Glucuronidation of Entacapone, Nitecapone, Tolcapone, and Some Other Nitrocatechols by Rat Liver Microsomes

Purpose. Nitrocatechol COMT inhibitors are a new class of bioactive compounds, for which glucuronidation is the most important metabolic pathway. The objective was to characterize the enzyme kinetics of nitrocatechol glucuronidation to improve the understanding and predicting of the pharmacokinetic behavior of this class of compounds. Methods. The glucuronidation kinetics of seven nitrocatechols and 4-nitrophenol, the reference substrate for phenol UDP-glucuronosyltrans-ferase activity, was measured in liver microsomes from creosote-treated rats and determined by non-linear fitting of the experimental data to the Michaelis-Menten equation. A new method that combined densitometric and radioactivity measurement of the glucuronides separated by HPTLC was developed for the quantification. Results. Apparent K_m values for the nitrocatechols varied greatly depending on substitution pattern being comparable with 4-nitrophenol (0.11 mM) only in the case of 4-nitrocatechol (0.19 mM). Simple nitrocatechols showed two-fold V_max values compared with 4-nitrophenol (68.6 nmol min^–1 mg^–1), while all disubstituted catechols exhibited much lower glucuronidation rate. V_max/K_m values were about 10 times higher for monosubstituted catechols compared to disubstituted ones. The kinetic parameters for COMT inhibitors were in the following order: K_m nitecapone >> entacapone > tolcapone; V_max nitecapone > entacapone > tolcapone; V_max/K_m tolcapone > nitecapone > entacapone. Conclusions. Nitrocatechols can in principle be good substrates of UGTs. However, substituents may have a remarkable effect on the enzyme kinetic parameters. The different behaviour of nitecapone compared to the other COMT inhibitors may be due to its hydrophilic 5-substituent. The longer elimination half-life of tolcapone in vivo compared to entacapone could not be explained by glucuronidation kinetics in vitro.     

Statins, neuromuscular degenerative disease and an amyotrophic lateral sclerosis-like syndrome: an analysis of individual case safety reports from vigibase.

BACKGROUND: The WHO Foundation Collaborating Centre for International Drug Monitoring (Uppsala Monitoring Centre [UMC]) has received many individual case safety reports (ICSRs) associating HMG-CoA reductase inhibitor drug (statin) use with the occurrence of muscle damage, including rhabdomyolysis, and also peripheral neuropathy. A new signal has now appeared of disproportionally high reporting of upper motor neurone lesions. AIM AND SCOPE: The aim of this paper is to present the upper motor neurone lesion cases, with other evidence, as a signal of a relationship between statins and an amyotrophic lateral sclerosis (ALS)-like syndrome. The paper also presents some arguments for considering that a spectrum of severe neuromuscular damage may be associated with statin use, albeit rarely. The paper does not do more than raise the signal for further work and analysis of what must be regarded as a potentially very serious and perhaps avoidable or reversible adverse reaction, though it also suggests action to be taken if an ALS-like syndrome should occur in a patient using statins. METHODS: The 43 reports accounting for the disproportional reports in Vigibase (the database of the WHO Programme for International Drug Monitoring) are summarised and analysed for the diagnosis of an ALS-like syndrome. The issues of data quality and potential reporting bias are considered. RESULTS: 'Upper motor neurone lesion' is a rare adverse event reported in relationship to drugs in Vigibase (a database containing nearly 4 million ICSRs). Of the total of 172 ICSRs on this reported term, 43 were related to statins, of which 40 were considered further: all but one case was reported as ALS. In 34/40 reports a statin was the sole reported suspected drug. The diagnostic criteria were variable, and seven of the statin cases also had features of peripheral neuropathy. Of a total of 5534 ICSRs of peripheral neuropathy related to any drug in Vigibase, 547 were on statins. The disproportional reporting of statins and upper motor neurone lesion persisted after age stratification, and such disproportionality was not seen for statins and Parkinson's disease, Alzheimer's disease, extrapyramidal disorders, or multiple sclerosis-like syndromes. DISCUSSION: Because the cases were sometimes atypical we propose the use of the term 'ALS-like syndrome' and speculate whether this is part of a spectrum of rare neuromuscular damage. The diagnosis of ALS is often problematic, and the insidiousness and chronicity of the disease make causality with a drug difficult to assess. The disproportionally high reporting makes this an important signal nevertheless, since ALS is serious clinically and statins are so widely used. Wide use of the statins also makes a chance finding more probable, but is unlikely to cause disproportional reporting when there are no obvious biases identified. CONCLUSION: We emphasise the rarity of this possible association, and also the need for further study to establish whether a causal relationship exists. We do advocate that trial discontinuation of a statin should be considered in patients with serious neuromuscular disease such as the ALS-like syndrome, given the poor prognosis and a possibility that progression of the disease may be halted or even reversed.     

Probing the ability of the coat and vertex protein of the membrane-containing bacteriophage PRD1 to display a meningococcal epitope

Bacteriophage PRD1 is an icosahedral dsDNA virus with a diameter of 740 A and an outer protein shell composed of 720 copies of major coat protein P3. Spike complexes at the vertices are composed of a pentameric base (protein P31) and a spike structure (proteins P5 and P2) where the N-terminal region of the trimeric P5 is associated with the base and the C-terminal region of P5 is associated with receptor-binding protein P2. The functionality of proteins P3 and P5 was investigated using insertions and deletions. It was observed that P3 did not tolerate changes whereas P5 tolerated changes much more freely. These properties support the hypothesis that viruses have core structures and functions, which remain stable over time, as well as other elements, responsible for host interactions, which are evolutionally more fluid. The insertional probe used was the apex of exposed loop 4 of group B meningococcal outer membrane protein PorA, a medically important subunit vaccine candidate. It was demonstrated that the epitope could be displayed on the virus surface as part of spike protein P5.     

CDK4 is a probable target gene in a novel amplicon at 12q13.3-q14.1 in lung cancer

Several chromosomal regions are recurrently amplified or deleted in lung tumors, but little is known about the underlying genes, which could be important mediators in tumor formation or progression. In lung cancer, the RB1-CCND1-CDKN2A pathway, involved in the G1-S transition, is damaged in nearly all tumors. In the present study, we localized a novel amplicon in lung tumors to a fragment of less than 0.5 Mb at 12q13.3-q14.1 by using comparative genomic hybridization (CGH) on cDNA microarrays. This approach enabled us to identify 10-15 genes with the most consistent amplifications. Semiquantitative RT-PCR analyses of 13 genes in this region showed that four of them (CDK4, CYP27B1, METTL1, and TSFM) were also highly up-regulated. Immunohistochemical (IHC) analysis of 141 tumor samples on a tissue microarray showed that CDK4 was expressed at a high level in 23% of lung tumors. Six (21.4%) of the tumors with high CDK4 expression (n = 28) were shown by fluorescence in situ hybridization (FISH) to contain the 12q13.3-q14.1 amplification. For CDK4, a positive correlation was found between gene copy number (FISH and CGH array), mRNA expression (RT-PCR), and level of protein expression (IHC). CDK4 expression did not correlate with CDKN2A methylation status. Amplification of CDK4 has been described in other tumor types, but its role in lung cancer remains to be elucidated. Although CDK4 amplification seems to be a relatively rare event (4.3%) in lung tumors, it indicates the significance of the RB1-CCND1 pathway in lung tumorigenesis.     

Comparative typing of Campylobacter jejuni by heat-stable serotyping and PCR-based restriction fragment length polymorphism analysis

Campylobacter jejuni has become the most common bacterial cause of human gastroenteritis worldwide. Rapid, discriminatory typing methods are required to identify potential clusters of infections. The major disadvantage of the well-evaluated and widely used Penner heat-stable serotyping method is the high level of nontypeability. The correlation of the types determined by the Penner heat-stable serotyping method and PCR-based restriction fragment length polymorphism (RFLP) analysis of the lipooligosaccharide (LOS) biosynthesis genes of C. jejuni was studied with 149 C. jejuni strains. Of these strains, 79 were patient strains belonging to 25 Penner serotypes, 60 were nontypeable patient strains, and 10 were reference strains. A 9.6-kb DNA fragment of the LOS gene cluster was amplified and digested with the restriction enzymes HhaI and DdeI. Altogether, 39 different RFLP types (including 30 HhaI profiles and 32 DdeI profiles) were identified. Type Hh1Dd1 was the most common type, with 36% of the strains and strains of 12 serotypes being of this type. A high level of discrimination was obtained, and a correlation between the Penner serotypes and the PCR-RFLP types could be seen. Also, variation in the LOS biosynthesis genes within a single Penner serotype was found. Although the PCR-RFLP method may not be sufficient to compensate for Penner serotyping, it can give valuable information about nontypeable strains and further characterize strains of common serotypes.     

Haplotype analysis in gelsoiin-related amyloidosis reveals independent origin of identical mutation (G654A) of gelsolin in Finland and Japan

Familial amyloidosis, Finnish type (FAF) (gelsolin-related amyloidosis) is an autosomal dominant form of systemic amyloidosis characterized by corneal lattice dystrophy and peripheral polyneuropathy. The accumulating protein in FAF consists of fragments of gelsolin, an actin-modulating protein. The gelsolin mutation G654A has been found in both Finnish and Japanese patients. To study the origin of the gelsolin mutation in these patients we performed haplotype analysis in 10 Finnish and 2 Japanese FAF families. Poymorphic DNA markers GSN, D9S103, AFMa061xd9, and AFMa139xb9 revealed a uniform disease haplotype in all the disease-associated chromosomes of the Finnish FAF families, which was different from the one observed in the Japanese families. The present results and the previously detected gelsolin mutation G654T in Czech and Danish FAF patients suggest that nucle otide 654 may represent a mutation hot spot in the gelsolin gene. The DNA markers studied here will be useful in future genealogical analyses of FAF. © 1995 Wiley-Liss, Inc.     

Effects of the androgenic anabolic steroid, nandrolone decanoate, on adrenocorticotropin hormone, corticosterone and proopiomelanocortin, corticotropin releasing factor (CRF) and CRF receptor1 mRNA levels in the hypothalamus, pituitary and amygdala of the rat

There is increasing abuse of androgenic anabolic steroids (AAS) by non-athletes. AAS abuse has been associated with psychiatric symptoms such as mania, major depression and aggression and the development of dependence. Little is known about the effects of AAS on hypothalamic-pituitary-adrenal axis function or corticotropin releasing factor, which may be involved in mediating some of the psychiatric symptoms associated with AAS abuse. Male Sprague-Dawley rats received one daily intra-muscular injection of the AAS nandrolone decanoate (ND, 15 mg/kg) or vehicle for 3 days. Animals were sacrificed either 1 h or 24 h after the last injection, brain regions dissected and trunk blood collected. Corticotropin releasing factor (CRF), CRF receptor1 (CRF-R1) and proopiomelanocortin (POMC) mRNAs were measured with solution hybridization/RNase protection. Circulating levels of corticosterone and adrenocorticotropin hormone (ACTH) were determined using radioimmunoassays. One hour following the last injection, ND significantly increased circulating levels of both corticosterone and ACTH levels. In the amygdala, CRF mRNA levels were unchanged 1 h after the last injection of ND but were significantly reduced at 24 h. The same was found for hypothalamic POMC. No significant AAS effects were observed on: hypothalamic CRF mRNA; POMC mRNA in the amygdala or CRF R1 mRNA in the anterior pituitary.