2.3. Data Extraction
The articles were randomly distributed between four authors, who
extracted the data independently (BMF, GOR, ETBM, and GNV) (Urbaniak &
Plous, 2013 - Research randomizerTM). Data were
extracted from the text, figures, or tables and inserted into a
standardized table. If only a graph was available, the data were
extracted using a digital screen ruler. The extracted data were
validated by a pair of reviewers. Any discrepancies were resolved
through discussion or by consultation with a third investigator (IGD,
IFK, JSR, and EMD). Afterwards, the expert group validated the extracted
data in the standardized way. If the data were not reported, or unclear,
we contacted the authors by email (max. 3 attempts).
Data to be extracted: 1st author, year of publication, country,
objectives, RAW 264.7 cultured cells (macrophage; Abelson murine
leukemia virus-transformed - Mus musculus , mouse), number/density
of cells plated, medium supplementation, incubation temperature,
atmospheric carbon dioxide (%), antibiotics, cell passage number, the
plate used for the test, cell confluence, number of technical replicates
and repetition of independent experiments. Concentration of LPS
(manufacture, 1 µg/mL), vehicle, dimethyl sulfoxide concentration
(DMSO), timing of incubation/exposure (12, 24 or 48h). Mediators of
inflammation production, continuous variables: Nitric Oxide/nitrites
(µM, mean, SD), and TNF-α, IL-1β, or IL-6 (pg mL-1,
mean, SD). If the type of error was unclear, it was recorded as SEM.
These data were converted to standard deviations (Hozo et al., 2005).
The authors’ conclusions and risk/limitations reported by the authors of
original studies were also extracted. We provided a narrative synthesis
of the findings from the included studies, structured around the type of
intervention, target characteristics, type of outcome, intervention
content, and control cells. We summarized the intervention effects for
each study by calculating the standardized mean differences in a
meta-analysis.