RESUMO
PURPOSE: This study was designed to investigate the relationship between serum relaxin concentration (SRC) and menstrual history and hormonal contraceptive use among elite collegiate female athletes. Evaluation of SRC in athletes is necessary, because relaxin has been associated with increased knee joint laxity and decreased anterior cruciate ligament (ACL) strength in animal models. METHODS: National Collegiate Athletic Association Division I female athletes participating in sports at high risk for ACL tears - basketball, field hockey, gymnastics, lacrosse, soccer, and volleyball - were invited to participate. All participants completed a questionnaire about their menstrual history and hormonal contraceptive use. Venipuncture was performed to obtain samples of serum progesterone and relaxin. Samples were obtained during the mid-luteal phase from ovulating participants, and between the actual or projected cycle days 21 to 24, from anovulatory participants. Serum concentration of relaxin and progesterone was determined by ELISA and the data were analyzed using SPSS statistical software with significance set at P = 0.05. RESULTS: 169 female athletes participated. The mean SRC among all participants was 3.08 ± 6.66 pg/mL). The mean SRC differed significantly between those participants using hormonal contraceptives (1.41 pg/mL) and those not using hormonal contraceptives (3.08 pg/mL, P = 0.002). Mean SRC was lowest among amenorrheic participants (1.02 pg/mL) and highest among oligomenorrheic participants (3.71 pg/mL) and eumenorrheic participants (3.06 pg/mL); these differences were not significant (P = 0.53). Mean serum progesterone concentration (SPC) differed significantly between those participants using hormonal contraceptives (2.80 ng/mL), and those not using hormonal contraceptives (6.99 ng/mL, P < 0.0001). CONCLUSIONS: There is a positive correlation between serum progesterone and SRC and an attenuation of SRC with hormonal contraceptive use. Our results underscore the significant role that hormonal contraceptives can play in decreasing relaxin levels, if future investigations establish a link between relaxin levels and ligamentous injury among female athletes.
RESUMO
Mycobacterium tuberculosis under stress stores triacylglycerol (TG). There are 15 genes in M. tuberculosis that belong to a novel family of TG synthase genes (tgs), but it is not known which of them is responsible for this accumulation of TG. In this paper, it is reported that M. tuberculosis H37Rv accumulated TG under acidic, static or hypoxic growth conditions, or upon treatment with NO, whereas TG accumulation was drastically reduced in the tgs1 (Rv3130c) disrupted mutant. Complementation with tgs1 restored this TG accumulation. C(26) was a major fatty acid in this TG, indicating that the TGS1 gene product uses C(26) fatty acid, which is known to be produced by the mycobacterial fatty acid synthase. TGS1 expressed in Escherichia coli preferred C(26 : 0)-CoA for TG synthesis. If TG storage is needed for the long-term survival of M. tuberculosis under dormant conditions, the tgs1 product could be a suitable target for antilatency drugs.