TASK DEFINITION: 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.
PROBLEM: Context: Hepatic osteodystrophy has been reported in patients with various chronic liver diseases, including liver cirrhosis. However, it has not been well investigated in patients with hepatitis B virus infection. The aim of this study was to investigate the association between hepatitis B surface antigen (HBsAg) seropositivity and bone mineral density (BMD) in a population representative of normal Koreans.', 'Subjects with both HBsAg and BMD levels examined during the 2008-2010 Korea National Health and Nutrition Examination Surveys were included. HBsAg-seropositive (+) subjects were compared with those who were HBsAg-seronegative (-). BMD was measured at the lumbar spine and femur by dual-energy X-ray absorptiometry. Multivariable logistic regression was performed for BMD .', 'In total, 11,306 participants were included in this study, among which 423 (3.7\xa0%) were HBsAg(+): 153 premenopausal female (3.4\xa0%), 83 postmenopausal female (3.5\xa0%), and 187 male (4.2\xa0%). Multivariable logistic regression analysis adjusted for age and body mass index showed that HBsAg(+) male had significantly lower BMD of the femoral neck than HBsAg(-) male (0.810\xa0±\xa00.009 vs. 0.827\xa0±\xa00.002\xa0g/cm(2), p\xa0=\xa00.035). Further adjustment for waist circumference, smoking, drinking, exercise, income, occupation, and vitamin D levels showed that HBsAg(+) male had significantly lower BMD of the femur neck (0.810\xa0±\xa00.010 vs. 0.831\xa0±\xa00.002\xa0g/cm(2), p\xa0=\xa00.032) and lumbar spine (0.953\xa0±\xa00.011 vs. 0.974\xa0±\xa00.003\xa0g/cm(2), p\xa0=\xa00.049) than HBsAg(-) male.\Question: Are males seropositive for hepatitis B surface antigen at risk of lower bone mineral density : the 2008-2010 Korea National Health and Nutrition Examination Surveys?

SOLUTION: HBsAg seropositivity was significantly associated with lower BMD in male. Future long-term prospective studies investigating bone turnover markers and hormones are needed to better understand the pathophysiology and clinical significance of chronic hepatitis B virus-related hepatic osteodystrophy.

PROBLEM: Context: We previously reported that human OA subchondral bone osteoblasts could be discriminated into two subpopulations identified by their levels of endogenous production (low [L] or high [H]) of PGE(2). Here, we investigated the OPG and RANKL expression levels, the histologic analysis of the subchondral bone as well as the osteoclast differentiation effect of osteoblasts on normal and both OA subpopulations (L and H), and further examined on the L OA osteoblasts the modulation of bone remodelling factors on the OPG and RANKL levels, as well as on the resorption activity.', 'Gene expression was determined using real-time PCR, PGE2 and OPG levels by specific ELISA, and membranous RANKL by flow cytometry. Histological observation of the subchondral bone was performed on human knee specimens. Osteoclast differentiation and formation was assayed by using the pre-osteoclastic cell line RAW 264.7. OPG and RANKL modulation on L OA osteoblasts was monitored following treatment with osteotropic factors, and the resorption activity was studied by the co-culture of differentiated PBMC/osteoblasts.', 'Human OA subchondral bone osteoblasts expressed less OPG than normal. Compared to normal, RANKL gene expression levels were increased in L OA and decreased in H OA cells. The OPG/RANKL mRNA ratio was significantly diminished in L OA compared to normal or H OA (p<0.02, p<0.03), and markedly increased in H OA compared to normal. Inhibition of endogenous PGE(2) levels by indomethacin markedly decreased the ratio of OPG/RANKL on the H OA. In contrast to H OA osteoblasts, L OA cells induced a significantly higher level of osteoclast differentiation and formation (p<0.05). Histological analysis showed a reduced subchondral bone on the L OA and an increased bone mass on the H OA compared to normal. Treatment of L OA osteoblasts with osteotropic factors revealed that the OPG/RANKL mRNA expression ratio was significantly reduced by vitamin D(3) and significantly increased by TNF-alpha, PTH and PGE(2), while IL-1Beta demonstrated no effect. OPG protein levels showed similar profiles. No true effect was noted on membranous RANKL upon treatment with IL-1Beta, PGE(2) and PTH, but a significant increase was observed with vitamin D3 and TNF-alpha. The resorption activity of the L OA cells was significantly inhibited by all treatments except IL-1Beta, with maximum effect observed with vitamin D(3) and PGE(2).\Question: Is the differential expression of osteoprotegerin ( OPG ) and receptor activator of nuclear factor kappaB ligand ( RANKL ) in human osteoarthritic subchondral bone osteoblasts an indicator of the metabolic state of these disease cells?

SOLUTION: OPG and RANKL levels, and consequently the OPG/RANKL ratio, differed according to human OA subchondral bone osteoblast classification; it is decreased in L and increased in H OA. These findings, in addition to those showing that L OA osteoblasts have a reduced subchondral bone mass and induce a higher level of osteoclast differentiation, strongly suggest that the metabolic state of the L OA osteoblasts favours bone resorption.

PROBLEM: Context: Vancomycin loading doses are recommended; however, the risk of nephrotoxicity with these doses is unknown. The primary objective of this study was to compare nephrotoxicity in emergency department (ED) sepsis patients who received vancomycin at high doses (>20 mg/kg) versus lower doses (≤20 mg/kg).', 'A retrospective cohort study was performed in three academic EDs. Inclusion criteria were age ≥ 18 years, intravenous vancomycin order, and hospital admission. Exclusion criteria were no documented weight, hemodialysis-dependent, and inadequate serum creatinine (SCr) values for the measured outcome. Analyses compared the incidence of nephrotoxicity for patients who received vancomycin at high dose (>20 mg/kg) versus low dose (≤20 mg/kg).', 'A total of 2,131 consecutive patients prescribed vancomycin over 6 months were identified. Of these, 1,330 patients had three SCr values assessed for the primary outcome. High-dose initial vancomycin was associated with a significantly lower rate of nephrotoxicity (5.8% vs. 11.1%). After age, sex, and initial SCr were adjusted for, the risk of high-dose vancomycin compared to low-dose was decreased for the development of nephrotoxicity (relative risk = 0.60; 95% confidence interval = 0.44 to 0.82).\Question: Is high Single-dose Vancomycin Loading Associated With Increased Nephrotoxicity in Emergency Department Sepsis Patients?

SOLUTION:
Initial dosing of vancomycin > 20 mg/kg was not associated with an increased rate of nephrotoxicity compared with lower doses. Findings from this study support compliance with initial weight-based vancomycin loading doses.