human
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Females experience a disproportionate number of anterior cruciate ligament injuries compared to males . Increased estradiol concentration has been suggested to alter ligament properties and strength . Determining whether the knee responds differently to an external load at various hormonal levels may be helpful in further explaining the gender disparity . METHODS  Estradiol , progesterone and testosterone  were quantified at menses , near ovulation and at the mid-luteal phase . With one knee serving as the control limb and the other as the experimental limb , displacement at 134N and stiffness between 90 and 134N were recorded with a knee ligament arthrometer on both knees before and after a loading protocol . The protocol consisted of three , 3-min , posterior to anterior normalized loads directed to the posterior calf with a ligament testing device . FINDINGS The loading protocol produced a measurable increase in displacement but not stiffness . Neither displacement nor stiffness measures however were affected by day of the menstrual cycle . No consistent relationships between hormonal concentrations and displacement or stiffness were evident . INTERPRETATION Following a controlled , static external load , displacement and stiffness were not affected differently by day of the menstrual cycle Background Ovulatory menstrual cycles are essential for women ’s fertility and needed to prevent bone loss . There is a medical/cultural expectation that clinical ly normal menstrual cycles are inevitably ovulatory . Currently within the general population it is unknown the proportion of regular , normal-length menstrual cycles that are ovulatory . Thus , the objective of this study was to determine the population point prevalence of ovulation in premenopausal , normally menstruating women . The null hypothesis was that such cycles are ovulatory . Methods This is a single-cycle , cross-sectional , population -based study —a sub- study of the HUNT3 health study in the semi-rural county ( Nord Trøndelag ) in mid-Norway . Participants included > 3,700 spontaneously ( no hormonal contraception ) menstruating women , primarily Caucasian , ages 20–49.9 from that county . Participation rate was 51.9 % . All reported the date previous flow started . A single , r and om serum progesterone level was considered ovulatory if ≥9.54 nmol/L on cycle days 14 to -3 days before usual cycle length ( CL ) . Results Ovulation was assessed in 3,168 women mean age 41.7 ( interquartile range , [ IQR ] 36.8 to 45.5 ) , cycle length 28 days ( d ) ( IQR 28 to 28 ) and body mass index ( BMI ) 26.3 kg/m2 ( 95 % CI 26.1 to 26.4 ) . Parity was 95.6 % , 30 % smoked , 61.3 % exercised regularly and 18 % were obese . 1,545 women with a serum progesterone level on cycle days 14 to -3 were presumed to be in the luteal phase . Of these , 63.3 % of women had an ovulatory cycle ( n = 978 ) and 37 % ( n = 567 ) were anovulatory . Women with/ without ovulation did not differ in age , BMI , cycle day , menarche age , cigarette use , physical activity , % obesity or self-reported health . There were minimal differences in parity ( 96.7 % vs. 94.5 % , P = 0.04 ) and major differences in progesterone level ( 24.5 vs. 3.8 nmol/L , P = 0.001 ) . Conclusion Anovulation in a r and om population occurs in over a third of clinical ly normal menstrual cycles For 714 consecutive patients who underwent autogenous patellar tendon graft anterior cruciate ligament reconstructions  we intraoperatively measured intercondylar notch width . We prospect ively recorded height , weight , sex , and which patients subsequently tore their contralateral anterior cruciate ligament or the 10-mm autograft . The patients were divided into two groups based on notch width ( group 1 , 15 mm ; group 2 , 16 mm ) . The mean notch width was 13.9 2.2 mm for women and 15.9 2.5 mm for men . There was no statistically significant difference in notch width between height groups for women or men . Analysis showed that , with height and weight as covariates , women had statistically significantly narrower notches than men . Twenty-three of 388 patients in group 1 and 4 of 326 patients in group 2 tore their contralateral anterior cruciate ligaments . Within groups , no statistically significant differences in contralateral tear rates existed between men and women . Once the men and women had reconstructions with equally sized 10-mm autografts , there was no difference in graft tear rate between groups or between men and women . Our results show that patients with narrower notches have a higher incidence of tearing their contralateral anterior cruciate ligament . After reconstruction with a 10-mm autograft , the incidence of graft rupture is the same for men and women Introduction Anterior cruciate ligament ( ACL ) injuries are more common among female athletes compared to male athletes . Several studies have been reported to explain the gender difference in ACL injury rates and several risk factors underlying gender disparity are believed to exist . Hormonal effects are considered to be one of the etiological factors for female non-contact ACL injuries . The objectives of this study were to determine if ACL injuries occurred r and omly or correlated with a specific phase of the female menstrual cycle in teenaged female athletes and then to determine if pre-menstrual and menstrual dysfunctions influenced these ACL injuries . Material s and methods Eighteen of 37 consecutive female athletes , with ACL injuries , met the study criteria : teenage , with regular menstrual cycle , and non-contact injury . The menstrual history , athletic activity , and injury history were collected . Results Seventy-two percent of the subjects had premenstrual symptoms and 83 % had  menstrual symptoms . The subjective activity level at the follicular phase was significantly lowest between the phases . A significant statistical association was found between the phase of the menstrual cycle and ACL injuries ( P = 0.0002 ) . There were more injuries in the ovulatory phase than expected , and fewer injuries occurred in the other phases . Conclusion The results showed a significant increase in non-contact ACL injuries in teenage female athletes during the ovulatory phase of the menstrual cycle and the subjective activity level and the premenstrual and menstrual symptoms might not affect the likelihood of the injuries . These findings suggest that sex hormones might play a role in the incidence of female non-contact ACL injuries BACKGROUND No definitive explanation for the difference in rate of male and female noncontact ACL injury has been found . The hormonal environment , known to be different in men and women has been hypothesized as a possible source for this difference in injury rate . PURPOSE To confirm earlier work looking at periodicity of noncontact ACL injury . To increase sample size by adding ankle sprains . To determine the rate of  noncontact ACL injury and ankle sprains in collegiate basketball and soccer . To determine if the use of oral contraceptives affects the rate of noncontact ACL injury and ankle sprains . METHODS Data was collected from a sample of NCAA schools over the 2000 - 2001 basketball and the 2001 - 2002 basketball and soccer seasons . RESULTS Recall and prospect i ve data collection of length of menstrual cycle did not produce equivalent results . Periodicity was present only in the recall group of " off pill " users . The rate of noncontact ACL injury and noncontact ankle sprains was twice as high in basketball as in soccer . There was no difference in rate of injuries between those athletes using  hormonal therapy and those athletes not using hormonal therapy . CONCLUSIONS Noncontact ACL injuries and ankle sprains occurred at significantly higher rates in basketball than in soccer but this rate difference was not linked to hormonal therapy usage . The overall rate of noncontact ACL injury and ankle sprain to women 's collegiate basketball and soccer players is very low Background Noncontact anterior cruciate ligament injuries occur two to eight times more often in women than in men . Changes in ligament laxity and strength have been associated with female hormones such as relaxin . Hypothesis Relaxin receptors are present within the female anterior cruciate ligament . Study Design Controlled laboratory study . Methods Remnants of anterior cruciate ligament were harvested from five women and five men undergoing routine ligament reconstruction . Relaxin was biotinylated and analyzed for biologic activity with use of the mouse interpubic ligament bioassay . Immunohistochemical localization of relaxin receptors was performed with appropriate negative controls and competitive binding assays to determine receptor specificity and saturability . Results Anterior cruciate ligament sections from women but not from men showed uniform specific binding that was limited to synovial lining cells , stromal fibroblasts , and cells lining blood vessels . Specific binding was confirmed in the presence of a 2000-fold excess of human insulin , the structural homolog of relaxin , and competitive inhibition was demonstrated in the presence of a 2000-fold excess of unlabeled relaxin . Conclusions Relaxin exhibits specific saturable binding in the female anterior cruciate ligament , where specific relaxin receptors were present . Clinical Relevance The high incidence of anterior cruciate ligament rupture in female athletes may be partially explained by the effects of relaxin 
    Output:
    
agent
Conclusion : The literature suggests an association between hormonal fluctuations and ACL injury .
Recent studies have suggested that oral contraceptives may offer up to a 20 % reduction in risk of injury .
***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Females experience a disproportionate number of anterior cruciate ligament injuries compared to males . Increased estradiol concentration has been suggested to alter ligament properties and strength . Determining whether the knee responds differently to an external load at various hormonal levels may be helpful in further explaining the gender disparity . METHODS  Estradiol , progesterone and testosterone  were quantified at menses , near ovulation and at the mid-luteal phase . With one knee serving as the control limb and the other as the experimental limb , displacement at 134N and stiffness between 90 and 134N were recorded with a knee ligament arthrometer on both knees before and after a loading protocol . The protocol consisted of three , 3-min , posterior to anterior normalized loads directed to the posterior calf with a ligament testing device . FINDINGS The loading protocol produced a measurable increase in displacement but not stiffness . Neither displacement nor stiffness measures however were affected by day of the menstrual cycle . No consistent relationships between hormonal concentrations and displacement or stiffness were evident . INTERPRETATION Following a controlled , static external load , displacement and stiffness were not affected differently by day of the menstrual cycle Background Ovulatory menstrual cycles are essential for women ’s fertility and needed to prevent bone loss . There is a medical/cultural expectation that clinical ly normal menstrual cycles are inevitably ovulatory . Currently within the general population it is unknown the proportion of regular , normal-length menstrual cycles that are ovulatory . Thus , the objective of this study was to determine the population point prevalence of ovulation in premenopausal , normally menstruating women . The null hypothesis was that such cycles are ovulatory . Methods This is a single-cycle , cross-sectional , population -based study —a sub- study of the HUNT3 health study in the semi-rural county ( Nord Trøndelag ) in mid-Norway . Participants included > 3,700 spontaneously ( no hormonal contraception ) menstruating women , primarily Caucasian , ages 20–49.9 from that county . Participation rate was 51.9 % . All reported the date previous flow started . A single , r and om serum progesterone level was considered ovulatory if ≥9.54 nmol/L on cycle days 14 to -3 days before usual cycle length ( CL ) . Results Ovulation was assessed in 3,168 women mean age 41.7 ( interquartile range , [ IQR ] 36.8 to 45.5 ) , cycle length 28 days ( d ) ( IQR 28 to 28 ) and body mass index ( BMI ) 26.3 kg/m2 ( 95 % CI 26.1 to 26.4 ) . Parity was 95.6 % , 30 % smoked , 61.3 % exercised regularly and 18 % were obese . 1,545 women with a serum progesterone level on cycle days 14 to -3 were presumed to be in the luteal phase . Of these , 63.3 % of women had an ovulatory cycle ( n = 978 ) and 37 % ( n = 567 ) were anovulatory . Women with/ without ovulation did not differ in age , BMI , cycle day , menarche age , cigarette use , physical activity , % obesity or self-reported health . There were minimal differences in parity ( 96.7 % vs. 94.5 % , P = 0.04 ) and major differences in progesterone level ( 24.5 vs. 3.8 nmol/L , P = 0.001 ) . Conclusion Anovulation in a r and om population occurs in over a third of clinical ly normal menstrual cycles For 714 consecutive patients who underwent autogenous patellar tendon graft anterior cruciate ligament reconstructions  we intraoperatively measured intercondylar notch width . We prospect ively recorded height , weight , sex , and which patients subsequently tore their contralateral anterior cruciate ligament or the 10-mm autograft . The patients were divided into two groups based on notch width ( group 1 , 15 mm ; group 2 , 16 mm ) . The mean notch width was 13.9 2.2 mm for women and 15.9 2.5 mm for men . There was no statistically significant difference in notch width between height groups for women or men . Analysis showed that , with height and weight as covariates , women had statistically significantly narrower notches than men . Twenty-three of 388 patients in group 1 and 4 of 326 patients in group 2 tore their contralateral anterior cruciate ligaments . Within groups , no statistically significant differences in contralateral tear rates existed between men and women . Once the men and women had reconstructions with equally sized 10-mm autografts , there was no difference in graft tear rate between groups or between men and women . Our results show that patients with narrower notches have a higher incidence of tearing their contralateral anterior cruciate ligament . After reconstruction with a 10-mm autograft , the incidence of graft rupture is the same for men and women Introduction Anterior cruciate ligament ( ACL ) injuries are more common among female athletes compared to male athletes . Several studies have been reported to explain the gender difference in ACL injury rates and several risk factors underlying gender disparity are believed to exist . Hormonal effects are considered to be one of the etiological factors for female non-contact ACL injuries . The objectives of this study were to determine if ACL injuries occurred r and omly or correlated with a specific phase of the female menstrual cycle in teenaged female athletes and then to determine if pre-menstrual and menstrual dysfunctions influenced these ACL injuries . Material s and methods Eighteen of 37 consecutive female athletes , with ACL injuries , met the study criteria : teenage , with regular menstrual cycle , and non-contact injury . The menstrual history , athletic activity , and injury history were collected . Results Seventy-two percent of the subjects had premenstrual symptoms and 83 % had  menstrual symptoms . The subjective activity level at the follicular phase was significantly lowest between the phases . A significant statistical association was found between the phase of the menstrual cycle and ACL injuries ( P = 0.0002 ) . There were more injuries in the ovulatory phase than expected , and fewer injuries occurred in the other phases . Conclusion The results showed a significant increase in non-contact ACL injuries in teenage female athletes during the ovulatory phase of the menstrual cycle and the subjective activity level and the premenstrual and menstrual symptoms might not affect the likelihood of the injuries . These findings suggest that sex hormones might play a role in the incidence of female non-contact ACL injuries BACKGROUND No definitive explanation for the difference in rate of male and female noncontact ACL injury has been found . The hormonal environment , known to be different in men and women has been hypothesized as a possible source for this difference in injury rate . PURPOSE To confirm earlier work looking at periodicity of noncontact ACL injury . To increase sample size by adding ankle sprains . To determine the rate of  noncontact ACL injury and ankle sprains in collegiate basketball and soccer . To determine if the use of oral contraceptives affects the rate of noncontact ACL injury and ankle sprains . METHODS Data was collected from a sample of NCAA schools over the 2000 - 2001 basketball and the 2001 - 2002 basketball and soccer seasons . RESULTS Recall and prospect i ve data collection of length of menstrual cycle did not produce equivalent results . Periodicity was present only in the recall group of " off pill " users . The rate of noncontact ACL injury and noncontact ankle sprains was twice as high in basketball as in soccer . There was no difference in rate of injuries between those athletes using  hormonal therapy and those athletes not using hormonal therapy . CONCLUSIONS Noncontact ACL injuries and ankle sprains occurred at significantly higher rates in basketball than in soccer but this rate difference was not linked to hormonal therapy usage . The overall rate of noncontact ACL injury and ankle sprain to women 's collegiate basketball and soccer players is very low Background Noncontact anterior cruciate ligament injuries occur two to eight times more often in women than in men . Changes in ligament laxity and strength have been associated with female hormones such as relaxin . Hypothesis Relaxin receptors are present within the female anterior cruciate ligament . Study Design Controlled laboratory study . Methods Remnants of anterior cruciate ligament were harvested from five women and five men undergoing routine ligament reconstruction . Relaxin was biotinylated and analyzed for biologic activity with use of the mouse interpubic ligament bioassay . Immunohistochemical localization of relaxin receptors was performed with appropriate negative controls and competitive binding assays to determine receptor specificity and saturability . Results Anterior cruciate ligament sections from women but not from men showed uniform specific binding that was limited to synovial lining cells , stromal fibroblasts , and cells lining blood vessels . Specific binding was confirmed in the presence of a 2000-fold excess of human insulin , the structural homolog of relaxin , and competitive inhibition was demonstrated in the presence of a 2000-fold excess of unlabeled relaxin . Conclusions Relaxin exhibits specific saturable binding in the female anterior cruciate ligament , where specific relaxin receptors were present . Clinical Relevance The high incidence of anterior cruciate ligament rupture in female athletes may be partially explained by the effects of relaxin 
    Output:
    