Reactor decay heat in 239Pu: solving the γ discrepancy in the 4-3000-s cooling period.

The ß feeding probability of (102,104,105,106,107)Tc, 105Mo, and 101Nb nuclei, which are important contributors to the decay heat in nuclear reactors, has been measured using the total absorption technique. We have coupled for the first time a total absorption spectrometer to a Penning trap in order to obtain sources of very high isobaric purity. Our results solve a significant part of a long-standing discrepancy in the γ component of the decay heat for 239Pu in the 4-3000 s range.

Voice outcome following thyroplasty in patients with cancer-related vocal fold paralysis.

Medialization laryngoplasty restores voice in patients with unilateral laryngeal paralysis. Of question was whether patients with vocal fold paralysis resulting from cancer or its treatment had as good a post-operative voice result as patients with vocal fold paralysis of benign etiology. The purpose of the present study was to compare post-operative perceptual, acoustic, aerodynamic, and quality of life data in these two patient groups. Twenty-eight patients with vocal fold paralysis secondary to malignancy or its treatment were age and gender-matched with patients with paralysis resulting from benign origin. Pre- and post-operative perceptual judgments of pitch, loudness and quality were rated independently by two speech-language pathologists. A digital audiotape of the patient's voice was analyzed using Soundscope software. Fundamental frequency, conversational intensity and perturbation were evaluated. Glottal flow rates in propositional speech, phonation times and extent of pitch and loudness ranges were also measured. Three quality of life surveys, the Short Form-36 general health survey, the Voice Handicap Index, and the Voice Outcomes Study were administered. Results of voice testing indicated that perceptual, acoustic and aerodynamic data were significantly improved 3 months after thyroplasty in all patients regardless of whether they had a history of cancer. Quality of life data, however, distinguished the two groups. In particular, the general health measure found a significant difference in physical functioning and overall vitality, although satisfaction with improved voice was equally appreciated in both patient groups. Of clinical significance is that though general health may differ, patients with cancer-related laryngeal paralysis can expect to have as good a voice outcome following thyroplasty as patients with paralysis of benign etiology.

Voice outcome following lateral laryngotomy to remove teflon granuloma.

Formation of a Teflon granuloma may lead to progressive dysphonia and airway compromise. Excision of the granuloma by lateral laryngotomy allows preservation of the uninvolved lamina propria. A sternothyroid muscle flap or Silastic implant to medialize the vocal fold restores a straight glottal edge and optimizes voice production. Fifteen patients underwent removal of a Teflon granuloma via a lateral approach. Analysis of data revealed improved acoustic and aerodynamic parameters of voice following surgery. Indices of acoustic perturbation were reduced, and vocal pitch normalized. While the dynamic pitch range was unchanged, the capacity to vary loudness was enhanced. Flow rates in speech, abnormally elevated before surgery, normalized after the procedure, and phonation times were significantly longer. Perceptual and stroboscopic data confirmed that voices were improved, but not normal.

A nuclear 3'-5' exonuclease involved in mRNA degradation interacts with Poly(A) polymerase and the hnRNA protein Npl3p.

Inactivation of poly(A) polymerase (encoded by PAP1) in Saccharomyces cerevisiae cells carrying the temperature-sensitive, lethal pap1-1 mutation results in reduced levels of poly(A)(+) mRNAs. Genetic selection for suppressors of pap1-1 yielded two recessive, cold-sensitive alleles of the gene RRP6. These suppressors, rrp6-1 and rrp6-2, as well as a deletion of RRP6, allow growth of pap1-1 strains at high temperature and partially restore the levels of poly(A)(+) mRNA in a manner distinct from the cytoplasmic mRNA turnover pathway and without slowing a rate-limiting step in mRNA decay. Subcellular localization of an Rrp6p-green fluorescent protein fusion shows that the enzyme residues in the nucleus. Phylogenetic analysis and the nature of the rrp6-1 mutation suggest the existence of a highly conserved 3'-5' exonuclease core domain within Rrp6p. As predicted, recombinant Rrp6p catalyzes the hydrolysis of a synthetic radiolabeled RNA in a manner consistent with a 3'-5' exonucleolytic mechanism. Genetic and biochemical experiments indicate that Rrp6p interacts with poly(A) polymerase and with Npl3p, a poly(A)(+) mRNA binding protein implicated in pre-mRNA processing and mRNA nuclear export. These findings suggest that Rrp6p may interact with the mRNA polyadenylation system and thereby play a role in a nuclear pathway for the degradation of aberrantly processed precursor mRNAs.

Rrp6p, the yeast homologue of the human PM-Scl 100-kDa autoantigen, is essential for efficient 5.8 S rRNA 3' end formation.

The eukaryotic 25 S, 18 S, and 5.8 S rRNAs are synthesized as a single transcript with two internal transcribed spacers (ITS1 and ITS2), which are removed by endo- and exoribonucleolytic steps to produce mature rRNA. Genetic selection for suppressors of a polyadenylation defect yielded two cold-sensitive alleles of a gene that we named RRP6 (ribosomal RNA processing). Molecular cloning of RRP6 revealed its homology to a 100-kDa human, nucleolar PM-Scl autoantigen and to Escherichia coli RNase D, a 3'-5' exoribonuclease. Recessive mutations in rrp6 result in the accumulation of a novel 5. 8 S rRNA processing intermediate, called 5.8 S*, which has normal 5' ends, but retains approximately 30 nucleotides of ITS2. Pulse-chase analysis of 5.8 S rRNA processing in an rrp6- strain revealed a precursor-product relationship between 5.8 S* and 5.8 S rRNAs, suggesting that Rrp6p plays a role in the removal of the last 30 nucleotides of ITS2 from 5.8 S precursors. A portion of 5.8 S* rRNA assembles into 60 S ribosomes which form polyribosomes, suggesting that they function in protein synthesis. These findings indicate that Rrp6p plays a role in 5.8 S rRNA 3' end formation, and they identify a functional intermediate in the rRNA processing pathway.