Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
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Question: Abstract: In 10-day-old suckling and adult mice, reovirus type 1 adheres selectively to and penetrates membranous epithelial (M) cells. To determine when M cells first appear, when they first transport reovirus, and if reovirus adheres to and is endocytosed by other epithelial cells in the first postnatal week, we examined neonatal mouse intestine by transmission electron microscopy after reovirus type 1 exposure. At 2 days M cells accounted for 0.9% of dome epithelial cells. By 9 days M cells had increased to 7.4%. Reovirus type 1 adherence to the surface of villus and dome epithelial cells showed marked variation in 2-6-day-old animals, but by 7 days only a few absorptive cell profiles had adherent reovirus. Adherence to greater than 50% of M-cell profiles occurred in all but 2 animals, but adherence to the majority of Peyer's patch absorptive cell profiles was present only in some 4- and 5-day-old animals. Adherence to a majority of undifferentiated cell profiles occurred in some animals at all ages. Membranous epithelial cells endocytosed reovirus at all ages but only at 2 days did rare villus and dome absorptive cells endocytose reovirus into the apical cytoplasm. Thus, adherence of reovirus to the apical surface of mucosal epithelial cells is nonselective in newborn mice but becomes more selective within the first postnatal week with adherence by day 7 to most M-cell profiles, to a substantial but variable number of undifferentiated cell profiles, but to few absorptive cell profiles.

Answer: Adherence to and penetration of the intestinal epithelium by reovirus type 1 in neonatal mice.


Question: Abstract: Tuberculous aortitis is a rare entity and its association with necrosis and perforation is even more unusual. Our pulmonary medicine service originally evaluated an elderly woman with a right pleural effusion and upper lobe infiltrate thought to be tuberculosis. An abdominal CT scan performed at that time showed extensive periaortic adenopathy. Isoniazid and rifampin were started, but both were stopped by the patient after less than 6 months of therapy. The patient later had night sweats, a left pleural effusion, and a tender abdominal mass thought to be a symptomatic aneurysm. At operation, the aorta was necrotic and had an inflammatory mass and perforation on the left side. Infrarenal aortic ligation and resection were performed to control infection. A previously placed axillofemoral graft obviated the need for concomitant revascularization. The patient was treated postoperatively with isoniazid and rifampin until hyperbilirubinemia developed, which necessitated alternate therapy with ethambutol and streptomycin. The patient died one month after operation of a presumed pulmonary embolus.

Answer: Tuberculous aortitis with associated necrosis and perforation: treatment and options.


Question: Abstract: The crossing over in five murine I-region recombinants (Is/Ik) was studied by restriction fragment length polymorphism analysis after Southern blot hybridization by using I-region-specific probes. These recombinants included three recently developed strains, B10.ASR1, B10.ASR11, and B10.ASR12; and two strains B10.S(9R) and B10.HTT derived earlier. Although these recombinants were reciprocal in haplotype orientation to the three recombinants we reported recently, these too crossed over within the same 7 kb stretch of DNA in the E beta gene. This 7 kb stretch of DNA included the 3' half of the first intron, the beta 1 exon, the second intron, and the beta 2 exon. A comparison of the cDNA sequences of the two parental E beta alleles revealed that although the beta 2 exons were identical, there were several nucleotide differences between the two beta 1 exons. This allowed us to determine the parental origin of the beta 1 exon in the recombinants at the level of transcription by using S1 nuclease mapping. Thus we were able to show that in each case the 3' portion of the first intron and the beta 1 exon were upstream from the site of crossover. All eight recombinants involving the k and s haplotypes now can be mapped within a 4.5 kb stretch of DNA, which includes only the beta 1-beta 2 intron and the beta 2 exon of the E beta gene. These findings imply that the I-E molecules expressed in these recombinants will probably have conserved sequences and therefore will exhibit identical I-E-restricted immune responses, despite the fact that crossing over could have occurred at different sites within the beta 1-beta 2 intron.

Answer:
Molecular mapping of murine I region recombinants. II. Crossing over in the E beta gene is restricted to a 4.5 kb stretch of DNA that excludes the beta 1 exon.


