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.

Q: 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.

A: Does production of infectious human immunodeficiency virus type 1 require depletion of APOBEC3G from virus-producing cells?
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Q: In this study, we compared the diagnostic performance of the standard SPECT with motion-frozen (MF) myocardial perfusion SPECT (MPS) in obese patients.', 'A total of 90 consecutive obese patients (body mass index, 30.1-46.8, average, 34.3 +/- 3.6; age, 63 +/- 12 y; 30% women) underwent standard supine rest (201)Tl/stress (99m)Tc dual-isotope gated MPS and cardiac catheterization within 3 mo. MF images were obtained by nonlinear warping of cardiac phases to the end-diastolic position. Total perfusion deficit (TPD) was obtained for summed (S-TPD) and motion-frozen (MF-TPD) datasets with sex-specific standard and MF normal limits.', 'The area under the receiver-operating-characteristic (ROC) curve for detection of coronary artery disease (CAD) by MF-TPD was significantly larger than that for S-TPD (0.93 +/- 0.25 vs. 0.88 +/- 0.32, P < 0.05). MF-TPD had higher specificity (77% vs. 55%, P < 0.05) and accuracy (89% vs. 80%, P < 0.05) than did S-TPD.

A: Does motion-frozen myocardial perfusion SPECT improve detection of coronary artery disease in obese patients?
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Q: Glycoprotein (GP) Ibalpha is the functionally dominant subunit of the platelet GPIb-IX-V receptor complex. The N-terminal domain of the GPIbalpha chain contains binding sites for alpha-thrombin and von Willebrand factor (VWF). The human platelet alloantigen (HPA)-2 polymorphism of the GPIbalpha gene is associated with a C/T transition at nucleotide 1018, resulting in a Thr/Met dimorphism at residue 145 of GPIbalpha. To study the structural and functional effects of this dimorphism, N-terminal fragments (AA1-289) of the HPA-2a and HPA-2b alloform of GPIbalpha expressed in CHO cells were used.', 'Of 74 moAbs directed against human GPIbalpha, 2 antibodies with epitope between AA1-59 could differentiate between both alloforms. In addition, VWF bound with a higher affinity to the recombinant HPA-2a fragment or to homozygous HPA-2a platelets. In contrast, no difference was found in the binding of alpha-thrombin to the recombinant alloform fragments or of antibodies directed against the alpha-thrombin binding anionic sulfated tyrosine sequence (AA269-282).

A:
Is von Willebrand factor but not alpha-thrombin binding to platelet glycoprotein Ibalpha influenced by the HPA-2 polymorphism?
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