pH-sensitive microemulsion-based gels for removal of colonic ammonia: a novel preventative oral preparation for hepatic encephalopathy in rats.

Microemulsions with limited stability in mimetic gastrointestinal environments have previously demonstrated potential for the effective removal of ammonia from artificial colonic fluid. Specialized pH­sensitive microemulsion­based gels for the removal of colonic ammonia (MBG­RCA), however, possess relative stability in the gastrointestinal (GI) tract of normal rats, indicating potential use in in vivo applications. An investigation of the effects of oral MBG­RCA was conducted in order to evaluate the reduction of intestinal ammonia and the prevention of hepatic encephalopathy (HE) in rat models. Eighty rats were allocated into eight 4­day treatment groups: The HE model (intraperitoneal injection of thioacetamide) group; the high­, medium­ and low­dose MBG­RCA therapeutic groups (15, 10 and 5 ml/kg MBG­RCA, respectively); and the normal, blank, lactulose and acetic acid control groups, each of which received daily treatment administration. Oral MBG­RCA effects were identified using behavioral monitoring observed by an infrared night vision supervisory control system, electroencephalograms, blood ammonia levels, intestinal ammonia levels, liver functionality and pathological observation. High­ and medium­dose oral administrations of MBG­RCA significantly decreased the blood and intestinal ammonia levels (P<0.05), improved liver functionality and reduced the clinical manifestations of HE in rats. MBG­RCA demonstrated high clearance of rat colonic ammonia while maintaining sufficient stability in the GI tract, indicating the potential for the development of new clinically relevant oral preparations for the prevention of HE. Additionally, such preparations are advantageous in that ammonia is eliminated without the production of potentially harmful metabolic byproducts.

Isolation and partial characterization of a novel pollen-specific cDNA with multiple polyadenylation sites from wheat.

A novel pollen-specific full-length cDNA clone PSG076 was isolated using suppression subtractive hybridization and 5'/3' RACE techniques. PSG076 was shown to exhibit multi-site polyadenylation by sequencing the 3' ends of the cDNAs. At least six transcripts with different length were produced from the single gene based on different poly(A) tail attachment sites. However, polyadenylation consensus sequence AAUAAA was not seen at the 3'-untranslated sequence. PSG076 contained a 299 bp 5' untranslated region and an open reading frame of 663 bp encoding a 221 amino acid peptide with pI of 4.31. A blast search revealed that this sequence did not show a significant similarity to any genes deposited in the public database. Southern blot indicated that PSG076 was a single copy gene. Northern blot and RT-PCR analysis indicated that PSG076 transcripts showed specific expression in mature pollen, and weak or undetectable signals in uninucleate microspore, immature seed, stem, young leave, root and ovary. Further analysis of the expression pattern in gametophyte showed that PSG076 transcripts were undetectable in uninucleate, binucleate microspore and pollen at early stage, and were first detectable and increased rapidly at middle and late stages of pollen development with the maximum level in mature pollen and also expressed in germinating pollen in vivo, suggesting that PSG076 might play a role in pollen germination and pollen tube growth in addition to its function in maturation. The evidences gathered in this work indicated that the six different transcripts from the single gene were differentially expressed during pollen development.