instruction:
In this task, you are given a passage which has a question and the context. You have to generate an answer to the question based on the information present in the context.
question:
Context: Pandemic strains of HIV-1 (group M) encode a total of nine structural (gag, pol, env), regulatory (rev, tat) and accessory (vif, vpr, vpu, nef) genes. However, some subtype A and C viruses exhibit an unusual gene arrangement in which the first exon of rev (rev1) and the vpu gene are placed in the same open reading frame. Although this rev1-vpu gene fusion is present in a considerable fraction of HIV-1 strains, its functional significance is unknown.', 'Examining infectious molecular clones (IMCs) of HIV-1 that encode the rev1-vpu polymorphism, we show that a fusion protein is expressed in infected cells. Due to the splicing pattern of viral mRNA, however, these same IMCs also express a regular Vpu protein, which is produced at much higher levels. To investigate the function of the fusion gene, we characterized isogenic IMC pairs differing only in their ability to express a Rev1-Vpu protein. Analysis in transfected HEK293T and infected CD4+ T cells showed that all of these viruses were equally active in known Vpu functions, such as down-modulation of CD4 or counteraction of tetherin. Furthermore, the polymorphism did not affect Vpu-mediated inhibition of NF-кB activation or Rev-dependent nuclear export of incompletely spliced viral mRNAs. There was also no evidence for enhanced replication of Rev1-Vpu expressing viruses in primary PBMCs or ex vivo infected human lymphoid tissues. Finally, the frequency of HIV-1 quasispecies members that encoded a rev1-vpu fusion gene did not change in HIV-1 infected individuals over time.\Question: Does a Naturally Occurring rev1-vpu Fusion Gene Confer a Fitness Advantage to HIV-1?
answer:
Expression of a rev1-vpu fusion gene does not affect regular Rev and Vpu functions or alter HIV-1 replication in primary target cells. Since there is no evidence for increased replication fitness of rev1-vpu encoding viruses, this polymorphism likely emerged in the context of other mutations within and/or outside the rev1-vpu intergenic region, and may have a neutral phenotype.


question:
Context: Patients affected by chronic lymphocytic leukemia (CLL) have an increased risk of developing a second cancer. There is not a definitive explanation for this phenomenon, although some hypotheses have been postulated. The aim of the present work was to assess the presence of second cancer in untreated patients with CLL who were cytogenetically characterized, and secondly to investigate if there is a correlation between the genetics of CLL and the emergence of second cancer.', 'We performed conventional cytogenetics and Fluorescent in situ hybridization analyses in a series of 106 patients.', 'We observed that nearly 8% of cases developed second cancer, mostly epithelial tumors. The majority of them presented two common features, del(13)(q14.3) and the presence of at least two genetic alterations.\Question: Does genetics of lymphocytes influence the emergence of second cancer in chronic lymphocytic leukemia?
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We suggest that the genetic background of CLL, particularly the presence of several genetic alterations, influences the emergence of second cancer in patients affected by CLL.


question:
Context: Oral tacrolimus, approved for the prophylaxis of organ rejection in liver or kidney transplants, has been reported to be effective in anecdotal cases of refractory inflammatory bowel disease.', 'To evaluate the usefulness of low-dose oral tacrolimus in refractory inflammatory bowel disease.', "Thirty-one adult Caucasian patients with steroid-dependent (n = 15) or steroid-refractory (n = 16) inflammatory bowel disease (Crohn's disease, n = 6; ulcerative colitis, n = 23; pouchitis, n = 2) were enrolled. Tacrolimus (0.1 mg/kg body weight per day) was administered orally in 30 patients and initially intravenously in one patient (0.01 mg/kg body weight per day), aiming for serum trough levels of 4-6 ng/mL. The median treatment duration was 12 months (range, 1-137 months).", "Twenty-eight patients (90.3%) experienced a clinical and laboratory response and 20 (64.5%) went into remission. One ulcerative colitis patient and two Crohn's disease patients did not improve. Three ulcerative colitis patients (9.7%) were colectomized at 1, 12 and 24 months after tacrolimus initiation. In 19 of 23 patients (82.6%) taking steroids, steroids were reduced or discontinued. Side-effects included a temporary rise of creatinine (n = 3, 9.7%), tremor or paraesthesias (n = 3, 9.7%), hyperkalaemia (n = 1, 3.2%), hypertension (n = 1, 3.2%) and an opportunistic infection (n = 1, 3.2%).\Question: Is rescue therapy with tacrolimus effective in patients with severe and refractory inflammatory bowel disease?
answer:

Oral tacrolimus is safe and effective in refractory inflammatory bowel disease.