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Valbenazine (VBZ) is a selective synaptic vesicle monoamine transporter 2 (VMAT2) inhibitor that counteracts the increased activity of the dopamine system by inhibiting VMAT2 activity, reducing the uptake and storage of monoamines from the cytoplasm into presynaptic vesicles, and decreasing the concentration of monoamines released into the synapse. VBZ is the first drug approved by the US FDA for using in adult patients with tardive dyskinesia. Compound P109 is a structural modification product of VBZ, which is substituted by cyclopropane methyl at position 9. It has similar pharmacological activity and pharmacological mechanism as VBZ. In order to study its metabolites in the human liver microsome incubation system, a Waters Eclipse Plus C18 column (150 mm×2.1 mm×3.5 μm) was used for separation, and 0.1% formic acid water (A)-0.1% formic acid acetonitrile (B) as the mobile phase for gradient elution. The high performance liquid chromatography coupled with four stage electrostatic field Orbitrap mass spectrometry (UHPLC-Q ExactiveTM-Orbitrap MS) was used to analyze samples in positive ion mode. Nine compounds (including P109 and its 8 metabolites) were screened, and retention time, accurate mass measurement results and fragmentation patterns were all characterized. By using the Xcaliber4.2 workstation, the accurate molecular mass was used to infer the possible element composition, and then combined with the mass spectrometry fragment information for data processing. The molecular formula prediction module was used to predict the molecular formula of the parent ion and the fragment ion, and to identify the structure of in vitro metabolites of P109. The results showed that P109 undergoes three main metabolic pathways via human liver microsomes: 1) Oxidation reaction occurs to produce compounds 2, 4 and 9; 2) Hydrolysis reaction occurs to produce metabolites 1, 3, 7 and 8; 3) Decyclopropanemethyl reaction occurs to produce metabolite 5. The reaction phenotypes of seven cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4) were studied using specific chemical inhibitor inhibition method. The content of P109 metabolites was determined by HPLC-MS/MS, and the data was analyzed by Excel software. The results showed that oxidative metabolites and dehydrogenation metabolite were mainly metabolized by CYP3A4, and the secondary metabolic subtype was CYP2C8. The decyclopropane-methyl metabolites were mainly metabolized by CYP2C8, and the secondary metabolites were CYP3A4 and CYP2D6. Hydrolysis of metabolites involved multiple subtypes of enzymes. This study can help to clarify the metabolic pathways of drugs in vivo, which is of great significance to the research of pharmacokinetics, pharmacodynamics, and drug safety evaluation. At the same time, it provides theoretical support for extrapolating the results of in vitro experiments to in vivo experiments.

Valbenazine (VBZ) is a selective synaptic vesicle monoamine transporter 2 (VMAT2) inhibitor that counteracts the increased activity of the dopamine system by inhibiting VMAT2 activity, reducing the uptake and storage of monoamines from the cytoplasm into presynaptic vesicles, and decreasing the concentration of monoamines released into the synapse. VBZ is the first drug approved by the US FDA for using in adult patients with tardive dyskinesia. Compound P109 is a structural modification product of VBZ, which is substituted by cyclopropane methyl at position 9. It has similar pharmacological activity and pharmacological mechanism as VBZ. In order to study its metabolites in the human liver microsome incubation system, a Waters Eclipse Plus-C18 column (150 mm×2.1 mm×3.5 μm) was used for separation, and 0.1% formic acid water (A)-0.1% formic acid acetonitrile (B) as the mobile phase for gradient elution. The high performance liquid chromatography coupled with four stage electrostatic field Orbitrap mass spectrometry (UHPLC-Q ExactiveTM Orbitrap MS) was used to analyze samples in positive ion mode. Nine compounds (including P109 and its 8 metabolites) were screened, and retention time, accurate mass measurement results and fragmentation patterns were all characterized. By using the Xcaliber4.2 workstation, the accurate molecular mass was used to infer the possible element composition, and then combined with the mass spectrometry fragment information for data processing. The molecular formula prediction module was used to predict the molecular formula of the parent ion and the fragment ion, and to identify the structure of in vitro metabolites of P109. The results showed that P109 undergoes three main metabolic pathways via human liver microsomes: 1) Oxidation reaction occurs to produce compounds 2, 4 and 9; 2) Hydrolysis reaction occurs to produce metabolites 1, 3, 7 and 8; 3) Decyclopropanemethyl reaction occurs to produce metabolite 5. The reaction phenotypes of seven cytochrome P450 isoenzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4) were studied using specific chemical inhibitor inhibition method. The content of P109 metabolites was determined by HPLC-MS/MS, and the data was analyzed by Excel software. The results showed that oxidative metabolites and dehydrogenation metabolites were mainly metabolized by CYP3A4, and the secondary metabolic subtype was CYP2C8. The decyclopropane-methyl metabolites were mainly metabolized by CYP2C8, and the secondary metabolites were CYP3A4 and CYP2D6. Hydrolysis of metabolites involved multiple subtypes of enzymes. This study can help to clarify the metabolic pathways of drugs in vivo, which is of great significance to the research of pharmacokinetics, pharmacodynamics, and drug safety evaluation. At the same time, it provides theoretical support for extrapolating the results of in vitro experiments to in vivo experiments. [ABSTRACT FROM AUTHOR]

The expression of a number of enzymes involved in drug metabolism, membrane function etc. was compared in hyperplastic and neoplastic lesions of the rat bladder and in human bladder tumours. Transitional cell carcinomas (TCC) in both rat and Man were characterized by decreased alkaline phosphatase (ALP) and increased gammaglutamyl transpeptidase (GGT), β-glucuronidase (β-Gl), succinate dehydrogenase (SD) and glucose-6-phosphate dehydrogenase (G6PD) activities. In addition, binding for antibodies specific for different cytochrome P-450 species (UT, PB, MC, MC) and microsomal epoxide hydrolase (mEHb) was elevated in both murine and human tumours. Comparison of the enzyme phenotype in hyperplastic lesions induced by freeze ulceration or uracil administration with that in preneoplastic papillary or nodular hyperplasia (PNH) and TCC suggested, however, that most of the alteration in enzyme content or activity was non-specific and related to requirements for epithelial cell proliferation. On the other hand, the decreased ALP, and increased GGT and β - Gl activity appeared more directly related to neoplastic transformation. The results suggested that qualitative differences exist between reactive hyperplasia and preneoplastic or neoplastic lesions in the urinary bladder. The finding of increased cytochrome P-450, in clear contrast to the reduction characteristic of preneoplastic hepatic lesions, may be important with regard to the observed difference in neoplastic transformation between the bladder and liver in response to drug metabolising enzyme inducers. [ABSTRACT FROM AUTHOR]

The effect of 4 weeks dietary administration of the hormone dehydroepiandrosterone (DHEA) on enzyme and morphological phenotype of focal lesions previously induced by dimethylaminoazobenzene (DAB) treatment was investigated in Sprague-Dawley rats. In contrast to the DAB-alone livers where large numbers of glycogen-storing, mixed cell nodules homogeneously positive for glutathione S-transferase P form (GST-P) were apparent, DHEA treated animals were characterized by significantly fewer, more heterogeneous lesions, in some cases demonstrating increased amphophilia and structured basophilia. The enhanced heterogeneity, in some ways reminiscent of that reported earlier for 'reversibility' or 'remodelling' of rapidly induced nodular lesions, was associated with increased catalase (CAT), acid phosphatase (AP) and glucose-6-phosphatase (G6Pase) and decreased glycogen content and phosphorylase (PHO) activity in both nodules and background parenchyma. Glucose-6-phosphate dehydrogenase (G6PD) activity was elevated irregularly, focal lesions also demonstrating a heterogeneous reaction. The experimental data suggest two separate effects of the hormone treatment, the first involving modulation of the usual altered phenotype of preneoplastic lesions with a shift towards 'tigroid' cell character and the second, similar to that reported earlier for rapidly induced nodules, involving enhanced phenotypic instability and leading to reduction in numbers. [ABSTRACT FROM AUTHOR]

Focal proliferative and neoplastic lung lesions induced in Syrian hamsters by dihydroxy-di - n-propylnitrosamine (DHPN) were investigated using a combined histochemical, autoradiographic and electron microscopic approach. Expression of elevated glucose-6-phosphate dehydrogenase (G6PD) and gammaglutamyl-transpeptidase (GGT) activites and levels of immunohistochemically demonstrable glutathione S-transferase placental form (GST-P) were evident in epithelial cells of focal proliferative populations and bronchioloalveolar neoplasms. Binding for the GST-C form, normally only weak, became very pronounced in the stromal elements of DHPN-induced lesions. Increased labelling with tritiated thymidine was associated with increase in morphological atypia within the tumours. Although the enzyme phenotype findings were equivocal the presence of lamellar bodies in some cells of focal proliferative and neoplastic lesions suggested an origin from alveolar type II cells. The present results regarding changed enzyme phenotype in lung lesions suggest important similarities at the biochemical level for the process of neoplasia in the different target organs of DHPN in the hamster and indicate that GST-P may be a useful 'marker' for lung neoplasia. [ABSTRACT FROM AUTHOR]

Immunohistochemical investigation of focal proliferative and neoplastic Syrian hamster pancreatic lesions induced by propylnitrosamine administration revealed a distinct pattern of expression of different molecular forms of glutathione S-transferase (GST) during neoplastic development. Initial increase in levels of GST placental (P) and B forms in early ductal/ductular proliferations and atypical (dysplastic) lesions was followed by a drop in the latter during transition to carcinoma. Unequivocal acinar cells observed within so-called 'pseudoductules' did not share the altered phenotype evident in ductular elements, suggesting their non-involvement in the generation of early lesions. However, the fact that component cells were occasionally of abnormal morphology did not allow the exclusion of acinar cell participation in histogenesis. Elevation of GST-A and C forms was limited to stromal elements surrounding the epithelial lesions and since they were associated with benign, cystic as well as atypical lesions and a similar increase was observed after common duct ligation, they appeared to be non-specific. The results indicated independent control of expression of individual GST forms and suggested that biochemical similarities exist between early, putative preneoplastic lesions induced by propylnitrosamines in the hamster lung, liver (both hepatocellular and intrahepatic bile duct) and pancreas. [ABSTRACT FROM AUTHOR]

Intrahepatic bile duct and gallbladder preneoplastic and neoplastic lesions induced in Syrian golden hamsters by propylnitrosamine treatment were investigated for the presence of polysaccharides and assayed immunohistochemically for expression of the enzymes glucose-6phosphate dehydrogenase (G6PD) and glutathione-S-transferase (GST) molecular forms. On the basis of an increase in G6PD and the GST-placental form, a sequence of altered cell populations ranging from simple ductular proliferation through dysplasia and cholangiofibroma to cholangiocellular carcinoma could be established, the latter three lesions being characterized by marked increase in polysaccharide production. While similar goblet cell (intestinal) metaplasia and increased polysaccharide storage were also evident in carcinogen-induced gallbladder lesions G6PD and GST-P expression was decreased when compared with control epithelium. [ABSTRACT FROM AUTHOR]

A morphometric comparison of seven hypotriploid populations with five pooled triploid populations of Meloidogyne arenaria was made using standard descriptive statistics, stepwise discriminant analysis (SDA), and cluster analysis. Six morphometric characters of females, 14 of second-stage juveniles (J2), and 18 of males were measured for each population. Useful differentiating characters included: body length in J2; stylet length in females and J2; stylet-knob dimensions in females and males; dorsal esophageal gland orifice distance in all three life stages; esophagus-length ratio in males and J2; excretory pore position in J2; and spicule length in males. SDA and cluster analysis showed that in each life stage, the hypotriploid populations were set off to varying degrees from the triploid populations. In addition, the relationships among populations differed when different life stages were compared. No consistent relationships could be detected among the populations, when morphometric data of the present study and morphological findings of the same populations in a parallel study were considered. Morphometric differences were not sufficient to propose any of the hypotriploid populations as new species.