In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
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Question: Context: The bradycardic agent zatebradine (UL-FS 49) reduces heart rate without negative inotropic or proarrhythmic effects. The aim was to experimentally characterize the influence of zatebradine on arterial baroreflex sensitivity (BRS) and heart rate variability (HRV) which are generally considered as estimates of vagal activity and have prognostic value in patients after myocardial infarction (MI).', 'Conscious rats were studied 3 days after left coronary artery ligation or sham-operation (SH). BRS was determined by linear regression analysis of RR-interval and mean arterial pressure changes evoked by intravenous (i.v.) injections of methoxamine and nitroprusside. HRV at rest was calculated from high-resolution electrocardiogram-recordings.', 'In MI-rats heart rate was similar to SH-rats, mean arterial pressure was lower and both BRS and HRV were markedly reduced. Zatebradine (0.5 mg/kg i.v.) reduced heart rate in MI-rats from 400 +/- 15 to 350 +/- 19 and in SH-rats from 390 +/- 19 to 324 +/- 6 beats/min without changing mean arterial pressure. Both BRS and HRV were restored in MI- and further increased in SH-rats by the drug. Effects of 0.05, 0.5 and 5 mg/kg zatebradine revealed a dose-dependency of heart rate reduction. The lowest dose enhanced reflex bradycardia despite little effect on heart rate and lack of effect on both reflex tachycardia and HRV.\Question: Does the bradycardic agent zatebradine enhance baroreflex sensitivity and heart rate variability in rats early after myocardial infarction?

Answer: Both BRS and HRV are reduced in rats early after MI, indicating a depressed reflex and tonic vagal activity. Treatment with zatebradine enhances both BRS and HRV. These data suggest that the drug has both peripheral and central effects, leading to an increase of vagal control of heart rate.


Question: Context: Tetrahydrocurcumin (THC) is an active metabolite of curcumin. It has been reported to have similar pharmacological activity to curcumin. The proteases that participate in extracellular matrix (ECM) degradation are involved in cancer cell metastasis. The present study investigates the effect of an ultimate metabolite of curcumin, THC, on the invasion and motility of highly-metastatic HT1080 human fibrosarcoma cells.', 'The effect of THC on HT1080 cell invasion and migration was determined using Boyden chamber assay. Cell-adhesion assay was used for examining the binding of cells to ECM molecules. Zymography assay was used to analyze the effect of THC on matrix metalloproteinase (MMP)-2, MMP-9, and urokinase plasminogen activator (uPA) secretion from HT1080 cells. Tissue inhibitor of metalloproteinase (TIMP)-2 and membrane-type 1 matrix metalloproteinase (MT1-MMP) proteins levels were analyzed by Western blotting.', 'Treatment with THC reduced HT1080 cell invasion and migration in a dose-dependent manner. THC also decreased the cell adhesion to Matrigel and laminin-coated plates. Analysis by zymography demonstrated that treatment with THC reduced the levels of MMP-2, MMP-9, and uPA. THC also inhibited the levels of MT1-MMP and TIMP-2 proteins detected by Western blot analysis.\Question: Does tetrahydrocurcumin inhibit HT1080 cell migration and invasion via downregulation of MMPs and uPA?

Answer: Our findings revealed that THC reduced HT1080 cell invasion and migration. The inhibition of cancer cell invasion is associated with the downregulation of ECM degradation enzymes and the inhibition of cell adhesion to ECM proteins.


Question: Context: To determine whether testosterone levels change as women with the polycystic ovary syndrome (PCOS) grow older.', 'A follow-up cross-sectional study of a cohort of women with PCOS identified up to 20-25 years ago.', 'Women with PCOS were recruited primarily from practice records between 1970 and 1990. Voter registration tapes and household directories were used to identify age-, race-, and neighborhood-matched controls.', 'Eighty-four women with PCOS, 20-57 years of age, and 37 age-matched controls participating in a study of the risk for cardiovascular disease in women with PCOS.', 'Clinical data were collected by questionnaire and fasting blood samples were obtained randomly throughout the menstrual cycle.', 'Total and non-SHBG-bound testosterone levels.', 'Total and non-SHBG-bound testosterone levels were similar in women with PCOS who were 20-42 years of age but were reduced by approximately 50% among women 42-47 years of age and remained stable in women older than 47 years of age. Testosterone levels were increased in younger and older women with PCOS compared with controls but were similar to controls in women 42-47 years of age.\Question: Do serum testosterone levels decrease in middle age in women with the polycystic ovary syndrome?

Answer:
Hyperandrogenism partly resolves before menopause in women with PCOS. This change may explain the tendency of women with PCOS to cycle regularly as they grow older. Testosterone levels remain elevated in older women with PCOS, however, and may contribute to their increased risk for cardiovascular disease, endometrial cancer, and other diseases.