Machine learning based quantification of synchrotron radiation-induced x-ray fluorescence measurements—a case study

In this work, we describe the use of artificial neural networks (ANNs) for the quantification of x-ray fluorescence measurements. The training data were generated using Monte Carlo simulation, which avoided the use of adapted reference materials. The extension of the available dataset by means of an ANN to generate additional data was demonstrated. Particular emphasis was put on the comparability of simulated and experimental data and how the influence of deviations can be reduced. The search for the optimal hyperparameter, manual and automatic, is also described. For the presented case, we were able to train a network with a mean absolute error of 0.1 weight percent for the synthetic data and 0.7 weight percent for a set of experimental data obtained with certified reference materials.

Association of sex and systemic therapy treatment outcomes in psoriasis: a two-country, multicentre, prospective, noninterventional registry study

BACKGROUND

Few systematic data on sex-related treatment responses exist for psoriasis.

OBJECTIVES

To evaluate sex differences with respect to systemic antipsoriatic treatment.

METHODS

Data from patients with moderate-to-severe psoriasis in the PsoBest or Swiss Dermatology Network of Targeted Therapies (SDNTT) registries were analysed. Treatment response was defined as achieving a ≥ 75% reduction in Psoriasis Area and Severity Index (PASI 75) or PASI ≤ 3 at treatment months 3, 6 and 12, supplemented by patient-reported outcomes [i.e. Dermatology Life Quality Index (DLQI) ≤ 1 and delta DLQI ≥ 4].

RESULTS

In total, 5346 patients registered between 2007 and 2016 were included (PsoBest, n = 4896; SDNTT, n = 450). The majority received nonbiological treatment (67·3% male, 69·8% female). Women showed slightly higher PASI response rates after 3 (54·8% vs. 47·2%; P ≤ 0·001), 6 (70·8% vs. 63·8%; P ≤ 0·001) and 12 months (72·3% vs. 66·1%; P ≤ 0·004). A significantly higher proportion of women achieved a reduction in DLQI ≥ 4 [month 3: 61·4% vs 54·8% (P ≤ 0·001); month 6: 69·6% vs. 62·4% (P ≤ 0·001); month 12: 70·7% vs. 64·4% (P ≤ 0·002)]. Regarding PASI ≤ 3, women on biologics showed a significantly superior treatment response compared with men at 3 (57·8% vs. 48·5%; P ≤ 0·004) and 6 months (69·2% vs. 60·9%; P ≤ 0·018). Women in the nonbiological treatment group had a significantly better treatment response (PASI response, PASI 75 and PASI ≤ 3) over 12 months compared with men.

CONCLUSIONS

We provide evidence that women experience better treatment outcomes with systemic antipsoriatic therapy than men.

Continued treatment with secukinumab is associated with high retention or regain of response

BACKGROUND

Conventional analyses present aggregate data, masking late responders and efficacy reductions. Secukinumab, a fully human monoclonal antibody that selectively neutralizes interleukin (IL)-17A, shows sustained efficacy in moderate-to-severe psoriasis.

OBJECTIVES

To determine stability of response to secukinumab, changes in efficacy were assessed in individual patients.

METHODS

This is a post hoc analysis of two phase III randomized controlled trials, FIXTURE (trial registration: NCT01358578) and CLEAR (trial registration: NCT02074982). Patients received secukinumab 300 mg (FIXTURE and CLEAR), etanercept 50 mg (FIXTURE) or ustekinumab 45 or 90 mg (CLEAR) over 52 weeks. Mutually exclusive response categories were defined: ≥ 90% improvement in the Psoriasis Area and Severity Index (PASI 90) ('excellent'), ≥ 75% improvement in PASI (PASI 75) and < PASI 90 ('good') and < PASI 75 ('insufficient'). Reductions in efficacy were defined as shifts from higher to lower response categories between two consecutive visits maintained for a third consecutive visit. Loss of efficacy was defined as a reduction of efficacy resulting in 'insufficient' response. All comparisons are descriptive.

RESULTS

At 52 weeks, in CLEAR, 90·2% (303/336) of patients on secukinumab achieved stable efficacy without loss and 77·7% (261/336) showed stable efficacy without any reduction of response [74·3% (252/339) and 59·9% (203/339) of patients for ustekinumab]. In FIXTURE, 83·5% (273/327) and 66·4% (217/327) of patients on secukinumab had stable efficacy without loss or reduction of response [58·3% (190/326) and 42·6% (139/326) for etanercept]. Response was regained by continuing secukinumab treatment in 50% (8/16) of patients in CLEAR and 26% (9/34) in FIXTURE. Similar patterns were observed for other response definitions.

CONCLUSIONS

Efficacy with secukinumab was stable over 52 weeks of treatment in most patients. Continued treatment with secukinumab resulted in regain of efficacy in some patients. Persistent loss of response was uncommon. What's already known about this topic? Secukinumab, a fully human monoclonal antibody that selectively neutralizes interleukin (IL)-17A, shows significant and sustained efficacy in the treatment of moderate-to-severe psoriasis. Secondary loss of response may be experienced by a minority of patients treated with secukinumab, as with other biologics, but the extent of this and the potential for regain of efficacy with continued treatment is not well understood. What does this study add? To determine stability of response to secukinumab and inform clinical practice, changes in efficacy were assessed at individual patient level using response categories. Efficacy with secukinumab was stable over 52 weeks of treatment in most patients, and continued treatment with secukinumab resulted in efficacy regain after loss in some patients. Persistent loss of response was uncommon. Patient factors such as body weight may affect the likelihood of loss of efficacy.

Synchrotron radiation micro X-ray fluorescence spectroscopy of thin structures in bone samples: comparison of confocal and color X-ray camera setups

In the quest for finding the ideal synchrotron-radiation-induced imaging method for the investigation of trace element distributions in human bone samples, experiments were performed using both a scanning confocal synchrotron radiation micro X-ray fluorescence (SR-µXRF) (FLUO beamline at ANKA) setup and a full-field color X-ray camera (BAMline at BESSY-II) setup. As zinc is a trace element of special interest in bone, the setups were optimized for its detection. The setups were compared with respect to count rate, required measurement time and spatial resolution. It was demonstrated that the ideal method depends on the element of interest. Although for Ca (a major constituent of the bone with a low energy of 3.69 keV for its Kα XRF line) the color X-ray camera provided a higher resolution in the plane, for Zn (a trace element in bone) only the confocal SR-µXRF setup was able to sufficiently image the distribution.

A setup for synchrotron-radiation-induced total reflection X-ray fluorescence and X-ray absorption near-edge structure recently commissioned at BESSY II BAMline

An automatic sample changer chamber for total reflection X-ray fluorescence (TXRF) and X-ray absorption near-edge structure (XANES) analysis in TXRF geometry was successfully set up at the BAMline at BESSY II. TXRF and TXRF-XANES are valuable tools for elemental determination and speciation, especially where sample amounts are limited (<1 mg) and concentrations are low (ng ml(-1) to µg ml(-1)). TXRF requires a well defined geometry regarding the reflecting surface of a sample carrier and the synchrotron beam. The newly installed chamber allows for reliable sample positioning, remote sample changing and evacuation of the fluorescence beam path. The chamber was successfully used showing accurate determination of elemental amounts in the certified reference material NIST water 1640. Low limits of detection of less than 100 fg absolute (10 pg ml(-1)) for Ni were found. TXRF-XANES on different Re species was applied. An unknown species of Re was found to be Re in the +7 oxidation state.

Classical group theory adapted to the mechanism of Pt3Ni nanoparticle growth: the role of W(CO)6 as the "shape-controlling" agent

Classical group theory was applied to prove the Pt3Ni crystallographic transformation from Platonic cubic to Archimedean cuboctahedral structures and the formation of Pt3Ni polypods. The role of W(CO)6 as a shape-controlling agent is discussed with respect to the crystallographic features of the clusters and superstructures generated as control samples.

Shear-induced dynamics of polymeric globules at adsorbing homogeneous and inhomogeneous surfaces

The dynamics and adsorption behavior of a single collapsed homopolymer on a surface in shear flow is investigated by means of Brownian hydrodynamics simulations. We study different homogeneous and inhomogeneous surface models and determine dynamic state diagrams as a function of the cohesive strength, the adhesive strength, and the shear rate. We find distinct dynamical adsorbed states that are classified into rolling and slipping states, globular and coil-like states, as well as isotropic and prolate states. We identify two different cyclic processes based on trajectories of the polymer stretching and the polymer separation from the surface. For adsorption on an inhomogeneous surface consisting of discrete binding sites, we observe stick-roll motion for highly corrugated surface potentials. Although the resulting high surface friction leads to low drift velocities and reduced hydrodynamic lift forces on such inhomogeneous surfaces, a shear-induced adsorption is not found in the presence of full hydrodynamic interactions. A hydrodynamically stagnant surface model is introduced for which shear-induced adsorption is observed in the absence of hydrodynamic interactions.

Quality of health care of atopic eczema in Germany: results of the national health care study AtopicHealth

BACKGROUND

The successful treatment of atopic eczema (AE) should result in the improvement of both physical symptoms and patient's quality of life (QoL). This study was conducted using a sample of dermatologists throughout Germany. This is due to dermatologists being the main health care providers of AE.

OBJECTIVES

Obtaining reliable data on quality of care of AE from both the patient's and the physician's perspective.

METHODS

This cross-sectional study assessed: the individual clinical history; dermatology-specific QoL (DLQI); state of health (EQ-5d-VAS); treatments; burden caused by disease and treatment; patient-defined treatment benefit (PBI).

RESULTS

Data from 1678 adult patients (60.5% female, mean age: 38.4 ± 15.9) were analysed. The most frequently used treatments during the last five years were emollients (90.4%) and topical corticosteroids (85.5%). In this study, 75.8% of the patients felt only moderately or not at all impaired by their treatment. The mean DLQI (0 = minimum-30 = maximum QoL impairment) was 8.5 ± 6.5. The EQ-5d-VAS (100 = best possible) was 63.6 ± 22.0 on average. 26.6% reported suffering 'often' or 'every night' from sleeplessness due to severe itching. Mean PBI was 2.4 ± 1.1 (4 = maximum benefit).

CONCLUSIONS

This study provides first data on the health care of adults with AE in Germany at a national level and reveals the need for a more effective care. Whereas most patients consider their treatment-related burden as low, the daily burden of the disease seems to be high: one third reports sleeplessness due to itching which indicates insufficient therapeutic regimes in these cases. A better implementation of the German national guideline for AE and a systematic analysis of the difficulties causing its limited effects is needed.

Compact pnCCD-based X-ray camera with high spatial and energy resolution: a color X-ray camera

For many applications there is a requirement for nondestructive analytical investigation of the elemental distribution in a sample. With the improvement of X-ray optics and spectroscopic X-ray imagers, full field X-ray fluorescence (FF-XRF) methods are feasible. A new device for high-resolution X-ray imaging, an energy and spatial resolving X-ray camera, is presented. The basic idea behind this so-called "color X-ray camera" (CXC) is to combine an energy dispersive array detector for X-rays, in this case a pnCCD, with polycapillary optics. Imaging is achieved using multiframe recording of the energy and the point of impact of single photons. The camera was tested using a laboratory 30 μm microfocus X-ray tube and synchrotron radiation from BESSY II at the BAMline facility. These experiments demonstrate the suitability of the camera for X-ray fluorescence analytics. The camera simultaneously records 69,696 spectra with an energy resolution of 152 eV for manganese K(α) with a spatial resolution of 50 μm over an imaging area of 12.7 × 12.7 mm(2). It is sensitive to photons in the energy region between 3 and 40 keV, limited by a 50 μm beryllium window, and the sensitive thickness of 450 μm of the chip. Online preview of the sample is possible as the software updates the sums of the counts for certain energy channel ranges during the measurement and displays 2-D false-color maps as well as spectra of selected regions. The complete data cube of 264 × 264 spectra is saved for further qualitative and quantitative processing.

Organisationsstrukturen moderner Wundversorgung

Die Heilung chronischer Wunden stellt in mehrfacher Hinsicht eine Herausforderung dar. Sie erfordert eine differenzierte Abklä-rung der Ulkusentität und eine enge Koope-ration verschiedener Berufsgruppen. Erschwerend im Management chronischer Wun-den ist das Fehlen konsentierter interdisziplinärer Leitlinien. Dagegen steht dem Therapeuten im Rahmen der modernen Wundbehandlung ein reichhaltiges Armamentarium an Wundauflagen und Verbandsstoffen zur Verfügung, die einen differenzierten Einsatz erfordern. Daneben ist eine Vernetzung stationärer und ambulanter Strukturen für eine erfolgreiche Wundbehandlung unabdingbar. Am Universitätsklinikum Hamburg-Eppendorf wurde 2010 das Comprehensive Wound Center gegründet. Neben einer kompetenten, fachübergreifenden und patientengerechten Diagnostik ist insbesondere die interdisziplinäre Zusammenarbeit verschiedener ärztlicher und pflegerischer Professionen angestrebt. Durch Vernetzung der internen Strukturen erfolgten im ambulanten als auch im stationären Management eine Umstrukturie-rung und eine sektorenübergreifende Wund-versorgung. Da bis zu 80 % chronischer Wun-den angiologischer Ursache sind, erfolgte zudem die Anbindung an die Klinik für Gefäß-medizin, die nach dem Konzept einer Organklinik konzipiert ist und bereits interdisziplinäre Zentrumsstrukturen aufweist. Durch eine zen-trale Koordinierung ist eine enge Kooperation zwischen niedergelassenen Ärzten und Pflegedienste innerhalb des Wundnetzes möglich. Neben der Patientenbetreuung hat das Comprehensive Wound Center einen weiteren Schwerpunkt in der Grundlagenforschung so-wie in der klinischen und versorgungswissenschaftlichen Forschung.

[Epidemiology of psoriasis in Germany--analysis of secondary health insurance data]

BACKGROUND

In Germany, population-based data on the epidemiology of psoriasis are still rare. This study aims to assess the prevalence of psoriasis in the total population as well as for subgroups relevant to health care. As further epidemiological parameters the severity and regional distribution of psoriasis were analysed.

METHODS

A secondary analysis of data collected routinely for the members of a nationwide statutory health insurance company was conducted. Prevalences were calculated for a closed cohort of continuously insured persons in 2005. Defined criteria for the existence of psoriasis were at least one diagnoses of psoriasis (ICD-10) relating to ambulatory or hospital treatment or disability.

RESULTS

33,981 of the 1,344,071 continuously insured persons in 2005 were diagnosed with psoriasis, thus the one-year-prevalence in this cohort was 2.53%. Up to the age of 80 years the prevalence rate was increasing with increasing age and highest for the age groups from 50 to 79 years (range: 3.99-4.18%). Insured persons up to 20 years had a prevalence of 0.73%. Regional differences showed up after stratification for broad categories (1 digit) of ZIP codes: Lowest prevalence rates were seen in the south (2.17%) and highest (2.78%) in the north and western regions of Germany.

CONCLUSIONS

If the prevalence rate of 2.5% assessed in this study is applied to the total resident population, 2 million people are treated because of psoriasis in Germany. Routine data from health insurance companies are a relevant and suitable data source to assess the prevalence of chronic diseases (under medical treatment) in the population.

In vitro to in vivo comparison of the substrate characteristics of sorafenib tosylate toward P-glycoprotein

Sorafenib (Nexavar) is a novel oral Raf kinase and vascular endothelial growth factor receptor inhibitor. Most anticancer drugs are substrates for ATP-binding cassette efflux pumps especially for P-glycoprotein (P-gp). To evaluate the influence of P-gp on the pharmacokinetics of sorafenib substrate properties for this transporter were investigated. Therefore, permeability of sorafenib across Caco-2 and P-gp-overexpressing cells was determined. To determine the in vivo relevance of these in vitro findings, pharmacokinetics of sorafenib in mdr1a/1b(-/-) and wild-type (WT) mice was studied. Sorafenib is highly permeable and exhibits a slight efflux across Caco-2 cells. In P-gp-overexpressing cells, a small concentration-dependent efflux was observed, which was completely blocked by the addition of ivermectin. In mdr1a/1b(-/-) and WT mice, unchanged compound represented by far the majority of radioactivity in plasma. After intravenous and oral administration, brain/plasma concentration ratios in mdr1a/1b(-/-) mice were 1.3- to 1.5-fold higher than those in WT mice. However, after intravenous or oral administration, plasma concentrations were similar in both mouse strains. In conclusion, sorafenib is highly permeable and a weak P-gp substrate in vitro. These findings were confirmed by the small factor of 1.3 to 1.5 observed for the brain/plasma ratios in mdr1a/1b(-/-) versus WT mice in vivo. Based on these in vitro and in vivo results, it is unlikely that P-gp has a major effect on the plasma concentrations of sorafenib in humans. Because of the high permeability and low P-gp-mediated transport, sorafenib might be able to cross the blood-brain barrier and target tumors within the brain.

Beneficial effects of K-ATP channel openers in diabetes: an update on mechanisms and clinical experiences

Stresses associated with the diabetic state participate in the demise of beta-cells and therapies that eliminate or reduce such stresses are much needed. K-ATP channel openers, of which diazoxide is the most studied, are potentially useful because experimental studies show that they can counteract chronic over-stimulation of beta-cells and protect against toxic conditions, including relative hypoxia. Several mechanisms may underlie the beneficial effects of diazoxide; these may include both indirect (counteracting over-stimulation) and direct mitochondrial effects. Side effects of diazoxide have limited its use in human trials. We have tested lower doses than previously of diazoxide and thereby largely eliminated side effects. In this setting, we demonstrate positive effects on beta-cell function in type 2 diabetic patients who were simultaneously treated with bedtime insulin. However, such effects were absent in insulin-naïve patients. In newly diagnosed type 1 diabetic patients, a 6-month intervention with diazoxide failed to result in better preservation of beta-cell function. K-ATP channel openers have a potential to improve beta-cell function in subgroups of type 2 diabetes patients. Analogues of diazoxide with more potency in relation to side effects would heighten the possibilities for K-ATP channel openers to be of therapeutic use in type 1 diabetes.

Cost-Effectiveness Model of Topical Treatment of Mild to Moderate Psoriasis Vulgaris in Germany

BACKGROUND

Psoriasis vulgaris requires lifelong treatment associated with considerable health cost. Studies showed that a combination of a steroid and a vitamin D(3) analogue is more effective than both compounds in monotherapy.

OBJECTIVE

To determine the cost-effectiveness of a fix calcipotriol/betamethasone combination (Daivobet/Dovobet/Taclonex) compared to a morning/evening non-fix calcipotriol/betamethasone combination in psoriasis treatment.

METHODS

A Markov model (discrete-time stochastic process based on transitions between health states) with 2 treatment arms (Daivobet/Dovobet/Taclonex vs. non-fix calcipotriol/betamethasone) over a 48-week time period was developed. The effectiveness criterion was the number of days with clearance or marked improvement. Clinical and health resource utilisation data were derived from randomised studies.

RESULTS

Treatment with Daivobet/Dovobet/Taclonex showed a higher cost-effectiveness compared to the non-fix combination, even when assuming a maximum compliance for the twice daily non-fix combination and varying the effectiveness of Daivobet/Dovobet/Taclonex by 10%.

CONCLUSION

Psoriasis treatment with a fix calcipotriol/betamethasone combination is more cost-effective than a non-fix morning/evening combination.

Twelve weeks' treatment with diazoxide without insulin supplementation in Type 2 diabetes is feasible but does not improve insulin secretion

AIMS

Treatment with K-ATP channel openers, such as diazoxide, can have beneficial effects on insulin secretion in both Type 1 and Type 2 diabetes. However, the precise conditions for obtaining beneficial effects without untoward events have not been determined. We tested the hypothesis that intermittent administration of diazoxide at bedtime for 12 weeks could produce beneficial effects in the absence of side-effects in Type 2 diabetic patients who were not taking insulin.

METHODS

After an 8-week run-in period, during which treatment with repaglinide and metformin was optimized, we randomized 26 patients to either diazoxide, 100 mg at bedtime, or placebo.

RESULTS

Side-effects were absent or minimal. HbA(1c) did not change. However day-time glucose concentrations by home glucose monitoring were approximately 1.5 mmol/l higher with diazoxide vs. placebo. Stimulation tests (C-peptide-glucagon and breakfast) did not indicate improved pancreatic B-cell function, except by posthoc analysis, in a subgroup of younger age.

CONCLUSION

Compared with previous results with diazoxide together with bedtime insulin, the present results are less favourable and indicate that concomitant insulin treatment is needed during intervention with K-ATP channel openers.

Results from an in vitro and a clinical/pharmacological phase I study with the combination irinotecan and sorafenib

PURPOSE

This single-centre, open-label, phase I dose-escalation study was performed to investigate the safety, pharmacokinetics (PK) and efficacy of sorafenib, a multi-kinase inhibitor, combined with irinotecan, a cytotoxic agent, in patients with advanced, refractory solid tumours.

PATIENTS AND METHODS

In an initial dose-escalation phase, patients received irinotecan 125 mg/m(2) and sorafenib 100, 200 and 400 mg twice daily (bid) (cohorts 1-3). In an extended phase, colorectal cancer (CRC) patients received fixed-dose irinotecan 140 mg and sorafenib 400 mg bid (cohort 4).

RESULTS

Thirty-four patients were treated: 20 in the dose-escalation phase (common tumour types: CRC [45%], ovarian [5%], pancreatic [5%]) and 14 patients in the CRC extension. Frequent drug-related adverse events were gastrointestinal symptoms, dermatological reactions and constitutional symptoms. The maximum tolerated dose was not reached. Generally, concomitant administration of irinotecan had no impact on the PK of sorafenib. Sorafenib 100 or 200 mg bid had no impact on the PK of irinotecan or its metabolite SN38. In contrast, sorafenib 400 mg bid significantly increased irinotecan and SN38 exposures; however, this was not associated with increased toxicities. Stable disease was achieved in 12/20 (60%) evaluable patients in cohorts 1-3, and 10/13 (77%) evaluable patients in cohort 4. A further patient from cohort 4 had a partial response of >200 days. The increase of SN38 exposure might be due to inhibition of formation of the SN38 glucuronide by sorafenib. In vitro, sorafenib strongly inhibited SN38 glucuronidation in human liver microsomes as indicated by a K(i) value of 2.7 micromol/l.

CONCLUSION

Sorafenib 400 mg bid can be combined with irinotecan 125 mg/m(2) or 140 mg for the treatment of patients with advanced, refractory solid tumours, although monitoring for toxicity is recommended.

Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) in cosmetic and dermatological preparations

Solid lipid nanoparticles (SLN) were developed at the beginning of the 1990 s as an alternative carrier system to emulsions, liposomes and polymeric nanoparticles. The paper reviews advantages-also potential limitations-of SLN for the use in topical cosmetic and pharmaceutical formulations. Features discussed include stabilisation of incorporated compounds, controlled release, occlusivity, film formation on skin including in vivo effects on the skin. As a novel type of lipid nanoparticles with solid matrix, the nanostructured lipid carriers (NLC) are presented, the structural specialties described and improvements discussed, for example, increase in loading capacity, physical and chemical long-term stability, triggered release and potentially supersaturated topical formulations. For both SLN and NLC, the technologies to produce the final topical formulation are described, especially the production of highly concentrated lipid nanoparticle dispersions >30-80% lipid content. Production issues also include clinical batch production, large scale production and regulatory aspects (e. g. status of excipients or proof of physical stability).

Electron probe microanalysis (EPMA) measurement of thin-film thickness in the nanometre range

The thickness of thin films of platinum and nickel on fused silica and silicon substrates has been determined by EPMA using the commercial software STRATAGEM for calculation of film thickness. Film thickness ranged in the order 10 nm. An attempt was made to estimate the confidence range of the method by comparison with results from other methods of analysis. The data show that in addition to the uncertainty of the spectral intensity measurement and the complicated fitting routine, systematic deviation caused by the underlying model should be added. The scattering in the results from other methods does not enable specification of a range of uncertainty, but deviations from the real thickness are estimated to be less than 20%.

Nanostructured lipid matrices for improved microencapsulation of drugs

At the beginning of the nineties solid lipid nanoparticles (SLN) have been introduced as a novel nanoparticulate delivery system produced from solid lipids. Potential problems associated with SLN such as limited drug loading capacity, adjustment of drug release profile and potential drug expulsion during storage are avoided or minimised by the new generation, the nanostructured lipid carriers (NLC). NLC are produced by mixing solid lipids with spatially incompatible lipids leading to special structures of the lipid matrix, i.e. three types of NLC: (I) the imperfect structured type, (II) the structureless type and (III) the multiple type. A special preparation process-applicable to NLC but also SLN-allows the production of highly concentrated particle dispersions (>30-95%). Potential applications as drug delivery system are described.

Biotransformation of cerivastatin in mice, rats, and dogs in vivo

Biotransformation of cerivastatin was investigated in mice, rats, and dogs in vivo using the 14C-labeled drug. Marked species differences exist, both in pathways and extent of cerivastatin metabolism. Unchanged drug, together with its lactone, predominates in dog plasma and represents 40% of the dose in the excreta, whereas in rat bile they account for approximately 10% of the dose. In mice, the drug is metabolized rapidly and almost completely. Biotransformation of cerivastatin occurs by three distinct phase I routes and by phase II conjugation with sugar-type moieties and taurine. Phase I routes are demethylation of the pyridinyl methyl ether, beta-oxidation of the 3,5-dihydroxy acid side chain, and reductive removal of the side chain 3-hydroxy group. In dogs, demethylation is the dominating phase I biotransformation. Phase II conjugation is equally important. In dog bile, different regioisomeric drug glucuronides and the benzylic glucuronide and glucoside conjugate of the demethylated drug were found. In rats, besides demethylation, beta-oxidation of the dihydroxy acid side chain-followed by reductive removal of the 5-hydroxy group-is the major reaction. The resulting pentenoic acid derivatives are observed in plasma and liver homogenate. These metabolites are subsequently conjugated with taurine and excreted in the bile. This metabolic sequence is also important in mice. Furthermore, only in mice, cerivastatin is subject to reductive removal of the 3-hydroxy group, together with demethylation. The 5-hydroxyheptenoic acids formed predominate in plasma and liver homogenate, whereas the corresponding taurine conjugates are excreted in the bile.

Metabolism of cerivastatin by human liver microsomes in vitro. Characterization of primary metabolic pathways and of cytochrome P450 isozymes involved

Biotransformation of cerivastatin, a new cholesterol-lowering drug, by human liver microsomes was investigated using the 14C-labeled drug. Metabolite profiles were established by HPLC and structures of metabolites were elucidated. Two metabolic pathways were equally important, demethylation of the benzylic methyl other and hydroxylation at one methyl group of the 6-isopropyl substituent. The product of combined hydroxylation and demethylation was observed as a minor metabolite. During sample preparation the lactone forms of both primary metabolites were isolated in small amounts. Detailed structural analysis by NMR and LC-ESI-MS showed that hydroxylation occurred with high regio- and stereoselectivity. The proposed structures were confirmed by chemical synthesis of enantiomerically pure reference compounds. Microsomes from a human lymphoblastoid AHH-1 cell line, stably expressing CYP 3A4, catalyzed the demethylation reaction. Upon incubation of cerivastatin with human liver microsomes in the presence of the specific CYP 3A inhibitor TAO, both hydroxylation and demethylation were considerably reduced. This indicates that CYP 3A enzymes play a major role in cerivastatin metabolism.

Pharmacokinetics of atropine in dogs after i.m. injection with newly developed dry/wet combination autoinjectors containing HI 6 or HLö 7

To cope with the rapid onset of the life-threatening cholinergic crisis after poisoning with organophosphorus compounds, atropine-oxime preparations should be available in autoinjectors allowing i.m. administration also in the absence of a physician. Such a scenario is conceivable in the battlefield, when nerve agents are disseminated, and can no longer be excluded in civilian areas, as demonstrated most recently in Tokyo. In addition, autoinjectors may be of value in agriculture when medical care is remote. The use of second generation oximes with broad antidotal spectrum, e.g., HI 6 (1-(((4-(aminocarbonyl)pyridinio)methoxy)methyl)-2-((hydr oxyimino)methyl) pyridinium dichloride monohydrate; CAS 34433-31-3) and HLö 7 (1-(((4-(aminocarbonyl)pyridinio)methoxy)methyl) 2,4-bis((hydroxyimino)methyl) pyridinium dimethanesulfonate; CAS 145613-73-6) is only possible in dry/wet autoinjectors because their stability is limited in concentrated solution. To detect a possible delay in atropine absorption by the two oximes, the pharmacokinetics of atropine after "autoinjection" in beagle dogs were determined. Commercially available autoinjectors from two manufacturers [STI International Ltd (BJ) and Astra Tech (AT)] were filled with atropine sulfate, either alone (2 mg) or in combination with HI 6 (500 mg) and HLö 7 (200 mg), respectively, and injected according to a complete cross-over design. Atropine concentration was determined as l-hyoscyamine equivalents in a radioreceptor assay (RRA). In the range of 0.1-6.9 ng/ml, atropine sulfate displaced [N-methyl-3H]-scopolamine methyl chloride ([3H]NMS) competitively from rat cerebral cortex membranes. At 200 pmol/l [3H]NMS, IC50 was 1.4 +/- 0.1 x 10(-9) M atropine (CV = 8.1%). The intra-assay deviation was about 6%; day-to-day deviation in determination of 1 nM (0.695 ng/ml) atropine was 2.6% (CV = 5.2%). AT autoinjectors containing HI 6 delivered only 1.81 mg atropine sulfate while 2.14 mg was released by the other injectors. According to the manufacturer, the reduced delivery was caused by a defective Teflon-coated O-ring as detected later on in the batch used. To allow comparison of the bioavailability of atropine from various autoinjectors, the AUCs were normalized to a constant dose. The atropine absorption half-time (7 min) was not affected either by the autoinjector type or by the combination with oximes. The other pharmacokinetic data likewise did not reveal any differences between the groups. Maximal plasma concentration was 33 ng ml-1, elimination half-life 52 min, Vapp 3.2 l kg-1 and Clpl 44 ml min-1 kg-1. The relatively high clearance of l-hyoscyamine is discussed.

Biotransformation of nifedipine in rat and dog

Following oral and/or intraduodenal administration, the biotransformation of 14C-labelled nifedipine (dimethyl 1,4-dihydro-2,6-dimethyl-4-(2-nitrophenyl)-pyridine-3, 5-dicarboxylate, Bay a 1040, Adalat, CAS 21829-25-4) has been reinvestigated in rats and dogs (dose: 5 mg/kg body weight in both species) to complete the metabolic data. Thirteen metabolites were isolated from the perfusate and bile of the isolated perfused rat liver model. Their structures were elucidated by spectroscopic methods (FAB-MS, combined GC/MS, NMR). The analyzed samples were used for the chromatographic (HPLC) comparison with urine and bile from the in vivo studies. The metabolites identified in rat urine (oral dose) account for 47.4% of the dose administered. 82.8% (rat) and 62.8% (dog) of the dose, resp., could be attributed to known structures in urine and bile following intraduodenal administration. Based on the structures identified the following biotransformation steps occurred: dehydrogenation of the 1,4-dihydropyridine system, hydroxylation of the methyl groups at 2- or 6-position followed by glucuronidation or by subsequent oxidation to the carboxylic acid, and oxidative ester cleavage.

Assessment of the efficacy of medical countermeasures in space flight

Changes in body fluids, electrolytes, and muscle mass are manifestations of adaptation to space flight and readaptation to the 1-g environment. The purposes of this paper are to review the current knowledge of biomedical responses to short- and long-duration space missions and to assess the efficacy of countermeasures to 1-g conditioning. Exercise protocols, fluid hydration, dietary and potential pharmacologic measures are evaluated, and directions for future research activities are recommended.