bluuebunny/crossref_metadata_2025_split huggingface dataset:
Transcriptional Regulation of the Cellobiose Operon of
Streptococcus mutans
Authors: Zeng Lin , Burne Robert A. 
Published: January 2009

ABSTRACT

The ability of
Streptococcus mutans
to catabolize cellobiose, a β-linked glucoside generated during the hydrolysis of cellulose, is shown to be regulated by a transcriptional regulator, CelR, which is encoded by an operon with a phospho-β-glucosidase (CelA) and a cellobiose-specific sugar
p
hospho
t
ransferase
s
ystem (PTS) permease (EII
Cel
). The roles of CelR, EII
Cel
components, and certain fructose/mannose-PTS permeases in the transcriptional regulation of the
cel
locus were analyzed. The results revealed that (i) the
celA
and
celB
(EIIB
Cel
) gene promoters require CelR for transcriptional activation in response to cellobiose, but read-through from the
celA
promoter contributes to expression of the EII
Cel
genes; (ii) the EII
Cel
subunits were required for growth on cellobiose and for transcriptional activation of the
cel
genes; (iii) CcpA plays little direct role in catabolite repression of the
cel
regulon, but loss of specific PTS permeases alleviated repression of
cel
genes in the presence of preferred carbohydrates; and (iv) glucose could induce transcription of the
cel
regulon when transported by EII
Cel
. CelR derivatives containing amino acid substitutions for five conserved histidine residues in two PTS regulatory domains and an EIIA-like domain also provided important insights regarding the function of this regulator. Based on these data, a model for the involvement of PTS permeases and the general PTS proteins enzyme I and HPr was developed that reveals a critical role for the PTS in CcpA-independent catabolite repression and induction of
cel
gene expression in
S. mutans
.
An Intact Urease Assembly Pathway Is Required To Compete with NikR for Nickel Ions in
Helicobacter pylori
Authors: Benanti Erin L. , Chivers Peter T. 
Published: January 2009

ABSTRACT

We examined the effects of urease and hydrogenase assembly gene deletions on NikR activation in
H. pylori
strains 26695 and G27. The loss of any component of urease assembly increased NikR activity under Ni
2+
-limiting conditions, as measured by reduced transcript levels and
63
Ni accumulation. Additionally, SlyD functioned in urease assembly in strain 26695.
The Molecular Alarmone (p)ppGpp Mediates Stress Responses, Vancomycin Tolerance, and Virulence inEnterococcus faecalis
Authors: Abranches Jacqueline , Martinez Alaina R. , Kajfasz Jessica K. , Chávez Violeta , Garsin Danielle A. , Lemos José A. 
Published: January 2009

ABSTRACTThe stringent response is a global bacterial response to stress that is mediated by accumulation of the alarmone (p)ppGpp. In this study, treatment with mupirocin was shown to induce high levels of (p)ppGpp production inEnterococcus faecalis, indicating that this nosocomial pathogen can mount a classic stringent response. In addition, (p)ppGpp was found to accumulate in cells subjected to heat shock, alkaline shock, and inhibitory concentrations of vancomycin. Sequence analysis of theE. faecalisgenome indicated that (p)ppGpp synthesis is catalyzed by the bifunctional synthetase/hydrolase RelA and the RelQ small synthase. The (p)ppGpp profiles of ΔrelA, ΔrelQ, and ΔrelAQstrains revealed that RelA is the major enzyme responsible for the accumulation of (p)ppGpp during antibiotic or physical stresses, while RelQ appears to be responsible for maintaining basal levels of alarmone during homeostatic growth. Compared to its parent, the ΔrelAstrain was more susceptible to several stress conditions, whereas complete elimination of (p)ppGpp in a ΔrelAQdouble mutant restored many of the stress-sensitive phenotypes of ΔrelA. Interestingly, growth curves and time-kill studies indicated that tolerance to vancomycin is enhanced in the ΔrelAstrain but diminished in the ΔrelQand ΔrelAQstrains. Finally, virulence of the ΔrelAQstrain but not of the ΔrelAor ΔrelQstrain was significantly attenuated in theCaenorhabditis elegansmodel. Taken together, these results indicate that (p)ppGpp pools modulate environmental stress responses, vancomycin tolerance, and virulence in this important nosocomial pathogen.
Impact of parental home smoking policies on policy choices of independently living young adults
Authors: Albers A B , Biener L , Siegel M , Cheng D M , Rigotti N A 
Published: January 2009

Objective:To determine whether adolescents living in parental homes where smoking is banned are more likely to move into smoke-free living quarters when they leave home.Methods:We analysed data on 693 youths from a 4-year, three-wave prospective study of a representative sample of Massachusetts adolescents (aged 12–17). All youths resided in independent living quarters at follow-up. The primary outcome was presence of a smoking ban in the living quarters at follow-up. The primary predictor was presence of a household smoking ban in the parental home, assessed 2 years before the outcome. Generalised linear mixed effects models examined the effect of a parental household smoking ban on the odds of moving into smoke-free living quarters at follow-up overall and stratified by smoking status at follow-up.Results:Youths leaving home had much higher odds of moving to smoke-free living quarters if their parental household had had a smoking ban (odds ratio (OR) = 12.70, 95% CI, 6.19 to 26.04). Other independent predictors included moving into a school or college residence (OR = 3.88, 95% CI 1.87 to 8.05), and not living with smokers at follow-up (OR = 3.91, 95% CI 1.93 to 7.92).Conclusions:A household smoking ban in the parental home appears to lead youths to prefer smoke-free living quarters once they leave home.
Quitting cigarettes completely or switching to smokeless tobacco: do US data replicate the Swedish results?
Authors: Zhu S-H , Wang J B , Hartman A , Zhuang Y , Gamst A , Gibson J T , Gilljam H , Galanti M R 
Published: January 2009

Background:Swedish male smokers are more likely than female smokers to switch to smokeless tobacco (snus) and males’ smoking cessation rate is higher than that of females. These results have fuelled international debate over promoting smokeless tobacco for harm reduction. This study examines whether similar results emerge in the United States, one of few other western countries where smokeless tobacco has long been widely available.Methods:US data source: national sample in Tobacco Use Supplement to Current Population Survey, 2002, with 1-year follow-up in 2003. Analyses included adult self-respondents in this longitudinal sample (n = 15 056). Population-weighted rates of quitting smoking and switching to smokeless tobacco were computed for the 1-year period.Results:Among US men, few current smokers switched to smokeless tobacco (0.3% in 12 months). Few former smokers turned to smokeless tobacco (1.7%). Switching between cigarettes and smokeless tobacco, infrequent among current tobacco users (<4%), was more often from smokeless to smoking. Men quit smokeless tobacco at three times the rate of quitting cigarettes (38.8% vs 11.6%, p<0.001). Overall, US men have no advantage over women in quitting smoking (11.7% vs 12.4%, p = 0.65), even though men are far likelier to use smokeless tobacco.Conclusion:The Swedish results are not replicated in the United States. Both male and female US smokers appear to have higher quit rates for smoking than have their Swedish counterparts, despite greater use of smokeless tobacco in Sweden. Promoting smokeless tobacco for harm reduction in countries with ongoing tobacco control programmes may not result in any positive population effect on smoking cessation.
Repair of Distal Biceps Tendon Rupture Using a Suture Anchor
Authors: Grégory Thomas , Roure Philippe , Fontès Didier 
Published: January 2009

Background Repair of a distal biceps tendon rupture is a challenging procedure and, to date, there is no consensus as to which technique should be used because of the specific complications reported for each. Purpose A new endoscopic technique is described that uses a suture anchor to repair distal biceps tendon ruptures. Study Design Case series; Level of evidence, 4. Methods The results of a cohort of 23 patients (25 elbows) are reported with a median follow-up of 26 months. All patients were male and their median age was 44 years (range, 30-58). Ten of the patients (12 ruptures) were professional athletes or had a high level of physical activity. All repairs were performed via a 3-cm incision made in the “safe area” of the anterior crease of the forearm. The whole procedure was performed within the tendon sheath. The tendon was reinserted using a single anchor. Results Of the 23 patients, 22 were satisfied and 20 patients returned to their preinjury sports and jobs. There was a mean loss of 8.6° of pronation and 5° of supination. A single severe neurologic complication, which required a second surgical procedure, was reported. There were also 2 ectopic ossifications without clinical consequences and a transitory radial nerve paralysis. Conclusions This study clearly demonstrated that endoscopic repair of the ruptured distal biceps tendon is safe, effective, and reproducible. It provides good functional outcome and early recovery with few complications. Postoperative median nerve palsy due to edema is a possible concern for patients involved in athletic activity and with a history of nerve entrapment; thus this technique should be used with caution in this group of patients.
Biomechanical Comparison of the Docking Technique with and without Humeral Bioabsorbable Interference Screw Fixation
Authors: Hurbanek Jason G. , Anderson Kyle , Crabtree Stephanie , Joshua Karnes G. 
Published: January 2009

Background Surgical reconstruction of the ulnar collateral ligament has evolved since Frank Jobe's original description. The “docking technique” is a popular modification that allows for securing the graft within a single humeral tunnel. More recently, interference screw fixation has been introduced as a means of improving the ultimate strength, stiffness, and kinematics of these constructs. Purpose This study was conducted to compare the biomechanical performance of the docking technique with and without interference screw fixation in the humerus. Study Design Controlled laboratory study. Methods Nine matched pairs of human cadaveric elbows (age 49.9 ± 8.0 years) were reconstructed with a tendon graft using the docking technique (group 1) or the docking technique with the addition of a 4.75-mm bioabsorbable humeral interference screw (group 2). Before the reconstruction, joint laxity was measured on each specimen with the ulnar collateral ligament intact and then after transection of the ligament. Laxity measurements were repeated after the reconstruction. Failure testing was then performed at 70° of elbow flexion. The specimens were preloaded with a 1-N·m moment and then loaded to failure at a displacement rate of 14 mm/s to approximate 50% strain per second. Results Within group 1, the elbow laxity of the reconstructed state was significantly greater than the intact state at all tested flexion angles (P <. 021). Within group 2, no statistically significant difference existed in elbow laxity between the intact state and the reconstructed state. When comparing laxities between groups, group 1 tended to be more lax at all tested flexion angles but was only significantly greater at 105° of flexion. The most common mode of failure for both groups involved the sutures pulling out of the tendon. No significant difference was found for ultimate moment of failure between the 2 groups. However, the moment associated with 3 mm of gap formation for group 2 (12.8 ± 4.2 N·m) was statistically greater than that of group 1 (7.5 ± 1.2 N·m) (P =. 001). The stiffness of group 2 (14.7 ± 6.4 N/mm) was significantly greater than group 1 (9.9 ± 3.1 N/mm) (P =. 044). Conclusion The biomechanical performance of the docking technique with and without a humeral interference screw is similar. Clinical Relevance The stiffness of the construct, along with the difference in moment that allows a 3-mm gap formation, suggests that the addition of a humeral interference screw is potentially beneficial. Further research in a healing model will help clarify this benefit.
Primary Repair Combined with Bone Marrow Stimulation in Acute Anterior Cruciate Ligament Lesions
Authors: Gobbi Alberto , Bathan Lyndon , Boldrini Lorenzo 
Published: January 2009

Background The anterior cruciate ligament has been shown to have poor healing ability, and reconstruction is the standard treatment. Hypothesis Primary anterior cruciate ligament repair combined with bone marrow stimulation could restore stability and function in athletes with acute anterior cruciate ligament incomplete tears. Study Design Case series; Level of evidence, 4. Methods Among a group of 99 patients with clinically diagnosed anterior cruciate ligament acute lesions, 26 athletes with arthroscopically confirmed incomplete anterior cruciate ligament proximal tears were treated with primary repair combined with bone marrow stimulation of the anterior cruciate ligament femoral attachment site. Postoperatively, all patients underwent a specific rehabilitation program. All patients were prospectively evaluated; outcome measures were assessed using Marx, Noyes, Tegner, Single Assessment Numeric Evaluation, Lysholm, and International Knee Documentation Committee scores. Anterior tibial translation was measured using Rolimeter instrument under anesthesia and at final follow-up. Results All athletes were followed up for a mean 25.3 months (range, 17-38 months). Mean age was 26.6 years. Mean preinjury Tegner was 7.1 (SD, 1.1) and final Tegner 6.7 (SD, 1.4); mean preinjury Marx was 11.0 (SD, 3.4) and final Marx 9.6 (SD, 3.1); mean preinjury Noyes was 82.5 (SD, 5.8) and final Noyes 83.3 (SD, 7.2). These scores were not statistically different at P values of. 020,. 011, and. 303, respectively. Final Single Assessment Numeric Evaluation rating was significantly lower than was preinjury Single Assessment Numeric Evaluation rating. This was mainly related to decreased self-confidence in high-risk sports and fear of new injury. Final Single Assessment Numeric Evaluation rating and Tegner scores were significantly higher than were their respective preoperative values. Mean Rolimeter side-to-side difference of anterior knee translation was significantly reduced from 3.5 mm (SD, 0.7) preoperatively to 1.3 mm (SD, 0.8) postoperatively. Conclusion In this athletic population, anterior cruciate ligament primary repair in acute incomplete lesion combined with bone marrow stimulation effectively restored knee stability and function.
Comparison of Single- versus Double-Tunnel Tendon-to-Bone Healing in an Ovine Model
Authors: Lu Yan , Markel Mark D. , Nemke Brett , Wynn Shawn , Graf Ben 
Published: January 2009

Background The double-bundle technique has recently gained much interest in ligament reconstruction. In addition to potential kinematic advantages, perhaps double tunnels have the potential for faster and more secure tendon-to-bone healing. Hypothesis Placement of tendons in 2 osseous tunnels, as opposed to 1, will enhance tendon fixation as determined biomechanically and histologically. Study Design Controlled laboratory study. Methods Fourteen sheep were used, and an extra-articular tendon graft reconstruction was performed on both knees of each sheep. In 1 randomly selected knee, the long digital extensor tendon was released from the femur and placed into a single tunnel in the proximal tibia. In the contralateral knee, the tendon was split and placed into 2 tibial tunnels. Ten sheep were analyzed by mechanical testing, and the remaining 4 were subjected to histologic evaluation at 6 weeks after surgery. Paired t tests were used for statistical analysis. Results Mechanical testing demonstrated that the peak load (981.8 ± 143.2 N, mean ± SD) and stiffness (570.9 ± 114.6 N/mm) at 6 weeks after surgery in the double-tunnel group were significantly greater than for the single-tunnel group (714.8 ± 94.2 N and 432.2 ± 56.7 N/mm, respectively; load, P =. 007; stiffness, P =. 03). Histologic analysis suggested similar tendon-to-bone healing for both groups. Conclusion This study demonstrated enhanced biomechanical fixation of the tendon to the surrounding bone in the double-tunnel compared with the single-tunnel technique in this ovine model. Clinical Relevance The double-tunnel technique may provide better fixation and healing in human ligament reconstruction.
Biomechanical Evaluation of Bioabsorbable versus Metallic Screws for Posterior Cruciate Ligament Inlay Graft Fixation
Authors: Gupta Aman , Lattermann Christian , Busam Matthew , Riff Andrew , Bach Bernard R. , Wang Vincent M. 
Published: January 2009

Background Although a tibial inlay technique for posterior cruciate ligament reconstruction is advantageous, metallic screw fixation of the bone block is required. This may pose problems for future surgery (eg, osteotomies, total knee replacement). Hypothesis There is no significant difference in the biomechanical integrity of bone block fixation using stainless steel versus bioabsorbable screw fixation of the tibial inlay graft in posterior cruciate ligament reconstruction. Study Design Controlled laboratory study. Methods Fourteen human cadaveric knees were randomized to receive either stainless steel or bioabsorbable screw fixation of a bone—patellar tendon—bone graft. Cyclic tensile testing of each construct was performed, followed by a load-to-failure test. Digital video digitization was used to optically determine tendon graft deformation. Results Cyclic creep deformation showed no significant difference between the 2 groups ( P = .8). The failure load (stainless steel, 461 ± 231 N; bioabsorbable, 638 ± 492 N; P = .7) and linear stiffness (stainless steel, 116 ± 22 N/mm, bioabsorbable, 106 ± 44 N/mm; P = .6) also showed no significant difference between the 2 groups. Optically measured graft deformation was not significant for distal ( P = .7) and midsubstance ( P = .8) regions, while proximal deformation was significantly higher for bioabsorbable fixation ( P = .02). All samples failed at the tibial insertion site with the tibial bone block fracturing at the screws. Conclusion Bioabsorbable screw fixation using a tibial inlay technique does not compromise the strength and stiffness characteristics afforded by metallic fixation. From a biomechanical perspective, bioabsorbable screws are a viable alternative to metal in the context of tibial inlay reconstruction. Clinical Relevance Use of bioabsorbable fixation can potentially eliminate future hardware problems after posterior cruciate ligament reconstruction using a tibial inlay technique.
Football Playing Surface and Shoe Design Affect Rotational Traction
Authors: Villwock Mark R. , Meyer Eric G. , Powell John W. , Fouty Amy J. , Haut Roger C. 
Published: January 2009

Background High rotational traction between football shoes and the playing surface may be a potential mechanism of injury for the lower extremity. Hypothesis Rotational traction at the shoe-surface interface depends on shoe design and surface type. Study Design Controlled laboratory study. Methods A mobile testing apparatus with a compliant ankle was used to apply rotations and measure the torque at the shoe-surface interface. The mechanical surrogate was used to compare 5 football cleat patterns (total of 10 shoe models) and 4 football surfaces (FieldTurf, AstroPlay, and 2 natural grass systems) on site at actual surface installations. Results Both artificial surfaces yielded significantly higher peak torque and rotational stiffness than the natural grass surfaces. The only cleat pattern that produced a peak torque significantly different than all others was the turf-style cleat, and it yielded the lowest torque. The model of shoe had a significant effect on rotational stiffness. Conclusion The infill artificial surfaces in this study exhibited greater rotational traction characteristics than natural grass. The cleat pattern did not predetermine a shoe's peak torque or rotational stiffness. A potential shoe design factor that may influence rotational stiffness is the material(s) used to construct the shoe's upper. Clinical Relevance The study provides data on the rotational traction of shoe-surface interfaces currently employed in football. As football shoe and surface designs continue to be updated, new evaluations of their performance must be assessed under simulated loading conditions to ensure that player performance needs are met while minimizing injury risk.
Host Students' Perspectives of Intercultural Contact in an Irish University
Authors: Dunne Ciarán 
Published: January 2009

Given the increasing numbers of international students in Ireland and the lack of attention afforded to host culture students in existing research on intercultural relations in higher education, a grounded theory study was conducted in an Irish university exploring host (Irish) students' perspectives on intercultural contact. The study focused on students' construction of cultural difference within the educational environment, the factors influencing intercultural contact, and students' experiences of such contact. The findings suggest that although nationality and age are used to differentiate students, the concept of “maturity”—underpinned by values and behaviors relating to academic motivations, responsibilities, and authority—is central to students' construction of cultural difference on campus. Diverse factors identified as impacting upon students' intercultural acquaintance prospects and relational development are presented and discussed. The findings highlight the complexity of promoting meaningful intercultural contact among students and also suggest conditions to foster intercultural contact based on students' feedback.
The effect of levetiracetam on tremor severity and functionality in patients with multiple sclerosis
Authors: Feys P ,   MB D’hooghe, Nagels G , Helsen WF 
Published: January 2009

Background Multiple sclerosis (MS) intention tremor is a disabling symptom, which is difficult to treat. Objectives To investigate the effects of levetiracetam, an antiepileptic drug, on tremor severity and related functionality in MS. Methods A randomized, double-blind, placebo-controlled, cross-over study examined the effects of 6 weeks of oral levetiracetam administration (starting dose = 250 mg/day, maximal dose = 2000 mg/day) in 18 MS patients with disabling intention tremor. Primary outcome was Fahn’s Tremor Rating Scale (FTRS) A&B. Secondary outcome measures were the nine-hole peg test, patient’s opinion rated with the visual analog scale, FTRS C, and an activities of daily life questionnaire and validated tremor indexes derived during the performance of a digitized spiral drawing task and a wrist step-tracking task. Repeated measures analysis of variance and Friedman tests were applied. Results In all, 14 patients completed the trial. Maximal dose intake ranged from 1000 to most commonly 2000 mg, depending on patients’ tolerance level. No significant effects of levetiracetam were found for any outcome measure. Further analyses on subgroups with different tremor severity showed no differential effects. Eight patients reported adverse events such as fatigue and stomach ache. Conclusions Levetiracetam intake of 2000 mg/day did not affect tremor severity or functionality in patients with MS.