Utilizing a model of chronic doxorubicin cardiomyopathy, this study examines the relationship between changes in expression and function of calcium handling proteins and contractile dysfunction. A ...possible mechanism to account for this relationship is suggested. New Zealand white rabbits were injected with either doxorubicin (1 mg/kg, twice weekly for 8 wk) or 0.9% NaCl. Gene transcript, protein levels, and the function of several proteins from the left ventricle were assessed. Protein levels of sarcoplasmic reticulum (SR) Ca2+ transporting ATPase (SERCA2a and b), Ca2+ release channel (RYR2), calsequestrin, Na/Ca exchanger, mRNA levels of RYR2, and 3H-ryanodine binding (B(max)) to RYR2 were significantly decreased in doxorubicin-treated rabbits; protein levels of phospholamban, dihydropyridine receptor alpha2 subunit, and SR Ca2+ loading rates were not decreased. However, only protein levels of SERCA2 and RYR2, mRNA levels of RYR2, and Bmax of RYR2 significantly regressed with left-ventricular fractional shortening. Analysis of contractile function of atrial preparations isolated from doxorubicin-treated rabbits revealed that doxorubicin diminished contractility (dF/dt) of rest-potentiated contractions consistent with SR dysfunction. Serum concentrations of free triiodothyronine (T3) decreased in doxorubicin-treated rabbits. Our results suggest that chronic doxorubicin administration in the rabbit causes a SR-dependent contractile dysfunction that may result, in part, from decreased T3.
Methylquinolines and related N-heterocyclic aromatic compounds are common contaminants associated with the use of hydrocarbons in both coal gasification and wood treatment processes. These compounds ...have been found in groundwater, and many are known mutagens. A stable, five-member bacterial consortium able to degrade 4-methylquinoline was established by selective enrichment using soil collected from an abandoned coal gasification site. The consortium was maintained for 5 years by serial transfer in a medium containing 4-methylquinoline. A gram-negative soil bacterium, strain Lep1, was isolated from the consortium and shown to utilize 4-methylquinoline as a source of carbon and energy during growth in liquid medium. A time course experiment demonstrated that both the isolate Lep1 and the consortium containing Lep1 were able to degrade 4-methylquinoline under aerobic conditions. Complete degradation of 4-methylquinoline by either strain Lep1 alone or the consortium was characterized by the production and eventual disappearance of 2-hydroxy-4-methylquinoline, followed by the appearance and persistence of a second metabolite tentatively identified as a hydroxy-4-methylcoumarin. Currently, there is no indication that 4-methylquinoline degradation proceeds differently in the consortium culture compared with Lep1 alone. This is the first report of 4-methylquinoline biodegradation under aerobic conditions
Mass spectrometry has become the technology of choice for detailed identification of proteins in complex mixtures. Although electrophoretic separation, proteolytic digestion, mass spectrometric ...analysis of unseparated digests, and database searching have become standard methods in widespread use, peptide sequence information obtained by collision-induced dissociation and tandem mass spectrometry is required to establish the most comprehensive and reliable results. Most tandem mass spectrometers in current use employ electrospray ionization. In this work a novel tandem mass spectrometer employing matrix-assisted laser desorption ionization-time-of-flight/time-of-flight operating at 200 Hz has been used to identify proteins interacting with known nucleoporins in the nuclear pore complex of Saccharomyces cerevisiae. Proteins interacting with recombinant proteins as bait were purified from yeast extracts and then separated by one-dimensional SDS-PAGE. Although peptide mass fingerprinting is sometimes sufficient to identify proteins, this study shows the importance of employing tandem mass spectrometry for identifying proteins in mixtures or as covalently modified forms. The rules for incorporating these features into MS-Tag are presented. In addition to providing an evaluation of the sensitivity and overall quality of collision-induced dissociation spectra obtained, standard conditions for ionization and fragmentation have been selected that would allow automatic data collection and analysis, without the need to adjust parameters in a sample-specific fashion. Other considerations essential for successful high throughput protein analysis are discussed.
Genetic screens provide a mechanism to identify genes involved with different cellular and organismal processes. Using a Flp/FRT screen in the
Drosophila
eye we identified mutations that result in ...alterations and de-regulation of cell growth and division. From this screen a group of undergraduate researchers part of the Fly-CURE consortium mapped and characterized a new allele of the gene
Hippo
,
Hpo
N.1.2
.
Genetic screens provide a mechanism to identify genes involved with different cellular and organismal processes. Using a Flp/FRT screen in the
eye we identified mutations that result in alterations ...and de-regulation of cell growth and division. From this screen a group of undergraduate researchers part of the Fly-CURE consortium mapped and characterized a new allele of the gene
,
The effect of age on the hypothalamic-hypophyseal-renal axis in normal man was determined by assaying plasma arginine vasopressin (AVP) responses to inhibitory and to secretory stimuli. Nine young ...(21-49 years) and 13 old (54-92 years) subjects received IV ethanol (375 mg/m2 per min). AVP levels fell progressively during the infusion in the young group, but fell for only 30 min in the old group and then rose paradoxically despite the continuing increase in blood ethanol. Eight young (22-48 years) and 8 old (52-66 years) men were provided identical osmolal loads by a 2-hour IV infusion of 3% NaCl at 0.1 ml/kg per min. Serum AVP rose 2.5 times the baseline in the young and 4.5 times the baseline in the old men despite identical free water clearances. Osmoreceptor sensitivity (the slope of AVP on osmolality) was greater in the old subjects. The heightened sensitivity to hyperosomolality helps examine the paradoxical response to ethanol, since osmolality increased during that time. This increased AVP response may severe to compensate for the reduced renal ability to conserve salt and water in aging man.
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