The Relevance of Integrating CYP2C19 Phenoconversion Effects into Clinical Pharmacogenetics

INTRODUCTION

CYP2D6 and CYP2C19 functional status as defined by genotype is modulated by phenoconversion (PC) due to pharmacokinetic interactions. As of today, there is no data on the effect size of PC for CYP2C19 functional status. The primary aim of this study was to investigate the impact of PC on CYP2C19 functional status.

METHODS

Two patient cohorts (total n=316; 44.2±15.4 years) were investigated for the functional enzyme status of CYP2C19 applying two different correction methods (PCBousman, PCHahn&Roll) as well as serum concentration and metabolite-to-parent ratio of venlafaxine, amitriptyline, mirtazapine, sertraline, escitalopram, risperidone, and quetiapine.

RESULTS

There was a decrease in the number of normal metabolizers of CYP2C19 and an increase in the number of poor metabolizers. When controlled for age, sex, and, in the case of amitriptyline, venlafaxine, and risperidone, CYP2D6 functional enzyme status, an association was observed between the CYP2C19 phenotype/functional enzyme status and serum concentration of amitriptyline, sertraline, and escitalopram.

DISCUSSION

PC of CYP2C19 changes phenotypes but does not improve correlations with serum concentrations. However, only a limited number of patients received perturbators of CYP2C19. Studies with large numbers of patients are still lacking, and thus, it cannot be decided if there are minor differences and which method of correction to use. For the time being, PC is relevant in individual patients treated with CYP2C19-affecting drugs, for example, esomeprazole. To ensure adequate serum concentrations in these patients, this study suggests the use of therapeutic drug monitoring.

Effect of CYP2D6 pharmacogenetic phenotype and phenoconversion on serum concentrations of antidepressants and antipsychotics: a retrospective cohort study

BACKGROUND

Pharmacogenetics (PGx), especially in regard to CYP2D6, is gaining more importance in routine clinical settings. Including phenoconversion effects (PC) in result interpretation could maximize its potential benefits. However, studies on genetics of pharmacokinetic genes including the functional enzyme status are lacking.

AIM

The retrospective analyses of clinical routine data aimed to investigating how the CYP2D6 functional enzyme status affects serum concentrations and metabolite-to-parent ratios of seven common psychotropic drugs and allows an evaluation of the relevance of this information for patient care.

METHOD

Two patient cohorts (total n = 316; 44.2 ± 15.4 years) were investigated for the CYP2D6 functional enzyme status and its associations with drug exposure and metabolism of venlafaxine, amitriptyline, mirtazapine, sertraline, escitalopram, risperidone and quetiapine.

RESULTS

We found an increase in intermediate and poor metabolizers, as well as a decrease in normal metabolizers of CYP2D6 when including PC. Moreover, we found associations between amitriptyline exposure with the phenoconversion-corrected activity score of CYP2D6 (Spearman correlation; p = 0.03), and risperidone exposure with CYP2D6 functional enzyme status (Kruskal-Wallis test; p = 0.01), as well as between metabolite-to-parent ratio of venlafaxine and risperidone with CYP2D6 functional enzyme status (Kruskal-Wallis test; p < 0.001; p = 0.05).

CONCLUSION

The data stress the relevance of PC-informed PGx in psychopharmacological treatment and suggest that PC should be included in PGx result interpretation when PGx is implemented in routine clinical care, especially before initiating amitriptyline- or risperidone-treatment, to start with a dose adequate to the respective CYP2D6 functional enzyme status. Moreover, PGx and therapeutic drug monitoring should be used complementary but not alternatively.

Reproduction impairments in metal-polluted environments and parental hormones: No evidence for a causal association in an experimental study in breeding feral pigeons exposed to lead and zinc

Humans are responsible for land-cover changes resulting in the emission of hazardous chemical elements including metallic trace elements i.e. MTEs. As a consequence, urban wildlife is exposed to high concentrations of MTEs, which exposure is linked to reproductive impairments. MTE effects on reproduction outputs might result from MTE exposure disrupting the endocrine pathways involved in reproductive behaviours. In birds, there is strong evidence that prolactin, corticosterone and testosterone are all involved in the regulation of parental effort during incubation and chick rearing. Endocrine-disrupting chemicals might stimulate or inhibit the production of those hormones and consequently alter parental investment and reproductive success outcomes. We measured baseline corticosterone, prolactin and testosterone plasma levels, and the corticosterone stress response of breeding feral pigeons (Columba livia) experimentally exposed to ecologically relevant lead and/or zinc concentrations. Independently of lead and/or zinc exposure, male and female plasma levels of corticosterone and prolactin (but not testosterone) showed temporal variations along the reproduction stages (i.e. incubation, early rearing and late rearing). In addition, both hatching and fledging success were slightly correlated with corticosterone, prolactin and testosterone levels. However, our study did not find any influence of lead or zinc exposure on hormone levels, suggesting that MTE effects on reproductive outputs might not be explained by MTE-induced modifications of corticosterone, prolactin and testosterone-linked behaviours during incubation and rearing. Alternatively, MTE-induced reproductive impairments might result from MTE exposure having direct effects on offspring phenotypes or prenatal indirect effects on the embryo (e.g. maternal transfer of MTEs, hormones or immune compounds).

Trace metals, melanin-based pigmentation and their interaction influence immune parameters in feral pigeons (Columba livia)

Understanding the effects of trace metals emitted by anthropogenic activities on wildlife is of great concern in urban ecology; yet, information on how they affect individuals, populations, communities and ecosystems remains scarce. In particular, trace metals may impact survival by altering the immune system response to parasites. Plumage melanin is assumed to influence the effects of trace metals on immunity owing to its ability to bind metal ions in feathers and its synthesis being coded by a pleiotropic gene. We thus hypothesized that trace metal exposure would interact with plumage colouration in shaping immune response. We experimentally investigated the interactive effect between exposure to an environmentally relevant range of zinc and/or lead and melanin-based plumage colouration on components of the immune system in feral pigeons (Columba livia). We found that zinc increased anti-keyhole limpet hemocyanin (KLH) IgY primary response maintenance, buffered the negative effect of lead on anti-KLH IgY secondary response maintenance and tended to increase T-cell mediated phytohaemagglutinin (PHA) skin response. Lead decreased the peak of the anti-KLH IgY secondary response. In addition, pheomelanic pigeons exhibited a higher secondary anti-KLH IgY response than did eumelanic ones. Finally, T-cell mediated PHA skin response decreased with increasing plumage eumelanin level of birds exposed to lead. Neither treatments nor plumage colouration correlated with endoparasite intensity. Overall, our study points out the effects of trace metals on some parameters of birds' immunity, independently from other confounding urbanization factors, and underlines the need to investigate their impacts on other life history traits and their consequences in the ecology and evolution of host-parasite interactions.

The adaptive function of melanin-based plumage coloration to trace metals

Trace metals produced by anthropogenic activities are of major importance in urban areas and might constitute a new evolutionary force selecting for the ability to cope with their deleterious effects. Interestingly, melanin pigments are known to bind metal ions, thereby potentially sequestering them in inert body parts such as coat and feathers, and facilitating body detoxification. Thus, a more melanic plumage or coat coloration could bring a selective advantage for animals living in polluted areas. We tested this hypothesis by investigating the link between melanin-based coloration and zinc and lead concentrations in feathers of urban feral pigeons, both at capture time and after one year of captivity in standardized conditions. Results show that differently coloured pigeons had similar metal concentrations at capture time. Metal concentrations strongly decreased after one year in standardized conditions, and more melanic pigeons had higher concentrations of zinc (but not lead) in their feathers. This suggests that more melanic pigeons have a higher ability to store some metals in their feathers compared with their paler counterparts, which could explain their higher success in urbanized areas. Overall, this work suggests that trace metal pollution may exert new selective forces favouring more melanic phenotypes in polluted environments.

Relationships between metals exposure and epidemiological parameters of two pathogens in urban pigeons

Human activities often generate or increase concentration of chemical compounds including pesticides, hydrocarbons and metals that can potentially affect ecological interactions. We found that elevated levels of zinc in pigeon feathers were associated with both low prevalence of Chlamydiaceae (ornithosis disease) and low intensity of blood pathogens (Haemosporidian parasites). In contrast, high levels of lead in pigeon feathers were associated with high blood pathogens intensities. Our results suggest that metals linked to human activities in cities such as zinc and lead may play a significant role in the ecology of host-parasite interactions and could potentially affect the epidemiology of diseases in the urban environment.

Host races of the pea aphid Acyrthosiphon pisum differ in male wing phenotypes

The evolution of reproductive isolation without geographic isolation (sympatric speciation) has recently gained strong theoretical and empirical supports. It is now widely admitted that many host-specific phytophagous insect species have arisen through shifting and adapting to new plants. The pea aphid Acyrthosiphon pisum has received considerable attention in this context and is now considered as a probable case of incipient sympatric speciation through host specialization. In Europe, three host races have been described so far, one on annual plants (pea and broad bean) and two on perennial plants (red clover and alfalfa, respectively). These host races are genetically differentiated and exhibit strong ecological specialization affecting their preferences and performances on alternative plants. Here, we investigate whether other life-history traits of ecological importance are associated with host specialization in the species. In particular, because A. pisum shows a genetically determined male wing variation, we tested if its host races also differ in their proportion of winged/wingless male phenotypes. We used a large collection of pea aphid lineages sampled on pea, broad bean, red clover and alfalfa and analyzed their male production by placing them in conditions inducing the sexual phase in A. pisum. Striking differences in the frequency of male dispersal genotypes were found between host populations; aphids producing winged males were in high proportion among lineages from annual hosts, while those producing wingless males were in high proportion on perennial ones. The evolutionary maintenance and ecological consequences of this association between habitat specialization and male wing variation are discussed.

Ecological specialization correlates with genotypic differentiation in sympatric host-populations of the pea aphid

The pea aphid, Acyrthosiphon pisum, encompasses distinct host races specialized on various Fabaceae species, but the extent of genetic divergence associated with ecological specialization varies greatly depending on plant and geographic origins of aphid populations. Here, we studied the genetic structure of French sympatric pea aphid populations collected on perennial (pea and faba bean) and annual (alfalfa and red clover) hosts using 14 microsatellite loci. Classical and Bayesian population genetics analyses consistently identified genetic clusters mostly related to plant origin: the pea/faba bean cluster was highly divergent from the red clover and the alfalfa ones, indicating they represent different stages along the continuum of genetic differentiation. Some genotypes were assigned to a cluster differing from the one expected from their plant origin while others exhibited intermediate genetic characteristics. These results suggest incomplete barriers to gene flow. However, this limited gene flow seems insufficient to prevent ecological specialization and genetic differentiation in sympatry.

Metabolic changes of the human donor cornea during organ-culture

PURPOSE

To study metabolic changes of the human cornea during organ-culture. Morphological changes have been extensively studied, whereas changes in human corneal metabolism have not been investigated yet.

MATERIAL AND METHODS

106 human corneas were stored for 1, 7, 15, 18, 21 and 28 days in a closed-system under standard eyebank conditions. After storage, glucose, lactate, ATP, ADP and AMP concentrations were determined in each cornea.

RESULTS

Glucose concentration decreased during the first two weeks with a minimum on day 15. ATP and ADP concentrations increased during the same period of time, but had their minimum later, on day 18. Lactate increased during the culture period up to day 21 and decreased thereafter.

CONCLUSION

From these data we conclude that the human cornea recovers during organ-culture, especially during the first two weeks. The changes occurring after a fortnight might be related to the artificial culture conditions. Nevertheless, the metabolic status is better than in post-mortem corneas. The changes may be partly avoided by changing the medium after at least two weeks of organ-culture.

[Correlation between glucose and lactate concentrations in the human cornea and in organ culture medium]

BACKGROUND

Metabolic changes of the human donor cornea during organ-culture are not at all reflected by the endothelium. Therefore metabolic investigations have become of increasing interest. It was the aim of this study to determine the correlation between glucose and lactate in storage medium and within the cornea itself and to find thereby an additional parameter for glucose metabolism during organ-culture.

METHODS

Glucose and lactate were examined in 166 organ-culture medium samples as well as in 106 human corneas by enzymatical optical methods. Investigations were carried out after 1, 7, 15, 21 and 28 days of organ-culture.

RESULTS

Glucose consumption was highest during the first two weeks of organ-culture. Glucose concentrations showed a good linear correlation between medium samples and the cornea (r = 0.923). The correlation coefficient for lactate was worse (r = 0.733).

CONCLUSION

Glucose and lactate levels in the organ-culture medium can be used as a marker for glucose metabolism in the cornea.

Boron-11 NMR of borocaptate: relaxation and in vivo detection in melanoma-bearing mice

Longitudinal and transverse relaxation rates for the 11B resonances in sodium borocaptate (BSH) at varying concentrations were measured in undiluted horse serum in a 4.7 Tesla field. The results could be fit by a model that assumes fast exchange of the BSH molecule between a free and a bound state, using values of 0.77+/-0.7 MHz for the 11B quadrupole coupling constant and (6.3+/-0.9) x 10(-9) s for the rotational correlation time in the bound state. These results were used as a basis for assessing the requirements and limitations of quantitative determination of BSH concentrations in vivo, using 11B NMR. Surface coil 11B NMR spectroscopy was performed on a total of 14 mice injected with BSH. Some of the animals (n=9) had implanted M2R melanoma tumors grown to various sizes in the rear thigh, in which case the surface coil was placed against the tumor, whereas for the other animals (without tumor), the coil was placed against the rear thigh muscle. NMR spectra were acquired under fully relaxed conditions. The spectra were quantitated by peak integration; apparent absolute BSH concentrations were derived by comparison with spectra from a phantom with known BSH concentration, using extrapolation of the time-domain data to zero preacquisition delay. The results indicate significantly higher 11B BSH signal intensities in tumors, compared with muscle tissue, whereas the uptake and clearance kinetics were similar.

Changes in human donor corneas preserved for longer than 4 weeks

PURPOSE

Corneas are usually stored for a maximum of approximately 30 days in European cornea banks. Although attempts are being made to prolong culture periods, data on their success are extremely limited to date. The following study was carried out to describe the capacities and limits of the established system.

METHODS

Thirty-seven human corneas were stored for < or = 12 weeks under standard eye bank conditions [modified minimal essential medium (MEM), 31 degrees C, closed system]. Twenty-one fresh human corneas served as control. Both the adenylate nucleotides and the glucose and lactate concentrations were measured in the tissue (all cellular layers) by using the bioluminescence technique. The endothelial-cell densities also were determined.

RESULTS

Endothelial-cell densities decreased from 2,963.4 +/- 58.7 cells/mm2 (fresh) to 2,649 cell/mm2 after 4 weeks and to 2,087 cells/mm2 after 6 weeks. Storage for periods >6 weeks led to total endothelial necrosis. Biochemical studies showed improving values during the first 4 weeks and acceptable conditions for < or = 6 weeks.

CONCLUSION

From these data, we conclude that long-term organ culture in a closed system is limited to approximately 6 weeks and thereby confirm the clinical results of Früh and Böhnke.

A sensitive assay for the quantification of glucose and lactate in the human cornea using a modified bioluminescence technique

BACKGROUND

Quantification of glucose and lactate concentrations in human corneal extracts has been performed using spectrophotometry. We employed a bioluminescence technique to obtain a more sensitive assay for glucose and lactate and to reduce the volume of the test sample.

MATERIALS AND METHODS

The NAD(P)H bioluminescence assay (Boehringer Mannheim, Germany) was modified for glucose and lactate. Standard curves were established using a standard solution with 0.004 mM and 0.01 mM concentrations of glucose and lactate, respectively.

RESULTS

Linear standard curves ranging from 0 to 200 pmol for glucose and from 0 to 250 pmol for lactate were established. The sample volume was reduced from 100 microliters to 25 microliters compared with spectrophotometry.

DISCUSSION

The modified bioluminescence technique provides a highly sensitive quantification of glucose and lactate in the human cornea and thus reveals more details of the overall metabolic status of the tissue.

Light-dependent oxygen consumption in bacteriochlorophyll-serine-treated melanoma tumors: on-line determination using a tissue-inserted oxygen microsensor

Successful application of anticancer therapy, and especially photodynamic therapy (PDT) mediated by type II (PDTII) processes, depends on the oxygen content within the tumor before, during and after treatment. The high consumption of oxygen during type II PDT imposes constraints on therapy strategies. Although rates of oxygen consumption and repletion during PDTII were suggested by theoretical studies, direct measurements have not been reported. Application of a novel oxygen sensor allowed continuous and direct in situ measurements (up to a depth of 8-9 mm from the tumor surface and for several hours) of temporal variations in the oxygen partial pressure (pO2) during PDT. Highly pigmented M2R mouse melanoma tumors implanted in CD1 nude mice were treated with bacteriochlorophyll-serine (Bchl-Ser; a new photodynamic reagent) and were subjected to fractionated illumination (700 < lambda < 900 nm) at a fluence rate of 12 mW cm-2. This illumination led to total oxygen depletion with an average consumption rate of 7.2 microM(O2) s-1. Spontaneous reoxygenation (at an average rate of 2.5 microM(O2)/s) was observed during the following dark period. These rates are in good agreement with theoretical considerations (Foster et al., Radiat. Res. 126, 296, 1991 and Henning et al., Radiat. Res. 142, 221, 1995). The observed patterns of oxygen consumption and recovery during prolonged periods of light/dark cycles were interpreted in terms of vasculature damage and sensitizer clearance. The presented data support the previously suggested advantages of fractionated illumination for type II photodynamic processes.

[Energy metabolism of the human cornea in various culture systems]

BACKGROUND

There are two well known systems to culture human corneas prior to transplantation. First, corneal storage at 4 degrees C especially in Optisol medium. Second, organ-culture at physiological temperatures in a modified minimal essential medium (MEM). In the cold storage system the number of endothelial cells after storage might be overestimated because the damaged cells are not able to leave the monolayer. It has been supposed that the lack in energy recruitment is the main reason for that, but has not been proven yet. It was the purpose of this study to describe the energy status of the human cornea after storage in both systems.

MATERIALS AND METHODS

32 human corneas were investigated. They were stored for 7 days in Optisol, and for 7 days in MEM plus 1 day in MEM supplemented with 5% dextran 500 and 12 days in modified MEM plus 1 day in MEM supplemented with 5% dextran 500. The endothelial cell density (ECD) as well as the hydration were determined. Glucose, lactate, ATP, ADP and AMP were measured to reflect the energy status.

RESULTS

Hydration was comparable in all three groups. ECD was slightly higher in Optisol stored corneas, although the amount of damaged cells was much higher. Optisol stored corneas showed a severe anaerobic situation, especially lacate concentrations were increased. In contrast ATP and ADP concentrations were twice as high in MEM than in Optisol stored corneas.

DISCUSSION

The severe anaerobic situation in Optisol stored corneas leads to a lack in energy recruitment. This reduces the ability of cell function (mitosis) and the function of the monolayer (migration, elimination). Whether these changes are reversible after transplantation has to be determined in future.

Employment of bioluminescence for the quantification of adenosine phosphates in the human cornea

BACKGROUND

Quantification of adenosine phosphates in human corneal extracts has been performed using spectrophotometry. We employed the bioluminescence technique to obtain a more sensitive assay for adenosine phosphates and to reduce the volume of the test sample.

METHODS

The bioluminescence assay for ATP, already known from sterility control, was modified and expanded. Standard curves were established using a standard solution with equimolar concentrations of ATP, ADP and AMP. To monitor the method, adenosine phosphates were measured in 35 human corneal extracts using both spectrophometry and bioluminescence.

RESULTS

Linear standard curves ranging from 1 to 45 pmol were established. The two methods yielded comparable results despite the use of a basic dilution of 1:100 for the new technique.

CONCLUSION

Bioluminescence provides a highly sensitive quantification of adenosine phosphates in the human cornea and facilitates an extremely detailed evaluation of the metabolic status of the cornea.

[Establishing human, conjunctival fibroblast cultures as a test system for evaluating ophthalmic drugs]

BACKGROUND

Chronic inflammation of the anterior eye segment caused by severe burns has to be treated by several drugs. Often it is very difficult to recognize the relationship between drug and side effects. Although the results were usually satisfying, proliferation of the conjunctival tissue was observed. Therefore the question was raised whether these proliferations might have been a side effect of the drugs. To answer this question, we established cultures of human conjunctival fibroblasts for ocular toxicity testing of drugs used in the therapy of severe eye burns.

MATERIALS AND METHODS

Conjunctival fibroblasts from young donors were cultured under standard conditions (37 degrees C, 5% C02, 95% RH) in Medium 199 supplemented with 20% FCS without antibiotics. At the time of inoculation the following drugs were added: aprotinin, prednisolone, chloramphenicol and methylhydroxypropylcellulose. Cell growth was observed and growth kinetics were estimated by hemocytometer over a period of 7 days.

RESULTS

The investigations of prednisolone showed the well-known dose-dependent anti-proliferative effect. The application of methylhydroxypropylcellulose resulted in decreased cell growth and in total cell detachment. Experiments with aprotinin and chloramphenicol showed no effects on the growth behaviour. The application of a drug mixture lead to similar results as in experiments with prednisolone.

DISCUSSION

The presented cell-culture system is able to reproduce specific effects, especially the toxicity of ophthalmic drugs but a complex interaction of an inflammatory reaction, e.g. after severe eye burns, cannot be simulated. The network of reactions and the interaction of many substances playing an important role during this process are too complex.

The cardiac care step-down unit at home

Clinical pathways have proven to be the key to shortening hospital stays for cardiac patients, allowing them to move out of the hospital and back home sooner. These pathways have truly facilitated the paradigm shift from institutional to home care.

Clinical and biochemical features of depression in Parkinson's disease

Among 49 consecutive patients with Parkinson's disease, 40% were depressed according to DSM-III; they had major depression or dysthymic disorder accompanied by sleep disturbance, fatigue, psychomotor retardation, loss of self-esteem, and excessive guilt. During a 10-day dopamine-free period, lumbar puncture was performed to measure the metabolites of dopamine, serotonin, and norepinephrine. Patients were given an overnight dexamethasone suppression test, and the effects of thyrotropin-releasing hormone and L-dopa on plasma growth hormone and prolactin were examined. Level of CSF 5-hydroxyindoleacetic acid was lowest in parkinsonian patients with major depression and was related to psychomotor retardation and loss of self-esteem.

Prolactin responses to neuroleptics in normal and schizophrenic subjects

The prolactin response to neuroleptics can serve as an index of dopamine blockade in humans. Plasma prolactin increments to single doses of chlorpromazine, and prolactin decrements to single doses of levodopa, were similar in normal and schizophrenic subjects. Antischizophrenic drugs of all chemical classes stimulated prolactin release,while chemically related drugs and other psychotropic agents ineffective in schizophrenia did not. The prolactin response to neuroleptic therapy occurred in all patients, and tolerance did not develop. Within subjects, prolactin responses were graded according to neuroleptic dose, but the upper limit of sensitivity of the response curve was achieved at doses below the therapeutic range. Relative prolactin-stimulating potency in humans of chlorpromazine, thioridazine, trifluoperazine, butaperazine, and haloperidol correlated well with their relative clinical potencies.

Relaxin immunoactivity in human plasma during a 24-hr period

Relaxin was secreted episodically in all 6 human subjects studied. A 24-hr rhythm was detected in the pooled data, with maximum secretion in the early-midmorning hours and a nadir in the early evening.

Twenty-four-hour secretory patterns of gonadotropins and prolactin in a case of Chiari-Frommel syndrome

Plasma LH, FSH and prolactin secretory patterns were derived from the measurement of 20-min interval plasma samples obtained during a complete 24-h period in a patient with persistent postpartum amenorrhea and galactorrhea (Chiari-Frommel syndrome), before and after clomiphene citrate therapy. During nocturnal sleep, polygraphic monitoring was carried out to precisely identify sleep onset, specific sleep stages and waking periods. During the evening and nighttime hours, LH and FSH concentrations were markedly reduced, compared to the daytime patterns both before and after clomiphene therapy. A sleep associated rise of prolactin concentration was present, similar to the pattern found in normal subjects but at higher concentrations. The reciprocal nature of the nocturnal secretory patterns for LH and FSH and prolactin in this patient suggests an alteration in hypothalamic dopaminergic mechanisms which are thougt to control the secretion of these hormones.