Transformation of Cochliobolus lunatus with pUT 720 changes the steroid hydroxylating ability of the fungus

Summary The filamentous fungus Cochliobolus lunatus, a known 11-hydroxylator of steroids, was transformed to bleomycin resistance using the heterologous plasmid pUT 720. This plasmid contains the Sh ble gene expressed under the control of the Aspergillus nidulans gpd and trpC expression signals. The bleomycin-resistant colonies appeared with a frequency of six per g of DNA. All colonies were real transformants and no abortive growth was observed. In all transformants tested the plasmid molecules became stably integrated into the genome of the host, and one of the plasmid molecules integrated in a site-specific manner. Transformants retained the ability to hydroxylate the steroid ring, but the hydroxy group was inserted at the 15 position.     

CYP2D6 genotyping strategy based on gene copy number determination by TaqMan real-time PCR

The genetic polymorphism of the cytochrome P450 monooxygenase, CYP2D6, comprises at least 43 alleles giving rise to distinct drug metabolism phenotypes termed ultrarapid, extensive, intermediate, and poor metabolizers. As a consequence, drug side effects or lack of drug effect may occur if standard doses are applied. Genetic prediction of drug oxidation phenotype as a basis for dose selection requires analysis of single nucleotide polymorphisms and of alleles with duplicated or deleted genes. Here we developed a novel method to determine the CYP2D6 gene dose per genome. A TaqMan real-time PCR assay to specifically amplify genomic CYP2D6 was established by using a specific set of amplification primers and probe, located in exon 9, which effectively prevent amplification of CYP2D7 and CYP2D8 pseudogenes. Quantitative CYP2D6 amplification data were normalized to albumin as an internal reference gene which was coamplified simultaneously in a single-tube biplex assay. The assay was validated with a selection of previously genotyped DNA samples containing none, one, two, or three CYP2D6 gene copies. The results were highly reproducible and closely matched the number of genes with no overlap between the groups. Analysis of DNA samples comprising all major alleles and genotypes revealed high sensitivity and specificity of the assay, as demonstrated by agreement of the determined gene dose with the presence of CYP2D6(*)2 x 2 (gene duplication) and CYP2D6(*) 5 (gene deletion) alleles. The predictability of the new strategy was systematically evaluated. The semiautomatic TaqMan assay allows high sample throughput and will be useful for pharmacogenetic studies and in the clinical setting.     

Rapid hydroxylation of methtryptoline (1-methyltetrahydro-β-carboline) in rat: Identification of metabolites by chiral gas chromatography-mass spectrometry

Summary Racemic methtryptoline (1-methyltetrahydro--carboline) and 5-hydroxymethtryptoline-9-carboxylic acid (6-hydroxy-1-methyltetrahydro--carboline-1-carboxylic acid) were administered intraperitoneally to rats and the components of their urine was subsequently investigated by chiral gas chromatography-mass spectrometry. Methtryptoline rapidly became hydroxylated in the 5- and 6-position and excreted in urine. There was about a ninefold predominance of the S(–) enantiomer over the other in the 5-hydroxylated species, while the 6-hydroxylation produced a small excess of the R(+) enantiomer. About 75% of the injected dose of methtryptoline was recovered in the urine as 5- and 6-hydroxylated compounds during the first 24 h period, demonstrating that hydroxylation represents the major metabolic pathway. Treatment with 6-hydroxymethtryptoline-9-carboxylic acid led to a fivefold increase in the urinary excretion of 5-hydroxymethtryptoline during the first 24 h period with a predominance of the S(–)-enantiomer, indicating a much smaller conversion rate than from methtryptoline. It was concluded that hydroxylation of methtryptoline is a likely pathway for the natural formation of 5-hydroxymethtryptoline.     

Effects of LSD and BOL on the catecholamine synthesis and turnover in various brain regions

In the rat, lysergic acid diethylamide (LSD) 0.5 mg/kg and 2-bromo lysergic acid diethylamide (BOL) 0.5 mg/kg increased the rate of the striatal in vivo tyrosine hydroxylation as measured by the DOPA accumulation after decarboxylase inhibition. Neither LSD nor BOL significantly changed the DOPA accumulation in the olfactory tubercle, a dopamine-rich part of the limbic system. LSD but not BOL increased the DOPA accumulation in the cerebral cortex and in the brain stem. LSD and BOL appeared not to alter the rate of -MT-induced disappearance of DA or of NA in the whole brain, nor did they change the rate of the -MT-induced disappearance of DA in the striatum. It is suggested that in the striatum LSD and BOL block autoreceptors (presynaptic receptors) regulating the tyrosine hydroxylation. These receptors may be DA receptors, but may also be 5-HT- or LSD-sensitive receptors.The regional differences observed between LSD and BOL suggest that LSD in the cerebral cortex and in the brain stem increases the DOPA accumulation by mechanism other than that functioning in the striatum. One possible explanation is that LSD and BOL may differ in their effects on 5-hydroxytryptaminergic systems in the cerebral cortex and in the brain stem.     

Effects of Diethyl Phthalate and Other Plasticizers on Laurate Hydroxylation in Rat Liver Microsomes

Diethyl phthalate (DEP) is used in pharmaceutical coatings, cosmetics, and plastic films to wrap foods. There is a health concern associated with the exposure to certain phthalate esters because they belong to a class of compounds referred to as peroxisome proliferators which have been shown to increase the incidence of liver tumors when administered to rats. In this study, we have compared DEP to four other commonly used plasticizers, 2-diethylhexyl phthalate (DEHP), dibutyl phthalate (DBP), 2-diethylhexyl adipate (DEHA), and acetyltributyl citrate (ATBC), for their ability to induce the cytochrome P450-mediated fatty acid -hydroxylation system, which is one of the initial cellular responses when animals are treated with peroxisome proliferators. The administration of DEHP, DBP, and DEHA to rats increased the specific activity of laurate 12-hydroxylase from 2.8 ± 1.1 in control rats to 30.3 ± 11.6, 14.5 ± 4.1, and 9.7 ± 1.9 nmol 12-hydroxylaurate formed/min/nmol P450, respectively. In contrast, laurate 12-hydroxylase activity in DEP-and ATBC-treated rats were 4.4 ± 1.2 and 4.4 ± 1.0 nmol 12-hydroxylaurate formed/min/nmol P450, respectively. In addition, whereas DEHP increased peroxisomal palmitoyl-CoA oxidation 6-fold, DEP increased this activity only 1.3-fold. Two protein bands, at 51 and 52 kDa, were found to increase 6- to 12-fold in microsomes of DEHP-, DBP-, and DEHA-treated rats, but these bands were increased only 2-fold in DEP- or ATBC-treated rats.     

Alterations of Collagen Matrix in Weight-Bearing Bones during Skeletal Unloading

Skeletal unloading induces loss of bone mineral density in weight-bearing bones. The objectives of this study were to characterize the post-translational modifications of collagen of weight-bearing bones subjected to hindlimb unloading for 8 weeks. In unloaded bones, tibiae and femurs, while the overall amino acid composition was essentially identical in the unloaded and control tibiae and femurs, the collagen cross-link profile showed significant differences. Two major reducible cross-links (analyzed as dihydroxylysinonorleucine and hydroxylysinonorleucine) were increased in the unloaded bones. In addition, the ratios of the former to the latter as well as pyridinoline to deoxypyridinoline were significantly decreased in the unloaded bones indicating a difference in the extent of lysine hydroxylation at the cross-linking sites between these two groups. These results indicate that upon skeletal unloading the relative pool of newly synthesized collagen is increased and it is post-translationally altered. The alteration could be associated with impaired osteoblastic differentiation induced by skeletal unloading that results in a mineralization defect.     

Oxygen sensing; a stunningly elegant molecular machinery highjacked in cancer

Oxygen is of fundamental importance for most living organisms, and the maintenance of oxygen homeostasis is a key physiological challenge for all large animals. Oxygen deprivation, hypoxia, is a critical component of many human diseases including cancer, heart disease, stroke, vascular disease, and anaemia. The discovery of oxygen sensing provides fundamental knowledge of a stunningly elegant molecular machinery; it also promises development of new therapeutics for serious diseases such as cancer. As a result of their impressive contributions to our understanding of the mechanisms by which cells sense oxygen and signal in hypoxia, Gregg Semenza, Peter Ratcliffe, and William Kaelin were awarded the Nobel Prize in 2019.     

Synthesis of [18O2]‐curcumin

Curcumin, a pigment isolated from rhizomes of Curcuma longa, is a potent cancer chemopreventive and chemotherapeutic agent and is now evaluated in phase III human clinical trials. This report describes an efficient synthesis of [¹⁸O₂]‐curcumin. [¹⁸O₂]‐Curcumin was prepared in three steps from 1‐iodo‐2‐methoxy‐4‐methylbenzene in an overall yield of 53%.     

球孢白僵菌、少根根霉和产黄青霉对广藿香醇生物转化的作用研究

目的应用生物转化法对广藿香醇的进行羟基化修饰。方法选择真菌球孢白僵菌、少根根霉和产黄青霉对广藿香醇进行生物转化。转化产物经过凝胶、硅胶柱层析及制备型高效液相色谱法分离纯化,进而采用MS、NMR技术鉴定转化产物结构。结果广藿香醇经球孢白僵菌转化得到3个产物,分别为12-羟基广藿香醇(1)、8S-羟基广藿香醇(2)以及5R-羟基广藿香醇(3);经少根根霉转化得到3个产物,分别为3R-羟基广藿香醇(4)、8S-羟基广藿香醇(2)以及5R-羟基广藿香醇(3);经产黄青霉转化得到2个产物,分别为6R-羟基广藿香醇(5)和7S-羟基广藿香醇(6)。结论化合物1~6均为广藿香醇的羟基化衍生物。