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:
Hypoxemia is a common complication of chronic obstructive pulmonary disease and a major factor in patients' prognosis and quality of life. The response to exercise has been evaluated by various means but no standardization has been accepted.", 'To suggest a simple outpatient technique for evaluating the response of arterial oxygen saturation to exercise for use as a marker of disease severity.', 'Ninety-six patients with various degrees of COPD were divided into three groups: mild (forced expiratory volume in 1 sec > 65%), moderate (FEV1 between 50 and 65%), and severe (FEV1 < 50%). Using continuous oximeter recording we measured oxygen saturation during 15 steps of climbing, and quantified oxygen desaturation by measuring the "desaturation area," defined as the area under the curve of oxygen saturation from the beginning of exercise through the lowest desaturation point and until after recovery to the baseline level of oxygen percent saturation. Desaturation was correlated to spirometry, lung gas volumes, blood gas analysis, and 6 min walking distance.', 'A good correlation was found between severity of COPD and baseline SaO2, lowest SaO2, recovery time, and desaturation area. A negative correlation was found between desaturation area and FEV1 (r = -0.65), FEV1/forced vital capacity (r = -0.58), residual volume to total lung capacity (r = 0.52), and diffusing lung capacity for carbon monoxide (r = -0.52). In stepwise multiple regression analysis only FEV1 correlated significantly to desaturation area. A good correlation was noted between 6 min walking distance and desaturation area with the 15 steps technique (r = 0.56).
answer:
Do quantitative 15 steps exercise oximetry as a marker of disease severity in patients with chronic obstructive pulmonary disease?


question:
The human immunodeficiency virus Vif protein overcomes the inhibitory activity of the APOBEC3G cytidine deaminase by prohibiting its packaging into virions. Inhibition of APOBEC3G encapsidation is paralleled by a reduction of its intracellular level presumably caused by the Vif-induced proteasome-dependent degradation of APOBEC3G.', 'In this report we employed confocal microscopy to study the effects of Vif on the expression of APOBEC3G on a single cell level. HeLa cells dually transfected with Vif and APOBEC3G expression vectors revealed efficient co-expression of the two proteins. Under optimal staining conditions approximately 80% of the transfected cells scored double-positive for Vif and APOBEC3G. However, the proportion of double-positive cells observed in identical cultures varied dependent on the fixation protocol and on the choice of antibodies used ranging from as low as 40% to as high as 80% of transfected cells. Importantly, single-positive cells expressing either Vif or APOBEC3G were observed both with wild type Vif and a biologically inactive Vif variant. Thus, the lack of APOBEC3G in some Vif-expressing cells cannot be attributed to Vif-induced degradation of APOBEC3G. These findings are consistent with our results from immunoblot analyses that revealed only moderate effects of Vif on the APOBEC3G steady state levels. Of note, viruses produced under such conditions were fully infectious demonstrating that the Vif protein used in our analyses was both functional and expressed at saturating levels.
answer:
Does production of infectious human immunodeficiency virus type 1 require depletion of APOBEC3G from virus-producing cells?


question:
To test the use of diffusion-weighted magnetic resonance imaging (DW-MRI) to differentiate between different degrees of severity of acute pancreatitis (AP).', 'Thirty-six patients who underwent DW-MRI and magnetic resonance cholangiopancreatography were divided into patients with mild AP (mAP, n = 15), patients with necrotizing AP (nAP, n = 8), and patients with a normal pancreas (nP, n = 15; controls). The pancreas was divided into head, body, and tail, and each segment was classified according to image features: pattern 1, normal; pattern 2, mild inflammation; and pattern 3, necrosis. Apparent diffusion coefficients (ADCs) were measured in each segment and correlated with clinical diagnoses.', 'A total of 108 segments was assessed (three segments per patient). Segments classified as pattern 1 in the nP and mAP groups showed similar ADC values (P = 0.29). ADC values calculated for the pancreatic segments grouped according to the different image patterns (1-3) were significantly different (P < 0.001). Comparisons revealed significant differences in signal intensity between all three patterns (P < 0.05).
answer:

Does diffusion-weighted magnetic resonance imaging indicate the severity of acute pancreatitis?