bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evolution of Drug-Resistant Viral Populations during Interruption of Antiretroviral Therapy
Authors: Wang Dongning , Hicks Charles B. , Goswami Neela D. , Tafoya Emi , Ribeiro Ruy M. , Cai Fangping , Perelson Alan S. , Gao Feng 
Published: April 2011

ABSTRACTAnalysis of a large number of HIV-1 genomes at multiple time points after antiretroviral treatment (ART) interruption allows determination of the evolution of drug-resistant viruses and viral fitnessin vivoin the absence of drug selection pressure. Using a parallel allele-specific sequencing (PASS) assay, potential primary drug-resistant mutations in five individual patients were studied by analyzing over 18,000 viral genomes. A three-phase evolution of drug-resistant viruses was observed after termination of ART. In the first phase, viruses carrying various combinations of multiple-drug-resistant (MDR) mutations predominated with each mutation persisting in relatively stable proportions while the overall number of resistant viruses gradually increased. In the second phase, viruses with linked MDR mutations rapidly became undetectable and single-drug-resistant (SDR) viruses emerged as minority populations while wild-type viruses quickly predominated. In the third phase, low-frequency SDR viruses remained detectable as long as 59 weeks after treatment interruption. Mathematical modeling showed that the loss in relative fitness increased with the number of mutations in each viral genome and that viruses with MDR mutations had lower fitness than viruses with SDR mutations. No single viral genome had seven or more drug resistance mutations, suggesting that such severely mutated viruses were too unfit to be detected or that the resistance gain offered by the seventh mutation did not outweigh its contribution to the overall fitness loss of the virus. These data provide a more comprehensive understanding of evolution and fitness of drug-resistant virusesin vivoand may lead to improved treatment strategies for ART-experienced patients.
Stimulation of Homology-Directed Repair at I-SceI-Induced DNA Breaks during the Permissive Life Cycle of Human Cytomegalovirus
Authors: Kulkarni A. S. , Fortunato E. A. 
Published: April 2011

ABSTRACT
Human cytomegalovirus (HCMV) selectively relocalizes many DNA repair proteins, thereby avoiding a potentially detrimental damage response. In the present study, we evaluated interactions between HCMV and the homology-directed repair (HDR) pathway. In permissive human foreskin fibroblasts, a fluorescence-based double-stranded break repair assay was used to determine that HCMV stimulated HDR. Repair of both stably integrated and extrachromosomal reporter substrates was observed to increase. HDR was also stimulated through individual expression of the viral immediate-early protein IE1-72, mimicking full virus infection. These experiments further demonstrate HCMV's role in modulating critical cellular processes during a permissive infection.
Hormonal stress in adolescent female volleyball players
Authors: Cruz-Márquez J C , Cruz-Campos J C , Cruz-Campos A , Cueto-Martín MªB , García-Jiménez Mª 
Published: April 2011

BackgroundCatecholamine and cortisol are markers of hormonal stress in young female athletes and may indicate adaptation to an active lifestyle and sports activity.ObjectiveTo discover if volleyball training produces changes in catecholamine and cortisol.DesignWe performed a prospective study during a sports season (September–May) with monthly measurements of catecholamine and cortisol in urine collected over a 24-h period, on a rest day and between days 5 and 25 of the menstrual cycle.Setting and participants24 women (mean age 17±0.5 years; height: 172.8±4.7 cm; weight: 60.7±3.8 kg), volleyball players from two youth teams competing regionally (years of training: 3±0.4) and 24 sedentary women (ages: 17±0.9; height: 161±5.8 cm; weight: 58±5.6) selected from the high school. Participating teams: Ranked first and second last season. All players who started the study completed it. None of the participants were taking contraceptives or receiving hormonal treatments.InterventionsThe players trained four days/week (an average of 8.3 h/week) and played 24 official matches. The sedentary women attended a physical education class 2 days/week (2 h/week), along with the players. Independent Variables: exercise, volleyball training and healthy lifestyle. Dependent Variables: urinary catecholamines and cortisol.ResultsThe sedentary participants had higher levels of epinephrine, norepinephrine, dopamine, metanephrine, normetanephrine and cortisol than the women athletes (p<0.05). Higher levels of catecholamines were recorded in September and October in both groups, whereas cortisol levels were higher in April and May. All levels were in normal ranges. There were no significant differences between players based on minutes of competition.ConclusionsPlaying volleyball and following a healthy lifestyle do not increase levels of catecholamines and cortisol in well-trained adolescent girls.
The effect of player position on patellar tendinopathy in volleyball
Authors: Mahieu N , De Ridder R , Reynaert L , Strubbe K , Poppe W , Cools A , Roosen P 
Published: April 2011

BackgroundThis pilot study is the first to investigate the role of player position on the development of patellar tendinopathy (PT) in competitive volleyball players.ObjectiveThe objective is to identify intrinsic risk factors depending on player position for developing PT.DesignRetrospective design.SettingEight male national volleyball teams participated in this study. They were tested at the beginning of the season 2009–2010.ParticipantsA total of 71 male players were included. For each player the position on the field was registered. By means of questionnaires, the participants injury history was documented.Assessment of risk factorsAnthropometrical data, muscle strength, muscle length and landing strategies were assessed.Main outcome measurementsThe strength of the hip muscles was measured with a hand-held dynamometer. Muscle length of gastrocnemius, soleus, hamstrings and quadriceps was determined by means of a plurimeter. A 2D video analyses was made of a vertical jump. Knee flexion angle, Q-angle and Ankle dorsiflexion angle during the landing were calculated.ResultsThe incidence of PT is higher in outside hitters (11%) and middle blockers (12.1%) than opposites (3.2%), setters (4.8%) and libero's (6%). When taking into account the players with a history of PT, the libero has a significant higher body mass, a higher body mass index and a shorter length of quadriceps. The setter has a lower hip flexion strength. The middle blocker has a higher ankle dorsiflexion ROM and lower hip exorotation strength. The outside hitter has a smaller Q-angle when standing, a higher ankle dorsiflexion ROM, a longer soleus length and a smaller hip flexion strength.ConclusionsThis study indicates that other factors may play in the development of PT depending on player position. However, the results in this study are preliminary and needs to be confirmed by future research.
The TOPGAME-study: effectiveness of extracorporeal shockwave therapy in jumping athletes with patellar tendinopathy
Authors: Zwerver J , van den Akker-Scheek I , Hartgens F , van de Worp H , Verhagen E , Diercks R L 
Published: April 2011

BackgroundPatellar tendinopathy is a common and often difficult-to-treat knee injury in jumping athletes. Extracorporeal shockwave therapy (ESWT) appears to be a promising treatment but its effectiveness has not been studied in athletes who keep playing sports.ObjectiveTo determine the effectiveness of ESWT in athletes with patellar tendinopathy with short duration of symptoms who are still in training and competition.DesignMulticenter two armed randomized controlled trial with blinded participants and outcome assessors.Setting and participantsNon-elite athletes aged 18–35. 57 volleyball, one handball and four basketball players with patellar tendinopathy (symptoms 3–12 months). Of these, 57 completed the study Intervention of three focused ESWT treatments (or placebo) at a weekly interval.Main outcome measurementsVISA-P score at 1, 12 and 22 weeks after the final treatment, when athletes were still in competition.ResultsThe mean VISA-P scores before and after treatment are summarized below. There was a significant effect for time (p<0.01) but no effect for treatment×time (p=0.82). One week after treatment more patients in the treatment group compared to patients in the placebo group evaluated the treatment as being beneficial (67% vs 37%, χ2=5.00 p=0.03).Mean VISA-P scoresESWTPlaceboBefore59.4±11.762.4±13.4After 1 week66.8±16.266.3±19.0After 12 week66.7±17.568.9±20.3After 22 week70.5±18.972.7±8.0ConclusionsThere was no effect of ESWT treatment protocol on the course of symptomatic patellar tendinopathy in jumping athletes who continued to train and compete.
Dependence of human maximum vertical counter-movement jump height on activation sequence of the biarticular muscles
Authors: Bračič M , Supej M , Matjačić Z 
Published: April 2011

BackgroundWhen executing vertical jumps a noticeable problem transpires in the efficient transfer of rotational energies of the trunk and the lower body segments into the largest possible vertical velocity. In the transfer of energy, the biarticular muscles rectus femoris (RF) and gastrocnemius (GAS) play an important (Bobbert & Van Ingen Schenau, 19881; Gregoireet al., 19842).ObjectiveThe hypothesis of the study were that athletes with greater maximum vertical counter movement jump height have better energy efficiency of two-legged jumps due to correct activation sequence of the biarticular muscles RF and GAS, which ensure a transfer of rotational kinetic energy between body segments following a proximal to distal principle.Setting and participants12 male elite athletes (age: 22.41±3.39 years; height 177.58±6.86 cm, body mass 74.92±5.23 kg) performed two-leg counter movement jumps (CMJ).MethodsEight camcorders with a frequency of 200 Hz were used for the 3D kinematic measurements of CMJ. The ground reaction forces of jumps were measured unilaterally and bilaterally using two independent and synchronized force platforms. The maximal jump height of the centre of body's mass (HCM) was determined by the time integration (tfl) of the vertical force (F=Fz-mg) signal: HCM=tfl2•g•8–1. Electromyographical data of the time to peak EMG (TTPEMG) from biarticular RF and GAS in concentric phase of the jump were analyzed.ResultsThe comparison between two groups showed that athletes with greater maximum vertical counter movement jump height (group_1: 64.10±5.08 cm vs group_2: 56.41±3.88 cm; p<0.05) have different activation sequence of the biarticular RF and GAS (group_1; TTPEMG_RF=110.53±20.11 ms, TTPEMG_GAS=137.88±22.43 ms vs group_2; TTPEMG_RF=143.56 ±32.23 ms, TTPEMG_GAS=84.81±25.67 ms; p<0.05) which indirectly implicate that the transfer of rotational kinetic energy between body segments follows a proximal to distal principle.ConclusionsIt is concluded that correct activation sequence of the RF and GAS is essential in the execution of vertical counter movement jump.
Possible differences in hematological status between junior and elite female volleyball players
Authors: Milić R , Dopsaj M 
Published: April 2011

BackgroundIron deficiency anaemia and iron deficiency without anemia have debilitating effects on athletic performance due to decreased work capacity and impaired cognition.ObjectiveThe main goal of this research was to identify possible differences in haematological status between junior and elite female volleyball players.Subjects38 female volleyball players belonging to Junior (J) and Elite (E) Serbian and Slovenian national volleyball teams were recruited for the study. The average age of 18 E athletes was 23.8±2.9 years, body height 177.9±9.5 cm, body weight 68.9±7.9 kg and their body mass index (BMI) was 21.7±0.9 kg/m2. Training experience was 12.0±3.2 years and training load in the last micro cycle was 18.4±1.2 h per week. The age of 20 J athletes was 16.9±1.2 years, body height 177.4±5.4 cm, body weight 65.2±3.5 kg and the mean BMI was 20.8±1.4 kg/m2. Training experience was 6.4±1.4 years and training load in the last micro cycle was 15.7±1.6 h per week.MethodsBlood collection was performed between 7 and 8 am at the beginning of the pre-competitive training period after a 12-h overnight fast. Venous blood was collected into evacuated tubes (Vacutainer, Becton Dickinson, USA) from the antecubital vein with minimal stasis. Blood analyses were performed on the instrument Advia 120 (Siemens, Tarrytown, USA), appropriately calibrated and controlled. 14 parameters were taken into account: RBC, Hb, Hct, Ret_abs and Ret (%), erythrocyte index (MCV, MCH, MCHC), RDW, TIBC, iron, ferritin, transferin saturation, soluble transferring receptor (s-TfR). Descriptive statistics and multivariate analysis of variance were employed to investigate differences between the two groups. The result was considered significant when p<0.05. SPSS 17.0 statistical package were used.ResultsStatistical analysis showed significant differences (p<0.05) between (J) and (E) female volleyball players in five parameters from performed blood analyses (RBC, Hct, MCHC, TIBC, ferritin) with lower absolute values in the elite group.ConclusionsThe current study is the first to demonstrate differences in the haematological status between junior and elite female volleyball players, the underlying reasons for which may include differences in training experience and training load.
Intrinsic risk factors for sport injuries in female volleyball
Authors: Sattler T 
Published: April 2011

Background/objectiveTo investigate the incidence and injury mechanism as well as intrinsic risk factors for acute sports injuries in female volleyball.DesignProspective epidemiological study.Setting and participants174 female volleyball players from Slovenian Divisions I and II were prospectively monitored during 2007–2008 season.MethodsAll injuries were prospectively documented by team coaches. Prior to the season all players underwent the following tests: anthropometry, sit and reach test, isokinetic strength testing of the knee and shoulder, postural stability testing and vertical jump testing. Main outcome measure was injury incidence; binary logistic regression was used afterwards in order to evaluate the role of different parameters from functional testing on injury occurrence.ResultsThe overall incidence of injuries for the females was 0.35±0.19 per 1000 h of volleyball played. The incidence of injuries in a game situation was higher than in practice (2.10±1.06 vs 0.42±0.24) The most frequent injury was acute ankle sprain 1.45 (1.98), followed by knee injury 0.69 (1.34). Majority of injuries occurred during the competition season (81.4%), in the middle of training (25.58%) or during a game (25.58%). Most injuries occurred during landing (41.4%). Risk factor analysis revealed that previous injury is an important risk factor for acute knee injuries and ankle sprains. Low hamstring quadriceps ratio was related with ankle sprains, while quadriceps strength asymmetry was related to acute knee injuries.ConclusionsThe results of our study suggest that isokinetic strength testing in previously injured female volleyball players could identify players with increased risk for acute knee injuries and ankle sprains.
Epidemiology of the injuries of the locomotor system in elite volleyball players
Authors: Aido R , Massada M , Leitão N , Magalhães C , Puga N 
Published: April 2011

BackgroundThe epidemiological study is an important tool in the understanding and development of any medical field. In Sports Medicine highlights their importance in the development of preventive strategies with the ultimate goal of protecting and enhancing the performance of athletes.ObjectiveThis observational study has the aim to identify the prevalence, incidence, aetiology, severity and anatomical location of injuries of the locomotor system occurred in volleyball elite players.Setting, participants and methods20 Portuguese volleyball players from the senior national team, with mean age of 24.29 years and 11.14 years of average sports volleyball, were evaluated during 4 months. All the injuries were recorded and reported with their clinical diagnosis.ResultsDuring the study, 55 injuries were detected with an incidence rate of 6.11 injuries per athlete per 1000 h of sporting activity. An higher incidence of injuries was observed during games when compared with the training sessions (10.11 vs 5.56). The 55 lesions were diagnosed in 18 athletes (90.00%) who comprised the study, noting the prevalence of overuse injuries (72.73%). The anatomical segment most affected was the lower limb (45.54%). Lower limb anatomic area with highest number of injuries was the knee and leg (27.27%). Muscular injuries (38.18%) and tendinopathys (34.54%) were the most frequent injuries reported. There was a predominance of lesions in the dominant member (64.86%). In eight players (40.00%) recurrence of previous injuries was diagnosed. The greatest number of lesions was considered of mild (58.18%) or moderate (34.54%) severity. The analysis between the injuries and the athlete's position stated that the opposites were the most affected players. The first month of sport activity was the period with more injuries recorded.ConclusionsThe results reported in this study show a predominance of overuse and recurrent injuries in elite volleyball athletes. These finding are consistent with previously conducted epidemiological records.
The relationship between patellar tendinopathy risk factors and ground reaction forces during cross-over block jump landings
Authors: Janssen I , Steele J R , Munro B J , Brown N A T 
Published: April 2011

BackgroundOveruse knee injuries, such as patellar tendinopathy, are one of the most prevalent and frequent injuries in volleyball with up to 50% of male indoor volleyball players sustaining this injury in their careers.ObjectiveThe aim of this research was to examine the intrinsic and extrinsic risk factors associated with patellar tendinopathy including muscle flexibility, muscle strength, vertical jump, and their relationship to vertical ground reaction forces (vGRF) during cross-over block jump landings.DesignStructural alignment, lower limb flexibility, and muscle strength assessed were measured for each participant who then performed five trials of a cross-over step block. vGRF (vGRF: 1500 Hz; Kistler) were collected for takeoff and landing.SettingA portable volleyball net was used to simulate a typical and realistic volleyball condition in a biomechanics laboratory. A standard volleyball was mounted on a post and used as a target.ParticipantsElite male (EM) (N=10), sub-elite male (SEM) (N=10), and sub-elite female (N=10) volleyball players with no existing knee joint injury or history of lower limb surgery participated in this study.Main outcome measurementsMagnitudes of and correlations among risk factor measures and peak vGRF.ResultsGender differences were observed with SEM displaying significantly smaller Q-angle (p=0.04), greater strength (p=0.00), and maximal jump height (p=0.00) than SEF. EM displayed passive greater hip extension (p=0.01) and trunk flexion (p=0.05), and significantly greater strength in their non-dominant quadriceps (p=0.01) than SEM. SEM generated significantly higher vGRF compared to SEF. Significant negative correlations were found between vGRF and Q-angle and gastrocnemius flexibility for SEF but not SEM or EM.ConclusionsThe results of this study may provide further insight why and which volleyball athletes may be prone to developing overuse knee injuries.
Developing an injury tracking software system specific for volleyball: a case example
Authors: Yasher K R , Liller K , Wong S , Jang S , Morris B J , Konin J G 
Published: April 2011

BackgroundInjury tracking systems are becoming increasingly popular in the realm of sports medicine. Identifying the prevalence and types of injuries can contribute to the identification of risk factors associated with sport specific injuries, as well as lead to the development of injury prevention programs, educational material, rule changes, and improved protective equipment.ObjectiveTo describe the process of creating an injury tracking system for volleyball in an effort to track variables associated with injury patterns.DesignA software program containing over 1000variables was developed by certified athletic trainers and public health experts. Variables included demographic information, environmental factors, and sport specific movements. Standardized definitions (ie, ‘injury’) were established and pilot tested for reliability and validity purposes using internally developed case studies.SettingData was collected via a web-based software program through the university academic program.ParticipantsParticipants included female volleyball players between 14–18 years of age.ResultsAnalysis of the results identified common injuries associated with volleyball and their associated mechanisms. These findings directly led to the implementation of educational programs designed to prevent such injuries from occurring in the future. Furthermore, internal assessments of the program development noted the requirement of frequent variable modifications, standardized training necessities, and ongoing discussion to assure accurate data input.ConclusionsThe development of an injury tracking system specific to volleyball requires time, funding, ongoing re-evaluation, standardized terms, training for data collectors, and plans for implementing the findings into practical information for coaches, players, parents, and health care providers. When developed successfully, the information collected can prove to be valuable.
The relationship between different adaptational changes and injury in the dominant shoulder of female overhead athletes
Authors: Tonin K , Stražar K , Vidmar G , Tomšič I , Burger H 
Published: April 2011

BackgroundAdaptational changes (gleno-humeral internal rotation deficit – GIRD, SICK scapula signs and muscular imbalances) develop in the dominant shoulder of overhead athletes.ObjectiveTo evaluate the incidence and the correlation between different adaptational changes and injury in the dominant shoulder. To evaluate the effect of (a)symmetrical hand-use on the development of adaptational changes and shoulder injury.DesignObservational cross-sectional correlational study.Setting and participants36 highly competitive female overhead athletes (21 handball players, 15 volleyball players), competing in Middle European volleyball league, EHF women's champions league and Slovene National leagues and National cups. Players were divided into two groups by the symmetry of hand-use.InterventionsParticipants completed a self-reported shoulder history questionnaire. Complete clinical examination of the shoulders was performed, including passive internal (IR) and external rotation (ER), SICK scapula and GIRD evaluation. Isokinetic testing of IR and ER was performed in concentric (c) and eccentric (e) modes at two testing speeds (60°/s, 150°/s). Fatiguability of IR and ER was measured. Stability spiking (eER/cIR) and cocking ratios (eIR/cER) were calculated.ResultsAll participants had decreased IR and increased ER ROM in dominant shoulders (p>0.001). Average GIRD was 20.6°, greater GIRD correlated with higher cIR peak torques (p=0.008). Dominant hand eER peak torques were lower, hence the spiking ratios were lower (p=0.015 and p=0.002). Players with previous injury showed more scapular abduction, increased ER and lower cocking ratios (p=0.04, p=0.036, p=0.06). Players with asymmetrical hand-use showed higher fatiguability of IR and ER (p=0.019, p=0.01).ConclusionsStatic and dynamic adaptational changes are found in the dominant shoulder and are positively correlated to each other and to history of injury. Hitters and throwers fatigue more. Preventive shoulder training is crucial for injury prevention of highly competitive overhead athletes with existing adaptational changes.