TASK DEFINITION: Given an abstract of a paper, generate a title for this paper such that conveys the key focus of the paper.
PROBLEM: Abstract: In the Drosophila embryo the establishment and specification of metameric units depends upon the selective activation of the segmentation and the homoeotic selector genes. The former are necessary for establishing the appropriate number of metameric or parasegmental units, whereas the latter control the pathways of differentiation followed by particular parasegments. Classical embryological manipulations have show n that these processes must be closely coordinated during normal development. However, previous studies of pair-rule genes have led to the suggestion that the specification of segmental identity proceeds independently of the establishment of metameres as physical units. These apparently conflicting perspectives can be reconciled by envisaging a common maternally derived positional information system which is independently interpreted by the components of both processes. In the case of the partitioning process, the gap and pair-rule genes would be instrumental in translating this information, whereas the activation of the homeotic genes would be mediated via other intermediaries (see ref. 9 for review). It is difficult to see, however, how such a system could ensure the precise regulation of the tw o types of genes implicit in the final differentiated pattern. This difficulty has led to the suggestion that the segmentation mechanism must define the precise boundaries of selector gene expression. Here we confirm this suggestion and propose that the gene fushi tarazu plays a key role in this process, integrating the processes of metameric partitioning and regional specification in the Drosophila embryo.

SOLUTION: The correct activation of Antennapedia and bithorax complex genes requires the fushi tarazu gene.

PROBLEM: Abstract: The concentration of interferon-alpha was measured by a specific two-site immunoradiometric assay in a variety of fluids and tissues collected during human pregnancy. Maternal blood and blood and tissues from non-pregnant adults contained little or no interferon-alpha. Fetal blood, fetal organs, placenta, membranes, amniotic fluid and decidua all contained significant and roughly equivalent amounts ranging from 1.1 to 10 u/ml (or per g of tissue). These findings demonstrate that the fetus and its immediate surroundings are permeated with interferon. It is suggested that this may play a role in regulation of the maternal-fetal graft relation.

SOLUTION: Alpha interferon in human pregnancy.

PROBLEM: Abstract: To determine if hiatus hernia (HH) contributes to the delayed clearance of acid from the esophagus in patients with gastroesophageal reflux (GER), we performed simultaneous esophageal pH recordings and radionuclide studies in three study populations: 12 GER patients with HH, 5 GER patients with no HH, and 8 subjects with HH but no GER symptoms. Acid clearance was measured at 5 cm. above the manometrically located lower esophageal sphincter (LES) after injecting a 15-ml. bolus of 0.1 N HCl at 15 cm. above the LES. The acid was labeled with 200 mu Ci of 99mTc-sulfur colloid. Acid clearance was also measured at 10 cm. above the LES after injection of a 15-ml. bolus of 0.1 N HCl at 20 cm. above the LES. Acid clearance at 5 cm. above the LES was faster in GER patients with no HH compared to GER patients with HH and asymptomatic HH subjects. Acid clearance was faster at 10 cm. than 5 cm. above the LES in all HH and non-HH subjects studied. In non-HH subjects, each swallow resulted in an increase in pH (a monophasic pH response) at 5 and 10 cm. above the LES. In symptomatic as well as asymptomatic HH subjects, swallows resulted in an initial fall followed by a rise in pH at 5 cm. above the LES (a biphasic pH response). Radionuclide studies showed reflux of the isotope-labeled acid into the esophagus followed by clearance (a biphasic response) accompanying swallows in 15 of the 20 HH subjects. Swallow-induced reflux was not detected by radionuclide scanning in non-HH subjects. Based on these observations, we conclude that during acid clearance a small amount of acid is trapped in the HH sac and refluxes into the esophagus during subsequent swallows when there is relaxation of the LES, and these repeated episodes of acid reflux from the HH account for the delayed acid clearance observed in GER patients with HH.

SOLUTION:
Identification and mechanism of delayed esophageal acid clearance in subjects with hiatus hernia.