bluuebunny/crossref_metadata_2025 huggingface dataset:
The Threat of Funding Cuts for Graduate Medical Education: Survey of Decision Makers
Authors: Kozak Richard J. , Kazzi A. Antoine , Langdorf Mark I. , Martinez Carlos T. J.
Published: September 2008

Objective: To assess the potential actions of medical school deans, graduate medical education (GME) committee chairs, and hospital chief executive officers (CEOs) regarding future funding reductions for residency training. Specifically, institutions with emergency medicine (EM) residencies were surveyed to see whether EM training was disproportionally at risk for reductions.

Methods: An anonymous 2‐page survey was used. Ninety‐eight EM residency programs were identified using the American Medical Association Graduate Medical Education Directory 1994–95. Seventy deans, 102 GME chairs, and 97 hospital CEOs were identified. The survey posed a hypothetical 25% forced reduction in residency positions and asked the decision makers for their responses. Options included: 1) proportional reductions of training positions from all residencies, 2) proportional reductions in either primary care or specialty residency positions, or 3) reduction or elimination of specific training programs. The survey asked for a first and second choice of residencies to be reduced or eliminated from an alphabetical list of 17. The survey elicited explanations for each program reduction.

Results: 200 (74%) of 269 surveys were returned. Eighty‐four responders selected specific residencies to be reduced or eliminated. EM was selected 8 times, making EM the seventh most vulnerable residency to be targeted for reductions. The decision makers who selected proportional reductions chose to reduce across all residencies 32 times, among only the specialty residencies 129 times, and among only the primary care residencies 3 times.

Conclusions: In the setting of anticipated residency cuts, favored proportional reductions in specialty residencies would likely affect EM training. However, most GME decision makers with an existing EM residency program do not consider the EM residency a top choice to be reduced or eliminated.
Wound Botulism Associated with Black Tar Heroin
Authors: Anderson Michael W. , Sharma Kanika , Feeney Colin M.
Published: September 2008

The incidence of wound botulism is increasing and the epidemiology of the disease is changing. The majority of new cases are associated with injection drug use, in particular, the use of Mexican black tar heroin. This case report and discussion of wound botulism illustrate the following important points: Dysphagia, dysphonia, diplopia, and descending paralysis, in association with injection drug use, should alert the treating physician to the possibility of wound botulism. In such patients, the onset of respiratory failure may be sudden and without clinically obvious signs of respiratory weakness. For the reported patient, maximum inspiratory force measurements were the only reliable indicator of respiratory muscle weakness. This is a measurement not routinely performed in the ED, but may prove essential for patients with suspected wound botulism. To minimize the effect of the botulinum toxin and to decrease length of hospital stay, antitoxin administration and surgical wound debridement should be performed early.
Vasopressin Can Increase Coronary Perfusion Pressure during Human Cardiopulmonary Resuscitation
Authors: Morris Daniel C. , Dereczyk Barnard E. , Grzybowski Mary , Martin Gerard B. , Rivers Emanuel F! , Wortsrnan Jacobo , Amico Janet A.
Published: September 2008

Objectives: To determine the hemodynamic effect of vasopressin on coronary perfusion pressure (CPP) in prolonged human cardiac arrest.

Methods: A prospective, open‐label clinical trial of vasopressin during cardiac resuscitation was performed. Ten patients presenting in cardiac arrest initially received resuscitative measures by emergency physicians according to Advanced Cardiac Life Support (ACLS) gcidelines. A central venous catheter for fluid and drug administration and a femoral artery catheter for measurement of CPP (aortic minus right atrial relaxation phase pressures) were placed. When each patient was deemed nonsalvageable, 1.0 mg epinephrine was given and CPP was measured for 5 minutes, followed by a dose of vasopressin (1.O Ukg). CPP measurements were continued for another 5 minutes.

Results: The mean duration of cardiac arrest (out‐of‐hospital interval plus duration of ED ACLS) was 39.6 ± 16.5 min. There was no improvement in CPP after 1.0 mg of epinephrine. Vasopressin administration resulted in a significant increase of CPP in 4 of the 10 patients. Patients responding to vasopressin had a mean increase in CPP of 28.2 ± 16.4 mm Hg (range: 10–51.5), with these peak increases occurring at 15 seconds to 4 minutes after administration. The increases in the vasopressin levels after administration did not differ between the responders and nonresponders.

Conclusions: In this human model of prolonged cardiac arrest, 40% of the patients receiving vasopressin had a significant increase in CPP. This pilot study suggests that investigation of earlier use of vasopressin as a therapeutic alternative in the treatment of cardiac arrest is warranted.
Specialization on Guadua Bamboo Seeds by Three Bird Species in the Atlantic Forest of Argentina
Authors: Areta Juan I. , Bodrati Alejandro , Cockle Kristina
Published: September 2008

Most bamboos are semelparous. Their synchronous masting events occur on a cycle of 3–120 yr and represent an extremely pulsed resource for granivorous birds. Although many bird species feed occasionally on bamboo seeds, there are constraints to specializing on such a fluctuating resource and few bird species are known to specialize on bamboo seeds. Three of these bird species are endemic to the Atlantic forest of South America: the purple‐winged ground‐dove Claravis godefrida, buff‐fronted seedeater Sporophila frontalis, and Temminck's seedeater Sporophila falcirostris. All three species are irregularly recorded in the province of Misiones, Argentina. We compared the temporal and spatial patterns of records of these birds in Misiones to masting events of the five common bamboos: yatevóGuadua trinii, takuaruzúGuadua chacoensis, takuapíMerostachys claussenii, pitinga Chusquea tenella, and takuarembóChusquea ramosissima. All bird records coincided with times and places where Guadua bamboos (G. trinii and G. chacoensis) were known or estimated to have seeds. None of the bird species occurred during masting events of Merostachys or Chusquea, unless Guadua was also masting. We discuss relevant ecological and morphological features of the birds that might bear on their association with Guadua bamboos and that might be key to their conservation.
Experimental Assessment of Factors Limiting Seedling Recruitment of an Amazonian Understory Herb
Authors: Schleuning Matthias , Huamán Vicky , Matthies Diethart
Published: September 2008

Understory herbs are an important and species‐rich component of tropical forests, but little is known about factors limiting recruitment of these herbs. In a Peruvian flood plain forest, we studied seedling recruitment of the widespread clonal herb Heliconia metallica. We analyzed natural recruitment and experimentally added seeds, excluded predators and removed the understory vegetation at occupied and unoccupied sites to test whether seed limitation, predation, disturbance, and the presence of mature conspecific plants influence seedling recruitment. The number of naturally recruited seedlings was higher at flooded sites and close to flowering H. metallica ramets. Predation caused considerable seed loss shortly after sowing. Seed survival strongly increased with the openness of a site, but was not affected by the presence of mature conspecifics. Seed addition increased the number of seedlings at both occupied and unoccupied sites. Two years after sowing, the number of established seedlings and their size increased with light availability at a site. In experimentally disturbed plots, light availability, seedling establishment, and survival were higher. The effect of disturbance on seedling survival was stronger at occupied sites, probably due to strong light competition from mature H. metallica plants. Herbivore damage on leaves of seedlings was lower at occupied sites, but seedlings grew faster at unoccupied sites. We conclude that seedling recruitment of H. metallica depends on natural disturbance and is limited by both seed availability and the presence of mature conspecific plants.
Temple, Economy, and Religion in First Millennium Babylonia
Authors: Kozuh Michael
Published: September 2008

The study of economy and religion in Babylonia during the first millennium bc is primarily that of two well‐documented temples, the Eanna temple of the city of Uruk and the Ebabbar of Sippar. The administrative archives of those temples – consisting of tens of thousands of cuneiform texts – allow us to understand parts of the temple economy in great detail, while at the same time this abundance of material frustrates traditional approaches to Babylonian religion. This essay aims in general to emphasize that Babylonian temples were large‐scale, multifaceted religious institutions. Capitalizing on recent advancements in our technical understanding of the temple economy, it integrates these advancements into issues of broader religious, historical, intellectual, and economic significance. In particular, it stresses three points: first, the temples’ amalgamated ruling structure fostered institutional permanence and should therefore be understood as a challenge to the ‘temple‐as‐household’ metaphor; second, large‐scale centralization of wealth in the temples was necessary for advancements in Babylonian learned culture (especially in astronomy and mathematics); and, finally, the centralization of manpower in the temples gave them particular advantages in the politics of the first millennium bc. In the end, I argue that all of these are in fact manifestations of Babylonian religion in themselves.
Harvey Cushing and the regulation of blood pressure in giraffe, rat and man: introducing ‘Cushing's mechanism’
Authors: Paton J. F. R. , Dickinson C. J. , Mitchell G.
Published: September 2008

The fundamental mechanism that underlies essential hypertension is a high total peripheral resistance. We review here possible origins of high total peripheral resistance in physiologically hypertensive giraffes, spontaneously hypertensive rats and humans with essential hypertension. We propose that a common link could be reduced brainstem perfusion, as first suggested by Cushing in 1901. Any tendency towards reduction of cerebral blood flow to the cardiovascular control centres in rest and sleep will be prevented by activation of a response arising in the brainstem. The response will proportionately increase systemic blood pressure and return cerebral blood flow to a new homeostatic level. New evidence we review here supports this idea and leads us to suggest that central regulation of blood pressure has two components: the classic Cushing's response, which is a terminal event, and a Cushing's mechanism, which is a physiological mechanism for long‐term control of mean arterial pressure. In giraffes, Cushing's mechanism is activated by increasing neck length during growth and subsequent gravitational hypotension that stimulates a rise in basal arterial blood pressure. In man and rats, the mechanism is activated by narrowing of the arteries supplying the brainstem. If we are correct, future successful treatment of essential hypertension in man will include methods of reducing cerebral arterial resistance.
Myonuclear domain size and myosin isoform expression in muscle fibres from mammals representing a 100 000‐fold difference in body size
Authors: Liu Jing‐Xia , Höglund Anna‐Stina , Karlsson Patrick , Lindblad Joakim , Qaisar Rizwan , Aare Sudhakar , Bengtsson Ewert , Larsson Lars
Published: September 2008

This comparative study of myonuclear domain (MND) size in mammalian species representing a 100 000‐fold difference in body mass, ranging from 25 g to 2500 kg, was undertaken to improve our understanding of myonuclear organization in skeletal muscle fibres. Myonuclear domain size was calculated from three‐dimensional reconstructions in a total of 235 single muscle fibre segments at a fixed sarcomere length. Irrespective of species, the largest MND size was observed in muscle fibres expressing fast myosin heavy chain (MyHC) isoforms, but in the two smallest mammalian species studied (mouse and rat), MND size was not larger in the fast‐twitch fibres expressing the IIA MyHC isofom than in the slow‐twitch type I fibres. In the larger mammals, the type I fibres always had the smallest average MND size, but contrary to mouse and rat muscles, type IIA fibres had lower mitochondrial enzyme activities than type I fibres. Myonuclear domain size was highly dependent on body mass in the two muscle fibre types expressed in all species, i.e. types I and IIA. Myonuclear domain size increased in muscle fibres expressing both the β/slow (type I; r= 0.84, P < 0.001) and the fast IIA MyHC isoform (r= 0.90; P < 0.001). Thus, MND size scales with body size and is highly dependent on muscle fibre type, independent of species. However, myosin isoform expression is not the sole protein determining MND size, and other protein systems, such as mitochondrial proteins, may be equally or more important determinants of MND size.
Age‐related analysis of insulin resistance, body weight and arterial pressure in the Zucker fatty rat
Authors: Di Nardo Francesco , Burattini Roberto , Cogo Carla E. , Faelli Emanuela , Ruggeri Piero
Published: September 2008

The evolution with ageing of insulin resistance, body weight (BW) and mean arterial pressure (MAP) was studied in a group of Zucker fatty rats (ZFRs, n= 22), between 7 and 16 weeks of age, compared with an age‐matched control group of Zucker lean rats (ZLRs, n= 22). The minimal model of glucose kinetics was applied to estimate glucose effectiveness, SG, and insulin sensitivity, SI, from insulinaemia and glycaemia measured during a 70 min intravenous glucose tolerance test. No correlation was found between SG and age in both ZFR and ZLR groups. No significant changes in mean SG between the two groups indicated no alteration of glucose‐mediated glucose disposal. Estimates of SI from individual ZFRs were independent of age and, on average, showed 83% reduction (P < 0.001) compared with the ZLR group. Despite the lack of alteration of SI with age, the ZFR group showed an age‐related increase of MAP, which correlated with increasing BW (r = 0.71 and P < 0.001). These results support the hypothesis that in our ZFRs, as a suitable genetic model of obesity and hypertension, insulin resistance is fully established at the age of 7 weeks and remains practically unaltered until at least the sixteenth week. An age‐related increase in arterial pressure, observed in this strain, relates more properly to increasing BW, rather than insulin resistance. Development of hypertension with increasing age and BW may result from an enhanced insulin‐mediated activity of the sympathetic nervous system, as observed in our previously reported study.
Inactivation of
Mycobacterium avium
Complex by UV Irradiation
Authors: Shin Gwy-Am , Lee Jung-Keun , Freeman Robert , Cangelosi Gerard A.
Published: September 2008

The effectiveness of two major UV technologies against a highly prevalent species of
Mycobacterium avium
complex was investigated. Our study indicates that
M. avium
is much more resistant to UV irradiation than most waterborne pathogens and that it is one of the rare microorganisms that are highly resistant to both chemical and UV disinfection in water.
Microbiological Analysis of Food Contact Surfaces in Child Care Centers
Authors: Cosby Catherine M. , Costello C. A. , Morris W. C. , Haughton B. , Devereaux M. J. , Harte F. , Davidson P. M.
Published: September 2008

A study of six child care centers was conducted to assess the microbiological quality of three food contact surfaces (one food serving surface and two food preparation surfaces) and one non-food contact surface (diaper changing surface) to determine the effectiveness of cleaning and sanitization procedures within the facilities. Aerobic plate counts (APCs) and
Escherichia coli
/coliform counts of 50-cm
2
areas on all surfaces were determined using standard microbiological swabbing methods. Samples were taken three times a day (preopening, lunchtime, and following final cleanup) twice per month for 8 months in each child care center (
n
= 288 sampling times). Mean log APCs over the survey period were 1.32, 1.71, 1.34, 1.96, 1.50, and 1.81 log CFU/50 cm
2
for the six centers. Mean log coliform counts were 0.15, 0.40, 0.33, 1.41, 0.28, and 1.12 CFU/50 cm
2
for the same centers. Coliforms were detected in 283 of 1,149 (24.7%) samples, with counts ranging from 1 to 2,000 CFU/50 cm
2
, while
E. coli
was detected in 18 of 1,149 (1.6%) samples, with counts ranging from 1 to 35 CFU/50 cm
2
. The findings of this study demonstrated that the extent of bacterial contamination was dependent on the center, time of day, and the area sampled. While no direct correlation between contamination and illness can be made, given the high risk of food-borne illness associated with children, microbial contamination of food contact or non-food contact surfaces is an aspect of food safety that requires more attention. Emphasis on training and the development of modified standard sanitation operating procedures for child care centers are needed to reduce potential hazards.
Relative Importance of
Ixodes ricinus
and
Ixodes trianguliceps
as Vectors for
Anaplasma phagocytophilum
and
Babesia microti
in Field Vole (
Microtus agrestis
) Populations
Authors: Bown K. J. , Lambin X. , Telford G. R. , Ogden N. H. , Telfer S. , Woldehiwet Z. , Birtles R. J.
Published: September 2008

The importance of
Ixodes ricinus
in the transmission of tick-borne pathogens is well recognized in the United Kingdom and across Europe. However, the role of coexisting
Ixodes
species, such as the widely distributed species
Ixodes trianguliceps
, as alternative vectors for these pathogens has received little attention. This study aimed to assess the relative importance of
I. ricinus
and
I. trianguliceps
in the transmission of
Anaplasma phagocytophilum
and
Babesia microti
among United Kingdom field voles (
Microtus agrestis
), which serve as reservoir hosts for both pathogens. While all instars of
I. trianguliceps
feed exclusively on small mammals,
I. ricinus
adults feed primarily on larger hosts such as deer. The abundance of both tick species and pathogen infection prevalence in field voles were monitored at sites surrounded with fencing that excluded deer and at sites where deer were free to roam. As expected, fencing significantly reduced the larval burden of
I. ricinus
on field voles and the abundance of questing nymphs, but the larval burden of
I. trianguliceps
was not significantly affected. The prevalence of
A. phagocytophilum
and
B. microti
infections was not significantly affected by the presence of fencing, suggesting that
I. trianguliceps
is their principal vector. The prevalence of nymphal and adult ticks on field voles was also unaffected, indicating that relatively few non-larval
I. ricinus
ticks feed upon field voles. This study provides compelling evidence for the importance of
I. trianguliceps
in maintaining these enzootic tick-borne infections, while highlighting the potential for such infections to escape into alternative hosts via
I. ricinus
.
Effect of Temperature on the Cannibalistic Behavior of
Bacillus subtilis
Authors: Nandy Subir Kumar , Prasad Vinay , Venkatesh K. V.
Published: September 2008

Bacillus subtilis
resorts to cannibalism to delay sporulation under severe nutritional limitation. We report the effect of temperature on the dynamics of cannibalism demonstrated by
B. subtilis
. A model consisting of a delay differential equation may explain the effect of temperature on the dynamics of cannibalism.
Molecular Microbial Diversity Survey of Sponge Reproductive Stages and Mechanistic Insights into Vertical Transmission of Microbial Symbionts
Authors: Schmitt Susanne , Angermeier Hilde , Schiller Roswitha , Lindquist Niels , Hentschel Ute
Published: September 2008

Many marine sponges, hereafter termed high-microbial-abundance (HMA) sponges, harbor large and complex microbial consortia, including bacteria and archaea, within their mesohyl matrices. To investigate vertical microbial transmission as a strategy to maintain these complex associations, an extensive phylogenetic analysis was carried out with the 16S rRNA gene sequences of reproductive (
n
= 136) and adult (
n
= 88) material from five different Caribbean species, as well as all published 16S rRNA gene sequences from sponge offspring (
n
= 116). The overall microbial diversity, including members of at least 13 bacterial phyla and one archaeal phylum, in sponge reproductive stages is high. In total, 28 vertical-transmission clusters, defined as clusters of phylotypes that are found both in adult sponges and their offspring, were identified. They are distributed among at least 10 bacterial phyla and one archaeal phylum, demonstrating that the complex adult microbial community is collectively transmitted through reproductive stages. Indications of host-species specificity and cospeciation were not observed. Mechanistic insights were provided using a combined electron microscopy and fluorescence in situ hybridization analysis, and an indirect mechanism of vertical transmission via nurse cells is proposed for the oviparous sponge
Ectyoplasia ferox
. Based on these phylogenetic and mechanistic results, we suggest the following symbiont transmission model: entire microbial consortia are vertically transmitted in sponges. While vertical transmission is clearly present, additional environmental transfer between adult individuals of the same and even different species might obscure possible signals of cospeciation. We propose that associations of HMA sponges with highly sponge-specific microbial communities are maintained by this combination of vertical and horizontal symbiont transmission.
The
Bacillus subtilis ydjL
(
bdhA
) Gene Encodes Acetoin Reductase/2,3-Butanediol Dehydrogenase
Authors: Nicholson Wayne L.
Published: September 2008

Bacillus subtilis
is capable of producing 2,3-butanediol from acetoin by fermentation, but to date, the gene encoding the enzyme responsible, acetoin reductase/2,3-butanediol dehydrogenase (AR/BDH), has remained unknown. A search of the
B. subtilis
genome database with the amino acid sequences of functional AR/BDHs from
Saccharomyces cerevisiae
and
Bacillus cereus
resulted in the identification of a highly similar protein encoded by the
B. subtilis ydjL
gene. A knockout strain carrying a
ydjL
::
cat
insertion mutation was constructed, which (i) abolished 2,3-butanediol production in early stationary phase, (ii) produced no detectable AR or BDH activity in vitro, and (iii) accumulated the precursor acetoin in early stationary phase. The
ydjL
::
cat
mutation also affected the kinetics of lactate but not acetate production during stationary-phase cultivation with glucose under oxygen limitation. A very small amount of 2,3-butanediol was detected in very-late-stationary-phase (96-hour) cultures of the
ydjL
::
cat
mutant, suggesting the existence of a second gene encoding a minor AR activity. From the data, it is proposed that the major AR/BDH-encoding gene
ydjL
be renamed
bdhA
.
Immunofluorescence Flow Cytometry Technique for Enumeration of the Brown-Tide Alga,
Aureococcus anophagefferens
Authors: Stauffer Beth A. , Schaffner Rebecca A. , Wazniak Catherine , Caron David A.
Published: September 2008

A new immunologically based flow cytometry (IFCM) technique was developed to enumerate
Aureococcus anophagefferens
, a small pelagophyte alga that is the cause of “brown tides” in bays and estuaries of the mid-Atlantic states along the U.S. coast. The method utilizes a monoclonal antibody conjugated to fluorescein isothiocyanate (FITC-MAb) to label the surface of
A. anophagefferens
cells which are then detected and enumerated by using a flow cytometer. Optimal conditions for FITC-MAb staining, including solution composition, incubation times, and FITC-MAb concentrations, were determined. The FITC-MAb method was tested for cross-reactivity with nontarget, similarly sized, photoautotrophic protists, and the method was compared to an enzyme-linked immunosorbent assay (ELISA) using the same MAb. Comparisons of the IFCM technique to traditional microscopy enumeration of cultures and spiked environmental samples showed consistent agreement over several orders of magnitude (
r
2
> 0.99). Comparisons of the IFCM and ELISA techniques for enumerating cells from a predation experiment showed a substantial overestimation (up to 10 times higher) of the ELISA in the presence of consumers of
A. anophagefferens
, presumably due to egested cell fragments that retained antigenicity, using the ELISA method, but were not characterized as whole algal cells by the IFCM method. Application of the IFCM method to environmental “brown-tide” samples taken from the coastal bays of Maryland demonstrated its efficacy in resolving
A. anophagefferens
abundance levels throughout the course of a bloom and over a large range of abundance values. IFCM counts of the brown-tide alga from natural samples were consistently lower than those obtained using the ELISA method and were equivalent to those of the polyclonal immunofluorescence microscopy technique, since both methods discriminate intact cells. Overall, the IFCM approach was an accurate and relatively simple technique for the rapid enumeration of
A. anophagefferens
in natural samples over a wide range of abundance values (10
3
to 10
6
cells ml
−1
).
Bioaccumulation, Retention, and Depuration of Enteric Viruses by
Crassostrea virginica
and
Crassostrea ariakensis
Oysters
Authors: Nappier Sharon P. , Graczyk Thaddeus K. , Schwab Kellogg J.
Published: September 2008

Crassostrea ariakensis
oysters are under review for introduction into the Chesapeake Bay. However, the human health implications of the introduction have not been fully addressed. This study evaluated rates of bioaccumulation, retention, and depuration of viruses by
Crassostrea virginica
and
C. ariakensis
when the two oyster species were maintained in separate tanks containing synthetic seawater of various salinities (8, 12, or 20 ppt). Oyster bioaccumulation tanks were seeded with 10
3
PFU/ml of hepatitis A virus (HAV), poliovirus, male-specific bacteriophage (MS2), and murine norovirus 1 (MNV-1) and 10
3
PCR units/ml of human norovirus (NoV). After 24 h, depuration commenced as oysters (
n
= 255) were placed in pathogen-free seawater under continuous filtration. Oysters (
n
= 6) were sampled weekly for 1 month from each tank. Viral RNA was recovered using a modified proteinase K, guanidine, and glassmilk method and analyzed by quantitative reverse transcription-PCR. The odds of
C. ariakensis
oysters harboring NoV, MNV-1, or HAV were statistically greater than the odds of
C. virginica
oysters harboring the same viruses (MNV-1 odds ratio [OR], 4.5;
P
= 0.01; NoV OR, 8.4;
P
< 0.001; HAV OR, 11.4;
P
< 0.001). Unlike
C. virginica, C. ariakensis
bioaccumulated and retained NoV, MNV-1, and HAV for 1 month at all salinities. Additionally, the odds of an oyster testing positive for NoV was 25.5 times greater (
P
< 0.001) when the oyster also tested positive for MNV-1. This research helps assess the threat of
C. ariakensis
as a vehicle for viral pathogens due to the consumption of raw oysters and validates the role for MNV-1 as a surrogate for NoV.
Quantitative rRNA-Targeted Solution-Based Hybridization Assay Using Peptide Nucleic Acid Molecular Beacons
Authors: Li Xu , Morgenroth Eberhard , Raskin Lutgarde
Published: September 2008

The potential of a solution-based hybridization assay using peptide nucleic acid (PNA) molecular beacon (MB) probes to quantify 16S rRNA of specific populations in RNA extracts of environmental samples was evaluated by designing PNA MB probes for the generaDechloromonasandDechlorosoma. In a kinetic study with 16S rRNA from pure cultures, the hybridization of PNA MB to target 16S rRNA exhibited a higher final hybridization signal and a lower apparent rate constant than the hybridizations to nontarget 16S rRNAs. A concentration of 10 mM NaCl in the hybridization buffer was found to be optimal for maximizing the difference between final hybridization signals from target and nontarget 16S rRNAs. Hybridization temperatures and formamide concentrations in hybridization buffers were optimized to minimize signals from hybridizations of PNA MB to nontarget 16S rRNAs. The detection limit of the PNA MB hybridization assay was determined to be 1.6 nM of 16S rRNA. To establish proof for the application of PNA MB hybridization assays in complex systems, target 16S rRNA fromDechlorosoma suillumwas spiked at different levels to RNA isolated from an environmental (bioreactor) sample, and the PNA MB assay enabled effective quantification of theD. suillumRNA in this complex mixture. For another environmental sample, the quantitative results from the PNA MB hybridization assay were compared with those from clone libraries.
Localization and Expression of MreB in
Vibrio parahaemolyticus
under Different Stresses
Authors: Chiu Shen-Wen , Chen Shau-Yan , Wong Hin-chung
Published: September 2008

MreB, the homolog of eukaryotic actin, may play a vital role when prokaryotes cope with stress by altering their spatial organization, including their morphology, subcellular architecture, and localization of macromolecules. This study investigates the behavior of MreB in
Vibrio parahaemolyticus
under various stresses. The behavior of MreB was probed using a yellow fluorescent protein-MreB conjugate in merodiploid strain SC9. Under normal growth conditions, MreB formed helical filaments in exponential-phase cells. The shape of starved or stationary-phase cells changed from rods to small spheroids. The cells differentiated into the viable but nonculturable (VBNC) state with small spherical cells via a “swelling-waning” process. In all cases, drastic remodeling of the MreB cytoskeleton was observed. MreB helices typically were loosened and fragmented into short filaments, arcs, and spots in bacteria under these stresses. The disintegrated MreB exhibited a strong tendency to attach to the cytoplasmic membrane. The expression of
mreB
generally declined in bacteria in the stationary phase and under starvation but was upregulated during the initial periods of cold shock and VBNC state differentiation and decreased afterwards. Our findings demonstrated the behavior of MreB in the morphological changes of
V. parahaemolyticus
under intrinsic or extrinsic stresses and may have important implications for studying the cellular stress response and aging.
Characterization of a T7-Like Lytic Bacteriophage (φSG-JL2) of
Salmonella enterica
Serovar Gallinarum Biovar Gallinarum
Authors: Kwon Hyuk-Joon , Cho Sun-Hee , Kim Tae-Eun , Won Yong-Jin , Jeong Jihye , Park Se Chang , Kim Jae-Hong , Yoo Han-Sang , Park Yong-Ho , Kim Sun-Joong
Published: September 2008

φSG-JL2 is a newly discovered lytic bacteriophage infecting
Salmonella enterica
serovar Gallinarum biovar Gallinarum but is nonlytic to a rough vaccine strain of serovar Gallinarum biovar Gallinarum (SG-9R),
S. enterica
serovar Enteritidis,
S. enterica
serovar Typhimurium, and
S. enterica
serovar Gallinarum biovar Pullorum. The φSG-JL2 genome is 38,815 bp in length (GC content, 50.9%; 230-bp-long direct terminal repeats), and 55 putative genes may be transcribed from the same strand. Functions were assigned to 30 genes based on high amino acid similarity to known proteins. Most of the expected proteins except tail fiber (31.9%) and the overall organization of the genomes were similar to those of yersiniophage φYeO3-12. φSG-JL2 could be classified as a new T7-like virus and represents the first serovar Gallinarum biovar Gallinarum phage genome to be sequenced. On the basis of intraspecific ratios of nonsynonymous to synonymous nucleotide changes (Pi[a]/Pi[s]), gene 2 encoding the host RNA polymerase inhibitor displayed Darwinian positive selection. Pretreatment of chickens with φSG-JL2 before intratracheal challenge with wild-type serovar Gallinarum biovar Gallinarum protected most birds from fowl typhoid. Therefore, φSG-JL2 may be useful for the differentiation of serovar Gallinarum biovar Gallinarum from other
Salmonella
serotypes, prophylactic application in fowl typhoid control, and understanding of the vertical evolution of T7-like viruses.
Cellulose Degradation by Micromonosporas Recovered from Freshwater Lakes and Classification of These Actinomycetes by DNA Gyrase B Gene Sequencing
Authors: de Menezes Alexandre B. , Lockhart Robert J. , Cox Michael J. , Allison Heather E. , McCarthy Alan J.
Published: September 2008

A number of
Micromonospora
strains isolated from the water column, sediment, and cellulose baits placed in freshwater lakes were shown to be able to degrade cellulose in lake water without any addition of nutrients. A selective isolation method was also developed to demonstrate that CFU arose from both spores and hyphae that inhabit the lake environment. Gyrase B gene sequencing performed on the isolates identified a number of new centers of variation within
Micromonospora
, but the most actively cellulolytic strains were recovered in a single cluster that equated with the type species of the genus,
M. chalcea
.
Mechanisms of Cation Exchange by
Pseudomonas aeruginosa
PAO1 and PAO1
wbpL
, a Strain with a Truncated Lipopolysaccharide
Authors: Shephard J. , McQuillan A. J. , Bremer P. J.
Published: September 2008

The ability of bacterial cells to sequester cations is well recognized, despite the fact that the specific binding sites and mechanistic details of the process are not well understood. To address these questions, the cation-exchange behavior of
Pseudomonas aeruginosa
PAO1 cells with a truncated lipopolysaccharide (LPS) (PAO1
wbpL
) and cells further modified by growth in a magnesium-deficient medium (PAO1
wbpL
− Mg
2+
) were compared with that of wild-type
P. aeruginosa
PAO1 cells.
P. aeruginosa
PAO1 cells had a negative surface charge (zeta potential) between pH 11 and 2.2, due to carboxylate groups present in the B-band LPS. The net charge on PAO1
wbpL
cells was increasingly positive below pH 3.5, due to the influence of NH
3
+
groups in the core LPS. The zeta potentials of these cells were also measured in Na
+
, Ca
2+
, and La
3+
electrolytes. Cells in the La
3+
electrolyte had a positive zeta potential at all pH values tested. Growing
P. aeruginosa
PAO1
wbpL
in magnesium-deficient medium (PAO1
wbpL
− Mg
2+
) resulted in an increase in its zeta potential in the pH range from 3.0 to 6.5. In cation-exchange experiments carried out at neutral pH with either
P. aeruginosa
PAO1 or PAO1
wbpL
, the concentration of bound Ca
2+
was found to decrease as the pH was reduced from 7.0 to 3.5. At pH 3.5, the bound Mg
2+
concentration decreased sharply, revealing the activity of surface sites for cation exchange and their pH dependence. Infrared spectroscopy of attached biofilms suggested that carboxylate and phosphomonoester functional groups within the core LPS are involved in cation exchange.
Modeling the Variability of Single-Cell Lag Times for
Listeria innocua
Populations after Sublethal and Lethal Heat Treatments
Authors: Métris A. , George S. M. , Mackey B. M. , Baranyi J.
Published: September 2008

Optical density measurements were used to estimate the effect of heat treatments on the single-cell lag times of
Listeria innocua
fitted to a shifted gamma distribution. The single-cell lag time was subdivided into repair time (the shift of the distribution assumed to be uniform for all cells) and adjustment time (varying randomly from cell to cell). After heat treatments in which all of the cells recovered (sublethal), the repair time and the mean and the variance of the single-cell adjustment time increased with the severity of the treatment. When the heat treatments resulted in a loss of viability (lethal), the repair time of the survivors increased with the decimal reduction of the cell numbers independently of the temperature, while the mean and variance of the single-cell adjustment times remained the same irrespective of the heat treatment. Based on these observations and modeling of the effect of time and temperature of the heat treatment, we propose that the severity of a heat treatment can be characterized by the repair time of the cells whether the heat treatment is lethal or not, an extension of the
F
value concept for sublethal heat treatments. In addition, the repair time could be interpreted as the extent or degree of injury with a multiple-hit lethality model. Another implication of these results is that the distribution of the time for cells to reach unacceptable numbers in food is not affected by the time-temperature combination resulting in a given decimal reduction.
Effects of Therapeutic Ceftiofur Administration to Dairy Cattle on
Escherichia coli
Dynamics in the Intestinal Tract
Authors: Singer Randall S. , Patterson Sheila K. , Wallace Richard L.
Published: September 2008

The goal of this study was to follow ceftiofur-treated and untreated cattle in a normally functioning dairy to examine enteric
Escherichia coli
for changes in antibiotic resistance profiles and genetic diversity. Prior to treatment, all of the bacteria cultured from the cows were susceptible to ceftiofur. Ceftiofur-resistant
E. coli
was only isolated from treated cows during and immediately following the cessation of treatment, and the 12
bla
CMY-2
-positive isolates clustered into two genetic groups.
E. coli
bacterial counts dropped significantly in the treated animals (
P
< 0.027), reflecting a disappearance of the antibiotic-susceptible strains. The resistant bacterial population, however, did not increase in quantity within the treated cows; levels stayed low and were overtaken by a returning susceptible population. There was no difference in the genetic diversities of the
E. coli
between the treated and untreated cows prior to ceftiofur administration or after the susceptible population of
E. coli
returned in the treated cows. A cluster analysis of antibiotic susceptibility profiles resulted in six clusters, two of which were multidrug resistant and were comprised solely of isolates from the treated cows immediately following treatment. The antibiotic treatment provided a window to detect the presence of ceftiofur-resistant
E. coli
but did not appear to cause its emergence or result in its amplification. The finding of resistant isolates following antibiotic treatment is not sufficient to estimate the strength of selection pressure nor is it sufficient to demonstrate a causal link between antibiotic use and the emergence or amplification of resistance.
BioluminescentAspergillus fumigatus, a New Tool for Drug Efficiency Testing and In Vivo Monitoring of Invasive Aspergillosis
Authors: Brock Matthias , Jouvion Grégory , Droin-Bergère Sabrina , Dussurget Olivier , Nicola Marie-Anne , Ibrahim-Granet Oumaïma
Published: September 2008

Aspergillus fumigatusis the main cause of invasive aspergillosis in immunocompromised patients, and only a limited number of drugs for treatment are available. A screening method for new antifungal compounds is urgently required, preferably an approach suitable for in vitro and in vivo studies. Bioluminescence imaging is a powerful tool to study the temporal and spatial resolutions of the infection and the effectiveness of antifungal drugs. Here, we describe the construction of a bioluminescentA. fumigatusstrain by fusing the promoter of the glyceraldehyde-3-phosphate dehydrogenase gene fromA. fumigatuswith the luciferase gene fromPhotinus pyralisto control the expression of the bioluminescent reporter.A. fumigatustransformed with this construct revealed high bioluminescence under all tested growth conditions. Furthermore, light emission correlated with the number of conidia used for inoculation and with the biomass formed after different incubation times. The bioluminescent strains were suitable to study the effectiveness of antifungals in vitro by several independent methods, including the determination of light emission with a microplate reader and the direct visualization of light emission with an IVIS 100 system. Moreover, when glucocorticoid-treated immunosuppressed mice were infected with a bioluminescent strain, light emission was detected from infected lungs, allowing the visualization of the progression of invasive aspergillosis. Therefore, this new bioluminescence tool is suitable to study the in vitro effectiveness of drugs and the disease development, localization, and burden of fungi within tissues and may also provide a powerful tool to study the effectiveness of antifungals in vivo.
Mechanism of Synergistic Inhibition of
Listeria monocytogenes
Growth by Lactic Acid, Monolaurin, and Nisin
Authors: Tokarskyy Oleksandr , Marshall Douglas L.
Published: September 2008

The combined lactic acid, monolaurin, and nisin effects on time-to-detection (optical density at 600 nm) extension were greater (
P
< 0.05) than any single or paired combination effect, which demonstrates a synergistic interaction among the antimicrobials. Monolaurin exposure caused C12:0 cell membrane incorporation. Lactic acid caused increased monolaurin C12:0 membrane incorporation, while nisin had no influence. We postulate that lactic acid-enhanced monolaurin C12:0 incorporation into the cell membrane increased membrane fluidity resulting in increased nisin activity.
New Strategy for Isolating Novel Nematicidal Crystal Protein Genes from
Bacillus thuringiensis
Strain YBT-1518
Authors: Guo Suxia , Liu Mei , Peng Donghai , Ji Sisi , Wang Pengxia , Yu Ziniu , Sun Ming
Published: September 2008

We have developed a strategy for isolating
cry
genes from
Bacillus thuringiensis
. The key steps are the construction of a DNA library in an acrystalliferous
B. thuringiensis
host strain and screening for the formation of crystal through optical microscopy observation and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analyses. By this method, three
cry
genes—
cry55Aa1
,
cry6Aa2
, and
cry5Ba2
—were cloned from rice-shaped crystals, producing
B. thuringiensis
YBT-1518, which consists of 54- and 45-kDa crystal proteins.
cry55Aa1
encoded a 45-kDa protein,
cry6Aa2
encoded a 54-kDa protein, and
cry5Ba2
remained cryptic in strain YBT-1518, as shown by SDS-PAGE or microscopic observation. Proteins encoded by these three genes are all toxic to the root knot nematode
Meloidogyne hapla
. The two genes
cry55Aa1
and
cry6Aa2
were found to be located on a plasmid with a rather small size of 17.7 kb, designated pBMB0228.
Accumulation of
trans
C
18:1
Fatty Acids in the Rumen after Dietary Algal Supplementation Is Associated with Changes in the
Butyrivibrio
Community
Authors: Boeckaert Charlotte , Vlaeminck Bruno , Fievez Veerle , Maignien Lois , Dijkstra Jan , Boon Nico
Published: September 2008

Optimization of the fatty acid composition of ruminant milk and meat is desirable. Dietary supplementation of algae was previously shown to inhibit rumen biohydrogenation, resulting in an altered milk fatty acid profile. Bacteria involved in biohydrogenation belong to the
Butyrivibrio
group. This study was aimed at relating accumulation of biohydrogenation intermediates with shifts in
Butyrivibrio
spp. in the rumen of dairy cows. Therefore, an experiment was performed with three rumen-fistulated dairy cows receiving a concentrate containing algae (9.35 g/kg total dry matter [DM] intake) for 20 days. Supplementation of the diet with algae inhibited biohydrogenation of C
18:2
omega 6 (
n
-6) and C
18:3
n
-3, resulting in increased concentrations of biohydrogenation intermediates, whereas C
18:0
decreased. Addition of algae increased ruminal C
18:1
trans
fatty acid concentrations, mainly due to 6- and 20-fold increases in C
18:1
trans
11 (
t
11) and C
18:1
t
10. The number of ciliates (5.37 log copies/g rumen digesta) and the composition of the ciliate community were unaffected by dietary algae. In contrast, supplementation of the diet with algae changed the composition of the bacterial community. Primers for the
Butyrivibrio
group, including the genera
Butyrivibrio
and
Pseudobutyrivibrio
, were specifically designed. Denaturing gradient gel electrophoresis showed community changes upon addition of algae without affecting the total amount of
Butyrivibrio
bacteria (7.06 log copies/g rumen DM). Clone libraries showed that algae affected noncultivated species, which cluster taxonomically between the genera
Butyrivibrio
and
Pseudobutyrivibrio
and might play a role in biohydrogenation. In addition, 20% of the clones from a randomly selected rumen sample were related to the C
18:0
-producing branch, although the associated C
18:0
concentration decreased through supplementation of the diet with algae.
Cloning and Characterization of α-Methylacyl Coenzyme A Racemase from
Gordonia polyisoprenivorans
VH2
Authors: Arenskötter Quyen , Heller Jens , Dietz David , Arenskötter Matthias , Steinbüchel Alexander
Published: September 2008

The
mcr
gene of
Gordonia polyisoprenivorans
VH2 is not clustered with genes required for rubber degradation. Its disruption by insertion of a kanamycin resistance cassette impaired growth on methyl-branched isoprenoids but not on linear hydrocarbons. Intact
mcr
from this bacterium or from
Nocardia farcinica
IFM 10152 complemented the mutant. Reverse transcription analysis showed similar
mcr
VH2
expression results during cultivation with poly(
cis
-1,4-isoprene) and propionate. Additional genes coding for a putative cytochrome P450 monooxygenase and a short-chain dehydrogenase/reductase involved in β-oxidation and poly(
cis
-1,4-isoprene) degradation were also characterized.
Biosynthesis of Ubiquinone Compounds with Conjugated Prenyl Side Chains
Authors: Lee Pyung Cheon , Salomon Christine , Mijts Benjamin , Schmidt-Dannert Claudia
Published: September 2008

Enzymatic steps from two different biosynthetic pathways were combined in
Escherichia coli
, directing the synthesis of a new class of biomolecules—ubiquinones with prenyl side chains containing conjugated double bonds. This was achieved by the activity of a C
30
carotenoid desaturase, CrtN, from
Staphylococcus aureus
, which exhibited an inherent flexibility in substrate recognition compared to other carotenoid desaturases. By utilizing the known plasticity of
E. coli
's native ubiquinone biosynthesis pathway and the unusual activity of CrtN, modified ubiquinone structures with prenyl side chains containing conjugated double bonds were generated. The side chains of the new structures were confirmed to have different degrees of desaturation by mass spectrometry and nuclear magnetic resonance analysis. In vivo
14
C labeling and in vitro activity studies showed that CrtN desaturates octaprenyl diphosphates but not the ubiquinone compounds directly. Antioxidant properties of conjugated side chain ubiquinones were analyzed in an in vitro β-carotene-linoleate model system and were found to be higher than the corresponding unmodified ubiquinones. These results demonstrate that by combining pathway steps from different branches of biosynthetic networks, classes of compounds not observed in nature can be synthesized and structural motifs that are functionally important can be combined or enhanced.