Disordered breathing and oxygen desaturation during sleep in patients with chronic obstructive pulmonary disease.
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Adult↗
Biomedical subjects
L A Hunt
Publications and source records attributed to L A Hunt.
Disordered breathing and oxygen desaturation during daytime naps.
Ten patients with and ten patients without chronic obstructive pulmonary disease (COPD) were monitored for the presence of disordered breathing and oxygen desaturation during daytime naps. Disordered breathing occurred commonly during naps in patients with COPD and often was associated with desaturation. Disordered breathing was also seen in patients without COPD, but desaturation was less frequent and less severe.
Adult↗
Glycosylation of VSV glycoprotein is similar in cystic fibrosis, heterozygous carrier, and normal human fibroblasts.
The single envelope glycoprotein of vesicular stomatitis virus was used as a specific probe of glycosyltransferase activities in fibroblasts from two cystic fibrosis patients, an obligate heterozygous carrier and a normal individual. Gel filtration of pronase-digested glycopeptides from both purified virions and infected cell-associated VSV glycoprotein which had been labeled with[3H] glucosamine did not reveal any significant differences in the glycosylation patterns between the different cell cultures. All 4 cell lines were apparently able to synthesize the mannose- and glucosamine- containing core structure and branch chains terminating in sialic acid which are characteristic of asparagine-linked carbohydrate side chains in cellular glycoproteins. Analysis of tryptic glycopeptides by anion-exchange chromotography indicated that the same 2 major sites on the virus polypeptide were recognized and glycosylated in all 4 VSV-infected cell cultures. These studies suggest that the basic biochemical defect(s) in cystic fibrosis is not an absence or deficiency in enzymes responsible for the biosynthesis of complex carbohydrate side chains.
Cell Line↗
In vitro translation of encephalomyocarditis viral RNA: synthesis of capsid precursor-like polypeptides.
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Animals↗
Mechanism of premature polypetide termination in a mouse ascites cell-free system programmed by encephalomyocarditis viral RNA.
The premature termination and release of encephalomyocarditis viral RNA-programmed polypeptides were analyzed in a cell-free system from mouse ascites tumor cells. The KCL concentration affects the size distribution of products but not the extent of polypeptide release. The same major products (60,000 to 140,000 molecular weight) are found in both the soluble and particulate fractions. The majority of released polypeptides are free protein, whereas the ribosome-bound product is mostly in the form of peptidyl-tRNA.
Animals↗
Association of vesicular stomatitis virus proteins with HeLa cell membranes and released virus.
The association of vesicular stomatitis virus proteins with intracellular and plasma membranes was examined by pulse and pulse-chase labeling of virus-infected HeLa cells with [35S]methionine and separation of cell homogenates into three major membrane fractions in discontinuous sucrose gradients. The glycoprotein G was primarily associated with rough endoplasmic reticulum-like membranes after short radioactive pulses (2 to 4 min) but accumulated in the plasma membrane-enriched fraction and the smooth internal membrane fraction with longer pulse or chase periods. The nucleocapsid protein N and the matrix protein M accumulated in the rough endoplasmic reticulum and plasma membrane-like fractions but not in the smooth internal membrane fraction. Only a fraction (35 to 40%) of the viral protein synthesized during a short pulse in the mid-cycle of infection was apparently utilized in released virus. The newly synthesized virus proteins first appeared in released virus in the order: M, N and L, and G.
Capsid↗
Glycosylation of vesicular stomatitis virus glycoprotein in virus-infected HeLa cells.
Glycosylation of the envelope glycoprotein of vesicular stomatitis virus was examined using virus-infected HeLa cells that were pulse-labeled with radioactive sugar precursors. The intracellular sites of glycosylation and the stepwise elongation of the carbohydrate side chains of the G protein were monitored by membrane fractionation and gel filtration of Pronase-digested glycopeptides. The results with short pulses of sugar label (5 to 10 mtein linkage (glucosamine and mannose) are added to G which was associated with the rough endoplasmic reticulum-enriched membrane fraction, whereas the more distal sugars (galactose, sialic acid, fucose, and possibly more glucosamine) are added in the light-density internal membrane fraction. Accumulation of mature G was observed in the plasma membrane-enriched fraction. The gel filtration studies indicated that the initial glycosylation event may be the en bloc addition of a mannose and glucosamine oligomer, followed by the stepwise addition of the more distal sugars.
Chromatography↗
Estimates of the diffusion resistance of some large sunflower leaves in the field.
Studies were made of resistance to gaseous exchange between large sunflower leaves and the bulk air in a crop canopy. Two components of the diffusive pathway for mass and sensible heat were evaluated; A) the resistance from the interior of the leaf to the leaf surface, and B) the resistance from the surface of the leaf through the leaf boundary air layer to the bulk air.IT WAS FOUND THAT: A) leaf resistance not only displays diurnal trends but shorter fluctuations, and B) boundary air layer resistance was significantly smaller than predicted from classical boundary layer formulae.
Journal Article↗
Cleavable signal peptides are rarely found in bacterial cytoplasmic membrane proteins (review).
Most proteins destined for secretion are synthesized with amino-terminal extensions, known as signal peptides, which play a vital role in their translocation across the membrane bordering the cytoplasm. Following translocation across the eukaryotic endoplasmic reticulum (ER) membrane or the bacterial cytoplasmic membrane, signal peptides are proteolytically removed from the preproteins. The process of membrane protein assembly can be likened to that of protein export in that it involves the translocation of portions of proteins across membranes. Moreover, the topological similarities between eukaryotic ER and plasma membrane proteins and bacterial cytoplasmic membrane proteins suggest that the mechanisms of membrane protein assembly may, like those of protein export, share fundamental similarities in eukaryotic and bacterial cells. However, whilst many of the ER and plasma membrane proteins of higher eukaryotes are synthesized with cleavable signal peptides, the same is true of only very few bacterial cytoplasmic membrane proteins. This fact is not widely appreciated, probably because certain exceptional (signal peptide-containing) bacterial membrane proteins, such as the major coat protein of bacteriophage M13, have been the subject of extensive investigations. In this review we highlight this anomaly and discuss it within the general context of membrane protein topology.
Bacterial Proteins↗