bluuebunny/crossref_metadata_2025 huggingface dataset:
The LysR-Type Transcriptional Regulator YofA Controls Cell Division through the Regulation of Expression of
ftsW
in
Bacillus subtilis
Authors: Lu Zuolei , Takeuchi Michio , Sato Tsutomu
Published: May 2007

We have carried out a functional analysis of LysR family transcriptional regulators in
Bacillus subtilis
. The cell density of cultures of a
yofA
insertion mutant declined sharply after the end of exponential growth, as measured by optical density at 600 nm. Complementation in
trans
and analysis of isopropyl-β-
d
-thiogalactopyranoside (IPTG)-dependent growth of an inducible
yofA
strain confirmed that YofA contributes to the cell density of a culture after the end of exponential growth. Microscopic observation suggested that cell division is inhibited or delayed in the
yofA
mutant during entry into stationary phase. Analysis of the transcription of cell division genes revealed that the expression of
ftsW
is inhibited in
yofA
mutants, and overexpression of
yofA
, driven by a multiple-copy plasmid, enhances the induction of
ftsW
expression. These results suggest that YofA is required for the final round of cell division before entry into stationary phase and that YofA positively regulates
ftsW
expression. The defects caused by mutation of
yofA
were suppressed in strains carrying P

spac

-
ftsW
in the presence of IPTG. Furthermore, maximal expression of
yofA
was observed at the onset of stationary phase, which coincided with the maximal
ftsW
expression. Our data indicate that YofA is involved in cell division through positive regulation of the expression of
ftsW
in
B. subtilis
.
Drug-Induced Conformational Changes in Multidrug Efflux Transporter AcrB from
Haemophilus influenzae
Authors: Dastidar Vishakha , Mao Weimin , Lomovskaya Olga , Zgurskaya Helen I.
Published: May 2007

In gram-negative bacteria, transporters belonging to the resistance-nodulation-cell division (RND) superfamily of proteins are responsible for intrinsic multidrug resistance.
Haemophilus influenzae
, a gram-negative pathogen causing respiratory diseases in humans and animals, constitutively produces the multidrug efflux transporter AcrB (AcrB
HI
). Similar to other RND transporters AcrB
HI
associates with AcrA
HI
, the periplasmic membrane fusion protein, and the outer membrane channel TolC
HI
. Here, we report that AcrAB
HI
confers multidrug resistance when expressed in
Escherichia coli
and requires for its activity the
E. coli
TolC (TolC
EC
) protein. To investigate the intracellular dynamics of AcrAB
HI
, single cysteine mutations were constructed in AcrB
HI
in positions previously identified as important for substrate recognition. The accessibility of these strategically positioned cysteines to the hydrophilic thiol-reactive fluorophore fluorescein-5-maleimide (FM) was studied in vivo in the presence of various substrates of AcrAB
HI
and in the presence or absence of AcrA
HI
and TolC
EC
. We report that the reactivity of specific cysteines with FM is affected by the presence of some but not all substrates. Our results suggest that substrates induce conformational changes in AcrB
HI
.
IcsA Surface Presentation in
Shigella flexneri
Requires the Periplasmic Chaperones DegP, Skp, and SurA
Authors: Purdy Georgiana E. , Fisher Carolyn R. , Payne Shelley M.
Published: May 2007

A
Shigella flexneri degP
mutant, which was defective for plaque formation in Henle cell monolayers, had a reduced amount of IcsA detectable on the bacterial surface with antibody. However, the mutant secreted IcsA to the outer membrane at wild-type levels. This suggests that IcsA adopts an altered conformation in the outer membrane of the
degP
mutant with reduced exposure on the cell surface. IcsA is, therefore, unlikely to be accessible to actin-nucleating proteins within the eukaryotic cell cytoplasm, which is required for bacterial movement within the host cell and cell-to-cell spread. The
degP
mutant was somewhat more sensitive to detergents, antibiotics, and the antimicrobial peptide magainin, indicating that the
degP
phenotype was not limited to IcsA surface presentation. The plaque defect of the
degP
mutant, which is independent of DegP protease activity, was suppressed by overexpression of the periplasmic chaperone Skp but not by SurA.
S. flexneri skp
and
surA
mutants failed to form plaques in Henle cell monolayers and were defective in cell surface presentation and polar localization of IcsA. Therefore, the three periplasmic folding factors DegP, Skp, and SurA were all required for IcsA localization and plaque formation by
S. flexneri
.
Gene Cloning and Characterization of the Very Large NAD-Dependentl-Glutamate Dehydrogenase from the PsychrophileJanthinobacterium lividum, Isolated from Cold Soil
Authors: Kawakami Ryushi , Sakuraba Haruhiko , Ohshima Toshihisa
Published: May 2007

NAD-dependentl-glutamate dehydrogenase (NAD-GDH) activity was detected in cell extract from the psychrophileJanthinobacterium lividumUTB1302, which was isolated from cold soil and purified to homogeneity. The native enzyme (1,065 kDa, determined by gel filtration) is a homohexamer composed of 170-kDa subunits (determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Consistent with these findings, gene cloning and sequencing enabled deduction of the amino acid sequence of the subunit, which proved to be comprised of 1,575 amino acids with a combined molecular mass of 169,360 Da. The enzyme from this psychrophile thus appears to belong to the GDH family characterized by very large subunits, like those expressed byStreptomyces clavuligerusandPseudomonas aeruginosa(about 180 kDa). The entire amino acid sequence of theJ. lividumenzyme showed about 40% identity with the sequences fromS. clavuligerusandP. aeruginosaenzymes, but the central domains showed higher homology (about 65%). Within the central domain, the residues related to substrate and NAD binding were highly conserved, suggesting that this is the enzyme's catalytic domain. In the presence of NAD, but not in the presence of NADP, this GDH exclusively catalyzed the oxidative deamination ofl-glutamate. The stereospecificity of the hydride transfer to NAD was pro-S, which is the same as that of the other known GDHs. Surprisingly, NAD-GDH activity was markedly enhanced by the addition of various amino acids, such asl-aspartate (1,735%) andl-arginine (936%), which strongly suggests that the N- and/or C-terminal domains play regulatory roles and are involved in the activation of the enzyme by these amino acids.
Pyocyanin Alters Redox Homeostasis and Carbon Flux through Central Metabolic Pathways in
Pseudomonas aeruginosa
PA14
Authors: Price-Whelan Alexa , Dietrich Lars E. P. , Newman Dianne K.
Published: May 2007

The opportunistic pathogen
Pseudomonas aeruginosa
produces colorful, redox-active antibiotics called phenazines. Excretion of pyocyanin, the best-studied natural phenazine, is responsible for the bluish tint of sputum and pus associated with
P. aeruginosa
infections in humans. Although the toxicity of pyocyanin for other bacteria, as well as its role in eukaryotic infection, has been studied extensively, the physiological relevance of pyocyanin metabolism for the producing organism is not well understood. Pyocyanin reduction by
P. aeruginosa
PA14 is readily observed in standing liquid cultures that have consumed all of the oxygen in the medium. We investigated the physiological consequences of pyocyanin reduction by assaying intracellular concentrations of NADH and NAD
+
in the wild-type strain and a mutant defective in phenazine production. We found that the mutant accumulated more NADH in stationary phase than the wild type. This increased accumulation correlated with a decrease in oxygen availability and was relieved by the addition of nitrate. Pyocyanin addition to a phenazine-null mutant also decreased intracellular NADH levels, suggesting that pyocyanin reduction facilitates redox balancing in the absence of other electron acceptors. Analysis of extracellular organic acids revealed that pyocyanin stimulated stationary-phase pyruvate excretion in
P. aeruginosa
PA14, indicating that pyocyanin may also influence the intracellular redox state by decreasing carbon flux through central metabolic pathways.
CsrA Inhibits Translation Initiation of
Escherichia coli hfq
by Binding to a Single Site Overlapping the Shine-Dalgarno Sequence
Authors: Baker Carol S. , Eöry Lél A. , Yakhnin Helen , Mercante Jeffrey , Romeo Tony , Babitzke Paul
Published: May 2007

Csr (carbon storage regulation) of
Escherichia coli
is a global regulatory system that consists of CsrA, a homodimeric RNA binding protein, two noncoding small RNAs (sRNAs; CsrB and CsrC) that function as CsrA antagonists by sequestering this protein, and CsrD, a specificity factor that targets CsrB and CsrC for degradation by RNase E. CsrA inhibits translation initiation of
glgC
,
cstA
, and
pgaA
by binding to their leader transcripts and preventing ribosome binding. Translation inhibition is thought to contribute to the observed mRNA destabilization. Each of the previously known target transcripts contains multiple CsrA binding sites. A position-specific weight matrix search program was developed using known CsrA binding sites in mRNA. This search tool identified a potential CsrA binding site that overlaps the Shine-Dalgarno sequence of
hfq
, a gene that encodes an RNA chaperone that mediates sRNA-mRNA interactions. This putative CsrA binding site matched the SELEX-derived binding site consensus sequence in 8 out of 12 positions. Results from gel mobility shift and footprint assays demonstrated that CsrA binds specifically to this site in the
hfq
leader transcript. Toeprint and cell-free translation results indicated that bound CsrA inhibits Hfq synthesis by competitively blocking ribosome binding. Disruption of
csrA
caused elevated expression of an
hfq
′-′
lacZ
translational fusion, while overexpression of
csrA
inhibited expression of this fusion. We also found that
hfq
mRNA is stabilized upon entry into stationary-phase growth by a CsrA-independent mechanism. The interaction of CsrA with
hfq
mRNA is the first example of a CsrA-regulated gene that contains only one CsrA binding site.
AtlA Functions as a Peptidoglycan Lytic Transglycosylase in the
Neisseria gonorrhoeae
Type IV Secretion System
Authors: Kohler Petra L. , Hamilton Holly L. , Cloud-Hansen Karen , Dillard Joseph P.
Published: May 2007

Type IV secretion systems require peptidoglycan lytic transglycosylases for efficient secretion, but the function of these enzymes is not clear. The type IV secretion system gene cluster of
Neisseria gonorrhoeae
encodes two peptidoglycan transglycosylase homologues. One, LtgX, is similar to peptidoglycan transglycosylases from other type IV secretion systems. The other, AtlA, is similar to endolysins from bacteriophages and is not similar to any described type IV secretion component. We characterized the enzymatic function of AtlA in order to examine its role in the type IV secretion system. Purified AtlA was found to degrade macromolecular peptidoglycan and to produce 1,6-anhydro peptidoglycan monomers, characteristic of lytic transglycosylase activity. We found that AtlA can functionally replace the lambda endolysin to lyse
Escherichia coli
. In contrast, a sensitive measure of lysis demonstrated that AtlA does not lyse gonococci expressing it or gonococci cocultured with an AtlA-expressing strain. The gonococcal type IV secretion system secretes DNA during growth. A deletion of
ltgX
or a substitution in the putative active site of AtlA severely decreased DNA secretion. These results indicate that AtlA and LtgX are actively involved in type IV secretion and that AtlA is not involved in lysis of gonococci to release DNA. This is the first demonstration that a type IV secretion peptidoglycanase has lytic transglycosylase activity. These data show that AtlA plays a role in type IV secretion of DNA that requires peptidoglycan breakdown without cell lysis.
Characterization of Biphenyl Dioxygenase of
Pandoraea pnomenusa
B-356 As a Potent Polychlorinated Biphenyl-Degrading Enzyme
Authors: Gómez-Gil Leticia , Kumar Pravindra , Barriault Diane , Bolin Jeffrey T. , Sylvestre Michel , Eltis Lindsay D.
Published: May 2007

Biphenyl dioxygenase (BPDO) catalyzes the aerobic transformation of biphenyl and various polychlorinated biphenyls (PCBs). In three different assays, BPDO
B356
from
Pandoraea pnomenusa
B-356 was a more potent PCB-degrading enzyme than BPDO
LB400
from
Burkholderia xenovorans
LB400 (75% amino acid sequence identity), transforming nine congeners in the following order of preference: 2,3′,4-trichloro ∼ 2,3,4′-trichloro > 3,3′-dichloro > 2,4,4′-trichloro > 4,4′-dichloro ∼ 2,2′-dichloro > 2,6-dichloro > 2,2′,3,3′-tetrachloro ∼ 2,2′,5,5′-tetrachloro. Except for 2,2′,5,5′-tetrachlorobiphenyl, BPDO
B356
transformed each congener at a higher rate than BPDO
LB400
. The assays used either whole cells or purified enzymes and either individual congeners or mixtures of congeners. Product analyses established previously unrecognized BPDO
B356
activities, including the 3,4-dihydroxylation of 2,6-dichlorobiphenyl. BPDO
LB400
had a greater apparent specificity for biphenyl than BPDO
B356
(
k
cat
/
K

m

= 2.4 × 10
6
± 0.7 × 10
6
M
−1
s
−1
versus
k
cat
/
K

m

= 0.21 × 10
6
± 0.04 × 10
6
M
−1
s
−1
). However, the latter transformed biphenyl at a higher maximal rate (
k
cat
= 4.1 ± 0.2 s
−1
versus
k
cat
= 0.4 ± 0.1 s
−1
). A variant of BPDO
LB400
containing four active site residues of BPDO
B356
transformed
para
-substituted congeners better than BPDO
LB400
. Interestingly, a substitution remote from the active site, A267S, increased the enzyme's preference for
meta
-substituted congeners. Moreover, this substitution had a greater effect on the kinetics of biphenyl utilization than substitutions in the substrate-binding pocket. In all variants, the degree of coupling between congener depletion and O
2
consumption was approximately proportional to congener depletion. At 2.4-Å resolution, the crystal structure of the BPDO
B356
-2,6-dichlorobiphenyl complex, the first crystal structure of a BPDO-PCB complex, provided additional insight into the reactivity of this isozyme with this congener, as well as into the differences in congener preferences of the BPDOs.
Crystal Structure of the
Vibrio cholerae
Quorum-Sensing Regulatory Protein HapR
Authors: De Silva Rukman S. , Kovacikova Gabriela , Lin Wei , Taylor Ronald K. , Skorupski Karen , Kull F. Jon
Published: May 2007

Quorum sensing in
Vibrio cholerae
involves signaling between two-component sensor protein kinases and the response regulator LuxO to control the expression of the master regulator HapR. HapR, in turn, plays a central role in regulating a number of important processes, such as virulence gene expression and biofilm formation. We have determined the crystal structure of HapR to 2.2-Å resolution. Its structure reveals a dimeric, two-domain molecule with an all-helical structure that is strongly conserved with members of the TetR family of transcriptional regulators. The N-terminal DNA-binding domain contains a helix-turn-helix DNA-binding motif and alteration of certain residues in this domain completely abolishes the ability of HapR to bind to DNA, alleviating repression of both virulence gene expression and biofilm formation. The C-terminal dimerization domain contains a unique solvent accessible tunnel connected to an amphipathic cavity, which by analogy with other TetR regulators, may serve as a binding pocket for an as-yet-unidentified ligand.
Human Body Temperature (37°C) Increases the Expression of Iron, Carbohydrate, and Amino Acid Utilization Genes in
Escherichia coli
K-12
Authors: White-Ziegler Christine A. , Malhowski Amy J. , Young Sarah
Published: May 2007

Using DNA microarrays, we identified 126 genes in
Escherichia coli
K-12 whose expression is increased at human body temperature (37°C) compared to growth at 23°C. Genes involved in the uptake and utilization of amino acids, carbohydrates, and iron dominated the list, supporting a model in which temperature serves as a host cue to increase expression of bacterial genes needed for growth. Using quantitative real-time PCR, we investigated the thermoregulatory response for representative genes in each of these three categories (
hisJ
,
cysP
,
srlE
,
garP
,
fes
, and
cirA
), along with the fimbrial gene
papB
. Increased expression at 37°C compared to 23°C was retained in both exponential and stationary phases for all of the genes and in most of the various media tested, supporting the relative importance of this cue in adapting to changing environments. Because iron acquisition is important for both growth and virulence, we analyzed the regulation of the iron utilization genes
cirA
and
fes
and found that growth in iron-depleted medium abrogated the thermoregulatory effect, with high-level expression at both temperatures, contrasting with
papB
thermoregulation, which was not greatly altered by limiting iron levels. A positive role for the environmental regulator H-NS was found for
fes
,
cirA
,
hisJ
, and
srlE
transcription, whereas it had a primarily negative effect on
cysP
and
garP
expression. Together, these studies indicate that temperature is a broadly used cue for regulating gene expression in
E. coli
and that H-NS regulates iron, carbohydrate, and amino acid utilization gene expression.
Rule change incidence on physiological characteristics of elite basketball players: a 10-year-period investigation
Authors: Cormery B , Marcil M , Bouvard M
Published: May 2007

Objective:

To evaluate, by examining data collected on professional basketball players during a 10-year period, the differences in aerobic capacity in function of the playing position and the impact on these parameters of the change in time regulation of 2000, which shortened the time allowed to attempt a field goal by 6 s and divided the duration of play in four quarters.

Methods:

Twice a year between 1994 and 2004, professional basketball players (n = 68) were studied for anthropometric characteristics and were submitted to an incremental exercise test on a cycle ergometer. Statistical analyses were carried out to determine the interaction between the playing position and the effect of the change in time regulation on the physiological characteristics of the players.

Results:

Anthropometric measurements were different in function of the playing position, the centres being taller and heavier than the forwards and the guards. Guards exhibited the highest V̇o2max (54.0 (SE 1.6) ml/min/kg) and were the most affected by the change in time regulation of 2000 with a 19.5% increase. Significant main effects of “before” versus “after” rule changes were found for maximal and submaximal O2consumption, which were increased by 12.8% at ventilatory threshold, 7.3% at respiratory compensation point and 7.8% at V̇o2max.

Conclusion:

While anthropometric characteristics remained constant during the last decade, the change in rule of 2000 may have contributed in modifying the physiological profile of basketball players, by generally increasing their level of fitness.
Reference intervals for serum creatine kinase in athletes
Authors: Mougios Vassilis
Published: May 2007

Background:

The serum concentration of creatine kinase (CK) is used widely as an index of skeletal muscle fibre damage in sport and exercise. Since athletes have higher CK values than non-athletes, comparing the values of athletes to the normal values established in non-athletes is pointless. The purpose of this study was to introduce reference intervals for CK in athletes.

Method:

CK was assayed in serum samples from 483 male athletes and 245 female athletes, aged 7–44. Samples had been obtained throughout the training and competition period. For comparison, CK was also assayed in a smaller number of non-athletes. Reference intervals (2.5th to 97.5th percentile) were calculated by the non-parametric method.

Results:

The reference intervals were 82–1083 U/L (37°C) in male and 47–513 U/L in female athletes. The upper reference limits were twice the limits reported for moderately active non-athletes in the literature or calculated in the non-athletes in this study. The upper limits were up to six times higher than the limits reported for inactive individuals in the literature. When reference intervals were calculated specifically in male football (soccer) players and swimmers, a threefold difference in the upper reference limit was found (1492 vs 523 U/L, respectively), probably resulting from the different training and competition demands of the two sports.

Conclusion:

Sport training and competition have profound effects on the reference intervals for serum CK. Introducing sport-specific reference intervals may help to avoid misinterpretation of high values and to optimise training.
Heart rate variability modifications following exercise training in type 2 diabetic patients with definite cardiac autonomic neuropathy
Authors: Pagkalos M , Koutlianos N , Kouidi E , Pagkalos E , Mandroukas K , Deligiannis A
Published: May 2007

Objectives:

Cardiac autonomic neuropathy (CAN) as a result of diabetic autonomic neuropathy is positively related to a poor prognosis in diabetic patients. The measurement of heart rate variability (HRV) is a remarkable index of cardiac autonomic dysfunction. The aim of this study was to examine the effects of long-term exercise training on HRV in type 2 diabetic patients with definite CAN.

Methods:

Seventeen type 2 diabetic patients with definite CAN (group A: 56.2 years (SD 5.8)) and 15 without CAN (group B: 55.8 years (SD 5.6)) participated in the study. All patients followed an aerobic exercise training programme three times a week for 6 months; the intensity of the session was 70% to 85% of heart rate reserve. At the beginning and end of the study all subjects underwent graded maximal exercise testing with spiroergometry for the evaluation of their aerobic capacity (VO2peak). Moreover, time and frequency domain indices of HRV were obtained from 24 h ambulatory continuous ECG Holter recordings.

Results:

At baseline, all measurements of HRV indices were significantly reduced in group A compared with group B (p<0.05). Moreover, group A reached a significantly lower VO2peakby 14.8% compared with group B (p<0.05). Following the exercise training programme, the SD of all normal-to-normal RR intervals in the entire recording (SDNN) was increased by 18.8% (p<0.05) and 13.8% (p<0.05), the square root of the average of sum of squares of difference between adjacent filtered RR intervals (rMSSd) was increased by 35% (p<0.05) and 15.2% (p<0.05), and the percentage of differences between adjacent filtered RR intervals which was greater than 50 ms for the entire analysis (pNN50) was increased by 400% (p<0.05) and 67.9% (p<0.05) in groups A and B, respectively. Regarding the frequency domain indices, only the high frequency power (HF) was found to be significantly increased in group A. At the end of the exercise training programme, SDNN, rMSSd and low frequency power (LF) were significantly lower (24.3% (p<0.05), 20.3% (p<0.05) and 40% (p<0.05), respectively) in group A compared with group B. Also, VO2peakincreased by 17.8% (p<0.05) in group A and by 11% (p<0.05) in group B. Furthermore, the exercise training programme had significant effects on blood lipid and glucose levels and glycosylated haemoglobin (HbA1c) in both groups.

Conclusions:

The results indicate that 6-month aerobic exercise training improves the cardiac autonomic nervous system function in type 2 diabetic patients. However, more favourable effects are found in type 2 diabetic patients with definite CAN.
Effect of plyometric training on sand versus grass on muscle soreness and jumping and sprinting ability in soccer players
Authors: Impellizzeri F M , Rampinini E , Castagna C , Martino F , Fiorini S , Wisloff U
Published: May 2007

Objective:

The lower impact on the musculoskeletal system induced by plyometric exercise on sand compared to a firm surface might be useful to reduce the stress of intensified training periods or during rehabilitation from injury. The aim of this study was to compare the effects of plyometric training on sand versus a grass surface on muscle soreness, vertical jump height and sprinting ability.

Design:

Parallel two-group, randomised, longitudinal (pretest−post-test) study.

Methods:

After random allocation, 18 soccer players completed 4 weeks of plyometric training on grass (grass group) and 19 players on sand (sand group). Before and after plyometric training, 10 m and 20 m sprint time, squat jump (SJ), countermovement jump (CMJ), and eccentric utilization ratio (CMJ/SJ) were determined. Muscle soreness was measured using a Likert scale.

Results:

No training surface × time interactions were found for sprint time (p>0.87), whereas a trend was found for SJ (p = 0.08), with both groups showing similar improvements (p<0.001). On the other hand, the grass group improved their CMJ (p = 0.033) and CMJ/SJ (p = 0.005) significantly (p<0.001) more than players in the sand group. In contrast, players in the sand group experienced less muscle soreness than those in the grass group (p<0.001).

Conclusions:

Plyometric training on sand improved both jumping and sprinting ability and induced less muscle soreness. A grass surface seems to be superior in enhancing CMJ performance while the sand surface showed a greater improvement in SJ. Therefore, plyometric training on different surfaces may be associated with different training-induced effects on some neuromuscular factors related to the efficiency of the stretch-shortening cycle.
Bone marrow trephine combined with immunohistochemistry is superior to bone marrow aspirate in follow-up of myeloma patients
Authors: Joshi R , Horncastle D , Elderfield K , Lampert I , Rahemtulla A , Naresh K N
Published: May 2007

Aims:

Multiple myeloma (MM) guidelines in the UK do not advocate performing bone marrow trephine biopsy (BMTB) during follow-up. In a recent study, it was found that the plasma cell per cent (PC%) in BMTB performed at the time of autologous stem cell transplant strongly correlated with survival. The current study addresses whether BMTB is superior to bone marrow aspiration (BMA) in documenting presence of disease and its volume at follow-up.

Methods:

The study involved 106 samples. A conventional 500-cell differential count was performed on the BMAs to document the PC%. The PC% on BMTBs had been estimated on CD138 immunostain. Furthermore, BMTBs had also been immunostained for CD56, cyclin D1 and light chains.

Results:

The mean (2SEM) PC% values in BMAs and BMTBs were 13.1 (2.6)% and 31.8 (5.8)% respectively. Based on BMA, BMTB and serum/urine paraprotein or light chain estimation, on 92 occasions (89%) there was detectable disease. The positive predictive value of both BMA and BMTB was 100%, and the negative predictive values for BMTB and BMA were 57% and 22% respectively. Among 98 secretory MM cases, the BMTB-PC% showed significant correlation with paraprotein levels, whereas BMA-PC% did not.

Conclusions:

It is strongly recommended that BMTB is performed and adequately investigated with immunohistochemistry during follow-up of MM.
Genetic architecture of chalcone isomerase non-coding regions in common bean (Phaseolus vulgaris L.)
Authors: McClean Phillip E. , Lee Rian K.
Published: May 2007

Sequence data for 2 non-coding regions of the chalcone isomerase gene were analyzed to study the genetic architecture of common bean ( Phaseolus vulgaris L.). One region corresponded to the first 596 nucleotides (nt) of the 5′-untranslated region (UTR). The other region was the 710 nt intron 3. Data were collected from 67 genotypes representing both landraces and cultivars from the geographical range of the cultivated form of the species. Variability in the 5′-UTR region was represented by single nucleotide polymorphisms (SNPs), whereas intron 3 variation was due to a collection of SNPs and insertion–deletion events. Diversity was greater in the 5′-UTR (π = 0.0175) than in intron 3 (π = 0.0089). For each region, diversity was greater for genotypes of Middle American than Andean origin. A single recombination event was observed, and the hybridization pattern necessary to derive the recombinant genotypes supported the previous observation of an ancestral gene pool from which modern domesticated genotypes are derived. For both regions, a strongly supported Andean group was observed, whereas the presence of 2 Middle American subgroups was also supported. Although a significantly positive Tajima’s D statistic was observed for the 5′-UTR for all genotypes, we conclude that this is more likely the result of a strong demographic effect and that balancing selection is occurring only among the Middle American genotypes.
Cardioprotective effects of nitric oxide-aspirin in myocardial ischemia-reperfused rats
Authors: Fu Yilong , Wang Zhongjing , Chen Woei Lee , Moore Philip K. , Zhu Yi Zhun
Published: May 2007

In this study, the cardioprotective effects of nitric oxide (NO)-aspirin, the nitroderivative of aspirin, were compared with those of aspirin in an anesthetized rat model of myocardial ischemia-reperfusion. Rats were given aspirin or NO-aspirin orally for 7 consecutive days preceding 25 min of myocardial ischemia followed by 48 h of reperfusion (MI/R). Treatment groups included vehicle (Tween 80), aspirin (30 mg·kg−1·day−1), and NO-aspirin (56 mg·kg−1·day−1). NO-aspirin, compared with aspirin, displayed remarkable cardioprotection in rats subjected to MI/R as determined by the mortality rate and infarct size. Mortality rates for vehicle ( n = 23), aspirin ( n = 22), and NO-aspirin groups ( n = 22) were 34.8, 27.3, and 18.2%, respectively. Infarct size of the vehicle group was 44.5 ± 2.7% of the left ventricle (LV). In contrast, infarct size of the LV decreased in the aspirin- and NO-aspirin-pretreated groups, 36.7 ± 1.8 and 22.9 ± 4.3%, respectively (both P < 0.05 compared with vehicle group; P < 0.05, NO-aspirin vs. aspirin ). Moreover, NO-aspirin also improved ischemiareperfusion-induced myocardial contractile dysfunction on postischemic LV developed pressure. In addition, NO-aspirin downregulated inducible NO synthase (iNOS; 0.37-fold, P < 0.01) and cyclooxygenase-2 (COX-2; 0.61-fold, P < 0.05) gene expression compared with the vehicle group after 48 h of reperfusion. Treatment with NG-nitro-l-arginine methyl ester (l-NAME; 20 mg/kg), a nonselective NOS inhibitor, aggravated myocardial damage in terms of mortality and infarct size but attenuated effects when coadministered with NO-aspirin. l-NAME administration did not alter the increase in iNOS and COX-2 expression but did reverse the NO-aspirin-induced inhibition of expression of the two genes. The beneficial effects of NO-aspirin appeared to be derived largely from the NO moiety, which attenuated myocardial injury to limit infarct size and better recovery of LV function following ischemia and reperfusion.
Influence of sex, high-fat diet, and exercise training on potassium currents of swine coronary smooth muscle
Authors: Yang Yan , Jones Allan W. , Thomas Tom R. , Rubin Leona J.
Published: May 2007

Potassium channels in vascular smooth muscle (VSM) control vasodilation and are potential regulatory targets. This study evaluated effects of sex differences, exercise training (EX), and high-fat diet (HF) on K+currents ( IK) of coronary VSM cells. Yucatan male and female swine were assigned to either sedentary confinement (SED), 16 wk of EX, 20 wk of HF, or 20 wk of HF with 16 wk of EX (HF-EX). VSM cells of normal-diet SED animals exhibited three components of IK: 4-aminopyridine-sensitive IK(KV), TEA-sensitive IK(BK), and 4-aminopyridine + TEA-insensitive IK. Females exhibited significantly higher basal IKthan males in the same group. EX increased basal IKin males and females. HF reduced IKin males and females and nullified effects of EX. Endothelin-1 increased IKsignificantly in males but not in females. In the presence of endothelin-1, 1) IK(KV)was similar in SED males and females and EX increased IK(KV)to a greater extent in males than in females and 2) IK(BK)was greater in SED females than in males and EX increased IK(BK)to a greater extent in males, resulting in IK(BK)similar to EX females. Importantly, HF nullified effects of EX on IK(KV)and IK(BK). These data indicate that basal IKof SED female swine is inherently greater than that shown in SED males and that males require EX to achieve comparable levels of IK. Importantly, HF reduced IKin males and females and nullified effects of EX, suggesting HF abrogates beneficial effects of EX on coronary smooth muscle.
Angiotensin II and endothelin-1 augment the vascular complications of diabetes via JAK2 activation
Authors: Banes-Berceli Amy K. L. , Ketsawatsomkron Pimonrat , Ogbi Safia , Patel Bela , Pollock David M. , Marrero Mario B.
Published: May 2007

The JAK/STAT pathway is activated in vitro by angiotensin II (ANG II) and endothelin-1 (ET-1), which are implicated in the development of diabetic complications. We hypothesized that ANG II and ET-1 activate the JAK/STAT pathway in vivo to participate in the development of diabetic vascular complications. Using male Sprague-Dawley rats, we performed a time course study [ days 7, 14, and 28 after streptozotocin (STZ) injection] to determine changes in phosphorylation of JAK2, STAT1, and STAT3 in thoracic aorta using standard Western blot techniques. On day 7 there was no change in phosphorylation of JAK2, STAT1, and STAT3. Phosphorylation of JAK2, STAT1, and STAT3 was significantly increased on days 14 and 28 and was inhibited by treatment with candesartan (AT1 receptor antagonist, 10 mg·kg−1·day−1 orally in drinking water), atrasentan (ETA receptor antagonist, 10 mg·kg−1·day−1 orally in drinking water), and AG-490 (JAK2 inhibitor, 5 mg·kg−1·day−1 intraperitoneally). On day 28, treatment with all inhibitors prevented the significant increase in systolic blood pressure (SBP; tail cuff) of STZ-induced diabetic rats (SBP: 157 ± 9.0, 130 ± 3.3, 128 ± 6.8, and 131 ± 10.4 mmHg in STZ, STZ-candesartan, STZ-atrasentan, and STZ-AG-490 rats, respectively). In isolated tissue bath studies, diabetic rats displayed impaired endothelium-dependent relaxation in aorta (maximal relaxation: 95.3 ± 3.0, 92.6 ± 7.4, 76.9 ± 12.1, and 38.3 ± 13.1% in sham, sham + AG-490, STZ + AG-490, and STZ rats, respectively). Treatment of rats with AG-490 restored endothelium-dependent relaxation in aorta from diabetic rats at 14 and 28 days of treatment. These results demonstrate that JAK2 activation in vivo participates in the development of vascular complications associated with STZ-induced diabetes.
Long-term effect of dietary α-linolenic acid or decosahexaenoic acid on incorporation of decosahexaenoic acid in membranes and its influence on rat heart in vivo
Authors: Ayalew-Pervanchon Adey , Rousseau Delphine , Moreau Daniel , Assayag Patrick , Weill Pierre , Grynberg Alain
Published: May 2007

The present study was designed to evaluate whether long-term intake of dietary α-linolenic acid (ALA), supplied as whole grain-extruded linseed, can increase endogenous production of n-3 long-chain polyunsaturated fatty acids (FAs) in healthy adult rats and influence the heart rate (HR) and adrenergic response in the same way as docosahexaenoic acid (DHA)-rich diets. DHA enrichment was evaluated using FA analysis of tissue phospholipids after 8, 16, 24, and 32 wk of feeding in male Wistar rats randomly assigned to three dietary groups ( n = 8 in each group): a reference fat diet (RFD), an ALA-rich (ALA) diet, and a DHA-rich (DHA) diet. At 1 wk before the animals were killed, under anesthesia, HR was measured from ECG recordings during an adrenergic stimulation challenge ( n = 8). There was a significant increase of DHA in the cardiac membrane in the ALA group compared with the RFD group. DHA content in the cardiac membrane was ∼10% in the ALA group vs. 20% in the DHA group and 4% in the RFD group. The cardiac FA profile was established after 2 mo and remained essentially unchanged thereafter. Regardless of the diet, DHA in the heart decreased with age. Nevertheless, DHA content in the heart remained at >15% in the DHA group and remained greater in older rats fed the ALA diet than in younger RFD-fed rats. Basal HR decreased in the ALA group (395 ± 24.9 beats/min) to a level between that of the DHA and RFD groups (375 ± 26.4 and 407 ± 36.7 beats/min, respectively). Both n-3 dietary intakes contribute to enhancement of the chronotropic response to adrenergic agonist stimulation. Regulation of HR by neurohumoral mediators may be controlled by lower content of DHA, e.g., by a dietary supply of extruded linseed (ALA).
Muscarinic potassium channels augment dynamic and static heart rate responses to vagal stimulation
Authors: Mizuno Masaki , Kamiya Atsunori , Kawada Toru , Miyamoto Tadayoshi , Shimizu Shuji , Sugimachi Masaru
Published: May 2007

Vagal control of heart rate (HR) is mediated by direct and indirect actions of ACh. Direct action of ACh activates the muscarinic K+(KACh) channels, whereas indirect action inhibits adenylyl cyclase. The role of the KAChchannels in the overall picture of vagal HR control remains to be elucidated. We examined the role of the KAChchannels in the transfer characteristics of the HR response to vagal stimulation. In nine anesthetized sinoaortic-denerved and vagotomized rabbits, the vagal nerve was stimulated with a binary white-noise signal (0–10 Hz) for examination of the dynamic characteristic and in a step-wise manner (5, 10, 15, and 20 Hz/min) for examination of the static characteristic. The dynamic transfer function from vagal stimulation to HR approximated a first-order, low-pass filter with a lag time. Tertiapin, a selective KAChchannel blocker (30 nmol/kg iv), significantly decreased the dynamic gain from 5.0 ± 1.2 to 2.0 ± 0.6 (mean ± SD) beats·min−1·Hz−1( P < 0.01) and the corner frequency from 0.25 ± 0.03 to 0.06 ± 0.01 Hz ( P < 0.01) without changing the lag time (0.37 ± 0.04 vs. 0.39 ± 0.05 s). Moreover, tertiapin significantly attenuated the vagal stimulation-induced HR decrease by 46 ± 21, 58 ± 18, 65 ± 15, and 68 ± 11% at stimulus frequencies of 5, 10, 15, and 20 Hz, respectively. We conclude that KAChchannels contribute to a rapid HR change and to a larger decrease in the steady-state HR in response to more potent tonic vagal stimulation.
Urocortin 1 administration from onset of rapid left ventricular pacing represses progression to overt heart failure
Authors: Rademaker Miriam T. , Charles Chris J. , Richards A. Mark
Published: May 2007

Urocortin 1 (Ucn1) may be involved in the pathophysiology of heart failure (HF), but the impact of Ucn1 administration on progression of the disease is unknown. The aim of this study was to investigate the effects of Ucn1 in sheep from the onset of cardiac overload and during the subsequent development of HF. Eight sheep underwent two 4-day periods of HF induction by rapid left ventricular pacing (225 beats/min) in conjunction with continuous infusions of Ucn1 (0.1 μg·kg−1·h−1iv) and a vehicle control (0.9% saline). Compared with control, Ucn1 attenuated the pacing-induced decline in cardiac output (2.43 ± 0.46 vs. 3.70 ± 0.89 l/min on day 4, P < 0.01) and increases in left atrial pressure (24.9 ± 1.0 vs. 11.9 ± 1.1 mmHg, P < 0.001) and peripheral resistance (38.7 ± 9.4 vs. 25.2 ± 6.1 mmHg·l−1·min, P < 0.001). Ucn1 wholly prevented increases in plasma renin activity (4.02 ± 1.17 vs. 0.87 ± 0.1 nmol·l−1·h−1, P < 0.001), aldosterone (1,313 ± 324 vs. 413 ± 174 pmol/l, P < 0.001), endothelin-1 (3.8 ± 0.5 vs. 2.0 ± 0.1 pmol/l, P < 0.001), and vasopressin (10.8 ± 4.1 vs. 1.8 ± 0.2 pmol/l, P < 0.05) during pacing alone and blunted the progressive increases in plasma epinephrine (2,132 ± 697 vs. 1,250 ± 264 pmol/l, P < 0.05), norepinephrine (3.61 ± 0.73 vs. 2.07 ± 0.52 nmol/l, P < 0.05), and atrial ( P < 0.05) and brain ( P < 0.01) natriuretic peptide levels. Ucn1 administration also maintained urine sodium excretion (0.75 ± 0.34 vs. 1.59 ± 0.50 mmol/h on day 4, P < 0.05) and suppressed pacing-induced declines in creatinine clearance ( P < 0.05). These findings indicate that Ucn1 treatment from the onset of cardiac overload has the ability to repress the ensuing hemodynamic and renal deterioration and concomitant adverse neurohumoral activation, thereby delaying the development of overt HF. These data strongly support a use for Ucn1 as a therapeutic option early in the course of the disease.
Cav1.3 channels produce persistent calcium sparklets, but Cav1.2 channels are responsible for sparklets in mouse arterial smooth muscle
Authors: Navedo Manuel F. , Amberg Gregory C. , Westenbroek Ruth E. , Sinnegger-Brauns Martina J. , Catterall William A. , Striessnig Jörg , Santana Luis F.
Published: May 2007

Ca2+sparklets are local elevations in intracellular Ca2+produced by the opening of a single or a cluster of L-type Ca2+channels. In arterial myocytes, Ca2+sparklets regulate local and global intracellular Ca2+. At present, the molecular identity of the L-type Ca2+channels underlying Ca2+sparklets in these cells is undetermined. Here, we tested the hypotheses that voltage-gated calcium channel-α 1.3 subunit (Cav1.3) can produce Ca2+sparklets and that Cav1.2 and/or Cav1.3 channels are responsible for Ca2+sparklets in mouse arterial myocytes. First, we investigated the functional properties of single Cav1.3 channels in tsA201 cells. With 110 mM Ba2+as the charge carrier, Cav1.3 channels had a conductance of 20 pS. This value is similar to that of Cav1.2 and native L-type Ca2+channels. As previously shown for Cav1.2 channels, Cav1.3 channels can operate in two gating modes characterized by short and long open times. Expressed Cav1.3 channels also produced Ca2+sparklets. Cav1.3 sparklets had properties similar to those produced by Cav1.2 and native L-type channels, including quantal amplitude, dihydropyridine sensitivity, bimodal gating, and dual-event duration times. However, the voltage dependencies of conductance and steady-state inactivation of the Ca2+current ( ICa) in arterial myocytes were similar to those recorded from cells expressing Cav1.2 but not Cav1.3 channels. Furthermore, nifedipine (10 μM) eliminated Ca2+sparklets in wild-type myocytes but not in myocytes expressing dihydropyridine-insensitive Cav1.2 channels. Accordingly, Cav1.3 transcript and protein were not detected in isolated arterial myocytes. We conclude that although Cav1.3 channels can produce Ca2+sparklets, Cav1.2 channels underlie ICa, Ca2+sparklets, and hence dihydropyridine-sensitive Ca2+influx in mouse arterial myocytes.
Progressive troponin I loss impairs cardiac relaxation and causes heart failure in mice
Authors: Liu Jing , Du Jianfeng , Zhang Chi , Walker Jeffery W. , Huang Xupei
Published: May 2007

Cardiac troponin I (TnI) knockout mice exhibit a phenotype of sudden death at 17–18 days after birth due to a progressive loss of TnI. The objective of this study was to gain insight into the physiological consequences of TnI depletion and the cause of death in these mice. Cardiac function was monitored serially between 12 and 17 days of age by using high-resolution ultrasonic imaging and Doppler echocardiography. Two-dimensional B-mode and anatomical M-mode imaging and Doppler echocardiography were performed using a high-frequency (∼20–45 MHz) ultrasound imaging system on homozygous cardiac TnI mutant mice (cTnI−/−) and wild-type littermates. On day 12, cTnI−/−mice were indistinguishable from wild-type mice in terms of heart rate, atrial and LV (LV) chamber dimensions, LV posterior wall thickness, and body weight. By days 16 through 17, wild-type mice showed up to a 40% increase in chamber dimensions due to normal growth, whereas cTnI−/−mice showed increases in atrial dimensions of up to 97% but decreases in ventricular dimensions of up to 70%. Mitral Doppler analysis revealed prolonged isovolumic relaxation time and pronounced inversion of the mitral E/A ratio (early ventricular filling wave-to-late atrial contraction filling wave) only in cTnI−/−mice indicative of impaired LV relaxation. cTnI−/−mouse hearts showed clear signs of failure on day 17, characterized by >50% declines in cardiac output, ejection fraction, and fractional shortening. B-mode echocardiography showed a profoundly narrowed tube-like LV and enlarged atria at this time. Our data are consistent with TnI deficiency causing impaired LV relaxation, which leads to diastolic heart failure in this model.
Clara cells impact the pulmonary innate immune response to LPS
Authors: Elizur Arnon , Adair-Kirk Tracy L. , Kelley Diane G. , Griffin Gail L. , deMello Daphne E. , Senior Robert M.
Published: May 2007

Airway epithelial cells secrete proinflammatory mediators in response to LPS, but cytokine production by a prominent nonciliated bronchiolar epithelial cell, the Clara cell, specifically, is unknown. To investigate Clara cell cytokine production in response to LPS, we used a transformed murine Clara cell line, C22, and isolated Clara cells from C57Bl/6 mice. Stimulation of both cell types with LPS resulted in significant upregulation of keratinocyte-derived chemokine (KC) and monocyte chemoattractant protein-1, but did not induce TNF-α production. To determine whether LPS induces cytokine production by Clara cells in vivo, LPS was instilled intratracheally into mice. KC was expressed by Clara cells, alveolar type 2 cells, and alveolar macrophages, 2 h after LPS administration, as determined by in situ hybridization. TNF-α, although not expressed in airway epithelial cells, was expressed primarily in alveolar macrophages in response to LPS. To assess the impact of Clara cells on KC and TNF-α production in the lung in the early response to LPS, mice were treated with naphthalene to selectively induce Clara cell injury before LPS stimulation. KC expression in the airways and the lung periphery, and KC and TNF-α levels in the bronchoalveolar lavage fluid, were significantly reduced in naphthalene-treated vs. vehicle-treated mice after LPS stimulation. Furthermore, transwell cocultures of C22 cells and RAW264.7 macrophages indicated that C22 cells released a soluble factor(s) in response to LPS that enhanced macrophage production of TNF-α. These results indicate that Clara cells elaborate cytokines and modulate the lung innate immune response to LPS.
Heterogeneity of hypoxia-mediated decrease inIK(V)and increase in [Ca2+]cytin pulmonary artery smooth muscle cells
Authors: Platoshyn Oleksandr , Yu Ying , Ko Eun A , Remillard Carmelle V. , Yuan Jason X.-J.
Published: May 2007

Hypoxic pulmonary vasoconstriction is caused by a rise in cytosolic Ca2+([Ca2+]cyt) in pulmonary artery smooth muscle cells (PASMC) via multiple mechanisms. PASMC consist of heterogeneous phenotypes defined by contractility, proliferation, and apoptosis as well as by differences in expression and function of various genes. In rat PASMC, hypoxia-mediated decrease in voltage-gated K+(Kv) currents ( IK(V)) and increase in [Ca2+]cytwere not uniformly distributed in all PASMC tested. Acute hypoxia decreased IK(V)and increased [Ca2+]cytin ∼46% and ∼53% of PASMC, respectively. Using combined techniques of single-cell RT-PCR and patch clamp, we show here that mRNA expression level of Kv1.5 in hypoxia-sensitive PASMC (in which hypoxia reduced IK(V)) was much greater than in hypoxia-insensitive cells (in which hypoxia negligibly affected IK(V)). These results demonstrate that 1) different PASMC express different Kv channel α- and β-subunits, and 2) the sensitivity of a PASMC to acute hypoxia partially depends on the expression level of Kv1.5 channels; hypoxia reduces whole-cell IK(V)only in PASMC that express high level of Kv1.5. In addition, the acute hypoxia-mediated changes in [Ca2+]cytalso vary in different PASMC. Hypoxia increases [Ca2+]cytonly in 34% of cells tested, and the different sensitivity of [Ca2+]cytto hypoxia was not related to the resting [Ca2+]cyt. An intrinsic mechanism within each individual cell may be involved in the heterogeneity of hypoxia-mediated effect on [Ca2+]cytin PASMC. These data suggest that the heterogeneity of PASMC may partially be related to different expression levels and functional sensitivity of Kv channels to hypoxia and to differences in intrinsic mechanisms involved in regulating [Ca2+]cyt.