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.

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?
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.

Context: The etiology of idiopathic scoliosis remains unknown, but growth is a risk factor for progression. Growth pattern differs in children with and without scoliosis. Cartilage oligomeric matrix protein (COMP) may be associated with scoliosis and growth. We, therefore, studied COMP in children with and without idiopathic scoliosis.', 'We included 105 children, with mean age 14.4 years (range 10-16), under observation or treatment for idiopathic scoliosis, and 103 children from an age-matched population-based cohort. COMP was measured in serum at the time of inclusion. Growth velocity was estimated from repeated height measurements. T tests, analysis of covariance or linear regression were used for statistical comparisons.', 'COMP was mean (SD) 11 (5) units/liter (U/L) in children with scoliosis and 13 (5) U/L in the control cohort (p = 0.005, adjusted for sex and sampling time of the day). When patients and controls were analyzed together, high COMP was correlated with high growth velocity (β = 0.19, p = 0.003). When patients and controls were analyzed separately, COMP was correlated with growth velocity in children with scoliosis (β = 0.27, p = 0.007), but not in children without scoliosis (β = 0.02, p = 0.83) (all analyses adjusted for age, sex and sampling time). Low COMP was significantly correlated with large curve size in children with scoliosis (β = -0.29, p = 0.003), but not after adjustment for age, sex and sampling time (β = -0.16; p = 0.14).\Question: Is serum level of cartilage oligomeric matrix protein lower in children with idiopathic scoliosis than in non-scoliotic controls?
COMP was lower in children with idiopathic scoliosis than in a control cohort. In children with scoliosis, high COMP was modestly correlated with high growth velocity, but not with curve severity.

Context: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are active in cancer therapy. Mechanisms engaged during these clinical responses need to be determined. We reported previously that epidermal growth factor stimulation markedly increased cyclin D1 protein expression in human bronchial epithelial (HBE) cells, and this was opposed by chemoprevention with all-trans-retinoic acid. The current study sought to determine whether the EGFR TKI erlotinib repressed cyclin D1 protein expression in immortalized HBE cells, lung cancer cell lines, and clinical aerodigestive tract cancers.', 'The BEAS-2B immortalized HBE cell line was exposed to varying concentrations of erlotinib, and effects on proliferation, cell cycle distribution, G1 cyclin expression, and cyclin D1 reporter activity were measured. Non-small-cell lung cancer cell lines were also evaluated for changes in proliferation and cyclin protein expression after erlotinib treatments. A proof of principle clinical trial was conducted. During this study, patients underwent a 9-day course of erlotinib treatment. Pretreatment and posttreatment tumor biopsies were obtained, and changes in candidate biomarkers were determined by immunostaining. Plasma pharmacokinetics and tumor tissue erlotinib concentrations were measured.', 'Erlotinib, at clinically achievable dosages, repressed BEAS-2B cell growth, triggered G1 arrest, and preferentially reduced cyclin D1 protein expression and transcriptional activation. Erlotinib also preferentially repressed proliferation and cyclin D1 protein expression in responsive, but not resistant, non-small-cell lung cancer cell lines. This occurred in the presence of wild-type EGFR sequence at exons 18, 19, and 21. Five patients were enrolled onto an erlotinib proof of principle clinical trial, and four cases were evaluable. Pharmacokinetic studies established therapeutic erlotinib plasma levels in all patients, but tissue levels exceeding 2 micromol/L were detected in only two cases. Notably, these cases had pathological evidence of response (necrosis) in posttreatment biopsies as compared with pretreatment biopsies. In these cases, marked repression of cyclin D1 and the proliferation marker Ki-67 was detected by immunohistochemical assays. Cases without pathological response to erlotinib did not exhibit changes in cyclin D1 or Ki-67 immunohistochemical expression and had much lower erlotinib tissue levels than did responding cases.\Question: Does epidermal growth factor receptor tyrosine kinase inhibition repress cyclin D1 in aerodigestive tract cancers?

Taken together, these in vitro and in vivo findings provide direct evidence for repression of cyclin D1 protein as a surrogate marker of response in aerodigestive tract cancers to erlotinib treatment. These findings also provide a rationale for combining an EGFR TKI with an agent that would cooperatively repress cyclin D1 expression in clinical trials for aerodigestive tract cancer therapy or chemoprevention.