Periodic naltrexone and propensity to take alcoholic beverage

For over 2 months, 45 rats were maintained on a daily regimen involving 2 hr a day of access to both water and palatable alcoholic beverage. At first, they took little ethanol. As days progressed, they eventually took over 2 g/kg of ethanol during the 2 hr. Previous research indicates that, without intervention, they would maintain this level of intake indefinitely. All rats were taken off the daily regimen for 30 days and then returned to it, i.e., rats received 30 days of "abstinence". For 35 days following abstinence, one-third of the subjects received placebos daily, one-third received naltrexone (NTX), 10 mg/kg, daily, and the one-third received NTX on days 1-5, 11-15, 21-25, and 31-35 and placebos on the other days. Abstinence reduced all rats' intakes of alcohol compared with pre-abstinence levels. Rats that received only placebos quickly returned to taking alcohol at pre-abstinence levels. Rats that received NTX daily increased their intakes up to the level normally expected for receiving NTX and no abstinence. Because rats receiving daily NTX always drank a fraction of the alcohol consumed by those receiving placebos, NTX's effects did not diminish. As rats sampled alcoholic beverage, however, the effects of abstinence did diminish. The rats of periodic NTX drank as rats getting NTX when they were given NTX and as rats getting placebos when they were given placebos. Furthermore, the rats of periodic NTX showed no carry-over effects from periods of NTX to no NTX. Abstinence and NTX together, apparently, reduce propensity to take alcoholic beverage more than either alone.

Reactivation of denatured proteins by 23S ribosomal RNA: role of domain V

Escherichia coli ribosome, its 50S subunit, or simply the 23S rRNA can reactivate denatured proteins in vitro. Here we show that protein synthesis inhibitors chloramphenicol and erythromycin, which bind to domain V of 23S rRNA of E. coli, can inhibit reactivation of denatured pig muscle lactate dehydrogenase and fungal glucose-6-phosphate dehydrogenase by 23S rRNA completely. Oligodeoxynucleotides complementary to two regions within domain V (which cover sites of chloramphenicol resistant mutations and the putative A site of the incoming aminoacyl tRNA), but not to a region outside of domain V, also can inhibit the activity. Domain V of 23S rRNA, therefore, appears to play a crucial role in reactivation of denatured proteins.

Technical, scale, and size efficiency in nursing home care: a nonparametric analysis of Connecticut homes

Maindiratta (1990) questioned the usefulness of the concept of scale efficiency in production as the most productive scale size (MPSS) usually requires altering the scale of output produced. If the decision making unit (DMU) is required to deliver a specific output bundle, then altering output along with the input scale to reach the MPSS is not a valid recommendation. He proposed a measure of the size efficiency of a DMU. In this paper, we apply Data Envelopment Analysis (DEA) to examine the levels of technical, scale, and size efficiency of individual nursing homes providing health care to the elderly. The data used relate to the operations of 140 nursing homes from Connecticut, USA during the year 1982-83. Maindiratta's model is input-oriented. By contrast, our study is output-oriented and we appropriately reformulate Maindiratta's model. The findings show that in several cases size efficiency is less than unity. This suggests that the most efficient production of output would require restructuring of the nursing home under investigation as more than one small unit. We also compare the efficiency levels of 'for-profit' homes with those of 'not-for-profit' homes.

Expedient Synthesis of (R)-Patulolide A

An efficient derivation of the title compound has been formulated from easily accessible 10-undecenoic acid (1). Thus, dodec-11-en-2-ol (3), prepared from 1, was pyranylated and subjected to bromination with NBS followed by acetolysis to furnish (2E)-1-acetoxy-11-(tetrahydropyranyloxy)dodec-2-ene (5). Its hydrolysis, oxidation, and depyranylation afforded the (2E)-hydroxy ester (9). This, on Candida rugosa lipase-catalyzed acetylation, SeO(2) oxidation, hydrolysis, and Yamaguchi macrolactonization, led to (R)-patulolide A (I) with 67.1% ee. The enantiomeric excess was improved to 97% by first resolving the alcohol 3 via porcine pancreatic lipase catalyzed acetylation and converting the corresponding (R)-acetate (13) to I as done above.

In vitro protein folding by ribosomes from Escherichia coli, wheat germ and rat liver: the role of the 50S particle and its 23S rRNA

Ribosomes from a number of prokaryotic and eukaryotic sources (e.g. Escherichia coli, wheat germ and rat liver) can refold a number of enzymes which are denatured with guanidine/HC1 prior to incubation with ribosomes. In this report, we present our observations on the refolding of denatured lactate dehydrogenase from rabbit muscle and glucose-6-phosphate dehydrogenase from baker's yeast by ribosomes from E. coli, wheat germ and rat liver. The protein-folding activity of E. coli ribosomes was found to be present in 50S particles and in 23S rRNA. The 30S particle or 16S rRNA did not show any protein-folding activity. The protein-folding activity of 23S rRNA may depend on its tertiary conformation. Loss of tertiary structure, by incubation with low concentrations of EDTA, inhibited the protein-folding activity of 23S rRNA. This low concentration of EDTA had no effect on folding of the denatured enzymes by themselves.

Interaction between the phage HK022 Nun protein and the nut RNA of phage lambda

The nun gene product of prophage HK022 excludes phage lambda infection by blocking the expression of genes downstream from the lambda nut sequence. The Nun protein functions both by competing with lambda N transcription-antitermination protein and by actively inducing transcription termination on the lambda chromosome. We demonstrate that Nun binds directly to a stem-loop structure within nut RNA, boxB, which is also the target for the N antiterminator. The two proteins show comparable affinities for boxB and they compete with each other. Their interactions with boxB are similar, as shown by RNase protection experiments, NMR spectroscopy, and analysis of boxB mutants. Each protein binds the 5' strand of the boxB stem and the adjacent loop. The stem does not melt upon the binding of Nun or N, as the 3' strand remains sensitive to a double-strand-specific RNase. The binding of RNA partially protects Nun from proteolysis and changes its NMR spectra. Evidently, although Nun and N bind to the same surface of boxB RNA, their respective complexes interact differently with RNA polymerase, inducing transcription termination or antitermination, respectively.

Rapid micropropagation for Mucuna pruriens f. pruriens L

A rapid micropropagation system was developed for Mucuna pruriens f. pruriens using explants from 1-week-old aseptically grown seedlings. Multiple shoot regeneration occurred following an initial callus growth on Revised Tobacco (RT) medium supplemented with 2.7 μM NAA and 9.8 μM 2iP. Maximum number of shoot regeneration was achieved only from seedling explant 6 to 7 days old. More than 90% of the regenerated shoots could be rooted on half-strength liquid RT medium supplemented with 2.7 μM NAA. Plantlets readily adopted to greenhouse conditions. This system provides a new tool for micropropagation of Mucuna pruriens f. pruriens, an important medicinal plant.

Bipartite function of a small RNA hairpin in transcription antitermination in bacteriophage lambda

Transcription of downstream genes in the early operons of phage lambda requires a promoter-proximal element known as nut. This site acts in cis in the form of RNA to assemble a transcription antitermination complex which is composed of lambda N protein and at least four host factors. The nut-site RNA contains a small stem-loop structure called boxB. Here, we show that boxB RNA binds to N protein with high affinity and specificity. While N binding is confined to the 5' subdomain of the stem-loop, specific N recognition relies on both an intact stem-loop structure and two critical nucleotides in the pentamer loop. Substitutions of these nucleotides affect both N binding and antitermination. Remarkably, substitutions of other loop nucleotides also diminish antitermination in vivo, yet they have no detectable effect on N binding in vitro. These 3' loop mutants fail to support antitermination in a minimal system with RNA polymerase (RNAP), N, and the host factor NusA. Furthermore, the ability of NusA to stimulate the formation of the RNAP-boxB-N complex is diminished with these mutants. Hence, we suggest that boxB RNA performs two critical functions in antitermination. First, boxB binds to N and secures it near RNAP to enhance their interaction, presumably by increasing the local concentration of N. Second, boxB cooperates with NusA, most likely to bring N and RNAP in close contact and transform RNAP to the termination-resistant state.

Molecular cloning and sequencing of an operon, carRS of Azospirillum brasilense, that codes for a novel two-component regulatory system: demonstration of a positive regulatory role of carR for global control of carbohydrate catabolism

A pleiotropic carbohydrate mutant, CR17, of Azospirillum brasilense RG (wild type) that assimilates C4 dicarboxylates (succinate and malate) but not carbohydrate (fructose, arabinose, galactose, glycerol, and gluconate) as C sources for growth was used to identify the car (carbohydrate regulation) locus by complementation analysis. The 2.8-kb genomic fragment that complemented the Car- defect of CR17 and overlapped the fru operon (S. Chattopadhyay, A. Mukherjee, and S. Ghosh, J. Bacteriol. 175:3240-3243, 1993) has now been completely sequenced. The sequence contains an operon, carRS, coding for two proteins, CARR and CARS, having 236 and 352 amino acid residues, respectively. The 3'-flanking region of the carRS operon showed sequence homology with the 5' terminus of the fruB gene of a related bacterium, Rhodobacter capsulatus. A complementation study with carRS deletion clones showed that only the carR+ gene was required to complement the Car- defect of CR17, signifying that the carbohydrate pleiotropy was due to a lesion within this gene. Although the 2.8-kb DNA containing the carRS operon when introduced by conjugation into CR17 also complemented the Car- defect, the complemented transconjugant was unable to utilize succinate as a C source. The reason for this is not clear. A sequence analysis of the two protein products strongly suggests that the protein pair may constitute a novel two-component regulatory system for global expression of carbohydrate catabolic pathways in A. brasilense.