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.

[EX Q]: Context: Microvascular alterations contribute to the development of stroke and vascular dementia. The goal of this study was to evaluate age and hypertension related changes of the basal lamina in cerebral microvessels of individuals, who died from non-cerebral causes.', 'We examined 27 human brains: 11 young and 16 old patients. Old patients were divided into two subgroups, those with hypertension (n = 8) and those without hypertension (n = 8). Basal lamina changes of the cerebral microvessels were determined in the putamen using antibodies against collagen type IV and by quantitative analysis of vessel number, total stained area of collagen, thickness of the vessel wall and lumen, and relative staining intensity using immunofluorescence. The total number of collagen positive vessels per microscopic field was reduced in old compared to young subjects (12.0+/-0.6 vs. 15.1+/-1.2, p = 0.02). The relative collagen content per vessel (1.01+/-0.06 vs. 0.76+/-0.05, p = 0.01) and the relative collagen intensity (233.1+/-4.5 vs. 167.8+/-10.6, p < 0.0001) shown by immunofluorescence were higher in the older compared to the younger patients with a consecutive reduction of the lumen / wall ratio (1.29+/-0.05 vs. 3.29+/-0.15, p < 0.0001). No differences were observed for these parameters between old hypertensive and non-hypertensive patients.
Answer: The present data show age-related changes of the cerebral microvessels in sections of human putamen for the first time. Due to the accumulation of collagen, microvessels thicken and show a reduction in their lumen. Besides this, the number of vessels decreases. These findings might represent a precondition for the development of vascular cognitive impairment. However, hypertension was not proven to modulate these changes.
[EX A]: Is aging associated with increased collagen type IV accumulation in the basal lamina of human cerebral microvessels?

[EX Q]: Context: To investigate localization and distribution of integrin subunit 1, 2 and 3 and morphological changes of ligand-recepter binding in thrombi of acute pulmonary embolism (PE) patients and explore activation of circulated immune cells, inflammatory immune adherence and coagulation response in acute venous thrombosis.', 'Thrombi were collected from patients with acute PE. Immunohistochemistry was done to detect the expression and distribution of integrin 1, 2 and 3 in cells within thrombi, and ligands of integrin subunit 1, 2 and 3 were also determined by immunohistochemistry within the thrombi.', '1) Acute venous thrombi were red thrombi composed of skeletons and filamentous mesh containing large amounts of red blood cells and white blood cells; 2) Integrin subunit 1, 2 and 3 were expressed on lymphocytes, neutrophils and platelets; 3) No expression of integrin 1 ligands: Laminin, Fibronectin, Collagen I or Collagen-II on lymphocytes; integrin 2 ligands including ICAM, factor X and iC3b are distributed on neutrophils, and ligand fibrinogen bound to neutrophils; integrin 3 was expressed on platelets which form the skeleton of thrombi and bound to fibrinogen to construct mesh structure; 4) Factor Xa was expressed on the filamentous mesh; 5) Filamentous mesh was fully filled with red blood cell dominant blood cells.
Answer: Acute venous thrombosis is an activation process of circulated lymphocytes, neutrophils and platelets mainly, and a whole process including integrin subunit 2 and 3 binding with their ligands. Activation of immune cells, inflammatory immune adherence and coagulation response are involved in the acute venous thrombosis.
[EX A]: Are activation of circulated immune cells and inflammatory immune adherence involved in the whole process of acute venous thrombosis?

[EX Q]: Context: Tuberculosis, which is caused by Mycobacterium tuberculosis, remains one of the leading causes of mortality worldwide. The C-type lectin DC-SIGN is known to be the major M. tuberculosis receptor on human dendritic cells. We reasoned that if DC-SIGN interacts with M. tuberculosis, as well as with other pathogens, variation in this gene might have a broad range of influence in the pathogenesis of a number of infectious diseases, including tuberculosis.', 'We tested whether polymorphisms in CD209, the gene encoding DC-SIGN, are associated with susceptibility to tuberculosis through sequencing and genotyping analyses in a South African cohort. After exclusion of significant population stratification in our cohort, we observed an association between two CD209 promoter variants (-871G and -336A) and decreased risk of developing tuberculosis. By looking at the geographical distribution of these variants, we observed that their allelic combination is mainly confined to Eurasian populations.
Answer: Our observations suggest that the two -871G and -336A variants confer protection against tuberculosis. In addition, the geographic distribution of these two alleles, together with their phylogenetic status, suggest that they may have increased in frequency in non-African populations as a result of host genetic adaptation to a longer history of exposure to tuberculosis. Further characterization of the biological consequences of DC-SIGN variation in tuberculosis will be crucial to better appreciate the role of this lectin in interactions between the host immune system and the tubercle bacillus as well as other pathogens.
[EX A]:
Is promoter variation in the DC-SIGN-encoding gene CD209 associated with tuberculosis?