bluuebunny/crossref_metadata_2025_split huggingface dataset:
ArecANull Mutation May Be Generated inStreptomyces coelicolor
Authors: Huang Tzu-Wen , Chen Carton W. 
Published: September 2006

ABSTRACTThe recombinase RecA plays a crucial role in homologous recombination and the SOS response in bacteria. AlthoughrecAmutants usually are defective in homologous recombination and grow poorly, they nevertheless can be isolated in almost all bacteria. Previously, considerable difficulties were experienced by several laboratories in generatingrecAnull mutations inStreptomyces, and the onlyrecAnull mutants isolated (fromStreptomyces lividans) appeared to be accompanied by a suppressing mutation. Using gene replacement mediated byEscherichia coli-Streptomycesconjugation, we generatedrecAnull mutations in a series ofStreptomyces coelicolorA3(2) strains. TheserecAmutants were very sensitive to mitomycin C but only moderately sensitive to UV irradiation, and the UV survival curves showed wide shoulders, reflecting the presence of arecA-independent repair pathway. The mutants segregated minute colonies with low viability during growth and produced more anucleate spores than the wild type. Some crosses between pairs ofrecAnull mutants generated no detectable recombinants, showing for the first time that conjugal recombination inS. coelicolorisrecAmediated, but other mutants retained the ability to undergo recombination. The nature of this novel recombination activity is unknown.
Rem, a New Transcriptional Activator of Motility and Chemotaxis in
Sinorhizobium meliloti
Authors: Rotter Christine , Mühlbacher Susanne , Salamon Daniel , Schmitt Rüdiger , Scharf Birgit 
Published: September 2006

ABSTRACT

The expression of 51 known genes clustered in the flagellar regulon of
Sinorhizobium meliloti
is organized as a three-class hierarchy: class IA comprises the master regulatory genes,
visN
and
visR
; class II, controlled by VisNR, comprises flagellar assembly and motility genes; and class III comprises flagellin and chemotaxis genes requiring class II for expression. The expression of
visN-visR
is constitutive throughout growth, whereas that of class II and class III genes is limited to exponential growth. A new OmpR-like, 25-kDa transcription factor, Rem, whose synthesis is confined to exponential growth, was shown to positively control swimming motility. No phosphorylation of the receiver domain of Rem was required for its activity. Gene expression in tester strains with known deficiencies placed the
rem
gene (class IB) below
visN-visR
(class IA) and above class II genes in the regulatory cascade. Footprinting analysis demonstrated that the Rem protein binds to class II gene promoters as well as to its own promoter, indicating that this protein is autoregulatory. An alignment of the Rem-protected DNA sequences revealed a conserved binding motif of imperfect tandem repeats overlapping a predicted −35 promoter box by 3 bp. This new promoter was confirmed by mapping the transcription start site of a typical class II gene,
flgB
, 5 nucleotides downstream of the −10 promoter box. The transcription of
rem
is under dual control of an upstream (Rem-activated) class II-type promoter and a downstream (VisNR-activated) σ
70
-like promoter. The central role of Rem as the growth-dependent transcriptional activator intermediate between the master regulator, VisNR, and the flagellar and motility genes is a new distinguishing feature of the
S. meliloti
regulatory cascade.
Potential of ultrasonography for epidemiological study of work-related wrist tenosynovitis
Authors: Violante F S , Bonfiglioli R , Graziosi F , Caso A , Isolani L , Fiorentini C , Mattioli S 
Published: September 2006

Objective:To explore the possible role of ultrasonography in case definitions for epidemiological studies of work-related wrist tenosynovitis.Methods:Clinical and ultrasonography (7.5 MHz linear probe) data systematically collected from meat workers (n = 128) with biomechanical exposure characterisation were analysed. The diagnostic accuracy of different combinations of potentially relevant ultrasonography findings (nonhomogeneity, thickening and anechoic halo) was evaluated using symptomatology as a reference standard. The concordance between ultrasonography findings and symptoms was then analysed.Results:Analysis of wrist biomechanical exposure was suggestive of increased prevalence of musculoskeletal disorders. Using symptoms as a reference standard, each of the three ultrasonography findings (and their combinations) showed good specificity (⩾85%) accompanied by low sensitivity (<60%); the positive likelihood ratio for at least two findings was 4.1. κ Values (95% confidence intervals) between symptoms and different sets of ultrasonography findings were as follows: for non-homogeneity, κ = 0.31 (0.19 to 0.43); at least one finding, κ = 0.28 (0.16 to 0.40); at least two findings, κ = 0.32 (0.20 to 0.44); all p<0.01.Conclusion:The use of ultrasonography in symptomatic subjects could contribute to a more specific epidemiological case definition of wrist tenosynovitis. The results of this study could help orient future research in this direction.
Do ambient noise exposure levels predict hearing loss in a modern industrial cohort?
Authors: Rabinowitz P M , Galusha D , Dixon-Ernst C , Slade M D , Cullen M R 
Published: September 2006

Background:Much of what is known about the exposure–response relationship between occupational noise exposures and hearing loss comes from cross-sectional studies conducted before the widespread implementation of workplace hearing conservation programmes. Little is known about the current relationship of ambient noise exposure measurements to hearing loss risk.Aim:To examine the relationship between rates of high frequency hearing loss and measured levels of noise exposure in a modern industrial workforce.Methods:Ten-year hearing loss rates were determined for 6217 employees of an aluminium manufacturing company. Industrial hygiene and human resources records allowed for reconstruction of individual noise exposures. Hearing loss rates were compared to ANSI 3.44 predictions based on age and noise exposure. Associations between hearing loss, noise exposure, and covariate risk factors were assessed using multivariate regression.Results:Workers in higher ambient noise jobs tended to experience less high frequency hearing loss than co-workers exposed at lower noise levels. This trend was also seen in stratified analyses of white males and non-hunters. At higher noise exposure levels, the magnitude of hearing loss was less than predicted by ANSI 3.44 formulae. There was no indication that a healthy worker effect could explain these findings. The majority of 10 dB standard threshold shifts (STS) occurred in workers whose calculated ambient noise exposures were less than or equal to 85 dBA.Conclusions:In this modern industrial cohort, hearing conservation efforts appear to be reducing hearing loss rates, especially at higher ambient noise levels. This could be related to differential use of hearing protection. The greatest burden of preventable occupational hearing loss was found in workers whose noise exposure averaged 85 dBA or less. To further reduce rates of occupational hearing loss, hearing conservation programmes may require innovative approaches targeting workers with noise exposures close to 85 dBA.
Respiratory symptoms and bronchial responsiveness among cleaning and disinfecting workers in the food industry
Authors: Massin N , Hecht G , Ambroise D , Héry M , Toamain J P , Hubert G , Dorotte M , Bianchi B 
Published: September 2006

Objectives:To measure the levels of exposure to nitrogen trichloride (NCl3) and aldehydes among cleaning and disinfecting workers in the atmosphere of food industry plants during cleaning and disinfecting operations, and to examine how they relate to irritant and chronic respiratory symptoms—which are indices of pulmonary function—and bronchial hyperresponsiveness (BHR) to methacholine.Methods:175 exposed workers (M = 149; F = 26) recruited from 17 enterprises of the food industry (8 cattle, pig, and ovine slaughterhouses, 8 fowl slaughterhouses, and 1 catering firm) and 70 non-exposed workers (M = 52; F = 18) were examined. Concentration levels of NCl3and aldhehydes were measured by personal sampling. Symptoms were assessed by means of a questionnaire and the methacholine bronchial challenge (MBC) test using an abbreviated method. Subjects were labelled MBC+ if forced expiratory volume in one second (FEV1) fell by 20% or more. The linear dose-response slope (DRS) was calculated as the percentage fall in FEV1 at last dose divided by the total dose administered.Results:277 air samples were taken in the 17 food industry plants. For a given plant and in a given workshop, the actual concentrations of chloramines, aldehydes, and quaternary ammonium compounds were measured with personal samplers during the different steps of the procedures. For each cleaner, a total exposure index Σ was calculated. A statistically significant concentration-response relationship was found between eye, nasal, and throat symptoms of irritation—but not chronic respiratory symptoms—and exposure levels or exposure duration. No relation was found between BHR and exposure.Conclusions:These data show that cleaning and disinfecting workers in the food industry are at risk of developing eye, nasal, and throat irritation symptoms. Although NCl3exposure does not seem to carry a risk of developing permanent BHR, the possibility of transient BHR cannot be ruled out entirely.
Mortality from non-malignant respiratory diseases among people with silicosis in Hong Kong: exposure–response analyses for exposure to silica dust
Authors: Tse L A , Yu I T S , Leung C C , Tam W , Wong T W 
Published: September 2006

Objectives:To examine the exposure–response relationships between various indices of exposure to silica dust and the mortality from non-malignant respiratory diseases (NMRDs) or chronic obstructive pulmonary diseases (COPDs) among a cohort of workers with silicosis in Hong Kong.Methods:The concentrations of respirable silica dust were assigned to each industry and job task according to historical industrial hygiene measurements documented previously in Hong Kong. Exposure indices included cumulative dust exposure (CDE) and mean dust concentration (MDC). Penalised smoothing spline models were used as a preliminary step to detect outliers and guide further analyses. Multiple Cox’s proportional hazard models were used to estimate the dust effects on the risk of mortality from NMRDs or COPDs after truncating the highest exposures.Results:371 of the 853 (43.49%) deaths occurring among 2789 workers with silicosis during 1981–99 were from NMRDs, and 101 (27.22%) NMRDs were COPDs. Multiple Cox’s proportional hazard models showed that CDE (p = 0.009) and MDC (p<0.001) were significantly associated only with NMRD mortality. Subgroup analysis showed that deaths from NMRDs (p<0.01) and COPDs (p<0.05) were significantly associated with both CDE and MDC among underground caisson workers and among those ever employed in other occupations with high exposure to silica dust. No exposure–response relationship was observed for surface construction workers with low exposures. A clear upward trend for both NMRDs and COPDs mortality was found with increasing severity of radiological silicosis.Conclusion:This study documented an exposure–response relationship between exposure to silica dust and the risk of death from NMRDs or COPDs among workers with silicosis, except for surface construction workers with low exposures. The risk of mortality from NMRDs increased significantly with the progression of International Labor Organization categories, independent of dust effects.
Transient risk factors for acute traumatic hand injuries: a case-crossover study in Hong Kong
Authors: Chow C Y , Lee H , Lau J , Yu I T S 
Published: September 2006

Objectives:To identify the remediable transient risk factors of occupational hand injuries in Hong Kong in order to guide the development of prevention strategies.Methods:The case-crossover study design was adopted. Study subjects were workers with acute hand injuries presenting to the government Occupational Medicine Unit for compensation claims within 90 days from the date of injury. Detailed information on exposures to specific transient factors during the 60 minutes prior to the occurrence of the injury, during the same time interval on the day prior to the injury, as well as the usual exposure during the past work-month was obtained through telephone interviews. Both matched-pair interval approach and usual frequency approach were adopted to assess the associations between transient exposures in the workplace and the short-term risk of sustaining a hand injury.Results:A total of 196 injured workers were interviewed. The results of the matched-pair interval analysis matched well with the results obtained using the usual frequency analysis. Seven significant transient risk factors were identified: using malfunctioning equipment/materials, using a different work method, performing an unusual work task, working overtime, feeling ill, being distracted and rushing, with odds ratios ranging from 10.5 to 26.0 in the matched-pair interval analysis and relative risks ranging between 8.0 and 28.3 with the usual frequency analysis. Wearing gloves was found to have an insignificant protective effect on the occurrence of hand injury in both analyses.Conclusions:Using the case-crossover study design for acute occupational hand injuries, seven transient risk factors that were mostly modifiable were identified. It is suggested that workers and their employers should increase their awareness of these risk factors, and efforts should be made to avoid exposures to these factors by means of engineering and administrative controls supplemented by safety education and training.
Low-Density Lipoprotein Modified by Macrophage-Derived Lysosomal Hydrolases Induces Expression and Secretion of IL-8 Via p38 MAPK and NF-κB by Human Monocyte-Derived Macrophages
Authors: Hakala Jukka K. , Lindstedt Ken A. , Kovanen Petri T. , Pentikäinen Markku O. 
Published: September 2006

Objective—Modified lipoproteins induce inflammatory reactions in the atherosclerotic arterial wall. We have previously found that macrophages in atherosclerotic lesions secrete lysosomal hydrolases that can modify low-density-lipoprotein (LDL) in vitro to generate “hydrolase-modified LDL” (H-LDL). Here, we studied whether H-LDL exerts inflammatory effects on cultured human macrophages.Methods and Results—Using cytokine cDNA arrays, we found that H-LDL induced expression of IL-8, but not of the anti-inflammatory cytokines IL-10 and transforming growth factor (TGF)-β, in human monocyte-derived macrophages. H-LDL induced rapid phosphorylation of the p38 mitogen-activated protein kinase (MAPK), nuclear translocation of 2 transcription factors, nuclear factor κB (NF-κB) and activator protein 1 (AP-1), and time-dependent secretion of IL-8 from the macrophages. Inhibition of MAPKs and of transcription factors showed that p38 MAPK and NF-κB, but not ERK1/2, JNK, or AP-1, were crucial for the H-LDL–induced IL-8 secretion from the macrophages.Conclusions—The results show that by activating p38 MAPK and NF-κB, macrophage hydrolases modify LDL into biologically active particles capable of triggering the secretion of IL-8 in macrophages. Thus, activated hydrolase-secreting macrophages in atherosclerotic lesions may sustain a proatherogenic extracellular environment by hydrolyzing LDL and triggering it to act in an autocrine or paracrine fashion to induce IL-8 secretion by the plaque macrophages.
Meniscal Repair with Biofix Arrows
Authors: Gifstad Tone , Grøntvedt Torbjørn , Drogset Jon Olav 
Published: September 2006

Background Absorbable meniscus arrows have, since they were introduced in 1993, become a common all-inside technique in meniscal repair. Potential advantages are conserving the meniscus, simplifying the surgical technique, reducing operating time, and reducing the risk of neurovascular damage. Despite extensive use all over the world, few long-term follow-up studies have been published. Hypothesis Meniscus arrows have, based on published material, a rate of success around 80% to 90%. Study Design Case series; Level of evidence, 4. Methods The Biofix arrow fixation technique was used in 123 patients in need of meniscal repair from January 1997 to December 2002 at our hospital. The patients underwent an interview by phone, mail, or e-mail during autumn 2004 that included questions about reoperation and Lysholm score. In addition, the operative charts were reviewed. Results There were 118 patients (96%) available for the questionnaire, and 45 of these (38%) had had reoperations done because of meniscal rerupture during the follow-up period. Another 3 patients were waiting for meniscal reoperations. In addition, the charts of 2 of those unavailable for the study showed that they had been reoperated, resulting in a total of 41% verified failures. The Lysholm score for the whole study group at follow-up was 85 (range, 36-100). The mean Lysholm score for those who had a second operation was 81 (range, 36-100), and it was 88 (range, 55-100) for the others (P = .009). The mean time between primary operation and reoperation was 17 months (range, 1-75 months). Mean postoperative follow-up was 4.7 years (range, 1.8-7.7 years). Conclusion Meniscal repair with Biofix arrows has an unacceptably low rate of success.
Pitching Biomechanics as a Pitcher Approaches Muscular Fatigue during a Simulated Baseball Game
Authors: Escamilla Rafael F. , Barrentine Steven W. , Fleisig Glenn S. , Zheng Naiquan , Takada Yoshihiro , Kingsley David , Andrews James R. 
Published: September 2006

Background The effects of approaching muscular fatigue on pitching biomechanics are currently unknown. As a pitcher fatigues, pitching mechanics may change, leading to a decrease in performance and an increased risk of injury. Hypothesis As a pitcher approaches muscular fatigue, select pitching biomechanical variables will be significantly different than they were before muscular fatigue. Study Design Controlled laboratory study. Methods Ten collegiate baseball pitchers threw 15 pitches per inning for 7 to 9 innings off an indoor throwing mound during a simulated baseball game. A pitching session ended when each pitcher felt he could no longer continue owing to a subjective perception of muscular fatigue. A 6-camera 3D automatic digitizing system collected 200-Hz video data. Twenty kinematic and 11 kinetic variables were calculated throughout 4 phases of the pitch. A repeated-measure analysis of variance (P < .01) was used to compare biomechanical variables between innings. Results Compared with the initial 2 innings, as a pitcher approached muscular fatigue during the final 2 innings he was able to pitch, there was a significant decrease in ball velocity, and the trunk was significantly closer to a vertical position. There were no other significant differences in kinematics or kinetics variables. Conclusion The relatively few differences observed imply that pitching biomechanics remained remarkably similar between collegiate starting pitchers who threw between 105 and 135 pitches for 7 to 9 innings and approached muscular fatigue. Clinical Relevance This study did not support the idea that there is an increase in shoulder and elbow forces and torques as muscular fatigue is approached. It is possible that if a pitcher remained in a fatigued state for a longer period of time, additional changes in pitching mechanics may occur and the risk of injury may increase.
Achilles Tendon Elongation after Rupture Repair
Authors: Kangas Jarmo , Pajala Ari , Ohtonen Pasi , Leppilahti Juhana 
Published: September 2006

Background A few prospective controlled trials comparing early functional rehabilitation after Achilles tendon repair and non-operative immobilization have been reported. Hypotheses There is no difference in Achilles tendon elongation between early motion and immobilization after Achilles tendon repair. Tendon elongation does not correlate with the clinical outcome. Study Design Randomized clinical trial; Level of evidence, 2. Methods Fifty patients with acute Achilles tendon rupture were randomized postoperatively to receive either early movement of the ankle between neutral and plantar flexion in a brace for 6 weeks or immobilization in tension using a below-knee cast with the ankle in a neutral position for 6 weeks. Full weightbearing was allowed after 3 weeks in both groups. Standardized radiographs to measure previously placed radiographic markers were taken on the first day postoperatively and at 1, 3, 6, 12, 24 weeks postoperatively, with the final radiograph a mean of 60 (SD, 6.4) weeks postoperatively. The outcome was assessed at the 3-month and final checkups by the clinical scoring method described by Leppilahti et al and included subjective factors and objective factors. Results Tendon elongation occurred in both groups but was somewhat less in the early motion group (median 2 mm in the early motion group vs median 5 mm in the cast group a mean of 60 weeks postoperatively, P = .054). The elongation curves first rose and then slowly fell in both groups. The patients who had less elongation achieved a better clinical outcome (ρ= -.42, P = .017). Tendon elongation did not correlate significantly with age, body mass index, or isokinetic peak torques. Conclusion Achilles tendon elongation was somewhat less in the early motion group and correlated with the clinical outcome scores. We recommend early functional postoperative treatment after Achilles rupture repair.
Radiographic Adaptations to the Stress of High-Level Rock Climbing in Junior Athletes
Authors: Schöffl Volker Rainer , Hochholzer Thomas , Imhoff Andreas B. , Schöffl Isabelle 
Published: September 2006

Background Radiographic adaptations and changes in adult climbers are a well-known fact, but few data are available for young climbers. Hypothesis Radiographic adaptations have been shown for highly active young climbers. The question arises whether these adaptations may lead to an early onset of osteoarthrosis in the fingers. Study Design Cohort study; Level of evidence, 2. Methods Ten members of the German Junior National Team (GJNT; 21.0 ± 1.6 years) and 10 recreational climbers (RC; 19.9 ± 1.9 years) were examined using a standard questionnaire and radiographs of the hand. For comparison, radiographs of 12 young nonclimbers (control group [CG]) were evaluated. Results The climbing level of GJNT increased significantly during the 5-year evaluation period (P < .01) and was significantly higher than that of the RC (1999: P < .01, 2004: P < .01). There was no increase in finger contractures or finger joint capsular width during the 5 years. Stress reactions were found in 8 of 10 of GJNT (1999 and 2004) and increased in RC from 2 of 10 (1999) to 3 of 10 (2004). No osteoarthrotic changes were found in 2004. There was no significant difference for the Barnett-Nordin Index between GJNT, RC, and CG. Years of climbing (P < .01), participation in climbing competitions (P < .01), hours of training per week (P < .01), number of training units per week (P < .05), and climbing level (2004) (P < .01) were significant factors for development of radiographic stress reaction in all athletes (GJNT and RC). Conclusion Intensive training and climbing leads to adaptive reactions such as cortical hypertrophy and broadened joint bases in the fingers. Nevertheless, osteoarthrotic changes are rare in young climbers. A longer follow-up is necessary to evaluate whether these adaptive stress reactions may lead to an early onset of osteoarthritis.