Specific receptors for glucocorticoid in the cytoplasm of the liver of AH 130 tumor-bearing rats.
(1/1604)
Specific receptors for dexamethasone (11beta, 17alpha, 21-trihydroxy-9alpha-fluoro-16alpha-methyl-1,4-pregnadiene-3,20-dione) in the cytoplasm of the liver from AH 130 (solid type) tumor-bearing rats markedly increased in the advanced stage of tumor growth. The cytoplasmic receptors of the livers of normal and tumor-bearing rats differed in their affinities for dexamethasone, and their apparent equilibrium (dissociation) constants (K) for dexamethasone were 4.0 and 2.6 X 10(-9) M, respectively. The rates of dissociation of dexamethasone-receptor complexes and the heat denaturations of the receptors in the livers of normal and tumor-bearing rats were similar. The glucocorticoid receptors of tumor-bearing rat liver had slightly higher affinities than did those of normal liver for all the steroids tested. Only a trace amount of receptors for dexamethasone could be detected in the cytoplasm of AH 130 ascites cells. (+info)
Activities of citrate synthase, NAD+-linked and NADP+-linked isocitrate dehydrogenases, glutamate dehydrogenase, aspartate aminotransferase and alanine aminotransferase in nervous tissues from vertebrates and invertebrates.
(2/1604)
1. The activities of citrate synthase and NAD+-linked and NADP+-linked isocitrate dehydrogenases were measured in nervous tissue from different animals in an attempt to provide more information about the citric acid cycle in this tissue. In higher animals the activities of citrate synthase are greater than the sum of activities of the isocitrate dehydrogenases, whereas they are similar in nervous tissues from the lower animals. This suggests that in higher animals the isocitrate dehydrogenase reaction is far-removed from equilibrium. If it is assumed that isocitrate dehydrogenase activities provide an indication of the maximum flux through the citric acid cycle, the maximum glycolytic capacity in nervous tissue is considerably greater than that of the cycle. This suggest that glycolysis can provide energy in excess of the aerobic capacity of the tissue. 2. The activities of glutamate dehydrogenase are high in most nervous tissues and the activities of aspartate aminotransferase are high in all nervous tissue investigated. However, the activities of alanine aminotransferase are low in all tissues except the ganglia of the waterbug and cockroach. In these insect tissues, anaerobic glycolysis may result in the formation of alanine rather than lactate. (+info)
Isolation and characterization of a second subunit of molecular chaperonin from Pyrococcus kodakaraensis KOD1: analysis of an ATPase-deficient mutant enzyme.
(3/1604)
The cpkA gene encoding a second (alpha) subunit of archaeal chaperonin from Pyrococcus kodakaraensis KOD1 was cloned, sequenced, and expressed in Escherichia coli. Recombinant CpkA was studied for chaperonin functions in comparison with CpkB (beta subunit). The effect on decreasing the insoluble form of proteins was examined by coexpressing CpkA or CpkB with CobQ (cobyric acid synthase from P. kodakaraensis) in E. coli. The results indicate that both CpkA and CpkB effectively decrease the amount of the insoluble form of CobQ. Both CpkA and CpkB possessed the same ATPase activity as other bacterial and eukaryal chaperonins. The ATPase-deficient mutant proteins CpkA-D95K and CpkB-D95K were constructed by changing conserved Asp95 to Lys. Effect of the mutation on the ATPase activity and CobQ solubilization was examined. Neither mutant exhibited ATPase activity in vitro. Nevertheless, they decreased the amount of the insoluble form of CobQ by coexpression as did wild-type CpkA and CpkB. These results implied that both CpkA and CpkB could assist protein folding for nascent protein in E. coli without requiring energy from ATP hydrolysis. (+info)
A cost/efficacy analysis of oral antifungals indicated for the treatment of onychomycosis: griseofulvin, itraconazole, and terbinafine.
(4/1604)
This analysis was conducted at HIP Health plan of New Jersey (a Northeastern group model health maintenance organization) to determine the most cost-effective therapy among the three currently available oral antifungal drugs that are indicated for the treatment of onychomycosis: griseofulvin, itraconazole, and terbinafine. Costs of an appropriate and complete treatment regimen were calculated for each of the three drugs based on average wholesale price. Efficacy was determined by meta-analysis of the published literature for those studies where appropriate treatment regimens for onychomycosis were put to use. Efficacy outcome measures were limited to mycologic cure rates in the more recalcitrant cases of toenail onychomycosis. From these measures of cost and efficacy, a cost/efficacy ratio was calculated for each drug by dividing the cost per treatment by the weighted average mycological cure rate. This ratio represents the cost per mycologically cured infection. The final outcome measure (the cost per mycologically cured infection) was $2,721.28, $1,845.05, and $648.96, for griseofulvin, itraconazole, and terbinafine continuous therapies, respectively. For itraconazole and terbinafine pulse therapy, the costs were $855.88 and $388.50, respectively. For both continuous and pulse therapy, terbinafine is apparently the most cost-effective drug, followed by itraconazole and then by griseofulvin. Terbinafine has the fewest drug interactions and the highest treatment success rate. (+info)
Inducing effect of diamines on transcription of the cephamycin C genes from the lat and pcbAB promoters in Nocardia lactamdurans.
(5/1604)
The diamines putrescine, cadaverine, and diaminopropane stimulate cephamycin biosynthesis in Nocardia lactamdurans, in shake flasks and fermentors, without altering cell growth. Intracellular levels of the P7 protein (a component of the methoxylation system involved in cephamycin biosynthesis) were increased by diaminopropane, as shown by immunoblotting studies. Lysine-6-aminotransferase and piperideine-6-carboxylate dehydrogenase activities involved in biosynthesis of the alpha-aminoadipic acid precursor were also greatly stimulated. The diamine stimulatory effect is exerted at the transcriptional level, as shown by low-resolution S1 protection studies. The transcript corresponding to the pcbAB gene and to a lesser extent also the lat transcript were significantly increased in diaminopropane-supplemented cultures, whereas transcription from the cefD promoter was not affected. Coupling of the lat and pcbAB promoters to the reporter xylE gene showed that expression from the lat and pcbAB promoters was increased by addition of diaminopropane in Streptomyces lividans. Intracellular accumulation of diamines in Nocardia may be a signal to trigger antibiotic production. (+info)
Transcriptional induction by aromatic amino acids in Saccharomyces cerevisiae.
(6/1604)
Aromatic aminotransferase II, product of the ARO9 gene, catalyzes the first step of tryptophan, phenylalanine, and tyrosine catabolism in Saccharomyces cerevisiae. ARO9 expression is under the dual control of specific induction and nitrogen source regulation. We have here identified UASaro, a 36-bp upstream element necessary and sufficient to promote transcriptional induction of reporter gene expression in response to tryptophan, phenylalanine, or tyrosine. We then isolated mutants in which UASaro-mediated ARO9 transcription is partially or totally impaired. Mutations abolishing ARO9 induction affect a gene called ARO80 (YDR421w), coding for a Zn2Cys6 family transcription factor. A sequence highly similar to UASaro was found upstream from the YDR380w gene encoding a homolog of bacterial indolepyruvate decarboxylase. In yeast, this enzyme is postulated to catalyze the second step of tryptophan catabolism to tryptophol. We show that ARO9 and YDR380w (named ARO10) have similar patterns of transcriptional regulation and are both under the positive control of Aro80p. Nitrogen regulation of ARO9 expression seems not directly to involve the general factor Ure2p, Gln3p, Nil1p, Uga43p, or Gzf3p. ARO9 expression appears, rather, to be mainly regulated by inducer exclusion. Finally, we show that Gap1p, the general amino acid permease, and Wap1p (Ycl025p), a newly discovered inducible amino acid permease with broad specificity, are the main aromatic amino acid transporters for catabolic purposes. (+info)
Production of nikkomycins Bx and Bz by mutasynthesis with genetically engineered Streptomyces tendae Tu901.
(7/1604)
The previously described Streptomyces tendae nikC::aph mutant was used to mutasynthesize nikkomycins Bx and Bz. The mutant is deficient in L-lysine 2-aminotransferase, which transaminates lysine to form piperideine 2-carboxylate, the precursor of the peptidyl side chain of the biologically active nikkomycins I, J, X, and Z, and is therefore unable to produce these nikkomycins. The mutant accumulates the biologically inactive biosynthetic nucleoside precursors nikkomycins Cx and Cz. Resting cell cultures of the mutant fed with benzoic acid produced the biologically active nikkomycins Bx and Bz, which contain 2-amino-4-hydroxy-3-methyl-4-(4'-hydroxyphenyl)butanoic acid as the peptidyl side chain. The structures of nikkomycins Bx and Bz were confirmed by mass spectrometry and NMR. Nikkomycins Bx and Bz exhibit significantly higher pH stability than their analogues nikkomycins X and Z. (+info)
Flux of the L-serine metabolism in rabbit, human, and dog livers. Substantial contributions of both mitochondrial and peroxisomal serine:pyruvate/alanine:glyoxylate aminotransferase.
(8/1604)
L-Serine metabolism in rabbit, dog, and human livers was investigated, focusing on the relative contributions of the three pathways, one initiated by serine dehydratase, another by serine:pyruvate/alanine:glyoxylate aminotransferase (SPT/AGT), and the other involving serine hydroxymethyltransferase and the mitochondrial glycine cleavage enzyme system (GCS). Under quasi-physiological in vitro conditions (1 mM L-serine and 0.25 mM pyruvate), flux through serine dehydratase accounted for only traces, and that through SPT/AGT substantially contributed no matter whether the enzyme was located in peroxisomes (rabbit and human) or largely in mitochondria (dog). As for flux through serine hydroxymethyltransferase and GCS, the conversion of serine to glycine occurred fairly rapidly, followed by GCS-mediated slow decarboxylation of the accumulated glycine. The flux through GCS was relatively high in the dog and low in the rabbit, and only in the dog was it comparable with that through SPT/AGT. An in vivo experiment with L-[3-3H,14C]serine as the substrate indicated that in rabbit liver, gluconeogenesis from L-serine proceeds mainly via hydroxypyruvate. Because an important role in the conversion of glyoxylate to glycine has been assigned to peroxisomal SPT/AGT from the studies on primary hyperoxaluria type 1, these results suggest that SPT/AGT in this organelle plays dual roles in the metabolism of glyoxylate and serine. (+info)