Given a passage with a context and an answer, 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.

[Q]: Context: Parkinsonian signs, especially gait impairment, are common and associated with morbidity and mortality in older persons. Our objective was to test the hypothesis that substantia nigra neurofibrillary tangles (NFTs) are related to parkinsonian signs in older persons with and without dementia.', "We studied 86 deceased older Catholic clergy without idiopathic Parkinson's disease from the Religious Order Study, a longitudinal clinical-pathological study. Mean age at death was 85.3 years. Signs of gait disturbance, bradykinesia, rigidity, and tremor were assessed proximate to death using a modified Unified Parkinson's Disease Rating Scale. Forty-micrometer paraffin-embedded sections of substantia nigra were bleached before tau immunohistochemistry and the optical disector was used to count NFTs. We used multivariable linear regression to examine parkinsonian signs as a function of nigra NFTs, controlling for age, sex, education, and cortical NFTs.", 'Substantia nigra NFTs were present in 67 of 86 persons (77.9%). After controlling for age, sex, education, and cortical NFTs, nigra NFTs were related to gait impairment (p < 0.001), but not bradykinesia, rigidity, or tremor. Results were not confounded by dementia, Braak score, neuroleptic medication, cerebral infarcts, or Lewy bodies.
Answer: NFTs in the substantia nigra are associated with gait impairment in older persons with and without dementia.
[A]: Are substantia nigra tangles related to gait impairment in older persons?


[Q]: Context: Cysteine, a sulfur-containing amino acid, plays an important role in a variety of cellular functions such as protein biosynthesis, methylation, and polyamine and glutathione syntheses. In trypanosomatids, glutathione is conjugated with spermidine to form the specific antioxidant thiol trypanothione (T[SH]2) that plays a central role in maintaining intracellular redox homeostasis and providing defence against oxidative stress.', 'We cloned and characterised genes coding for a cystathionine β-synthase (CβS) and cysteine synthase (CS), key enzymes of the transsulfuration and assimilatory pathways, respectively, from the hemoflagellate protozoan parasite Trypanosoma rangeli.', 'Our results show that T. rangeli CβS (TrCβS), similar to its homologs in T. cruzi, contains the catalytic domain essential for enzymatic activity. Unlike the enzymes in bacteria, plants, and other parasites, T. rangeli CS lacks two of the four lysine residues (Lys26 and Lys184) required for activity. Enzymatic studies using T. rangeli extracts confirmed the absence of CS activity but confirmed the expression of an active CβS. Moreover, CβS biochemical assays revealed that the T. rangeli CβS enzyme also has serine sulfhydrylase activity.
Answer: These findings demonstrate that the RTS pathway is active in T. rangeli, suggesting that this may be the only pathway for cysteine biosynthesis in this parasite. In this sense, the RTS pathway appears to have an important functional role during the insect stage of the life cycle of this protozoan parasite.
[A]: Is transsulfuration an active pathway for cysteine biosynthesis in Trypanosoma rangeli?


[Q]: Context: With male gender as a strong predictor of cardiovascular instability, we hypothesized that gender-specific differences in circulating carbon monoxide levels contributed to dysregulated microvascular function in preterm male infants.', 'Infants born at 24 to 34 weeks of gestation (N = 84) were studied in a regional tertiary neonatal unit. Carboxyhemoglobin levels were measured through spectrophotometry in umbilical arterial blood and at 24, 72, and 120 hours after birth. Microvascular blood flow was determined through laser Doppler flowmetry.', 'Carboxyhemoglobin levels demonstrated a strong inverse relationship with gestational age (r = -0.636; P < .001) and were higher in boys (P = .032). Repeated-measures analysis of variance showed a significant decrease in arterial carboxyhemoglobin levels over time (P < .001), with significant between-subjects effects for gestational age (P = .011) and gender (P = .025). Positive correlations with microvascular blood flow at 24 hours of age (r = 0.495; P < .001) and 120 hours of age (r = 0.548; P < .001) were observed. With controlling for gestational age, carboxyhemoglobin levels at 72 hours were greater for infants who died in the first week of life (P = .035).
Answer: The gestational age- and gender-specific differences in carboxyhemoglobin levels and the relationship with dysregulated microvascular blood flow, a state related to greater illness severity and hypotension, are novel findings not confined solely to sick preterm infants. Both inducible heme oxygenase-dependent and non-heme oxygenase-dependent pathways may initially play a central role in carbon monoxide production, inducing pathophysiologic processes in a gender-specific manner.
[A]:
Is carbon monoxide a significant mediator of cardiovascular status following preterm birth?