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.

Example Input: 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.
Example Output: Is aging associated with increased collagen type IV accumulation in the basal lamina of human cerebral microvessels?

Example Input: Context: Thailand has the lowest incidence of gastric cancer in the world. Helicobacter pylori infection, a low serum pepsinogen I/II ratio, and interleukin (IL)-1beta-511 polymorphisms are suspected to be risk factors for gastric cancer.', 'A total of 167 Thais, comprising 56 cancer patients and 111 volunteers without cancer, underwent an esophagogastroduodenoscopic examination and three fixed-point biopsies; a cancer tissue biopsy was also done, and blood samples were collected. The subjects without cancer were divided into normal subjects and chronic gastritis patients. IL-1beta-511 polymorphisms were analyzed by polymerase chain reaction-restriction fragment length polymorphism, and the serum levels of pepsinogen I and II were determined by a radioimmunoassay. Helicobacter pylori IgG antibody and tissue pathology were tested in all groups.', 'The pepsinogen I/II ratio was significantly lower in the gastric cancer group than in the normal and chronic gastritis groups [odds ratio (OR), 2.3; 95% confidence interval (CI), 1.10-4.80; P = 0.025]. Gastric cancer patients were positive for the H. pylori IgG antibody more frequently than negative (OR, 2.946; 95% CI, 1.4-6.39; P = 0.005). However, only 15 (27%) cancer patients were both positive for H. pylori IgG antibody and had low serum pepsinogen I/II. The C/C genotype was found more frequently in the gastric cancer group than in the group with a normal gastric mucosa (OR, 0.64; 95% CI, 0.50-0.81; P = 0.014).
Answer: A low serum pepsinogen I/II ratio combined with positivity for H. pylori IgG, and a IL-1beta-511 C/C genotype may be independent risk factors for gastric cancer in Thais.
Example Output: Are helicobacter pylori infection in combination with the serum pepsinogen I/II ratio and interleukin-1beta-511 polymorphisms independent risk factors for gastric cancer in Thais?

Example Input: Context: The canals of Hering (CoH), which are the most peripherally located bile drainage pathway, are considered a niche of hepatic progenitor cells. Recently, CoH loss has been described as an early feature of primary biliary cirrhosis (PBC). We investigated the correlation between CoH loss and the histopathological variables of PBC.', 'Liver biopsy specimens from 62 PBC patients (M:F=8:54, age=58 ± 12 years) were evaluated prior to ursodeoxycholic acid treatment. Liver biopsies of patients with normal liver (n=11), chronic viral hepatitis (n=36) and non-alcoholic fatty liver disease (n=13) were used as controls. The number of CoH per definite area of hepatic parenchyma (c to p ratio) was calculated in individual cases. We compared the c to p ratios of PBC patients with that of controls and analysed the correlations with histological variables and clinical features.', 'The c to p ratios in PBC patients with mild and extensive fibrosis were lower than those in controls with each degree of fibrosis. The c to p ratios were negatively correlated with stage, fibrosis, bile duct loss, orcein-positive granule deposition and hepatitis activities in PBC (p<0.01) and with alkaline phosphatase and total bilirubin levels at liver biopsies (p<0.05).
Answer: The number of CoH was low in early stages and further decreased with stage progression in PBC. CoH loss, reflecting a reduced supply of progenitor cells to the biliary tree, may be involved in the histological progression of PBC.
Example Output:
Does canals of Hering loss relate to the progression of the histological stages of primary biliary cirrhosis?