Metabolismus von Psychopharmaka durch das Cytochrom P450-Enzymsystem im Alter

Altern geht mit einer Reihe physiologischer Veränderungen einher. Da in höherem Lebensalter überdurchschnittlich viele Arzneistoffe eingenommen werden und häufig mehrere Erkrankungen gleichzeitig vorliegen, können Auffälligkeiten in den Arzneimittelkonzentrationen im Blut nicht nur altersbedingt, sondern auch krankheitsbedingt oder durch Arzneimittelwechselwirkungen verursacht sein.rnrnDie vorliegende Arbeit untersucht die Fragestellung, ob der Arzneimittelmetabolismus bei Alterspatenten generell, oder nur bei Patienten mit Multimorbidität und –medikation verändert ist, und in welchem Lebensalter diese Veränderungen einsetzen. Im Mittelpunkt stand dabei die Frage, ob die Aktivitäten distinkter Arzneimittel-abbauender Enzyme der Cytochrom P450-Enzym-Familie (CYP) verändert sind. Da viele Psychopharmaka nur bei Patienten im Alter zwischen 18 und 65 Jahren zugelassen sind, wurde die Hypothese geprüft, dass sich Patienten im Alter über und unter 65 Jahren in ihren Medikamentenspiegeln unterscheiden.rnrnFür die Untersuchungen wurde eine Datenbank aus Blutspiegelmessungen erstellt, die im Rahmen des pharmakotherapiebegleitenden TDM erhoben worden waren. Die Blutspiegel stammten von insgesamt 4197 Patienten, die mit Amisulprid, Aripiprazol, Citalopram, Clozapin, Donepezil, Escitalopram, Mirtazapin, Quetiapin, Risperidon, Sertralin, Venlafaxin oder Ziprasidon behandelt wurden. Die Messungen wurden ergänzt mit Angaben aus den TDM-Anforderungsscheinen bezüglich Tagesdosis, Begleitmedikamenten, Schweregrad der Erkrankung, Therapieerfolg und Verträglichkeit der Medikation. Zusätzlich wurden klinische Befunde der Leber- und Nierenfunktion einbezogen, sowie Angaben zur Berechnung des BMI. Die in vivo-CYP-Enzymaktivitäten wurden anhand von metabolischen Ratios (Serumkonzentrationen Metabolit/ Serumkonzentration Muttersubstanz) beurteilt.rnrnIm Mittel stieg der Schweregrad der Erkrankung mit dem Alter und der Therapieerfolg verschlechterte sich. Dies betraf im Einzelnen nur Patienten, die mit Amisulprid oder Clozapin behandelt worden waren. Ältere Patienten litten häufiger an Nebenwirkungen als jüngere.rnUnter Aripiprazol, Quetiapin, Sertralin und Venlafaxin erreichten Alterspatienten mit niedrigeren Tagesdosen gleiche Therapieerfolge wie jüngere Patienten.rnPatienten, die mit Clozapin oder Amisulprid behandelt wurden, zeigten im Alter schlechtere Behandlungserfolge bei gleicher (Clozapin) bzw. niedrigerer (Amisulprid) Tagesdosis.rnTherapieerfolg und mittlere Tagesdosis änderten sich bei Patienten, die Ziprasidon, Donepezil, Citalopram, Escitalopram und Mirtazapin einnahmen, nicht altersabhängig.rnrnAltersabhängige Unterschiede der Serumspiegel zeigten sich für Amisulprid, Aripiprazol, Donepezil, Mirtazapin, Desmethylmirtazapin, Quetiapin und DesmethylsertralinrnAllerdings lagen die Altersgrenzen außer bei Donepezil deutlich niedriger als die gängig angenommene, nämlich bei 35 Jahren (Aripiprazol), 70 Jahren (Donepezil), 55 Jahren (D-Sertralin), 41 Jahren (Amisulprid), 49 Jahren (Quetiapin) und 58 Jahren (Mirtazapin).rnEs bestand kein Zusammenhang zwischen dem Auftreten veränderter Serumspiegel im Alter und dem Verteilungsvolumen, der Plasmaproteinbindung oder der Eliminationshalbwertszeit der untersuchten Wirkstoffe.rnrnBei Patienten ohne Comedikation fand sich in keinem Fall eine altersabhängige Veränderung der Ratio. Es ergab sich daher kein Hinweis auf eine Veränderung der CYP-Aktivität im Alter. Die Einnahme von Comedikation nahm mit dem Alter zu, hierfür ließ sich eine Altersgrenze von 49 Jahren definieren. Unter Polytherapie wurden Veränderungen der CYP-Aktivität beobachtet.rnrnDer Einfluss veränderter Leber- oder Nierenfunktion auf die Biotransformation von Pharmaka wurde anhand von Serumspiegeln von Patienten, die mit Donepezil, Venlafaxin, Citalopram oder Escitalopram behandelt wurden, untersucht. rnBei keinem Wirkstoff wurden unter auffälligen Leber- oder Nierenparametern signifikant veränderte Serumspiegel gemessen.rnEine Abhängigkeit der Serumspiegel vom Körpergewicht wurde nur für Desmethylsertralin gefunden. Die Spiegel waren bei Patienten mit einem Body Mass Index unter 20 signifikant höher als bei Patienten mit einem Index über 20. Aufgrund der kleinen Fallgruppe und der Tatsache, dass der Serumspiegel der Muttersubstanz nicht stieg, konnte nicht zwingend von einem Alterseinfluss aufgrund der veränderten Körperzusammensetzung ausgegangen werden.rnInsgesamt ergaben sich aus den Untersuchungen Hinweise auf moderate altersabhängige Veränderungen der Pharmakokinetik. Es ließen sich allerdings keine allgemeinen Dosierempfehlungen für Alterspatienten ableiten. Es zeigte sich jedoch, dass mit altersabhängigen Veränderungen der Pharmakokinetik bereits nach dem 50. Lebensjahr zu rechnen ist. Weitere Untersuchungen sollten auch den Alterseffekt auf gastrointestinale Transporter einbeziehen, die die aktive Aufnahme von Arzneistoffen ins Blut bewerkstelligen. Unklar ist auch die Rolle des Alterns auf die Aktivität des P-Glykoproteins. rn

Cardiogoniometric parameters for detection of coronary artery disease at rest as a function of stenosis localization and distribution

Cardiogoniometry (CGM), a spatiotemporal electrocardiologic 5-lead method with automated analysis, may be useful in primary healthcare for detecting coronary artery disease (CAD) at rest. Our aim was to systematically develop a stenosis-specific parameter set for global CAD detection. In 793 consecutively admitted patients with presumed non-acute CAD, CGM data were collected prior to elective coronary angiography and analyzed retrospectively. 658 patients fulfilled the inclusion criteria, 405 had CAD verified by coronary angiography; the 253 patients with normal coronary angiograms served as the non-CAD controls. Study patients--matched for age, BMI, and gender--were angiographically assigned to 8 stenosis-specific CAD categories or to the controls. One CGM parameter possessing significance (P < .05) and the best diagnostic accuracy was matched to one CAD category. The area under the ROC curve was .80 (global CAD versus controls). A set containing 8 stenosis-specific CGM parameters described variability of R vectors and R-T angles, spatial position and potential distribution of R/T vectors, and ST/T segment alterations. Our parameter set systematically combines CAD categories into an algorithm that detects CAD globally. Prospective validation in clinical studies is ongoing.

Influence of end-expiratory level and tidal volume on gravitational ventilation distribution during tidal breathing in healthy adults

Our understanding of regional filling of the lung and regional ventilation distribution is based on studies using stepwise inhalation of radiolabelled tracer gases, magnetic resonance imaging and positron emission tomography. We aimed to investigate whether these differences in ventilation distribution at different end-expiratory levels (EELs) and tidal volumes (V (T)s) held also true during tidal breathing. Electrical impedance tomography (EIT) measurements were performed in ten healthy adults in the right lateral position. Five different EELs with four different V (T)s at each EEL were tested in random order, resulting in 19 combinations. There were no measurements for the combination of the highest EEL/highest V (T). EEL and V (T) were controlled by visual feedback based on airflow. The fraction of ventilation directed to different slices of the lung (VENT(RL1)-VENT(RL8)) and the rate of the regional filling of each slice versus the total lung were analysed. With increasing EEL but normal tidal volume, ventilation was preferentially distributed to the dependent lung and the filling of the right and left lung was more homogeneous. With increasing V (T) and maintained normal EEL (FRC), ventilation was preferentially distributed to the dependent lung and regional filling became more inhomogeneous (p < 0.05). We could demonstrate that regional and temporal ventilation distribution during tidal breathing was highly influenced by EEL and V (T).

Impact of del32-71-GH (exon 3 skipped GH) on intracellular GH distribution, secretion and cell viability: a quantitative confocal microscopy analysis

BACKGROUND: Familial isolated growth hormone deficiency (IGHD) is a disorder with about 5-30% of patients having affected relatives. Among those familial types, IGHD type II is an autosomal dominant form of short stature, associated in some families with mutations that result in missplicing to produce del32-71-GH, a GH peptide which cannot fold properly. The mechanism by which this mutant GH may alter the controlled secretory pathway and therefore suppress the secretion of the normal 22-kDa GH product of the normal allele is not known in detail. Previous studies have shown variance depending on cell type, transfection technique used, as well as on the method of analysis performed. AIM: The aim of our study was to analyse and compare the subcellular distribution/localization of del32-71-GH or wild-type (wt)-GH (22-kDa GH), each stably transfected into AtT-20, a mouse pituitary cell line endogenously producing ACTH, employed as the internal control for secretion assessment. METHODS: Colocalization of wt- and del32-71 mutant GH form was studied by quantitative confocal microscopy analysis. Using the immunofluorescent technique, cells were double stained for GH plus one of the following organelles: endoplasmic reticulum (ER anti-Grp94), Golgi (anti-betaCOP) or secretory granules (anti-Rab3a). In addition, GH secretion and cell viability were analysed in detail. RESULTS/CONCLUSIONS: Our results show that in AtT-20 neuroendocrine cells, in comparison to the wt-GH, the del32-71-GH has a major impact on the secretory pathway not only affecting GH but also other peptides such as ACTH. The del32-71-GH is still present at the secretory vesicles' level, albeit in reduced quantity when compared to wt-GH but, importantly, was secretion-deficient. Furthermore, while focusing on cell viability an additional finding presented that the various splice site mutations, even though leading eventually to the same end product, namely del32-71-GH, have different and specific consequences on cell viability and proliferation rate.

A Functional-Based Distribution Diagnostic for a Linear Model with Correlated Outcomes: Technical Report

Despite the widespread popularity of linear models for correlated outcomes (e.g. linear mixed modesl and time series models), distribution diagnostic methodology remains relatively underdeveloped in this context. In this paper we present an easy-to-implement approach that lends itself to graphical displays of model fit. Our approach involves multiplying the estimated marginal residual vector by the Cholesky decomposition of the inverse of the estimated marginal variance matrix. Linear functions or the resulting "rotated" residuals are used to construct an empirical cumulative distribution function (ECDF), whose stochastic limit is characterized. We describe a resampling technique that serves as a computationally efficient parametric bootstrap for generating representatives of the stochastic limit of the ECDF. Through functionals, such representatives are used to construct global tests for the hypothesis of normal margional errors. In addition, we demonstrate that the ECDF of the predicted random effects, as described by Lange and Ryan (1989), can be formulated as a special case of our approach. Thus, our method supports both omnibus and directed tests. Our method works well in a variety of circumstances, including models having independent units of sampling (clustered data) and models for which all observations are correlated (e.g., a single time series).

Cholesky Residuals for Assessing Normal Errors in a Linear Model with Correlated Outcomes: Technical Report

Despite the widespread popularity of linear models for correlated outcomes (e.g. linear mixed models and time series models), distribution diagnostic methodology remains relatively underdeveloped in this context. In this paper we present an easy-to-implement approach that lends itself to graphical displays of model fit. Our approach involves multiplying the estimated margional residual vector by the Cholesky decomposition of the inverse of the estimated margional variance matrix. The resulting "rotated" residuals are used to construct an empirical cumulative distribution function and pointwise standard errors. The theoretical framework, including conditions and asymptotic properties, involves technical details that are motivated by Lange and Ryan (1989), Pierce (1982), and Randles (1982). Our method appears to work well in a variety of circumstances, including models having independent units of sampling (clustered data) and models for which all observations are correlated (e.g., a single time series). Our methods can produce satisfactory results even for models that do not satisfy all of the technical conditions stated in our theory.

Semiparametric Normal Transformation Models for Spatially Correlated Survival Data

There is an emerging interest in modeling spatially correlated survival data in biomedical and epidemiological studies. In this paper, we propose a new class of semiparametric normal transformation models for right censored spatially correlated survival data. This class of models assumes that survival outcomes marginally follow a Cox proportional hazard model with unspecified baseline hazard, and their joint distribution is obtained by transforming survival outcomes to normal random variables, whose joint distribution is assumed to be multivariate normal with a spatial correlation structure. A key feature of the class of semiparametric normal transformation models is that it provides a rich class of spatial survival models where regression coefficients have population average interpretation and the spatial dependence of survival times is conveniently modeled using the transformed variables by flexible normal random fields. We study the relationship of the spatial correlation structure of the transformed normal variables and the dependence measures of the original survival times. Direct nonparametric maximum likelihood estimation in such models is practically prohibited due to the high dimensional intractable integration of the likelihood function and the infinite dimensional nuisance baseline hazard parameter. We hence develop a class of spatial semiparametric estimating equations, which conveniently estimate the population-level regression coefficients and the dependence parameters simultaneously. We study the asymptotic properties of the proposed estimators, and show that they are consistent and asymptotically normal. The proposed method is illustrated with an analysis of data from the East Boston Ashma Study and its performance is evaluated using simulations.

Antitumor activity of an epithelial cell adhesion molecule targeted nanovesicular drug delivery system

Site-specific delivery of anticancer agents to tumors represents a promising therapeutic strategy because it increases efficacy and reduces toxicity to normal tissues compared with untargeted drugs. Sterically stabilized immunoliposomes (SIL), guided by antibodies that specifically bind to well internalizing antigens on the tumor cell surface, are effective nanoscale delivery systems capable of accumulating large quantities of anticancer agents at the tumor site. The epithelial cell adhesion molecule (EpCAM) holds major promise as a target for antibody-based cancer therapy due to its abundant expression in many solid tumors and its limited distribution in normal tissues. We generated EpCAM-directed immunoliposomes by covalently coupling the humanized single-chain Fv antibody fragment 4D5MOCB to the surface of sterically stabilized liposomes loaded with the anticancer agent doxorubicin. In vitro, the doxorubicin-loaded immunoliposomes (SIL-Dox) showed efficient cell binding and internalization and were significantly more cytotoxic against EpCAM-positive tumor cells than nontargeted liposomes (SL-Dox). In athymic mice bearing established human tumor xenografts, pharmacokinetic and biodistribution analysis of SIL-Dox revealed long circulation times in the blood with a half-life of 11 h and effective time-dependent tumor localization, resulting in up to 15% injected dose per gram tissue. These favorable pharmacokinetic properties translated into potent antitumor activity, which resulted in significant growth inhibition (compared with control mice), and was more pronounced than that of doxorubicin alone and nontargeted SL-Dox at low, nontoxic doses. Our data show the promise of EpCAM-directed nanovesicular drug delivery for targeted therapy of solid tumors.

Distribution of amyloid precursor protein and amyloid-beta immunoreactivity in DBA/2J glaucomatous mouse retinas

PURPOSE: Evidence suggests that altered metabolism of amyloid precursor protein (APP) may play a role in the pathophysiology of retinal ganglion cell (RGC) death in the etiology of glaucoma. The authors sought to determine the distribution of APP and amyloid-beta (Abeta) in DBA/2J glaucomatous mouse retinas. METHODS: The retinas of 3- and 15-month-old DBA/2J mice and C57/BL-6 mice (control group) were fixed with 4% paraformaldehyde and processed for immunohistochemistry. Antibodies used included a polyclonal antibody to the C terminus of Abeta 40 and a polyclonal antibody to the APP ectodomain. Immunohistochemically stained tissue was graded using light microscopy. Distribution and semiquantitative expression of APP and Abeta in young and old glaucomatous and normal retinas were determined and compared. RESULTS: Strong APP and Abeta immunoreactivity was found in the RGC layer, optic nerve, and pia/dura of old DBA/2J retinas, with considerably higher intensity found in the old compared with the young DBA/2J mice. In contrast to glaucomatous mice, the control group did not show any notable age-related difference. CONCLUSIONS: Disruption of the homeostatic properties of secreted APP with consecutive Abeta cytotoxicity might be a contributing factor of ganglion cell loss in glaucomatous mouse retinas.

Online distribution management framework by incorporating wind generation

In distribution system operations, dispatchers at control center closely monitor system operating limits to ensure system reliability and adequacy. This reliability is partly due to the provision of remote controllable tie and sectionalizing switches. While the stochastic nature of wind generation can impact the level of wind energy penetration in the network, an estimate of the output from wind on hourly basis can be extremely useful. Under any operating conditions, the switching actions require human intervention and can be an extremely stressful task. Currently, handling a set of switching combinations with the uncertainty of distributed wind generation as part of the decision variables has been nonexistent. This thesis proposes a three-fold online management framework: (1) prediction of wind speed, (2) estimation of wind generation capacity, and (3) enumeration of feasible switching combinations. The proposed methodology is evaluated on 29-node test system with 8 remote controllable switches and two wind farms of 18MW and 9MW nameplate capacities respectively for generating the sequence of system reconfiguration states during normal and emergency conditions.

Bayesian change-point analysis in linear regression model with scale mixtures of normal distributions

In this thesis, we consider Bayesian inference on the detection of variance change-point models with scale mixtures of normal (for short SMN) distributions. This class of distributions is symmetric and thick-tailed and includes as special cases: Gaussian, Student-t, contaminated normal, and slash distributions. The proposed models provide greater flexibility to analyze a lot of practical data, which often show heavy-tail and may not satisfy the normal assumption. As to the Bayesian analysis, we specify some prior distributions for the unknown parameters in the variance change-point models with the SMN distributions. Due to the complexity of the joint posterior distribution, we propose an efficient Gibbs-type with Metropolis- Hastings sampling algorithm for posterior Bayesian inference. Thereafter, following the idea of [1], we consider the problems of the single and multiple change-point detections. The performance of the proposed procedures is illustrated and analyzed by simulation studies. A real application to the closing price data of U.S. stock market has been analyzed for illustrative purposes.

Subcellular distribution of the insulin-like growth factor (IGF) binding proteins (IGFBPs) 2 and 3 in articular chondrocytes

The insulin-like growth factor (IGF) is a major anabolic regulator in articular cartilage. The IGF-binding proteins (IGFBPs) are increased during osteoarthritis (OA), but the function of the later proteins remains unknown. In general, the IGFBPs are pluripotential effectors capable of IGF regulation and of acting on their own to control key cell functions, including survival and proliferation. The independent functions are often associated with their cell location, and therefore this study explores the distribution of IGFBP-2 and IGFBP-3 in articular chondrocytes. Immunohistochemistry was used to localize IGFBP-2 in normal human articular cartilage. Bovine chondrocytes were used for subcellular fractionation (hypotonic cell lysis) under nonreducing conditions and nuclear purification (centrifugation on sucrose cushions). Cell fraction markers and IGFBPs were assayed in the subcellular fractions by Western immunoblot. The IHC results showed association of IGFBP-2 with chondrocytes, but not with the nuclei. Subcellular fractionation of isolated chondrocytes yielded intact nuclei as assessed at the light microscopic level; the nuclear marker histone H1 was exclusively associated with this fraction. More than 90% of the cytoplasmic marker GAPDH and all the detectable IGFBP-2 were in the cytoplasmic fraction. Immunoreactive IGFBP-3 was found in the cytoplasmic and peri-nuclear/nuclear fractions. Chondrocytes contain intracellular IGFBP-2 and IGFBP-3 but only IGFBP-3 is associated with nuclei. This suggests the hypothesis that the actions of these IGFBPs in articular cartilage extend beyond the classic modulation of IGF receptor action.

Bone mineral density at distal tibia using dual-energy X-ray absorptiometry in normal women and in patients with vertebral osteoporosis or primary hyperparathyroidism

To assess the effect of age and disease on mineral distribution at the distal third of the tibia, bone mineral content (BMC) and bone mineral density (BMD) were measured at lumbar spine (spine), femoral neck (neck), and diaphysis (Dia) and distal epiphysis (Epi) of the tibia in 89 healthy control women of different age groups (20-29, n = 12; 30-39, n = 11; 40-44, n = 12; 45-49, n = 12; 50-54, n = 12; 55-59, n = 10; 60-69, n = 11; 70-79, n = 9), in 25 women with untreated vertebral osteoporosis (VOP), and in 19 women with primary hyperparathyroidism (PHPT) using dual-energy x-ray absorptiometry (DXA; Hologic QDR 1000 and standard spine software). A soft tissue simulator was used to compensate for heterogeneity of soft tissue thickness around the leg. Tibia was scanned over a length of 130 mm from the ankle joint, fibula being excluded from analysis. For BMC and BMD, 10 sections 13 mm each were analyzed separately and then pooled to define the epiphysis (Epi 13-52 mm) and diaphysis area (Dia 91-130 mm). Precision after repositioning was 1.9 and 2.1% for Epi and Dia, respectively. In the control group, at any site there was no significant difference between age groups 20-29 and 30-39, which thus were pooled to define the peak bone mass (PBM).(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of left ventricular relaxation on the pressure half time of aortic regurgitation

BACKGROUND The severity of aortic regurgitation can be estimated using pressure half time (PHT) of the aortic regurgitation flow velocity, but the correlation between regurgitant fraction and PHT is weak. AIM To test the hypothesis that the association between PHT and regurgitant fraction is substantially influenced by left ventricular relaxation. METHODS In 63 patients with aortic regurgitation, subdivided into a group without (n = 22) and a group with (n = 41) left ventricular hypertrophy, regurgitant fraction was calculated using the difference between right and left ventricular cardiac outputs. Left ventricular relaxation was assessed using the early to late diastolic Doppler tissue velocity ratio of the mitral annulus (E/ADTI), the E/A ratio of mitral inflow (E/AM), and the E deceleration time (E-DT). Left ventricular hypertrophy was assessed using the M mode derived left ventricular mass index. RESULTS The overall correlation between regurgitant fraction and PHT was weak (r = 0.36, p < 0.005). In patients without left ventricular hypertrophy, there was a significant correlation between regurgitant fraction and PHT (r = 0.62, p < 0.005), but not in patients with left ventricular hypertrophy. In patients with a left ventricular relaxation abnormality (defined as E/ADTI< 1, E/AM< age corrected lower limit, E-DT >/= 220 ms), no associations between regurgitant fraction and PHT were found, whereas in patients without left ventricular relaxation abnormalities, the regurgitant fraction to PHT relations were significant (normal E/AM: r = 0.57, p = 0.02; E-DT< 220 ms: r = 0.50, p < 0.001; E/ADTI < 1: r = 0.57, p = 0.02). CONCLUSIONS Only normal left ventricular relaxation allows a significant decay of PHT with increasing aortic regurgitation severity. In abnormal relaxation, which is usually present in left ventricular hypertrophy, wide variation in prolonged backward left ventricular filling may cause dissociation between the regurgitant fraction and PHT. Thus the PHT method should only be used in the absence of left ventricular relaxation abnormalities.