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: We study the Azospirillum brasilense tolerance to water deficit and the dynamics of adaptive process at the level of the membrane.', 'Azospirillum brasilense was exposed to polyethylene glycol (PEG) growth and PEG shock. Tolerance, phospholipids and fatty acid (FA) composition and membrane fluidity were determined. Azospirillum brasilense was able to grow in the presence of PEG; however, its viability was reduced. Cells grown with PEG showed membrane fluidity similar to those grown without, the lipid composition was modified, increasing phosphatidylcholine and decreasing phosphatidylethanolamine amounts. The unsaturation FAs degree was reduced. The dynamics of the adaptive response revealed a decrease in fluidity 20\xa0min after the addition of PEG, indicating that the PEG has a fluidizing effect on the hydrophobic region of the cell membrane. Fluidity returned to initial values after 60\xa0min of PEG exposure.\Question: Is reorganization of Azospirillum brasilense cell membrane mediated by lipid composition adjustment to maintain optimal fluidity during water deficit?

SOLUTION: Azospirillum brasilense is able to perceive osmotic changes by changing the membrane fluidity. This effect is offset by changes in the composition of membrane phospholipid and FA, contributing to the homeostasis of membrane fluidity under water deficit.

PROBLEM: Context: Cannabis use disorders (CUD) may influence the course of bipolar disorder (BD), but key confounding factors such as tobacco smoking have not been adequately addressed. This study examined whether CUD was associated with a more severe illness course in tobacco smoking BD patients.', 'A sample of French and Norwegian tobacco smoking patients with BD I and II (N=642) was investigated. DSM-IV diagnoses and other characteristics were obtained through personal interviews using structured questionnaires. The association between CUD and illness course was assessed in regression analyses.', 'In bivariate analyses, CUD was associated with earlier BD onset, higher frequency of manic (in BD I) and depressive episodes and hospitalizations per illness year, and a higher occurrence of psychotic episodes. After controlling for potential confounders, the relationships with earlier BD onset (B=-5.60 95% CI=-7.65 to -3.64), and increased rates of manic episodes (OR=1.93, 95% CI: 1.15 to 3.23) and hospitalizations (OR=2.93, 95% CI: 1.85 to 4.64) remained statistically significant.\Question: Is cannabis use disorder associated with greater illness severity in tobacco smoking patients with bipolar disorder?

SOLUTION: Despite the multivariate approach, differences between the two samples may lead to spurious findings related to hidden confounders. Substance use and mood episode information was collected retrospectively, and potential birth cohort effects could not be controlled for.

PROBLEM: Context: Porphyromonas gingivalis infection induces apoptosis inhibition in gingival epithelial cells; however, it is not fully understood which bacterial effectors are involved in this process. The aim of this study is to evaluate whether the P.\xa0gingivalis lipopolysaccharide (LPS), specifically the O-antigen region, affects adherence, invasion, viability and apoptosis of gingival epithelial cells.', "Gingival epithelial cells (OKF6/TERT2 line) were infected by different freshly prepared P.\xa0gingivalis clinical isolates, obtained from subjects with chronic periodontitis (CP3 and CP4) and healthy individuals (H1 and H3). Periodontitis and healthy isolates show differences in O-antigen production, as healthy isolates lack the O-antigen region. In addition, cells were infected by a site-specific mutant lacking the O-antigen portion. After 24\xa0h postinfection, cell proliferation, viability and apoptosis were evaluated by Trypan blue, MTS and annexin V assays, respectively. Bacterial invasion, adhesion and proliferation were measured by gentamicin/metronidazole protection assays. Finally, toll-like receptor (TLR)2 and TLR4 mRNA expression was evaluated by quantitative reverse transcription-polymerase chain reaction. Statistical analysis was performed using ANOVA, Tukey's or Dunnett's tests (p\xa0<\xa00.05).", 'At 24\xa0h postinfection, strains lacking the O-antigen region (healthy isolates and O-antigen ligase-deficient strain) were unable to increase proliferation and viability, or decrease apoptosis as compared with strains producing intact LPS (periodontitis isolates and reference strain). However, the presence of the O-antigen neither contributed to changes in the ability of the bacteria to adhere to or invade cells, nor to intracellular survival. The presence of O-antigen also increased the expression of TLR4 (nearly sixfold), which correlated with inhibition of apoptosis.\Question: Is the Porphyromonas gingivalis O antigen required for inhibition of apoptosis in gingival epithelial cells following bacterial infection?

SOLUTION:
The O-antigen region of P. gingivalis LPS is required to increase gingival epithelial cell viability upon infection by bacteria and this increase is attributable to a reduction in apoptosis. Moreover, although bacterial internalization is required, the effects observed are not due to alterations in P. gingivalis adherence, invasion or intracellular survival. Interestingly, inhibition of apoptosis correlates with increased TLR4 expression, suggesting a role for TLR4 in this process.