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Human pharmacogenetics of methyl conjugation.

Methyl conjugation is an important pathway in drug metabolism. Activities of three human drug-metabolizing methyltransferase enzymes, catechol-O-methyltransferase (COMT) (EC 2.1.1.6), thiopurine methyltransferase ( TPMT ) (EC 2.1.1.67), and thiol methyltransferase (TMT) (EC 2.1.1.9), are controlled by inheritance. COMT activity in the red blood cell (RBC) is regulated by a single genetic locus with two alleles, COMTL for low activity and COMTH for high activity. Gene frequencies of these two alleles were approximately equal in a white population sample of Northern European origin. The genetically controlled level of COMT activity in the RBC reflects the level of enzyme activity in other tissues and is significantly correlated with individual variations in the methyl conjugation of catechol drugs such as L-dopa and methyldopa. TPMT catalyzes the S-methylation of thiopurines and thiopyrimidines . RBC TPMT activity is also controlled by a single genetic locus with two alleles, TPMTL for low and TPMTH for high activity. The gene frequencies of these two alleles were 0.06 and 0.94, respectively, in a white population sample. RBC TPMT activity reflects the level of enzyme activity in other cells and tissues such as the lymphocyte and kidney. TMT catalyzes the S-methylation of aliphatic sulfhydryl compounds such as the drugs captopril and D-penicillamine. The heritability of the level of RBC membrane TMT activity has been estimated on the basis of family studies to be approximately 0.98. Regulation of these three methyl-conjugating enzymes by inheritance raises the possibility that genetically determined methylator status may be one factor responsible for variations in drug metabolism in humans.

Alleles↗

Dopamine metabolism in red blood cells in schizophrenia.

A method was developed for the separation by thin-layer chromatography of 14C-labelled 3-methoxy, 4-hydroxyphenethylamine, 3-hydroxy, 4-methoxyphenethylamine and 3,4-dimethoxyphenethylamine (DMPEA) after incubation of dopamine with catechol-O-methyltransferase (COMT) in lysates of human red blood cells (RBC). 14 C-methyl-S-adenosyl-menthionine was used as the methyl donor. Total COMT activity with noradrenaline or dopamine as substrates, respectively, and the pattern of 14C-methylated metabolites of dopamine were measured in RBC of 47 schizophrenic patients and in 34 control subjects. There were no differences between patients and controls. DMPEA was not formed by RBC in schizophrenic patients (or in controls), a finding which argues against the "pnk spot"/DMPEA hypothesis of schizophrenia. The methods used seem suitable for studies of other human disorders where COMT might be involved.

5-Methoxytryptamine↗

[Influence of 4-methylesculetol on the response of segments of isolated coronary arteries to adrenaline, in presence of pyrogallol].

The adrenaline (AD) induced relaxation in the smooth muscle is increased by bioflavonoids, possibly via cathecol-0-methyltransferase (COMT) inhibition. In order to test this hypothesis, we studied the influence of 4-methylesculetin (4-Me), alone or associated with ascorbic acid, on the response of isolated coronary strips to AD, in the presence of pyrogallol. Both 4-Me being enhanced by the addition of ascorbic acid. The effects were reduced or abolished in the presence off pyrogallol, a well known COMT inhibitor. It is concluded that 4-Me inhibits COMT, as other bioflavonoids.

Animals↗

The activity of catechol-O-methyltransferase and monoamine oxidase in the uterine artery of pigs during the oestrous cycle.

Activities of catechol-O-methyltransferase (COMT), total monoamine oxidase (MAO) and both types of MAO-A and MAO-B activities were examined in uterine artery on the 0-2nd, 13-14th and 16-18th days of the oestrous cycle in pigs. It was shown that activity of COMT was the lowest on the 0-2nd day, while on the 16-18th day of the oestrous cycle it increased by 52.4% (p < 0.05). Total activity of MAO was the highest at periovulatory phase, whereas on days 13-14 and 16-18 of oestrous cycle is was lower by 83.5% (p < 0.01) and 58.1% (p < 0.01) compared with its activity at periovulatory phase, and was higher on day 16-18 by 153.3% (p < 0.01) in relation to the luteal phase (13-14th day). MAO-A activity was 31.3% (p < 0.01) and MAO-B 62.5% (p < 0.05) of the total activity of MAO. Their activities were also highest at periovulatory phase, then decreased by 86.8-87.4% (p < 0.01) on 13-14th day and by 54.8-57.5% (p < 0.01) or 16-18th day of oestrous cycle. Activities of MAO-A and MAO-B were higher by 223.0-258.2% (p < 0.01) on 16-18th day in relation to the luteal phase (13-14th day). On that base we suppose that variations of COMT and MAO activities can significantly change the catecholamines content in the blood vessels of reproductive organs of pigs.

Animals↗

The role of monoamine oxidase and catechol O-methyltransferase in dopaminergic neurotransmission.

The action of dopamine (DA) released in the synaptic cleft is mainly terminated by its reuptake and catabolism by the enzymes monoamine oxidase (MAO) and catechol O-methyltransferase (COMT). Preclinical data show that the reduction of the catabolism of DA elicited by MAO and COMT inhibitors leads to an enhancement of DA neurotransmission. Moreover, there is evidence suggesting that MAO-B inhibition might protect DA neurons from oxidative stress. Nevertheless, due to differences in enzyme localization and activity between man and rodents, results obtained in experimental animals might not reflect the actual situation in humans. Today the availability of potent and selective MAO and COMT inhibitors makes it feasible for the clinician to test whether the blockade of catabolic enzymes would result in a symptomatic improvement in Parkinsonian patients, and whether MAO-B inhibition might additionally exert a neuroprotective effect.

Catechol O-Methyltransferase↗

Pharmacokinetics of continuous-release carbidopa/levodopa.

This article reviews the pharmacokinetics of Sinemet CR, a controlled-release (CR) levodopa preparation. The main influences on the kinetic profile are as follows: absorption, which depends on the dissolution characteristics of the tablet, the pattern of gastric emptying, and the rate of uptake in the small intestine; distribution, which is determined by rates of levodopa transport from gut to blood and from blood to brain; and biotransformation, which is affected peripherally by L-aromatic amino acid decarboxylase (LAAAD) and catechol-O-methyl transferase (COMT), and centrally by LAAAD, COMT, and monoamine oxidase. The kinetics of Sinemet CR are limited by rates of absorption (which depend on the dose administered), the conformation of the tablet, and daily variations in the patterns of gastric emptying (influenced by the presence or absence of food). Levodopa must also compete with food-derived amino acids for transport across the gut-blood and blood-brain barriers; this competition effectively limits the drug's rate of distribution. Finally, biotransformation is limited by the activity of LAAAD and COMT in the periphery. Plasma profiles of levodopa after administration of Sinemet CR can vary, depending on the age of the patient and the time of day when the drug is administered. Nevertheless, the pharmacokinetic profile of the preparation has a number of advantages over that of Sinemet, in that it offers a steadier climb to peak plasma concentrations that are less extreme and of greater duration.

Aging↗

Cyclic GMP, cyclic AMP, glucose at birth, and maturation of rat liver mitochondria.

The improvement in mitochondrial functions which normally occurs in newborn rat liver in vivo during the few hours following delivery is inhibited by a glucose injection at birth (Meister, R., Comte, J., Baggetto, L., G., Godinot, C. and Gautheron, D.C. (1983) Biochim. Biophys. Acta 722, 36-42). To test whether this improvement could be correlated to changes in cyclic nucleotides, the levels of cAMP and cGMP have been measured during the 2 h following birth. At birth, a short rise followed by a decrease of cAMP occurs, then a significant increase of cAMP level is observed between 45 min and 2 h. The cAMP level for animals injected at birth with glucose is lower than for control animals at each time studied. The cGMP level is not significantly affected in control animals, while in glucose-treated animals a significant decrease of cGMP is observed in the postnatal 2 h. The present work shows also that the glucose-induced inhibition of mitochondrial maturation is mimicked by injection at birth of either 8-Br-cGMP or nitroprusside. The latter transiently increases intracellular cGMP. In contrast, the glucose-induced inhibition is prevented by the injection at birth of either dbcAMP or alkylxanthines together with glucose (Comte, J., Meister, R., Baggetto, L.G., Godinot, C. and Gautheron, D.C. (1986) Biochem. Pharmacol. 35, 2411-2416). It is concluded that the postnatal improvement of mitochondrial functions is stimulated by cAMP and inhibited by cGMP, and that glucose-induced inhibition of the maturation is at least partly supported by a decrease in cAMP but not correlated to an increase in cGMP.

Adenosine Diphosphate↗

Associations between (pharmaco-)genetic markers and postoperative pain after inguinal hernia repair - a prospective study protocol.

BACKGROUND: Postoperative pain is a common complication following surgery, with severity and duration varying between patients. Chronic postoperative pain after inguinal hernia surgery has an incidence rate of approximately 10%. Risk factors for acute and chronic pain following hernia surgery include age, sex, psychosocial factors, and demographic background. Additionally, genetic polymorphisms in enzymes involved in pain mechanisms, as well as the metabolism of analgesics might influence pain perception, pain development, and response to pain medications. Key enzymes include the catechol-o-methyltransferase (COMT), the &#xb5;-opioid receptor 1 (OPRM1), and the cytochrome P450 2D6 (CYP2D6). CYP2D6 plays a crucial role in metabolizing analgesics such as tramadol, codeine, and oxycodone. It is also suspected to be involved in the synthesis of catecholamines and endogenous morphines suggesting a potential role in pathophysiology of pain. We hypothesize that the CYP2D6 activity influences the development of postoperative pain after hernia surgery. METHODS: This study is a prospective, observational, multicenter association study investigating adult patients scheduled for inguinal hernia surgery using a robotic-assisted (rTAPP) approach. Patients are enrolled during the preoperative surgical consultation. A buccal swab is collected for genetic testing at this time. Pain at the site of the hernia is assessed using the validated EuraHSQoL score preoperatively and at 2, 4, and 6&#xa0;weeks postoperatively. Additionally, information on co-medication and details of the surgery will be collected. The planned number of participants is 350 patients. The primary objective is to analyze the association between different genotype-predicted CYP2D6 phenotypes and patient-reported pain intensity 6&#xa0;weeks after surgery. Secondary objectives include the association between further genetic variants, such as the COMT rs4680 and OPRM1 rs1799971 genotype, and pain severity. Additionally, the potential of pharmacogenetic panel testing to optimize analgesic therapy in hernia surgery patients will be explored. DISCUSSION: The findings of this study are expected to provide valuable insights into identifying patients at higher risk for postoperative pain before surgery. This knowledge could pave the way for tailored interventions during and after surgery for these specific patients. TRIAL REGISTRATION: Deutsches Register Klinischer Studien https://www.drks.de/DRKS00034796 Registered on August 07, 2024.

Genetic Association Studies↗

Monoamine metabolism in human brain.

Norepinephrine (NE), dopamine (DA), tyrosine hydroxylase (TH), catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) levels were measured in human brain tissue obtained at autopsy from a series of 39 patients dying of various medical and accidental causes. The nine following brain areas were studied: globus pallidus, thalamus, hypothalamus, hippocampus, substantia nigra, floor of the fourth ventricle, orbital cortex, caudate nucleus, and mammillary bodies. Enzyme activity correlated positively with age in all brain areas for MAO (with both benzylamine and tryptamine substrates) but no consistent pattern of correlation was found for COMT and TH. Mean MAO activity was significantly higher in women than men. There is increased brain MAO activity during late childhood and adolescence. These data are consistent with previous evidence suggesting that age and sex are important determinants of amine metabolism in the human central nervous system.

Adolescent↗

High rates of schizophrenia in adults with velo-cardio-facial syndrome.

BACKGROUND: Velo-cardio-facial syndrome (VCFS), a syndrome characterized by an increased frequency of schizophrenia and bipolar disorder, is associated with small interstitial deletions of chromosome 22q11. METHODS: We evaluated 50 adults with VCFS using a structured clinical interview (Schedules for Clinical Assessment in Neuropsychiatry or Psychiatric Assessment Schedule for Adults With Developmental Disability if IQ <50) to establish a DSM-IV diagnosis. The schizophrenia phenotype in individuals with VCFS and schizophrenia was compared with a matched series of individuals with schizophrenia and without VCFS (n = 12). The King's Schizotypy Questionnaire was administered to individuals with VCFS (n = 41), their first-degree relatives (n = 68), and a series of unrelated normal controls (n = 316). All individuals with VCFS deleted for the N25 probe (n = 48) were genotyped for a genetic polymorphism in the COMT gene that results in variations in enzymatic activity. RESULTS: Fifteen individuals with VCFS (30%) had a psychotic disorder, with 24% (n = 12) fulfilling DSM-IV criteria for schizophrenia. In addition, 6 (12%) had major depression without psychotic features. The individuals with schizophrenia had fewer negative symptoms and a relatively later age of onset compared with those with schizophrenia and without VCFS. We found no evidence that possession of the low-activity COMT allele was associated with schizophrenia in our sample of individuals with VCFS. CONCLUSIONS: The high prevalence of schizophrenia in this group suggests that chromosome 22q11 might harbor a gene or genes relevant to the etiology of schizophrenia in the wider population.

Adolescent↗

Association of codon 108/158 catechol-O-methyltransferase gene polymorphism with the psychiatric manifestations of velo-cardio-facial syndrome.

Velo-cardio-facial-syndrome (VCFS) is a common congenital disorder associated with typical facial appearance, cleft palate, cardiac defects, and learning disabilities. The majority of patients have an interstitial deletion on chromosome 22q11. In addition to physical abnormalities, a variety of psychiatric illnesses have been reported in patients with VCFS, including schizophrenia, bipolar disorder, and attention deficit hyperactivity disorder. The psychiatric manifestations of VCFS could be due to haploin-sufficiency of a gene(s) within 22q11. One candidate that has been mapped to this region is catechol-O-methyltransferase (COMT). We recently identified a polymorphism in the COMT gene that leads to a valine-->methionine substitution at amino acid 158 of the membrane-bound form of the enzyme. Homozygosity for COMT158met leads to a 3-4-fold reduction in enzymatic activity, compared with homozygotes for COMT158val. We now report that in a population of patients with VCFS, there is an apparent association between the low-activity allele, COMT158met, and the development of bipolar spectrum disorder, and in particular, a rapid-cycling form.

Abnormalities, Multiple↗

Failure to replicate an association between the catechol-O-methyltransferase polymorphism and attention deficit hyperactivity disorder in a second, independently recruited Israeli cohort.

Attention deficit hyperactivity disorder (ADHD) is a developmental syndrome expressed along three domains: inattention, hyperactive-impulsive, and combined type. Both environmental and genetic factors contribute to the etiology of this complex disease. We previously reported an association in 48 ADHD triads (both parents and proband) between the catechol-O-methyl- transferase (COMT) polymorphism (especially the high enzyme activity val allele) and the Diagnostic and Statistical Manual of Mental Disorders (DSM IV) combined category (excluding inattention) of ADHD (however, see erratum, Am. J. Med. Genet. [Neuropsychiatr. Genet.] 96:893). In the current report, we attempted to replicate this finding in an independently recruited group of 70 nuclear families using the haplotype relative risk design. In the current investigation, no evidence for association of the COMT polymorphism and ADHD (or any of the DSM IV subtypes) was observed in either the current cohort or the expanded cohort of 118 Israeli triads. Am. J. Med. Genet. (Neuropsychiatr. Genet.) 96:858-860, 2000.

Attention Deficit Disorder with Hyperactivity↗

Evidence for an association with the serotonin transporter promoter region polymorphism and autism.

We have examined three functional polymorphisms, serotonin transporter promoter region polymorphism (5-HTTLPR), dopamine D4 exon III repeat region (DRD4), and catechol-O-methyltransferase (COMT), in a small family-based design toward identifying candidate genes that confer risk for autism. A significant excess of the long/long 5-HTTLPR genotype was observed (likelihood ratio = 7.18; P = 0.027; 2 df; n = 33 families) as well as preferential transmission of the long allele of the 5-HTTLPR (TDT chi-square = 5.44; P<0.025; 1 df). No association was observed between the COMT and DRD4 polymorphisms and autism in this sample. Some previous studies have observed linkage between autism and the 5-HTTLPR polymorphism and the current results are similar to those first reported by Klauck et al. [1997: Hum Genet 100:224-229; 1997: Hum Mol Genet 6:2233-2238]. Additionally, elevated serotonin levels have been consistently found in 30%-50% of autistic patients and may represent a marker for familial autism. Hyperserotonemia in autism appears to be due to enhanced 5-HT uptake, as free 5-HT levels are normal and the current report of an excess of the long/long 5-HTTLPR genotype in autism could provide a partial molecular explanation for high platelet serotonin content in autism.

Alleles↗

Evaluation of potential gene-gene interactions for attention deficit hyperactivity disorder in the Han Chinese population.

Several lines of evidence suggest that attention-deficit/hyperactivity disorder (ADHD) is a polygenic disorder produced by the interaction of several genes with minor effects. To explore potential gene-gene interactions among candidate genes for ADHD, we studied the dopamine D2 receptor (DRD2), dopamine D4 receptor (DRD4), dopamine transporter (DAT1), and catechol-O-methyltransferase (COMT) genes in the Han Chinese population. A sample of 340 children with ADHD was diagnosed according to the DSM-IV criteria. We also recruited 226 unrelated controls. Identified polymorphisms included a 48-base-pair-repeat in Exon 3 of DRD4, a 40-base-pair-repeat in the 3' untranslated region of DAT1, a restriction-fragment-length polymorphism at codon 158 of COMT, and a -241A > G transition in the promoter of DRD2. Associations of polymorphisms with ADHD and its subtypes were examined by comparing allele frequencies between probands and controls. Binary logistic regression analysis was used to examine the potential gene-gene interactions. Binary logistic regression analysis with the sample of refined phenotypes showed that male gender and long-repeat genotypes of DRD4 and DAT1 were independent risk factors for ADHD. We found no evidence for gene-gene interactions among the candidate genes studied. The present study suggests that dopamine candidate genes are associated with increased vulnerability to ADHD in the Han Chinese population.

Adolescent↗

A multigene test for the risk of sporadic breast carcinoma.

BACKGROUND: Although the identification of the BRCA1 and BRCA2 genes have been of great interest, these genes account for less than 5% of all breast carcinoma cases. The remaining cases are sporadic. Reanalysis of a large twin study suggested that genetic factors may play a significant role in sporadic breast and other carcinomas. Sporadic breast carcinoma is polygenically inherited. Multiple genes are likely to have an additive effect, each gene accounting for a fraction of the variance. One factor that may have an impact on the development of hormonally responsive breast tumors is the duration of exposure of the breast to estrogen. Therefore, one of the demographic risk factors for breast carcinoma is an early age of onset of menarche. The current study was based on the hypothesis that genes that play a role in demographic risk factors may be breast carcinoma risk genes in their own right. The authors hypothesized that six genes relevant to the timing of the onset of menarche and related risk factors might be candidate genes for breast carcinoma. These were the leptin gene (LEP), the leptin receptor gene (LEPR), the catechol-0-methyltransferase gene (COMT), the dopamine D(2) receptor gene (DRD2), the estrogen 1 receptor gene (ESR1), and the androgen receptor gene (AR). METHODS: The authors examined 67 women with postmenopausal sporadic breast carcinoma and 145 gender and race-matched controls. RESULTS: Five of these genes accounted for a significant percent of the variance (r(2)) of breast carcinoma. The following r(2) and P values were calculated: LEP: 0.073, P < or = 0.0001; LEPR: 0.064, P < or = 0.0002; COMT: 0.073, P < or = 0.0001; AR: 0.040, P < or = 0.0035; and DRD2: 0.018, P < or = 0.05. When evaluated in a multivariate regression analysis, they accounted collectively for 24% of the variance of breast carcinoma (P < or = 0.0001). These genes accounted for 40% of the variance (P < or = 0.00001) in a subset of age-matched cases. Individual gene scores were added to form a breast carcinoma risk score (BCRS) that ranged from 0 to 17. When the BCRS was evaluated in a receiver operator characteristic plot, the area under the curve was 0.80 for the full set and 0.869 for the age-matched set. The relative breast carcinoma risk for the different BCRS scores ranged from 0.10 to 11.9. CONCLUSIONS: These results demonstrate a potentially powerful method of evaluating the additive effect of multiple breast carcinoma risk genes to form a potentially clinically useful assessment of women's risk for sporadic breast carcinoma.

Adult↗

Théodule Ribot's ambiguous positivism: philosophical and epistemological strategies in the founding of French scientific psychology.

Théodule Ribot (1839-1916) is regarded by many historians of psychology as the "father" of the discipline in France. Ribot contributed to the development of a "new psychology" independent from philosophy, relying on the methods of the natural sciences. However, such an epistemological transition encountered fierce opposition from both the champions of the old-fashioned metaphysical psychology and the representatives of the "scientific spirit." This article focuses on the objections raised by the latter, and especially philosophers of science, against the possibility of a scientific psychology. For instance, according to Auguste Comte, psychology does not satisfy certain basic methodological requirements. To overcome these objections, Ribot, in his La Psychologie Anglaise Contemporaine (1870/1914), devised an epistemological strategy that amounted to invoking criticisms of Comte's views made by other representatives of the positivist school, such as John Stuart Mill and Herbert Spencer.

France↗

Lack of effect of polymorphisms in dopamine metabolism related genes on imaging of TRODAT-1 in striatum of asymptomatic volunteers and patients with Parkinson's disease.

SPECT scanning using (99)Tc-TRODAT-1, a ligand that binds to dopamine transporters, may be useful for detection of early Parkinson's disease (PD), diagnosis of presymptomatic individuals, and monitoring disease progression. Understanding whether genetic factors contribute to inter-individual variability is crucial for interpreting imaging results in the context of disease pathophysiology. We tested whether polymorphisms in the genes for catechol-O-methyltransferase (COMT), monoamine-oxidase B (MAO-B), and the dopamine transporter (DAT) influence dopamine uptake parameters in the striatum in vivo in asymptomatic volunteers and patients with PD as measured with (99)Tc-TRODAT-1. (99)Tc-TRODAT-1 binding declined with age in both asymptomatic volunteers and PD patients, and depended on disease duration in PD patients. We found no significant association between COMT, MAO-B, and DAT polymorphisms and results of (99)Tc-TRODAT-1 testing in asymptomatic volunteers or patients with PD. In PD patients, the age of disease onset and speed of progression did not differ based on these polymorphisms. These results demonstrate that these specific genetic variations do not alter the fidelity of (99)Tc-TRODAT-1 as a measure of dopaminergic function in asymptomatic volunteer individuals or patients with PD.

Adolescent↗

Coadministration of entacapone with levodopa attenuates the severity of dyskinesias in hemiparkinsonian rats.

Levodopa-induced dyskinesias (LIDs) have been associated with a sequence of events that includes pulsatile stimulation of dopamine receptors. The degree of nigrostriatal degeneration, the half-life of dopaminomimetic agents, and the dose of levodopa used to treat parkinsonian symptoms are factors directly correlated with the development of motor complications in Parkinson's disease patients. Long-acting agents producing continuous dopaminergic stimulation are less likely to prime for dyskinesia than short-acting drugs that produce pulsatile stimulation of dopamine receptors. Inhibition of the enzyme catechol-O-methyl transferase (COMT) by entacapone extends the half-life of levodopa and minimizes variability in plasma levodopa levels. The aim of the present study was to characterize the effect of the early administration of the COMT inhibitor entacapone in the recently described model of LIDs in rats with a nigrostriatal lesion induced by 6-hydroxydopamine (6-OHDA). Male Sprague-Dawley rats received a unilateral 6-OHDA administration in the nigrostriatal pathway. Animals were treated either with levodopa (6 mg/kg, twice at day, i.p.) plus entacapone (30 mg/kg per day, i.p.) or levodopa (6 mg/kg, twice at day, i.p.) plus vehicle for 22 consecutive days. Early administration of entacapone, in association with levodopa, induces a decrease in the severity of dyskinesia and delays their onset in hemiparkinsonian rats. All dyskinesia subtypes evaluated, such as axial, limb, and orofacial dyskinesias, have shown similar reductions. These results suggest that entacapone, by extending levodopa elimination half-life, might reduce its propensity to induce motor complications.

Analysis of Variance↗