter enzymes.
Physiology of Candida utilis yeast in zinc-limited chemostat culture
Authors: Lawford H. G. , Pik J. R. , Lawford G. R. , Williams T. , Kligerman A.
Published: May 2010

Candida utilis NRRL Y-900 was grown in aerobic continuous culture in a minimal salts medium with sucrose (1% w/v) as the carbon source. Increasing the concentration of zinc in the medium from 2.3 μM to about 30 μM results in an increase in the apparent critical dilution rate from 0.3 to 0.47 h−1, and in the maximum biomass productivity from 1.5 g dry weight per litre per hour (at D = 0.33 h−1) to 2.56 g per litre per hour (at D = 0.45 h−1). The maximum steady-state level of cell-associated zinc (at D = 0.4 h−1) is 4 nmol Zn2+/mg dry weight, during carbon-limited growth, and about 9 nmol Zn2+/mg dry weight when FeCl3 is omitted from the medium. At input zinc concentrations <20 μM, the cellular zinc concentration decreases linearly in proportion to the input zinc concentration and at <4.5 μM Zn2+ the culture becomes zinc-limited. Zinc-limitation results in a decrease in the growth yield Ysucrose from 0.54 to 0.38 g cells/g sucrose consumed, and Y0 from 22 to 13 g cells/g-atom O2, suggesting an altered efficiency of energy metabolism. The composition of the culture biomass with respect to protein and RNA content is not affected by zinc limitation.
Demonstration of a cell-associated, inactive precursor of an exocellular protease produced by Pseudomonas aeruginosa
Authors: Jensen S. E. , Fecycz I. T. , Stemke G. W. , Campbell J. N.
Published: May 2010

The enzymatically active form of protease 1, the major exocellular protein produced by Pseudomonas aeruginosa strain 34362, has been shown to exist exclusively exocellularly with no significant cell-associated activity. However, the presence of a cell-associated, enzymatically inactive protein which is serologically cross-reactive with, and convertible to, active enzyme has been demonstrated. One method of conversion of "precursor" to active enzyme is via limited proteolysis. Two assay systems for precursor were developed, one a radioimmune assay, and the other a proteolytic activation procedure. Localization studies suggest that the cell-associated precursor resides primarily in the envelope (periplasmic) fraction, and that the association while more tenacious than classical periplasmic enzymes is still an ionic rather than a covalent one. Kinetics of production studies showed the precursor to be synthesized early in the growth cycle and to accumulate prior to the rapid release of the active enzyme. Molecular weight studies showed only slight changes produced upon activation.
Characterization of leptospiral catalase and peroxidase
Authors: Corin Robert E. , Cox C. D.
Published: May 2010

Peroxidase from Leptospira biflexa strain B-16 and catalase from Leptospira interrogans canicola Hond Utrecht were characterized and compared and both appeared to be heme enzymes as judged by their inhibition profiles and rapid inactivation during catalysis. Neither enzyme exhibited monovalent or divalent cation requirements. Dialysis of cell-free extracts resulted in loss of peroxidase activity but catalase was unaffected by this procedure. Peroxidase had a Km for H2O2 of 12.5 μM while catalase had a Km of 70 mM for H2O2. Catalase and peroxidase were physically separated by sedimentation in linear sucrose gradients. The specific activities of each enzyme seemed to be a function of the state of growth at which the cells were harvested and both enzymes were found associated with membranes, peroxidase by hydrophobic and catalase by ionic interactions. Speculative deductions are presented concerning the phylogenetic interrelationships of both enzymes as well as their significance in the biology and pathogenicity of leptospires.
The effect of cortisol on glycogen and fructose-1, 6-bisphosphatase in baby hamster kidney cells infected with Chlamydia trachomatis
Authors: Reed Stella I. , Hann William D.
Published: May 2010

This study was designed to assay changes in glycogen synthesis which may occur as a result of cortisol treatment of chlamydial-infected cells. Monolayers of baby hamster kidney (BHK) cells, unlabeled and prelabeled with [6-14C]glucose, were treated with various concentrations of cortisol before (pretreated) or during (post-treated) infection with Chlamydia trachomatis. At designated times after absorption, the cells were harvested and assayed for total glycogen and 14C accumulation in glycogen. The total amount of glycogen accumulated in cells during the period of greatest chlamydial glycogen synthesis (36 h) was not affected by cortisol treatment. Cortisol treatment appeared to have retarded the accumulation of glycogen in treated infected cells until 30 h after infection. Treated infected cells prelabeled with [6-14C]glucose accumulated a greater amount of 14C in glycogen than untreated infected cells. All cortisol-treated, infected cells exhibited elevated levels of fructose-1, 6-bisphosphatase activity, whereas untreated infected cells did not. The hypothesis that cortisol affects chlamydia multiplication by altering the intracellular environment of the host cell is compatible with the results obtained.
The lipid components of Candida boidinii and Hansenula polymorpha grown on methanol
Authors: Rattray James B. M. , Hambleton James E.
Published: May 2010

The lipid contents of Candida boidinii and Hansenula polymorpha grown on 2% glucose were low. Increased quantities were present in C. boidinii grown on 1 or 4% methanol and in H. polymorpha on 1% methanol. The lipid compositions of both yeasts were characterized by low levels of triacylglycerol and high contents of unsaturated fatty acid and phospholipid. Growth on methanol did not affect the quantity of total phospholipid in C. boidinii, but resulted in a decreased value for H. polymorpha grown on 4% methanol. Modification of the phospholipid composition of both yeasts involved a general increase in the phosphatidylserine–phosphatidylinositol levels at the expense of phosphatidylcholine. The possible relationship between the phospholipid component and the development of membranous systems accompanying growth on methanol has been considered.
Ultrastructure of the cell wall of a Synechocystis strain
Authors: Lounatmaa K. , Vaara T. , Österlund K. , Vaara M.
Published: May 2010

The ultrastructure of the cell wall of a Synechocystis strain, isolated from the Gulf of Finland, was studied using several electron microscopic techniques. This cyanobacterium has numerous projections which were observed to penetrate the cell wall complex. An additional layer (AL) was associated with the outer membrane. An additional external wall layer (EL) was connected to the outer membrane complex by thin fibers as revealed by ruthenium red staining. A hexagonal arrangement of the subunits in the additional external wall layer with a lattice constant of 15.5 nm was found.
The presence of two neuraminidases in an influenza virus
Authors: Arora D. J. S. , Hill-Schubert J. , Vincent L.
Published: May 2010

The wild type influenza strain A/Aichi/2/68 (H3N2), when disrupted with SDS and electrophoresed on cellulose acetate paper, yielded two separate neuraminidases, NA(H+) and NA(H−). These enzymes after extraction were biologically active and possessed different specific activities. Enzyme NA(H+) possessed neuraminidase as well as hemagglutinin activities whereas enzyme NA(H−) demonstrated only neuraminidase activity. Similar results were obtained when the Aichi strain was treated with Tween–ether and the two enzymes were separated by affinity chromatography. Techniques used failed to separate the hemagglutinin activity from neuraminidase NA(H+). These results suggest that the dual activity present in enzyme NA(H+) may be characteristic of this protein. Both enzymes are antigenically different and are apparently present as distinct entities in the Aichi strain. Experiments showed that only enzyme NA(H−) of the Aichi strain was incorporated into the hybrid X-32 virus during genetic recombination.
Lethal effect of polymyxin B sulfate in experimental Proteus rettgeri infection in mice
Authors: Bannatyne Robert M. , Cheung Rose
Published: May 2010

The mouse model of intraperitoneal sepsis with Proteus rettgeri was used to evaluate the anti-endotoxic effect of polymyxin B sulfate. An unexpected reversal of the usual protective effect of polymyxin in experimental enterobacterial sepsis was observed in which the lethality of the infection was enhanced.
Effect of chlorpromazine on phototactic behavior in Chlamydomonas
Authors: Hirschberg Rona , Hutchinson William
Published: May 2010

Chlorpromazine, an antipsychotic drug, causes a light intensity dependent reversal of phototaxis in the green alga Chlamydomonas reinhardi. At moderate light intensity, drug-treated cells swim away from the light (negative phototaxis) while untreated cells swim toward it (positive phototaxis). At low light, both treated and untreated cells exhibit normal positive phototactic responses. It appears that light and chlorpromazine may affect a common control system for phototaxis.
Purification and characterization of rhodanese from Acinetobacter calcoaceticus
Authors: Vandenbergh Peter A. , Berk Richard S.
Published: May 2010

Rhodanese (thiosulfate: cyanide sulfur transferase, EC 2.8.1.1) was found to be constitutively present as an intracellular enzyme in Acinetobacter calcoaceticus. The soluble enzyme was purified 40.9-fold by a procedure which included ultracentrifugation, ethanol precipitation, CM-Sephadex batchwise separation, QAE-50 ion exchange chromatography, and sucrose density gradient ultracentrifugation. The enzyme had a molecular weight of approximately 35 000 with a pH optimum of 8–8.5. Activity was substantially enhanced by supplements of 2-mercaptoethanol and to a lesser extent by cysteine–HCl or reduced glutathione. No degradation of the enzyme into smaller subunits was observed when treated with 2-mercaptoethanol.
Characterization of a bacterium of the genus Azospirillum from cellulolytic nitrogen-fixing mixed cultures
Authors: Wong Peter P. , Stenberg Nancy E. , Edgar Linda
Published: May 2010

A bacterium with the taxonomic characteristics of the genus Azospirillum was isolated from cellulolytic N2-fixing mixed cultures. Its characteristics fit the descriptions of both Azospirillum lipoferum (Beijerinck) comb. nov. and Azospirillum brasilense sp. nov. It may be a variant strain of A. lipoferum. In mixed cultures with cellulolytic organisms, the bacterium grew and fixed N2 with cellulose as a sole source of energy and carbon. The mixed cultures used cellulose from leaves of wheat (Triticum aestivum L.), corn (Zea mays L.), and big bluestem grass (Andropogon gerardii Vitm). Microaerophilic N2-fixing bacteria of the genus Azospirillum, such as the bacterium we isolated, may be important contributors of fixed N2 in soil with partial anaerobiosis and cellulose decomposition.
Distribution of viable marine bacteria in neritic seawater around Japan
Authors: Kogure Kazuhiro , Simidu Ushio , Taga Nobuo
Published: May 2010

The direct viable count (DVC) method of determining the number of living bacteria in natural seawater was applied to samples collected from areas around Japan ranging from polluted to oligotrophic. In summer, the DVC comprised 1.5–39.8% (mean, 11.2%) of the total direct count (TDC) in Tokyo Bay, which was highly eutrophic. In offshore areas (Sagami Bay and the Kuroshio region), the percentages ranged from 0.7 to 7.9 (mean, 2.8%). In winter, slightly higher percentages were observed in Sagami Bay. The majority of DVC cells were free-living. The distribution of bacteria correlated closely with particulate or dissolved organic matter.
Persistence of Pseudomonas aeruginosa in chlorinated swimming pools
Authors: Seyfried Patricia L. , Fraser David J.
Published: May 2010

Various types of swimming pools were investigated for the quantitative isolation of Pseudomonas aeruginosa. Incidence of the organism increased when the free chlorine residual dropped below 0.4 mg/L in pool water which had a pH of 6.9–7.8. As the water pH became more alkaline the efficiency of disinfection decreased. Excessive slime production caused certain strains to become more resistant to chlorine treatment. Immunotyping and phage typing, used to study the dynamics of P. aeruginosa populations in swimming pool waters, demonstrated that high densities of the organism consisted mainly of single predominant strains.
Purification and properties of polygalacturonic acid trans-eliminase from Bacillus stearothermophilus
Authors: Karbassi A. , Vaughn R. H.
Published: May 2010

A strain of thermophilic bacteria, Bacillus stearothermophilus, with pectolytic activity has been isolated. It produced an endo-polygalacturonic acid trans-eliminase (endo-PATE, EC 4.2.2.1) extracellularly when grown at 65 °C on a pectic acid medium. The PATE was purified 62-fold by the rapid affinity chromatographic method on a Sepharose–polygalacturonamide linked matrix. The absorbed PATE was eluted from the column with a continuous gradient of 0–10−3 M ethylenediaminetetraacetic acid (EDTA) in phosphate buffer at pH 7.6.The endo-PATE of this organism was much more heat stable than similar enzymes from the mesophilic Bacillus polymyxa and the thermotolerant Bacillus pumilus. The maximum activity of the enzyme occurred at 70 °C. With pectic acid as the substrate, the endo-PATE had an optimal pH of 9.0, the highest optimal pH compared with those of similar enzymes from other species of the genus.The molecular weight of the endo-PATE, as determined by chromatography on a Sephadex G-100 gel column, was 24 000.
Characterization of an Escherichia coli mutant which utilizes glycerol in the absence of cyclic adenosine monophosphate
Authors: Fraser Ann D. E. , Yamazaki Hiroshi
Published: May 2010

The aerobic catabolism of glycerol depends on the expression of the glpK operon specifying a glycerol kinase and the glpD operon specifying an sn-glycerol-3-phosphate (G3P) dehydrogenase. It has not been clearly established how the expression of these operons is dependent on adenosine 3′,5′-cyclic monophosphate (cAMP). We have isolated a promoterlike mutant (CA8306B) which, owing to a mutation in the glpK operon, can utilize glycerol in the absence of cAMP. Glycerol kinase and G3P dehydrogenase are inducible in CA8306B and its wild-type parent CA8000. The induced level of glycerol kinase in CA8306B is 30% that of CA8000and this level is increased fivefold by the addition of cAMP. However, the induced level of G3P dehydrogenase in CA8306B is similar to that of CA8000 and is unaffected by cAMP addition. These results suggest that the promotion of the glpK operon requires cAMP whereas the promotion of the glpD operon does not.
Relationships between selected strains of typical and atypical Aeromonas salmonicida, Aeromonas hydrophila, and Haemophilus piscium
Authors: Paterson W. D. , Douey D. , Desautels D.
Published: May 2010

Serological analyses of typical and atypical Aeromonas salmonicida divided the representative strains into two distinguishable groups based on their antigenic composition. However, the serological groupings do not coincide with divisions constructed on the basis of physiological reactions. All of the A. salmonicida strains and the two A. hydrophila strains examined share at least one antigen and are sensitive to A. salmonicida bacteriophage 40 RR2.8t. These data reinforce the reasons for placing these two species in the genus Aeromonas. Haemophilus piscium, the causative agent of ulcer disease, was serologically indistinguishable from A. salmonicida and sensitive to A. salmonicida bacteriophages. This information, in addition to published H. piscium DNA studies, suggests this organism is actually an atypical A. salmonicida; more H. piscium isolates should be characterized to confirm this identification.
Differentiation of Rhizobium japonicum strain derivatives by antibiotic sensitivity patterns, lectin binding, and utilization of biochemicals
Authors: Meyer Michael C. , Pueppke Steven G.
Published: May 2010

Several strains of Rhizobium japonicum have been reported to consist of mixtures of stable derivatives having distinct colony morphologies and physiological characteristics. We isolated derivatives from strains of R. japonicum and systematically compared them with previously isolated derivatives with respect to the utilization of biochemicals, antibiotic sensitivity, and soybean lectin binding. With the exception of a pair of derivatives from 3I1b 110, one of which utilized pyruvate and one of which did not, sibling derivatives had essentially identical biochemical utilization patterns. The sibling derivatives of parental strains 3I1b 110 and 3I1b 140 exhibited marked variation in their sensitivities to several antibiotics, including gentamicin, sulfamethoxazole, and tetracycline. Compared with the derivatives with small colony morphology, derivatives with large colony morphology were in general more sensitive to these antibiotics. With one exception, the binding of soybean lectin to the derivatives was quantitatively the same as that to the parental strain. The anomaly was 110-Y which, in contrast to its parental strain and sibling derivatives, failed to bind detectable amounts of the lectin. 110-Y, as well as all the other derivatives and parental strains, nodulated Disoy soybean.
AMP metabolism in the marine bacterium Beneckea natriegens
Authors: Pickard Michael A. , Whelihan Jo Anne , Knowles Christopher J.
Published: May 2010

The catabolism of AMP by preparations from Beneckea natriegens has been reexamined. In the absence of ATP, cell-free extracts catabolized AMP via adenosine to inosine. When ATP was present, adenylate kinase converted AMP to ADP, lowering the rate of AMP catabolism. Particle-free supernatants (225 000 × g) metabolized AMP alone slowly, but adenylate kinase was active when ATP was added. Washed particulate fractions contained AMP nucleotidase activity which converted AMP to adenosine; in the presence of ATP, adenosine formation was reduced by residual adenylate kinase associated with the particulate fraction. IMP was not detected as a metabolite in these experiments.
The effect of trans-[Rh(4-ethylpyridine)4Cl2]Cl∙2H2O on nucleic acid and protein syntheses in Escherichia coli
Authors: Seeman S. L. , Jack T. R.
Published: May 2010

The effect of the transition metal compound trans-[Rh(4-ethylpyridine)4Cl2]Cl∙2H2O on the syntheses of DNA, RNA, and protein has been investigated for an auxotrophic bacterial strain, Escherichia coli JS-1, incapable of thymidine, uridine, and histidine syntheses. At low concentration (7.4 × 10−6 M), this rhodium complex interferes with normal cell division and induces the formation of filaments comparable to those observed in the presence of the cis-(NH3)2PtClx antitumour agents. Once the suppressed growth rate of the filamenting cells has been taken into account, the rhodium compound is found not to alter macromolecular synthesis. Again this is consistent with similar observations made for the platinum compounds.
A simple and rapid method for qualitative and quantitative study of the fungal flora of leaves
Authors: Langvad Finn
Published: May 2010

A simple and rapid method for microscopical and cultural examination of leaf mycoflora is described. Scotch tape with adhesive on both sides is attached to microscope slides. An impression of the leaf surface is made by pressing the leaf onto the tape. After staining with lactophenol–aniline blue and mounting in AH water-soluble mounting medium the preparation is ready for examination under the microscope. Impressions can also be used for cultural studies by covering them with a thin film of agar medium and incubating them in a moist chamber for 2–3 days. These slide cultures will show both the number and the pattern of distribution of the fungi originally present on the leaf surface.
Assimilation of selenate and selenite by Salmonella typhimurium
Authors: Brown T. A. , Shrift A.
Published: May 2010

A comparative study of selenate and selenite assimilation by Salmonella typhimurium revealed that selenite was not transported by the sulphate permease. Selenite uptake could be detected both in wild-type cells repressed for sulphate transport and in mutants that lacked a functional sulphate permease. In contrast, selenate was assimilated by the same process as was sulphate; selenate transport was repressed under the same conditions which repressed sulphate uptake and was absent in permeaseless mutants. Selenite transport was absent if cells were glucose starved or treated with either azide or p-chloromercuribenzoate. The pH optimum was between pH 6 and pH 7; transport was most rapid at 36 °C. The double reciprocal plot for selenite transport at different substrate concentrations was biphasic: between 10 and 50 μM SeO32− the apparent Km was 37.8 μM, and at higher concentrations, 2.87 mM. The transport rate for 0.1 mM SeO32− was significantly stimulated by sulphite concentrations up to 5.0 mM, with a maximum at 3.0 mM SO32−. The results establish a selenite transport process, in S. typhimurium, as the initial step of an assimilatory pathway selective for selenium.
Slow growing Bacillus subtilis: deoxyribonucleic acid replication in turbidostat cultures
Authors: Shay L. K. , Copeland J. C.
Published: May 2010

Comparisons of slowly growing Bacillus subtilis cultures grown in batch culture, a chemostat, and a turbidostat were made. Cultures in a turbidostat were found to grow optimally and to be in balanced growth. The duration of deoxyribonucleic acid (DNA) replication, or C period, was estimated by means of an autoradiographic analysis, a genetic analysis, and determinations of DNA per cell. These measurements were performed on cells growing at different slow rates. The results showed that the C period increased with increasing generation times, but the increase in duration of the C period was not proportional to the increase in generation time.