bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of Benzoyl Coenzyme A Biosynthesis Genes in the Enterocin-Producing Bacterium “
Streptomyces maritimus
”
Authors: Xiang Longkuan , Moore Bradley S.
Published: January 2003

The novel benzoyl coenzyme A (benzoyl-CoA) biosynthesis pathway in “
Streptomyces maritimus
” was investigated through a series of target-directed mutations. Genes involved in benzoyl-CoA formation were disrupted through single-crossover homologous recombination, and the resulting mutants were analyzed for their ability to biosynthesize the benzoyl-CoA-primed polyketide antibiotic enterocin. Inactivation of the unique phenylalanine ammonia-lyase-encoding gene
encP
was previously shown to be absolutely required for benzoyl-CoA formation in “
S. maritimus
”. The fatty acid β-oxidation-related genes
encH
, -
I
, and -
J
, on the other hand, are necessary but not required. In each case, the yield of benzoyl-CoA-primed enterocin dropped below wild-type levels. We attribute the reduced benzoyl-CoA formation in these specific mutants to functional substitution and cross-talk between the products of genes
encH
, -
I
, and -
J
and the enzyme homologues of primary metabolism. Disruption of the benzoate-CoA ligase
encN
gene did not perturb enterocin production, however, demonstrating that
encN
is extraneous and that benzoic acid is not a pathway intermediate. EncN rather serves as a substitute pathway for utilizing exogenous benzoic acid. These experiments provide further support that benzoyl-CoA is formed in a novel bacterial pathway that resembles the eukaryotic assembly of benzoyl-CoA from phenylalanine via a β-oxidative path.
Regulation of theBacillus subtilisHeat Shock GenehtpGIs under Positive Control
Authors: Versteeg Saskia , Escher Angelika , Wende Andy , Wiegert Thomas , Schumann Wolfgang
Published: January 2003

The heat shock genes ofBacillus subtilisare assigned to four classes on the basis of their regulation mechanisms. While classes I and III are negatively controlled by two different transcriptional repressors, class II is regulated by the alternative sigma factor σB. All heat shock genes with unidentified regulatory mechanisms, among themhtpG, constitute class IV. Here, we show that expression ofhtpGis under positive control. We identified a DNA sequence (GAAAAGG) located downstream of the σA-dependent promoter ofhtpG. The heat inducibility of the promoter could be destroyed by inversion, nucleotide replacements, or removal of this DNA sequence. Fusion of this sequence to the vegetativelepApromoter conferred heat inducibility. Furthermore, we were able to show that the heat induction factor is dependent on the absolute temperature rather than the temperature increment and that nonnative proteins within the cytoplasm fail to inducehtpG.
Characterization of a Novel Intracellular Endopeptidase of the α/β Hydrolase Family from
Streptomyces coelicolor
A3(2)
Authors: Nagy István , Banerjee Tisha , Tamura Tomohiro , Schoofs Geert , Gils Ann , Proost Paul , Tamura Noriko , Baumeister Wolfgang , De Mot René
Published: January 2003

In a proteasome-lacking mutant of
Streptomyces coelicolor
A3(2), an intracellular enzyme with chymotrypsin-like activity, absent from the wild type, was detected. Complementation that restored proteasome function did not suppress expression of the endopeptidase. Since the enzyme was not found in two other
S. coelicolor
proteasome mutants, its expression probably resulted from a secondary mutation arisen in the proteasome mutant. Purification of the endopeptidase revealed its identity to SCO7095, a putative hydrolase encoded by the
S. coelicolor
A3(2) genome with no known homologue. Based on the prediction of a Ser-Asp-His catalytic triad and an α/β hydrolase fold, SCO7095 was assigned to peptidase clan SC. N-terminally His-tagged SCO7095 was efficiently expressed in
Escherichia coli
cells and purified for further characterization. Although SCO7095 is distantly related to several proline iminopeptidases, including
Thermoplasma acidophilum
tricorn-interacting F1, no aminopeptidase activity was detected. On synthetic substrates, the monomeric enzyme exhibited not only chymotrypsin-like activity but also thrombin-like activity.
Functional and Mutational Analysis of Conjugative Transfer Region 2 (Tra2) from the IncHI1 Plasmid R27
Authors: Lawley Trevor D. , Gilmour Matthew W. , Gunton James E. , Tracz Dobryan M. , Taylor Diane E.
Published: January 2003

The transfer 2 region (Tra2) of the conjugative plasmid drR27 (derepressed R27) was analyzed by PSI-BLAST, insertional mutagenesis, genetic complementation, and an H-pilus assay. Tra2 contains 11 mating-pair formation (Mpf) genes that are essential for conjugative transfer, 9 of which are essential for H-pilus production (trhA, -L, -E, -K, -B, -V, -C, -P, and -W). TrhK has similarity to secretin proteins, suggesting a mechanism by which DNA could traverse the outer membrane of donors. The remaining two Mpf genes,trhUandtrhN, play an auxiliary role in H-pilus synthesis and are proposed to be involved in DNA transfer and mating-pair stabilization, respectively. Conjugative transfer abilities were restored for each mutant when complemented with the corresponding transfer gene. In addition to the essential Mpf genes, three genes,trhO,trhZ, andhtdA, modulate R27 transfer frequency. Disruption oftrhOandtrhZseverely reduced the transfer frequencies of drR27, whereas disruption ofhtdAgreatly increased the transfer frequency of wild-type R27 to drR27 levels. A comparison of the essential transfer genes encoded by the Tra2 and Tra1 (T. D. Lawley, M. W. Gilmour, J. E. Gunton, L. J. Standeven, and D. E. Taylor, J. Bacteriol. 184:2173-2183, 2002) of R27 to other transfer systems illustrates that the R27 conjugative transfer system is a chimera composed of IncF-like and IncP-like transfer systems. Furthermore, the Mpf/type IV secretion systems encoded by IncH and IncF transfer systems are distinct from that of the IncP transfer system. The phenotypic and ecological significance of these observations is discussed.
Accumulation ofS-Adenosyl-l-Methionine Enhances Production of Actinorhodin but Inhibits Sporulation inStreptomyces lividansTK23
Authors: Kim Dong-Jin , Huh Jung-Hyun , Yang Young-Yell , Kang Choong-Min , Lee In-Hyung , Hyun Chang-Gu , Hong Soon-Kwang , Suh Joo-Won
Published: January 2003

S-Adenosyl-l-methionine synthetase (SAM-s) catalyzes the biosynthesis of SAM from ATP andl-methionine. Despite extensive research with many organisms, its role inStreptomycessp. remains unclear. In the present study, the putative SAM-s gene was isolated from a spectinomycin producer,Streptomyces spectabilis. The purified protein from the transformedEscherichia coliwith the isolated gene synthesized SAM froml-methionine and ATP in vitro, strongly indicating that the isolated gene indeed encoded the SAM-s protein. The overexpression of the SAM-s gene inStreptomyces lividansTK23 inhibited sporulation and aerial mycelium formation but enhanced the production of actinorhodin in both agar plates and liquid media. Surprisingly, the overexpressed SAM was proven by Northern analysis to increase the production of actinorhodin through the induction ofactII-ORF4, a transcription activator of actinorhodin biosynthetic gene clusters. In addition, we found that a certain level of intracellular SAM is critical for the induction of antibiotic biosynthetic genes, since the control strain harboring only the plasmid DNA did not show any induction ofactII-ORF4 until it reached a certain level of SAM in the cell. From these results, we concluded that the SAM plays important roles as an intracellular factor in both cellular differentiation and antibiotic production inStreptomycessp.
Escherichia coliCells with Increased Levels of DnaA and Deficient in Recombinational Repair Have Decreased Viability
Authors: Grigorian Aline V. , Lustig Rachel B. , Guzmán Elena C. , Mahaffy Joseph M. , Zyskind Judith W.
Published: January 2003

ThednaAoperon ofEscherichia colicontains the genesdnaA,dnaN, andrecFencoding DnaA, β clamp of DNA polymerase III holoenzyme, and RecF. When the DnaA concentration is raised, an increase in the number of DNA replication initiation events but a reduction in replication fork velocity occurs. Because DnaA is autoregulated, these results might be due to the inhibition ofdnaNandrecFexpression. To test this, we examined the effects of increasing the intracellular concentrations of DnaA, β clamp, and RecF, together and separately, on initiation, the rate of fork movement, and cell viability. The increased expression of one or more of thednaAoperon proteins had detrimental effects on the cell, except in the case of RecF expression. A shorter C period was not observed with increased expression of the β clamp; in fact, many chromosomes did not complete replication in runout experiments. Increased expression of DnaA alone resulted in stalled replication forks, filamentation, and a decrease in viability. When the three proteins of thednaAoperon were simultaneously overexpressed, highly filamentous cells were observed (>50 μm) with extremely low viability and, in runout experiments, most chromosomes had not completed replication. The possibility that recombinational repair was responsible for the survival of cells overexpressing DnaA was tested by using mutants in different recombinational repair pathways. The absence of RecA, RecB, RecC, or the proteins in the RuvABC complex caused an additional ∼100-fold drop in viability in cells with increased levels of DnaA, indicating a requirement for recombinational repair in these cells.
clpPofStreptococcus salivariusIs a Novel Member of the Dually Regulated Class of Stress Response Genes in Gram-Positive Bacteria
Authors: Chastanet Arnaud , Msadek Tarek
Published: January 2003

Nucleotide sequence analysis of theStreptococcus salivarius clpPlocus revealed potential binding sites for both the CtsR and HrcA repressors. Dual regulation by HrcA and CtsR was demonstrated by usingBacillus subtilisas a heterologous host, and CtsR was shown to bind directly to theclpPpromoter sequence. This is the first example of aclpPgene under the control of HrcA.
Osmotic Stress Signaling and Osmoadaptation in Yeasts
Authors: Hohmann Stefan
Published: January 2003

The ability to adapt to altered availability of free water is a fundamental property of living cells. The principles underlying osmoadaptation are well conserved. The yeast Saccharomyces cerevisiae is an excellent model system with which to study the molecular biology and physiology of osmoadaptation. Upon a shift to high osmolarity, yeast cells rapidly stimulate a mitogen-activated protein (MAP) kinase cascade, the high-osmolarity glycerol (HOG) pathway, which orchestrates part of the transcriptional response. The dynamic operation of the HOG pathway has been well studied, and similar osmosensing pathways exist in other eukaryotes. Protein kinase A, which seems to mediate a response to diverse stress conditions, is also involved in the transcriptional response program. Expression changes after a shift to high osmolarity aim at adjusting metabolism and the production of cellular protectants. Accumulation of the osmolyte glycerol, which is also controlled by altering transmembrane glycerol transport, is of central importance. Upon a shift from high to low osmolarity, yeast cells stimulate a different MAP kinase cascade, the cell integrity pathway. The transcriptional program upon hypo-osmotic shock seems to aim at adjusting cell surface properties. Rapid export of glycerol is an important event in adaptation to low osmolarity. Osmoadaptation, adjustment of cell surface properties, and the control of cell morphogenesis, growth, and proliferation are highly coordinated processes. The Skn7p response regulator may be involved in coordinating these events. An integrated understanding of osmoadaptation requires not only knowledge of the function of many uncharacterized genes but also further insight into the time line of events, their interdependence, their dynamics, and their spatial organization as well as the importance of subtle effects.
QUANTUM GAME WITH INCOMPLETE INFORMATION
Authors: HAN YONG-JIAN , ZHANG YONG-SHENG , GUO GUANG-CAN
Published: January 2003

Quantum game is an interesting field and many scientists have done a lot of innovative work in it. We give a quantum model about incomplete information. In this model we find whether the pure-strategy Bayes-Nash equilibrium exists or not is strongly dependent on the entanglement of the initial state. We also find the player Bob can always find an initial state and a pure-strategy Bayes-Nash equilibrium to get more payoff than classical game with some parameter.
SCALING LAWS IN STOCHASTIC SYSTEMS WITH ANOMALOUS DIFFUSION
Authors: KHARCHENKO DMITRII
Published: January 2003

We consider the stochastic system with an anomalous diffusion. According to the obtained relations between characteristics of diffusion processes the special class of models which exhibit the anomalous behaviour is considered. It was shown that indexes of super- and subdiffusion are related to the Hürst exponent which defines the properties of the phase space inherent to the proposed model of stochastic system.
SURVIVAL OF THE FITTEST AND ZERO SUM GAMES
Authors: PATEL APOORVA
Published: January 2003

Competition for available resources is natural amongst coexisting species, and the fittest contenders dominate over the rest in evolution. The dynamics of this selection is studied using a simple linear model. It has similarities to features of quantum computation, in particular conservation laws leading to destructive interference. Compared to an altruistic scenario, competition introduces instability and eliminates the weaker species in a finite time.
QUANTUM COHERENCE, CORRELATED NOISE AND PARRONDO GAMES
Authors: LEE CHIU FAN , JOHNSON NEIL F. , RODRIGUEZ FERNEY , QUIROGA LUIS
Published: January 2003

We discuss the effect of correlated noise on the robustness of quantum coherent phenomena. First we consider a simple, toy model to illustrate the effect of such correlations on the decoherence process. Then we show how decoherence rates can be suppressed using a Parrondo-like effect. Finally, we report the results of many-body calculations in which an experimentally-measurable quantum coherence phenomenon is significantly enhanced by non-Markovian dynamics arising from the noise source.
ASSESSMENT OF PROXIMAL INTERPHALANGEAL JOINTS IN PATIENTS WITH OSTEOARTHRITIS VIA LASER DOPPLER PERFUSION IMAGING
Authors: NG EDDIE YIN-KWEE , TAN JOON HOW
Published: January 2003

The study aims to determine whether the LDPI technique can provide an objective indication of synovial hyperaemia associated with inflamed finger joints. In addition, it hopes to obtain more information about the influence of pain and stiffness on the cutaneous blood flow and assess whether skin perfusion can be used as an index to evaluate these clinical parameters of Osteoarthritis.

Except for the deformed joint, the red laser source (λ = 632.8 nm, visible red) failed to detect any hyperaemic areas associated with joint inflammation in patients with Osteoarthritis (OA). Measurements taken over the PIP joints of both groups have shown a good repeatability for all between-day measurements. However, the variation in between-day perfusion of the OA group is greater compared to the normal control. For majority of the subjects, perfusion in the adjacent skin tends to be lower and fluctuate less than that in their PIP joints. The study also indicates some correlation between the blood perfusion with pain and stiffness of the finger joints.

Overall, the present finding suggests that a longer wavelength near-infrared laser have considerable potential for this form of imaging and that LDI can offer a convenient means of rapidly assessing an inflamed joint non-invasively. Further clinical studies in these areas are warranted.
THE PERIODIC PREDATOR-PREY LOTKA–VOLTERRA MODEL WITH IMPULSIVE EFFECT
Authors: TANG SANYI , CHEN LANSUN
Published: January 2003

In this paper, a classical periodic Lotka–Volterra predator-prey system with impulsive effect is investigated. We analyze the dynamics of positive solutions of such models. Among other results we show that if some trivial or semi-trivial positive solution is linearly stable, then it is globally asymptotically stable with respect to the positive solutions. By using the method of coincidence degree, a set of sufficient conditions are derived for the existence of at least one strictly positive (componentwise) periodic solution. We use bifurcation theorem to show the existence of coexistence states which arise near the sem-trivial periodic solution. As an application, we also examine some special cases of the system which can be used in the biological pest control.
FINITE ELEMENT SIMULATION OF ELASTIC COMPLIANCE TECHNIQUE FOR FORMULATING A TEST METHOD TO DETERMINE THE FRACTURE TOUGHNESS OF BONE
Authors: PARUCHURU SATYA PRASAD , WANG XIAODU , AGRAWAL C. M.
Published: January 2003

Compact Sandwich Specimen (CSS) is the best specimen to test the fracture toughness of bone from small laboratory animals. There exists a direct method to calculate the stress intensity factor (K) of bone using CSS. However, energy release rate (G) is the fundamental measure of fracture toughness of a material. The direct relation between K, G, Young's Modulus (E), and Poisson's ratio (ν), defined for homogeneous materials may not apply to bone, which has a non-homogeneous microstucture. Therefore, a direct test method is required to calculate G of bone using CSS.

Elastic compliance technique is used to measure G of a material. This paper presents an experimentally tested and reliable procedure to simulate the elastic compliance technique by finite element analysis. The procedure may eventually be used in formulating the direct test method to calculate G of bone and bone-biomaterial interface, using CSS.
Modulations of Signal Transduction Pathways during Sepsis and the Effects of Insulin and Mifepristone
Authors: Maitra Subir R. , Chen Elliott , Rosa Dominik , Valane Patrick D. , El‐Maghrabi M. Raafat , Brathwaite Collin E. M.
Published: January 2003

Objectives: The phosphorylation states and the inferred activation of specific members of the mitogen‐activated protein kinase (MAPK) pathways (p42/44, p38, and SAPK/JNK) were quantitated in the livers of rats by Western blot analysis during the progression of sepsis. In addition, the authors examined the effects of insulin and mifepristone (RU‐486) administration on these signal transduction pathways during sepsis. Methods: Sepsis was brought about by the cecal ligation and puncture (CLP) method. The control group underwent sham operation. One experimental group was injected with insulin (0.5 U/kg, IV); prior to the CLP or sham procedure, the second group was injected with RU‐486, a glucocorticoid antagonist (mifepristone, 20 mg/kg, IP), and the third group was injected with saline (control). Results: The activities of SAPK/JNK were unaltered throughout the course of sepsis, while those of p42/44 MAPK increased four‐fold after 24 hours of sepsis. The activation of p38 MAPK was also increased after 0.5 and 1.5 hours of sepsis, but returned to normal during late sepsis (24 hours). Rats that had received RU‐486 before CLP showed no change in p42/44 MAPK compared with the untreated group, but the drug appeared to suppress the activation after 24 hours post‐CLP. SAPK/JNK activation, on the other hand, was slightly enhanced by RU‐486 pretreatment after 1.5 and 24 hours of CLP compared with the untreated CLP and the treated sham‐operated rats. Insulin, given preoperatively, had no effect on the activation of SAPK/JNK, although p42/44 MAPK pathways were activated by the hormone at 0.5 hours and 1.5 hours post‐CLP only, but not in the sham‐operated controls or at 24 hours post‐CLP. The p38 MAPK activation seen after 0.5 and 1.5 hours of CLP was suppressed by RU‐486. Insulin pretreatment appears to suppress the phosphorylation of p38 in both the CLP and sham‐operated groups. Conclusions: The data suggest that sepsis induces two phases of MAPK activation, an early phase in which p38 is active, followed by a second, more pronounced phase of p42/44 MAPK activation that occurs only late in sepsis. Hormonal administration results suggest that RU‐486 suppresses the activation of p38 seen in early sepsis, and the activation of p42/44 MAPK seen in late sepsis.
A Randomized, Clinical Trial Comparing Oral Celecoxib 200 mg, Celecoxib 400 mg, and Ibuprofen 600 mg for Acute Pain
Authors: Salo David F. , Lavery Robert , Varma Vikram , Goldberg Jennifer , Shapiro Tara , Kenwood Alan
Published: January 2003

Objective: Celecoxib is a selective cyclooxygenase‐2 (COX‐2) inhibitor used to treat pain. The objective of this study was to compare the efficacies of celecoxib and ibuprofen for the treatment of acute pain. The null hypothesis was that no difference between celecoxib and ibuprofen exists. Methods: The study was a prospective, randomized, double‐blind, controlled clinical trial. After consent, patients rated their pain on a 100‐mm visual analog scale (VAS) and categorical intensity pain scale. Patients were then randomized to receive 200‐mg or 400‐mg celecoxib or 600‐mg ibuprofen (all orally). Patients were contacted 5 hours after receiving study medication when a second VAS score was recorded, along with categorical pain intensity, pain relief score, side effects, and number of rescue medications taken. The main outcome measures were change in visual analog pain and categorical pain intensity scores, and pain relief scores, at five hours. Results: One hundred ten patients were evaluated and 105 were enrolled. Thirty‐four received celecoxib 200 mg, 32 received celecoxib 400 mg, and 39 received ibuprofen 600 mg. Ninety‐one were available for the five‐hour VAS and 88 for the five‐hour categorical pain intensity and pain relief analysis: The two patients who were unable to read a VAS were excluded, and two enrolled patients withdrew prior to medication. One patient was excluded because his injury was a fracture, and therefore did not meet the inclusion criteria. There was no statistical difference among the treatment groups in age, time from injury to medication, initial VAS score, percent lost to follow‐up, or treatment with adjunctive therapy. There was no statistical difference in change of VAS among the groups at five hours: ibuprofen 600 mg (‐23.8 mm [95% CI = ‐31.56 mm to ‐16.1 mm] [n = 32]), celecoxib 200 mg (‐16.1 mm [95% CI = ‐24.3 mm to ‐7.98 mm] [n = 31]), and celecoxib 400 mg (‐12.4 mm [95% CI = ‐23.1 mm to ‐1.8 mm] [n = 30]) (p = 0.16). There was no significant difference between the groups, at five hours, in change of categorical pain intensity (p = 0.11) or pain relief scores (p = 0.059), though the pain relief scale approached significance favoring ibuprofen. Conclusions: No significant difference exists among emergency department (ED) patients treated for acute pain, at five hours, with celecoxib 200 mg, celecoxib 400 mg, or ibuprofen 600 mg, though the power of the study to detect a change was low, 36%. However, the magnitude of pain relief for celecoxib, coupled with the cost of the medication, questions its use in the immediate ED setting.
The Status of Bedside Ultrasonography Training in Emergency Medicine Residency Programs
Authors: Counselman Francis L. , Sanders Arthur , Slovis Corey M. , Danzl Daniel , Binder Louis S. , Perina Debra G.
Published: January 2003

Bedside ultrasonography (BU) is rapidly being incorporated into emergency medicine (EM) training programs and clinical practice. In the past decade, several organizations in EM have issued position statements on the use of this technology. Program training content is currently driven by the recently published “Model of the Clinical Practice of Emergency Medicine,” which includes BU as a necessary skill. Objective: The authors sought to determine the current status of BU training in EM residency programs. Methods: A survey was mailed in early 2001 to all 122 Accreditation Council for Graduate Medical Education (ACGME)‐accredited EM residency programs. The survey instrument asked whether BU was currently being taught, how much didactic and hands‐on training time was incorporated into the curriculum, and what specialty representation was present in the faculty instructors. In addition, questions concerning the type of tests performed, the number considered necessary for competency, the role of BU in clinical decision making, and the type of quality assurance program were included in the survey. Results: A total of 96 out of 122 surveys were completed (response rate of 79%). Ninety‐one EM programs (95% of respondents) reported they teach BU, either clinically and/or didactically, as part of their formal residency curriculum. Eighty‐one (89%) respondents reported their residency program or primary hospital emergency department (ED) had a dedicated ultrasound machine. BU was performed most commonly for the following: the FAST scan (focused abdominal sonography for trauma, 79/87%); cardiac examination (for tamponade, pulseless electrical activity, etc., 65/71%); transabdominal (for intrauterine pregnancy, ectopic pregnancy, etc., 58/64%); and transvaginal (for intrauterine pregnancy, ectopic pregnancy, etc., 45/49%). One to ten hours of lecture on BU was provided in 43%, and one to ten hours of hands‐on clinical instruction was provided in 48% of the EM programs. Emergency physicians were identified as the faculty most commonly involved in teaching BU to EM residents (86/95%). Sixty‐one (69%) programs reported that EM faculty and/or residents made clinical decisions and patient dispositions based on the ED BU interpretation alone. Fourteen (19%) programs reported that no formal quality assurance program was in place. Conclusions: The majority of ACGME‐accredited EM residency programs currently incorporate BU training as part of their curriculum. The majority of BU instruction is done by EM faculty. The most commonly performed BU study is the FAST scan. The didactic component and clinical time devoted to BU instruction are variable between programs. Further standardization of training requirements between programs may promote increasing standardization of BU in future EM practice.
Does Soccer Headgear Attenuate the Impact When Heading a Soccer Ball?
Authors: Naunheim Rosanne S. , Ryden Amanda , Standeven John , Genin Guy , Lewis Larry , Thompson Paul , Bayly Phil
Published: January 2003

There is increasing concern that repetitive blows to the head, such as those from heading a soccer ball, can cause measurable cognitive impairment. Reducing acceleration of impact could reduce neurologic sequelae. Objective: To measure the effectiveness of four different types of soccer headgear in reducing the acceleration of impact. Methods: A standard magnesium headform was instrumented with a triaxial accelerometer. A soccer ball was propelled at the headform at three different speeds known to occur in soccer play: 9, 12, and 15 m/sec (20, 26, and 34 mph). The main outcome was the peak acceleration of the headform associated with these impacts with and without protective headgear. Results: Peak accelerations were found in a range from 144 m/s2 to 289 m/s2 (14.67‐29.5 G, G = 9.81 m/s2). Using multivariate analysis of variance (MANOVA) methods to compare the headbands and controls, there was no significant difference in the measured accelerations at the center of gravity with or without headgear (p = 0.50). However, the interaction term of headbands, pressure, and speed was significant at F = 5.51 and p = 0.00001. Using contrasts within conditions, some headbands were found to cause a decrease in peak acceleration at the highest speed and pressure. Conclusions: Currently available headgear for soccer heading shows little ability to attenuate impact during simulated soccer heading. However, statistically significant decreases are present at the highest speeds and pressures tested, suggesting the headbands may play a role in decreasing impact for more forceful blows.
Left Ventricular Function after Monophasic and Biphasic Waveform Defibrillation: The Impact of Cardiopulmonary Resuscitation Time on Contractile Indices
Authors: Niemann James T. , Garner Daniel , Lewis Roger J.
Published: January 2003

Previous work has suggested that low‐energy biphasic waveform defibrillation (BWD) is followed by less post‐resuscitation left ventricular (LV) dysfunction when compared with higher‐energy monophasic waveform defibrillation (MWD). To the best of the authors' knowledge, the effect of cardiopulmonary resuscitation (CPR) duration and total ischemia time on LV function after countershock, controlling for waveform type, has not been evaluated. Objective: To determine the effect of CPR duration on LV function after MWD and BWD. Methods: VF was electrically induced in anesthetized and instrumented swine. After 5 minutes of VF, the animals were randomized to MWD (n = 22) or one of two BWDs (n = 46). If countershock terminated VF but was followed by a nonperfusing rhythm, conventional manual CPR without drug therapy was performed until restoration of spontaneous circulation (ROSC), defined as a systolic arterial pressure >60 mm Hg for 10 minutes without vasopressor support. Systolic LV pressure (LVP), LV dP/dt (first derivative of pressure measured over time), and cardiac output (CO) were measured at intervals for 60 minutes postresuscitation. CPR times (times to ROSC) and hemodynamic variables for the three groups were compared. Multivariable linear regression was performed to assess the contribution of defibrillation waveform, total joules, and CPR time on LVP, LV dP/dt, and CO at 15, 30, and 60 minutes postresuscitation. Results: When analyzed as groups, significant differences in median number of shocks to terminate VF, total joules, or CPR time were not observed between waveform groups. Regression analysis demonstrated that increasing CPR time was associated with a significant effect on indices of LV function at 15 and 30 minutes postresuscitation. Global LV function was not influenced by waveform type or total joules. Conclusions: Adjustment for CPR time, a determinant of total myocardial ischemia time, is necessary when defibrillation waveforms are compared for their effect on postresuscitation cardiac function and short‐term outcome.
Calculating X-ray absorption near-edge structure at very low energy
Authors: Joly Yves
Published: January 2003

The measurement and calculation of X-ray absorption near-edge structure at very low energy can provide important information about a metallic center in biological compounds. A rapid overview of the biological applications of this technique is given, then a new method of calculating the spectra is presented. This technique, based on the use of the finite-difference method to solve the Schrödinger equation, is especially precise and potentially applicable to metalloproteins. Examples of its use on an oxide and an organic compound illustrate the kind of spectroscopic information that can be obtained.
Fluids from Aging Ocean Crust That Support Microbial Life
Authors: Cowen James P. , Giovannoni Stephen J. , Kenig Fabien , Johnson H. Paul , Butterfield David , Rappé Michael S. , Hutnak Michael , Lam Phyllis
Published: January 2003

Little is known about the potential for life in the vast, low-temperature (<100°C) reservoir of fluids within mid-ocean ridge flank and ocean basin crust. Recently, an overpressured 300-meter-deep borehole was fitted with an experimental seal (CORK) delivering crustal fluids to the sea floor for discrete and large-volume sampling and characterization. Results demonstrate that the 65°C fluids from 3.5-million-year-old ocean crust support microbial growth. Ribosomal RNA gene sequence data indicate the presence of diverse Bacteria and Archaea, including gene clones of varying degrees of relatedness to known nitrate reducers (with ammonia production), thermophilic sulfate reducers, and thermophilic fermentative heterotrophs, all consistent with fluid chemistry.
Pregnancy-Stimulated Neurogenesis in the Adult Female Forebrain Mediated by Prolactin
Authors: Shingo Tetsuro , Gregg Christopher , Enwere Emeka , Fujikawa Hirokazu , Hassam Rozina , Geary Colleen , Cross James C. , Weiss Samuel
Published: January 2003

Neurogenesis occurs in the olfactory system of the adult brain throughout life, in both invertebrates and vertebrates, but its physiological regulation is not understood. We show that the production of neuronal progenitors is stimulated in the forebrain subventricular zone of female mice during pregnancy and that this effect is mediated by the hormone prolactin. The progenitors then migrate to produce new olfactory interneurons, a process likely to be important for maternal behavior, because olfactory discrimination is critical for recognition and rearing of offspring. Neurogenesis occurs even in females that mate with sterile males. These findings imply that forebrain olfactory neurogenesis may contribute to adaptive behaviors in mating and pregnancy.
Genesis of the Heaviest Elements in the Milky Way Galaxy
Authors: Sneden Christopher , Cowan John J.
Published: January 2003

We review the origin and evolution of the heavy elements, those with atomic numbers greater than 30, in the early history of the Milky Way. There is a large star-to-star bulk scatter in the concentrations of heavy elements with respect to the lighter metals, which suggests an early chemically unmixed and inhomogeneous Galaxy. The relative abundance patterns among the heavy elements are often very different from the solar system mix, revealing the characteristics of the first element donors in the Galaxy. Abundance comparisons among several halo stars show that the heaviest neutron-capture elements (including barium and heavier) are consistent with a scaled solar system rapid neutron-capture abundance distribution, whereas the lighter such elements do not conform to the solar pattern. The stellar abundances indicate an increasing contribution from the slow neutron-capture process (s-process) at higher metallicities in the Galaxy. The detection of thorium in halo and globular cluster stars offers a promising, independent age-dating technique that can put lower limits on the age of the Galaxy.
Single-Gene Greenbeard Effects in the Social Amoeba
Dictyostelium discoideum
Authors: Queller David C. , Ponte Eleonora , Bozzaro Salvatore , Strassmann Joan E.
Published: January 2003

Selection can favor reproductive altruism if an altruism allele aids copies of itself by helping relatives. The alternative “greenbeard” mechanism, in which an allele directly recognizes and aids copies of itself in others, is generally thought to be too complex for a single gene to carry out. The
csA
gene in
Dictyostelium discoideum
acts as a single-gene greenbeard. When wild-type cells are mixed with
csA
-knockout cells, the wild type is more altruistic, but is also able preferentially to direct the benefits to other wild-type cells. Both properties derive directly from homophilic cell adhesion of the protein encoded by
csA
.
Long-Distance Signaling in Nodulation Directed by a CLAVATA1-Like Receptor Kinase
Authors: Searle Iain R. , Men Artem E. , Laniya Titeki S. , Buzas Diana M. , Iturbe-Ormaetxe Inaki , Carroll Bernard J. , Gresshoff Peter M.
Published: January 2003

Proliferation of legume nodule primordia is controlled by shoot-root signaling known as autoregulation of nodulation (AON). Mutants defective in AON show supernodulation and increased numbers of lateral roots. Here, we demonstrate that AON in soybean is controlled by the receptor-like protein kinase GmNARK (
Glycine max
nodule autoregulation receptor kinase), similar to
Arabidopsis
CLAVATA1 (CLV1). Whereas CLV1 functions in a protein complex controlling stem cell proliferation by short-distance signaling in shoot apices, GmNARK expression in the leaf has a major role in long-distance communication with nodule and lateral root primordia.
Three-Dimensional Mapping of Dislocation Avalanches: Clustering and Space/Time Coupling
Authors: Weiss Jérôme , Marsan David
Published: January 2003

There is growing evidence for the complex, intermittent, and heterogeneous character of plastic flow. Here we report a three-dimensional mapping of dislocation avalanches during creep deformation of an ice crystal, from a multiple-transducers acoustic emission analysis. Correlation analysis shows that dislocation avalanches are spatially clustered according to a fractal pattern and that the closer in time two avalanches are, the larger the probability is that they will be closer in space. Such a space/time coupling may contribute to the self-organization of the avalanches into a clustered pattern.
Transcriptional Regulation in the
Streptococcus pneumoniae rlrA
Pathogenicity Islet by RlrA
Authors: Hava David L. , Hemsley Carolyn J. , Camilli Andrew
Published: January 2003

The proper temporal expression of virulence genes during infection is crucial to the infectious life cycle of microbial pathogens, particularly in pathogens that encounter a multitude of environments in eukaryotic hosts.
Streptococcus pneumoniae
normally colonizes the nasopharynges of healthy adults but can cause a range of diseases at a variety of host sites. Transcriptional regulators that are essential for full virulence of
S. pneumoniae
in different animal models have been identified. One such regulator,
rlrA
, is required for colonization of the nasopharynx and lung infection but is dispensable for systemic infection. Previous work has shown that
rlrA
lies in a 12-kb pathogenicity islet, divergently opposed to three putative sortase-anchored surface proteins and three sortase enzymes. In addition to
rlrA
, one of the putative surface proteins and one of the sortases have also been shown to be essential for lung infection. In this work, we demonstrate that RlrA is a positive regulator of all seven genes in the
rlrA
pathogenicity islet, with transcriptional activation occurring at four different promoters in the islet with AT-rich sequences. These promoters direct the expression of
rlrA
itself, the three sortases,
rrgA
, and
rrgBC
. These data are consistent with the model whereby the
rlrA
pathogenicity islet acts in an autonomous manner to alter the bacterial surface components that interact with the pulmonary and nasopharyngeal environments.
Expression ofspoTinBorrelia burgdorferiduring Serum Starvation
Authors: Concepcion Marc B. , Nelson David R.
Published: January 2003

Borrelia burgdorferi, the causative agent of Lyme disease, is transmitted by the tickIxodes scapularis. A 2.9-kb fragment containing a putativespoTgene was isolated fromB. burgdorferigenomic DNA by PCR amplification and cloned into a pBAD24 vector. The cloned gene complementedEscherichia colimutant strain CF1693, which contains deletions of both therelAandspoTgenes. ThespoTgene inE. coliencodes a bifunctional enzyme capable of synthesizing and degrading (p)ppGpp, which mediates the stringent response during carbon source starvation.B. burgdorferihas been reported to have a stress response to serum starvation. Thin-layer chromatography was used to detect (p)ppGpp extracted from H332PO4-labeledB. burgdorfericells starved for serum in RPMI.B. burgdorferi spoTgene expression was characterized during fatty acid starvation. Northern analysis ofspoTrevealed detectable message at 2.5 min of starvation in RPMI. Expression ofspoTduring serum starvation increased ∼6-fold during the 30 min that starvation conditions were maintained. Further, expression ofspoTdecreased when serum was added to serum-starved cells. Reverse transcriptase PCR (RT-PCR) was used to detectspoTmRNA from ∼106cells starved for serum in RPMI for 2.5 to 30 min or incubated in tick saliva for 15 min. Northern blot analysis suggests thatspoTtranscript was ∼900 nucleotides in length. RT-PCR amplification of the transcript using several sets of primers confirmed this finding. Additionally, a truncated clone containing only the first 950 bp of the 2,001-bpspoTopen reading frame was able to complementE. coliCF1693. The data suggest thatB. burgdorferiexhibits a stringent response to serum starvation and during incubation in tick saliva.
Genetic Analysis of the AdnA Regulon in
Pseudomonas fluorescens
: Nonessential Role of Flagella in Adhesion to Sand and Biofilm Formation
Authors: Robleto Eduardo A. , López-Hernández Inmaculada , Silby Mark W. , Levy Stuart B.
Published: January 2003

AdnA is a transcription factor in
Pseudomonas fluorescens
that affects flagellar synthesis, biofilm formation, and sand adhesion. To identify the AdnA regulon, we used a promoterless Tn
5
-
lacZ
element to study the phenotypes of insertion mutants in the presence and absence of AdnA. Of 12,000 insertions, we identified seven different putative open reading frames (ORFs) activated by AdnA (named
aba
for activated by AdnA).
aba120
and
aba177
showed homology to
flgC
and
flgI
, components of the basal body of the flagella in
Pseudomonas aeruginosa
. Two other insertions,
aba18
and
aba51
, disrupted genes affecting chemotaxis. The mutant loci
aba160
(possibly affecting lipopolysaccharide synthesis) and
aba175
(unknown function) led to loss of flagella. The mutant bearing
aba203
became motile when complemented with
adnA
, but the mutated gene showed no similarity to known genes. Curiously,
aba18
,
aba51
,
aba160
, and
aba203
mutants formed biofilms even in the absence of AdnA, suppressing the phenotype of the
adnA
deletion mutant. The combined findings suggest that flagella are nonessential for sand attachment or biofilm formation. Sequence and promoter analyses indicate that AdnA affects at least 23 ORFs either directly or by polar effects. These results support the concept that AdnA regulates cell processes other than those directly related to flagellar synthesis and define a broader cadre of genes in
P. fluorescens
than that described so far for its homolog, FleQ, in
P. aeruginosa
.
Targeted Disruption of the α-Amylase Gene in the Hyperthermophilic Archaeon
Sulfolobus solfataricus
Authors: Worthington Penny , Hoang Viet , Perez-Pomares Francisco , Blum Paul
Published: January 2003

Sulfolobus solfataricus
secretes an acid-resistant α-amylase (
amyA
) during growth on starch as the sole carbon and energy source. Synthesis of this activity is subject to catabolite repression. To better understand α-amylase function and regulation, the structural gene was identified and disrupted and the resulting mutant was characterized. Internal α-amylase peptide sequences obtained by tandem mass spectroscopy were used to identify the
amyA
coding sequence. Anti-α-amylase antibodies raised against the purified protein immunoprecipitated secreted α-amylase activity and verified the enzymatic identity of the sequenced protein. A new gene replacement method was used to disrupt the
amyA
coding sequence by insertion of a modified allele of the
S. solfataricus lacS
gene. PCR and DNA sequence analysis were used to characterize the altered
amyA
locus in the recombinant strain. The
amyA
::
lacS
mutant lost the ability to grow on starch, glycogen, or pullulan as sole carbon and energy sources. During growth on a non-catabolite-repressing carbon source with added starch, the mutant produced no detectable secreted amylase activity as determined by enzyme assay, plate assay, or Western blot analysis. These results clarify the biological role of the α-amylase and provide additional methods for the directed genetic manipulation of the
S. solfataricus
genome.
Convergent Evolution of Amadori Opine Catabolic Systems in Plasmids ofAgrobacterium tumefaciens
Authors: Baek Chang-Ho , Farrand Stephen K. , Lee Ko-Eun , Park Dae-Kyun , Lee Jeong Kug , Kim Kun-Soo
Published: January 2003

Deoxyfructosyl glutamine (DFG, referred to elsewhere as dfg) is a naturally occurring Amadori compound found in rotting fruits and vegetables. DFG also is an opine and is found in tumors induced by chrysopine-type strains ofAgrobacterium tumefaciens. Such strains catabolize this opine via a pathway coded for by their plasmids. NT1, a derivative of the nopaline-typeA. tumefaciensstrain C58 lacking pTiC58, can utilize DFG as the sole carbon source. Genes for utilization of DFG were mapped to the 543-kb accessory plasmid pAtC58. Two cosmid clones of pAtC58 allowed UIA5, a plasmid-free derivative of C58, harboring pSa-C that expresses MocC (mannopine [MOP] oxidoreductase that oxidizes MOP to DFG), to grow by using MOP as the sole carbon source. Genetic analysis of subclones indicated that the genes for utilization of DFG are located in a 6.2-kbBglII (Bg2) region adjacent torepABC-type genes probably responsible for the replication of pAtC58. This region contains five open reading frames organized into at least two transcriptionalsoc(santhopine catabolism) groups:socRandsocABCD. Nucleotide sequence analysis and analyses of transposon-insertion mutations in the region showed that SocR negatively regulates the expression ofsocRitself andsocABCD. SocA and SocB are responsible for transport of DFG and MOP. SocA is a homolog of known periplasmic amino acid binding proteins. The N-terminal half of SocB is a homolog of the transmembrane transporter proteins for several amino acids, and the C-terminal half is a homolog of the transporter-associated ATP-binding proteins. SocC and SocD could be responsible for the enzymatic degradation of DFG, being homologs of sugar oxidoreductases and an amadoriase fromCorynebacteriumsp., respectively. The protein products ofsocABCDare not related at the amino acid sequence level to those of themocandmotgenes of Ti plasmids responsible for utilization of DFG and MOP, indicating that these two sets of genes and their catabolic pathways have evolved convergently from independent origins.
Transcription of theSalmonellaInvasion Gene Activator,hilA, Requires HilD Activation in the Absence of Negative Regulators
Authors: Boddicker Jennifer D. , Knosp Boyd M. , Jones Bradley D.
Published: January 2003

Salmonella entericaserovar Typhimurium causes human gastroenteritis and a systemic typhoid-like infection in mice. Infection is initiated by entry of the bacteria into intestinal epithelial cells and is mediated by a type III secretion system that is encoded by genes inSalmonellapathogenicity island 1. The expression of invasion genes is tightly regulated by environmental conditions such as oxygen and osmolarity, as well as by many bacterial factors. ThehilAgene encodes an OmpR/ToxR family transcriptional regulator that activates the expression of invasion genes in response to both environmental and genetic regulatory factors. HilD is an AraC/XylS regulator that has been postulated to act as a derepressor ofhilAexpression that promotes transcription by interfering with repressor binding at thehilApromoter. Our research group has identified four genes (hilE,hha,pag, andams) that negatively affecthilAtranscription. Since the postulated function of HilD at thehilApromoter is to counteract the effects of repressors, we examined this model by measuringhilA::Tn5lacZYexpression in strains containing negative regulator mutations in the presence or absence of functional HilD. Single negative regulator mutations caused significant derepression ofhilAexpression, and two or more negative regulator mutations led to very high level expression ofhilA. However, in all strains tested, the absence ofhilDresulted in low-level expression ofhilA, suggesting that HilD is required for activation ofhilAexpression, whether or not negative regulators are present. We also observed that deletion of the HilD binding sites in the chromosomalhilApromoter severely decreasedhilAexpression. In addition, we found that a single point mutation at leucine 289 in the C-terminal domain of the α subunit of RNA polymerase leads to very low levels ofhilA::Tn5lacZYexpression, suggesting that HilD activates transcription ofhilAby contacting and recruiting RNA polymerase to thehilApromoter.