instruction:
Given a passage, construct a question on the basis of the information present in the passage. Construct the question in such a way that (i) it is unambiguous, (ii) it is answerable from the passage, (iii) its answer is unique (iv) it answer uses text phrases from the passage. Avoid creating questions that (i) can't be answered correctly without actually understanding the passage and (ii) uses the same words or phrases given in the passage.
question:
Severe malaria (SM) is classically associated with Plasmodium falciparum infection. Little information is available on the contribution of P. vivax to severe disease. There are some epidemiological indications that P. vivax or mixed infections protect against complications and deaths. A large morbidity surveillance conducted in an area where the four species coexist allowed us to estimate rates of SM among patients infected with one or several species.', 'This was a prospective cohort study conducted within the framework of the Malaria Vaccine Epidemiology and Evaluation Project. All presumptive malaria cases presenting at two rural health facilities over an 8-y period were investigated with history taking, clinical examination, and laboratory assessment. Case definition of SM was based on the World Health Organization (WHO) criteria adapted for the setting (i.e., clinical diagnosis of malaria associated with asexual blood stage parasitaemia and recent history of fits, or coma, or respiratory distress, or anaemia [haemoglobin < 5 g/dl]). Out of 17,201 presumptive malaria cases, 9,537 (55%) had a confirmed Plasmodium parasitaemia. Among those, 6.2% (95% confidence interval [CI] 5.7%-6.8%) fulfilled the case definition of SM, most of them in children <5 y. In this age group, the proportion of SM was 11.7% (10.4%-13.2%) for P. falciparum, 8.8% (7.1%-10.7%) for P. vivax, and 17.3% (11.7%-24.2%) for mixed P. falciparum and P. vivax infections. P. vivax SM presented more often with respiratory distress than did P. falciparum (60% versus 41%, p = 0.002), but less often with anaemia (19% versus 41%, p = 0.0001).
answer:
Are plasmodium vivax and mixed infections associated with severe malaria in children : a prospective cohort study from Papua New Guinea?

question:
Large concentrations of meperidine inhibit N-methyl-D-aspartate-(NMDA) receptor channels by channel block mechanisms. Extracellular pH regulates the activity and drug sensitivity of NMDA-receptor channels. We examined the influence of extracellular pH on sensitivity to meperidine of epsilon/zeta heteromeric NMDA-receptor channels expressed in Xenopus oocytes. Inhibition of epsilon1/zeta1, epsilon2/zeta1, epsilon3/zeta1, and epsilon4/zeta1 channels by meperidine was dependent on pH, with more inhibition at acidic pH and less inhibition at alkaline pH. The degree of voltage-dependence of meperidine block was only slightly affected by changes in pH, whereas affinity for meperidine was greatly reduced at alkaline pH. Furthermore, interaction of meperidine with Mg(2+) block was reduced at alkaline pH. Because the percentage of the protonated form of meperidine is only slightly affected by pH, changes in properties of the meperidine binding site may be involved in mechanisms of alteration of meperidine potency by pH.
answer:
Is n-methyl-D-aspartate receptor channel block by meperidine dependent on extracellular pH?

question:
To investigate the specific role of Frizzled-related protein (FRZB) and Secreted frizzled-related protein 1 (SFRP1) in the onset and progression of Osteoarthritis (OA) using Frzb(-/-) and Sfrp1(-/-) mice in the destabilization of medial meniscus model (DMM), a slowly progressing model of OA. Secreted frizzled-related proteins (SFRPs) were identified as secreted Wingless-type (Wnt) antagonists. The Wnt signaling cascade is a major regulator in cartilage development, homeostasis and degeneration.', 'The DMM model was surgically induced in eight-week-old male C57/Bl6 Frzb(-/-), Sfrp1(-/-) or wild-type mice by transection of the medial meniscotibial ligament. Cartilage damage in the femoral and tibial articular surfaces was calculated following the Osteoarthritis Research Society International (OARSI) histopathology initiative guidelines. Histomorphometry was used to evaluate the subchondral bone plate thickness.', 'OA severity scores were significantly higher in the tibia of Frzb(-/-) mice as compared to littermates, whereas no interaction was seen between genotype and intervention in Sfrp1(-/-) mice. Moreover, the DMM model resulted in significantly greater subchondral bone changes compared to sham but was not different between Frzb(-/-) mice and littermates. In contrast, the subchondral bone properties in Sfrp1(-/-) mice were significantly different from littermates.
answer:
Does loss of Frzb and Sfrp1 differentially affect joint homeostasis in instability-induced osteoarthritis?