The interaction of 7-substituted actinomycin D analogs with DNA

The interaction of actinomycin D and three new 7-substituted analogs with calf thymus DNA has been studied by a number of physical techniques. The methods utilized in this investigation include visible absorption spectrometry and ultrafiltration methodology for the determination of equilibrium binding constants; viscometry; and circular dichroism. The studies show that the 7-substituted actinomycin D analogs retain the G . C base pair specific DNA binding demonstrated by actinomycin D. The mode of binding to native DNA, despite substitution at position 7, is practically unaltered. The retention of this binding specificity by these analogs seems to be unaffected by changes in the electon properties of the chromophore.     

Evaluation of N-phenyl homopiperazine analogs as potential dopamine D3 receptor selective ligands

A series of N-(2-methoxyphenyl)homopiperazine analogs was prepared and their affinities for dopamine D₂, D₃, and D₄ receptors were measured using competitive radioligand binding assays. Several ligands exhibited high binding affinity and selectivity for the D₃ dopamine receptor compared to the D₂ receptor subtype. Compounds 11a, 11b, 11c, 11f, 11j and 11k had K_i values ranging from 0.7 to 3.9 nM for the D₃ receptor with 30- to 170-fold selectivity for the D₃ versus D₂ receptor. Calculated log P values (log P = 2.6–3.6) are within the desired range for passive transport across the blood–brain barrier. When the binding and the intrinsic efficacy of these phenylhomopiperazines was compared to those of previously published phenylpiperazine analogues, it was found that (a) affinity at D₂ and D₃ dopamine receptors generally decreased, (b) the D₃ receptor binding selectivity (D₂:D₃ K_i value ratio) decreased and, (c) the intrinsic efficacy, measured using a forskolin-dependent adenylyl cyclase inhibition assay, generally increased.     

Sterol effects on phospholipid biosynthesis in the yeast strain GL7

Cells of the yeast sterol auxotroph GL7 were grown on either ergosterol or cholesterol to mid-logarithmic phase and total membrane fractions prepared. Activities of phospholipid biosynthetic enzymes in the two cell types were determined. The rates of phosphatidyl-ethanolamine-phosphatidyl-choline-N-methyl transferase and acyl-CoA-alpha-glycerol-3-phosphate transcylase were significantly greater in ergosterol-grown than in cholesterol-grown cells. These reactions were also inhibited by the polyene antibiotic filipin. By contrast the activities of long-chain fatty acyl-CoA synthetase, CTP-phosphatidate-cytidyl transferase, phosphatidylserine decarboxylase and of phosphatidylinositol synthetase were identical in the two (ergosterol and cholesterol) cultures and unaffected by filipin. The ergosterol effect on phosphatidyl-ethanolamine N-methyl transferase was greatest in cells harvested in early log phase, intermediate in the mid-log phase cells, and not significant in stationary phase cells.     

Synthesis and in vitro binding of N-phenyl piperazine analogs as potential dopamine D3 receptor ligands

A series of N-(2-methoxyphenyl)piperazine and N-(2,3-dichlorophenyl)piperazine analogs were prepared and their affinities for dopamine D(2), D(3), and D(4) receptors were measured in vitro. Binding studies were also conducted to determine if the compounds bound to sigma (sigma(1) and sigma(2)) and serotonin (5-HT(1A), 5-HT(2A), 5-HT(2B), 5-HT(2C), 5-HT(3), 5-HT(4), 5-HT(5), 5-HT(6), and 5-HT(7)) receptors. The results of the current study revealed a number of compounds (12b, 12c, 12e, and 12g) having a high affinity for D(3) (K(i) at D(3) receptors ranging from 0.3 to 0.9 nM) versus D(2) (K(i) at D(2) receptors ranging from 40 to 53 nM) receptors and a log P value indicating that they should readily cross the blood brain barrier (log P = 2.6-3.5). All of the compounds evaluated in this study had a high affinity for serotonin 5-HT(1A) receptors. These compounds may be useful as probes for studying the behavioral pharmacology of the dopamine D(3) receptor, as well as lead compounds for the development of radiotracers for studying D(3) receptor regulation in vivo with the functional imaging technique, positron emission tomography.     

Perspectives of new potential therapeutic applications of somatostatin analogs

At the present time only two long-acting somatostatin (SS) analogs, octreotide and lanreotide, are commonly used in the routine therapy. Both analogs have a high affinity mainly to a somatostatin receptor subtype 2 (SSTR2). The established indications for SS analogs treatment include acromegaly, neuroendocrine tumors of the pancreas and gastrointestinal tract, and some gastro-enterologic diseases (pancreatitis, gastrointestinal bleedings, refractory diarrheas, pancreatic and intestinal fistulas). The recent investigations allow to predict the enlargement of therapeutic applications of SS analogs. It concerns pituitary tumors other than somatotropinoma, tumors of other endocrine glands like thyroid and adrenal gland, as well as some non-endocrine tumors. The progress depends on the introduction of new SS analogs with high affinity for SS receptor subtypes other than SSTR2, because some tumors present the high expression of SSTR1 (e.g. prostatic cancers) or SSTR5 (e.g. colonic cancers). Great hopes are connected with the coupling of SS analogs with the radioactive isotopes or non-radioactive cytotoxic agents to destruct the neoplastic cells highly expressing the specific subtypes of SS receptors. The pre- or postoperative in vivo imaging of SS receptors by means of the receptor scintigraphy, as well as the post-operative identification of SS receptor subtypes in the excised tumor tissues using immunohistochemistry, should play an important role in the prediction of the effects of SS analog treatment. Beside oncology, new therapeutic applications of SS analogs could be presumed among others in ophthalmology; it concerns the treatment of progressive Graves-Basedow ophtalmopathy, diabetic retinopathy, glaucoma and corneal diseases connected with corneal vascularization.     

Mutagenesis in cdc7 strains of yeast. The fate of premutational lesions induced by ultraviolet light

cdc7-1 cells bearing UV-revertible mutations are virtually immutable by all means so far tested. By mating UV treated cdc7-1 cells with untreated cdc7+ cells carrying the same revertible alleles it is possible to rescue premutational lesions as revertants and to study their fate in cdc7-1 cells. If storage intervenes between treatment and mating there is a rapid decline in revertants rescued. This is not related to the death of cdc7-1 cells with storage nor does it reflect a progressive loss in their ability to mate.     

The specificity of induced conformational changes. The case of yeast glyceraldehyde-3-phosphate dehydrogenase.

The specificity of induced conformational changes and of the probes used to detect them has been investigated in yeast glyceraldehyde-3-phosphate dehydrogenase. Cyanylation of the active-site SH groups in two of the four identical subunits of glyceraldehyde-3-phosphate dehydrogenase has no effect on reactivity of the unmodified SH groups toward the cyanylating reagent (2-nitro-5-thiocyanogenzoic acid, NTCB) but results in total loss of catalytic activity. Cyanylation of the dicarboxamidomethylated enzyme was four orders of magnitude slower than with the unmodified enzyme in contrast to cyanylation of the dicyanylated enzyme. Cyanylation by NTCB as well as alkylation by iodoacetate and acylation with beta-(2-furyl)acryloyl phosphate are enhanced in the presence of NAD+ while alkylation by iodoacetamide is inhibited by NAD+. In the absence of NAD+, hydrolysis of the acylated enzyme is faster than phosphorolysis while the reverse is true in the presence of NAD+. NAD+ accelerates hydrolysis of the 3-phosphoglyceroylated enzyme about 60-fold but decreases the rate of hydrolysis of the furylacryloylated enzyme by a factor of 17. Other examples of the specificity of the induced conformational changes and the probes are described. The conformational changes induced by NAD+ make the protein specifically reactive toward its physiological substrates and less reactive toward extraneous competing compounds.     

Homoazasterol-mediated inhibition of yeast sterol biosynthesis.

A naturally occurring azasterol has been shown to inhibit sterol transmethylation in both in vitro and in vivo in the yeast Saccharomyces cerevisiae. The inhibition was competitive, with a calculated dissociation constant of 43 muM. The compound prevented the accumulation of ergosterol in aerobically adapting cells. Cultures forced to gain energy by respiration were found to be much more sensitive to growth inhibition by the azasterol than those cells fermenting glucose. The growth inhibition is reversible at low concentrations of the azasterol.     

Facile preparation of new 4-phenylamino-3-quinolinecarbonitrile Src kinase inhibitors via 7-fluoro intermediates: identification of potent 7-amino analogs

A more efficient preparation of 4-[(2,4-dichloro-5-methoxyphenyl)amino]-7-fluoro-6-methoxy-3-quinolinecarbonitrile (2), the penultimate intermediate in the synthesis of bosutinib (1a), was developed. New 7-alkoxy-4-phenylamino-3-quinolinecarbonitrile Src inhibitors were prepared from 5 and 9, the 6-ethoxy and 6-hydrogen analogs of 2. In addition, the fluoro group of 2 was readily displaced by primary and secondary amines to give 7-amino analogs. Two of these 7-amino analogs, 15 and 18, were potent Src inhibitors with in vivo activity.     

Regulation of sterol biosynthesis in yeast: induction of 3-hydroxy-3-methylglutaryl-CoA reductase by glucose

Anaerobically cultured yeast cells have a very low HMG-CoA reductase activity and a low sterol content. When these cells are transfered to phosphate buffer containing 1.2 % glucose and held under aerobic conditions, the specific activity of the HMG-CoA reductase increases up to sixfold within 8 hrs. The increase in the reductase activity is paralled by an increase in the sterol content. This induction of HMG-CoA reductase in resting yeast cells is inhibited by cycloheximide indicating that a $\text{de novo}$ synthesis of enzyme protein is mediated by glucose under aerobic conditions. It appears that the regulation of sterol synthesis in yeast is closely connected with the aerobic glucose metabolism.     

酵母微生物油脂的生物合成研究

摘要：目的 微生物油脂可作为制备绿色能源生物柴油的原料。对酵母微生物油脂的生物合成方法进行研究。方法 以斯达油脂酵母Lipomyces starkeyi AS 2.1560为菌种进行微生物油脂生物合成。首先获得大量细胞,将细胞收集后,转移至葡萄糖溶液中进行油脂合成。结果 斯达油脂酵母可在不含有其他营养成分的葡萄糖溶液中快速合成油脂,细胞油脂含量可达到细胞干重的60%以上。菌龄对油脂生成影响不明显,糖浓度过高抑制油脂生成,40 g/L葡萄糖溶液中60 h合成油脂最多,达到65.2%,并有进一步积累的可能,在（0.5～6）×108个/mL,接种细胞的密度越大,油脂合成能力越低。合成油脂成分主要为棕榈酸和油酸。结论 斯达油脂酵母细胞增殖与油脂生物合成可分开进行,其油脂成分与普通动植物油脂成分相似。     

Multiple potential clinical benefits for 1alpha,25-dihydroxyvitamin D3 analogs in kidney transplant recipients

Therapeutic trials of 1alpha,25(OH)(2)D(3) and related synthetic analogs are merited in diverse clinical fields, including treatment or prevention of bone disease, cancer, immune-mediated diseases, cardiovascular diseases, and prostatic hypertrophy. Potential difficulties of carrying out such trials successfully, include experimental data suggesting relatively modest therapeutic effects of 1alpha,25(OH)(2)D(3) analogs as stand-alone intervention and the likely requirement for large study group size and lengthy follow-up periods, if individual prophylactic effects are to be proven. Thus, it may be wise to identify patient groups with multiple potential benefits, accelerated disease risks, and the possibility for exploring synergistic pharmacological effects, in whom to carry out clinical trials of 1alpha,25(OH)(2)D(3) analogs. With this consideration in mind, the suitability of kidney transplant recipients for such studies is discussed. Although, highly effective in reversing end-stage renal disease, kidney transplantation continues to be limited by heightened risk of osteoporosis, persistent hyperparathyroidism, acute and chronic immunological injury, new cancer diagnosis, and cardiovascular events. In addition, kidney transplant recipients generally receive multiple immunosuppressants with a high prevalence of medication-related toxicities. Finally, it is pointed out that clinical trials carried out in organ transplant recipients provide a unique opportunity for longitudinal comparison of target tissue structural and gene expression profiles among treated and control patient groups. It is proposed that addition of a 1alpha,25(OH)(2)D(3) analog to conventional post-kidney transplant medication regimens is likely to be associated with measurable effects to prevent or retard multiple important complications and that this patient group is especially suitable for carrying out clinical trials of these compounds.