Performance of a Low-Cost Acoustic Insect Detector System with Sitophilus oryzae (Coleoptera: Curculionidae) in Stored Grain and Tribolium castaneum (Coleoptera: Tenebrionidae) in Flour.

Reduction of postharvest losses is gaining increased priority in warm regions where insect infestation may cause rapid deterioration of staple commodities. Acoustic detection can be used to assess the likelihood of insect infestations in bags of grain, flour, and other commodities that are stored in small holdings in developing countries, enabling rapid targeting of treatments. A portable postharvest insect detection system was developed with the goal to provide low-cost capability to acoustically assess infestations in small-scale storage facilities. Electret microphones input pest insect sounds to a 32-bit microcontroller platform that digitized and stored the signals on a digital memory card transferable to a portable laptop computer. The insect sounds then were analyzed by custom-written software that matched their spectra to those of known pests. Infestations of Sitophilus oryzae (L) in 2.6-kg bags could be detected down to densities of 1.9 adults/kg in grain and Tribolium castaneum (Herbst) down to 3.8 adults/kg in flour in laboratory settings. Also, differences in the rates of sounds per insect in treatments with different numbers ranging from 5 to 50 insects suggested that the sound rates of adults of different species at different population densities may be noticeably affected by aggregation pheromones or other behaviorally active semiochemicals. Further testing is needed but previous experience with acoustic detection systems suggests that the prototype has potential for use in small storage facilities where early detection of infestations is difficult to provide.

Disrupting Mating Behavior of Diaphorina citri (Liviidae).

Severe economic damage from citrus greening disease, caused by 'Candidatus Liberibacter asiaticus' bacteria, has stimulated development of methods to reduce mating and reproduction in populations of its insect vector, Diaphorina citri (Hemiptera: Liviidae). Male D. citri find mating partners by walking on host plants, intermittently producing vibrational calls that stimulate duetting replies by receptive females. The replies provide orientational feedback, assisting the search process. To test a hypothesis that D. citri mating can be disrupted using vibrational signals that compete with and/or mask female replies, courtship bioassays were conducted in citrus trees with or without interference from female reply mimics produced by a vibrating buzzer. Statistically significant reductions occurred in the rates and proportions of mating when the buzzer produced reply mimics within 0.4 s after male courtship calls compared with undisturbed controls. Observations of courtship behaviors in the two bioassays revealed activity patterns that likely contributed to the reductions. In both disruption and control tests, males reciprocated frequently between structural bifurcations and other transition points where signal amplitudes changed. Males in the disruption bioassay had to select among vibrational signals combined from the buzzer and the female at each transition point. They often turned towards the buzzer instead of the female. There was a statistically significant reduction in the proportion of males mating if they contacted the buzzer, possibly due to its higher vibration amplitude and duration in comparison with female replies. Potential applications of D. citri mating disruption technology in citrus groves are discussed.

Pharmacokinetics, pharmacodynamics, safety and tolerability of an intravaginal ring releasing anastrozole and levonorgestrel in healthy premenopausal women: a Phase 1 randomized controlled trial.

STUDY QUESTION: What are suitable doses of the aromatase inhibitor anastrozole (ATZ) and the progestin levonorgestrel (LNG), when delivered to the systemic circulation by an intravaginal ring (IVR), for further clinical development as a potential new therapy for the treatment of endometriosis? SUMMARY ANSWER: Anticipated targets for pharmacokinetics, pharmacodynamics and safety/tolerability were achieved for both drug components of the IVR at the doses investigated, supporting selection of the doses to be investigated in Phase 2 studies. WHAT IS KNOWN ALREADY: Aromatase is a key enzyme in the biosynthesis of estrogens and is known to increase local levels of estradiol (E2) at extragonadal sites. Up-regulation of aromatase expression has been demonstrated in endometriotic lesions and the use of oral aromatase inhibitors has been shown to reduce endometriosis-associated pelvic pain in small-scale clinical trials. STUDY DESIGN, SIZE, DURATION: This Phase 1, randomized, multicentre, parallel-group, three-arm, open-label study assessed the pharmacokinetics, pharmacodynamics, safety and tolerability of various IVRs intended for systemic drug delivery. After screening, healthy, ovulating women aged 18-35 years were randomized to use IVRs releasing one of the three ATZ/LNG dose combinations (in vitro nominal daily drug release rates on Day 29: ATZ/LNG 500 µg/20 µg [low dose], ATZ/LNG 1000 µg/30 µg [mid dose] or ATZ/LNG 1500 µg/40 µg [high dose]) for two consecutive 28-day wearing periods without a treatment break. PARTICIPANTS/MATERIALS, SETTING, METHODS: Sixty women were included in the per protocol set. The primary variables were plasma concentrations of ATZ and LNG at the end of each treatment period and the mean size of largest follicle-like structures (FLSs) over 56 days. Serum concentrations of several hormones were also evaluated, with emphasis on E2 levels. MAIN RESULTS AND THE ROLE OF CHANCE: At the end of the first treatment period, geometric mean plasma concentrations of LNG and ATZ, respectively, were 0.228 and 12.5 µg/l for the low dose, 0.269 and 19.8 µg/l for the mid dose and 0.384 and 37.3 µg/l for the high dose; results were similar at the end of the second treatment period. Over the entire treatment period, mean FLS sizes were higher in all three treatment groups than during the pretreatment cycle; more women in the mid- and high-dose groups had FLSs of at least 30 mm (32-45%) than those in the low-dose group (14-24%). Changes in the mean size of FLSs were similar to those reported for low-dose progestin-only oral contraceptives and generally resolved during the 2-month treatment period. Serum E2 levels were decreased, but only one woman in each of the mid- and high-dose groups, and no woman in the low-dose group, had a serum E2 level below 20 pg/ml in both cycles. All ATZ and LNG combinations showed good tolerability. LIMITATIONS, REASONS FOR CAUTION: This was an exploratory study; no formal power calculation was performed. WIDER IMPLICATIONS OF THE FINDINGS: The results of this first-in-human study of the ATZ/LNG IVR facilitated the selection of ATZ and LNG doses to be investigated in the Phase 2 studies of patients with endometriosis. STUDY FUNDING/COMPETING INTEREST: The study was funded by Bayer Pharma AG. T.R. is an employee of DINOX GmbH, which received funding from Bayer Pharma AG to perform this study. M.-H.S.-M., K.W., R.N., S.K., J.K., H.S. and B.R. are or have been employees of Bayer Pharma AG. H.S. is a named inventor on EP 2 552 404 B1, a patent application relating to this work. TRIAL REGISTRATION NUMBER: EudraCT number: 2011-005620-18. TRIAL REGISTRATION DATE: 16 November 2011. DATE OF FIRST PATIENT'S ENROLMENT: 14 March 2012.

Acoustic Detection of Rhynchophorus ferrugineus (Coleoptera: Dryophthoridae) and Oryctes elegans (Coleoptera: Scarabaeidae) in Phoenix dactylifera (Arecales: Arecacae) Trees and Offshoots in Saudi Arabian Orchards.

Rhynchophorus ferrugineus (Olivier) (Coleoptera: Dryophthoridae) larvae are cryptic, internal tissue-feeding pests of palm trees that are difficult to detect; consequently, infestations may remain hidden until they are widespread in an orchard. Infested trees and propagable offshoots that develop from axillary buds on the trunk frequently are transported inadvertently to previously uninfested areas. Acoustic methods can be used for scouting and early detection of R. ferrugineus, but until now have not been tested on multiple trees and offshoots in commercial date palm orchard environments. For this report, the acoustic detectability of R. ferrugineus was assessed in Saudi Arabian date palm orchards in the presence of commonly occurring wind, bird noise, machinery noise, and nontarget insects. Signal analyses were developed to detect R. ferrugineus and another insect pest, Oryctes elegans Prell (Coleoptera: Scarabaeidae), frequently co-occurring in the orchards, and discriminate both from background noise. In addition, it was possible to distinguish R. ferrugineus from O. elegans in offshoots by differences in the temporal patterns of their sound impulses. As has been observed often with other insect pests, populations of the two species appeared clumped rather than uniform or random. The results are discussed in relation to development of automated methods that could assist orchard managers in quickly identifying infested trees and offshoots so that R. ferrugineus infestations can be targeted and the likelihood of transferring infested offshoots to uninfested areas can be reduced.

A two-centre, open-label, randomised study of ovulation inhibition with three transdermal contraceptive patches, each containing different amounts of ethinyl estradiol and gestodene in healthy, young women.

Here we report the findings of a two-centre, open-label, randomised, Phase IIa study designed to investigate whether an ethinyl estradiol (EE)/gestodene (GSD) patch that has been developed (referred to herein as the 'EE/GSD patch') reliably inhibits ovulation in comparison with patches delivering lower doses of these hormones. The study rationale was to provide justification of the doses of EE and GSD selected for the EE/GSD patch. Healthy women, aged 18-35 years, were randomised to receive treatment with either the EE/GSD patch, a 'reduced-GSD patch' (delivering similar amounts of EE and approximately half the amount of GSD) or a 'reduced-EE/GSD patch' (delivering half the amount of EE and GSD). Treatment was administered for three 28-day cycles (three × 7 patch-wearing days, plus a 7-day patch-free interval). The primary pharmacodynamic variable was the percentage of women with ovulation in at least one of Cycles 2 and/or 3, as indicated by Hoogland score. Pharmacokinetic parameters for EE and GSD were also measured. Results indicated that the EE/GSD patch effectively suppressed ovulation, while patches delivering lower doses of EE and GSD were less effective for this purpose. All three patches showed comparable tolerability.

[Regulatory framework of innovative therapies : From bench to bedside]. / Regulatorischer Rahmen für neuartige Therapien. Vom Labor zur klinischen Prüfung.

Novel therapies, e.g., cell and gene therapy or tissue engineering, are summarized in the European Union as advanced therapy medicinal products (ATMPs). In terms of composition and product properties, ATMPs are highly complex, and given their multiple potential actions they are subject to continuously developing regulatory requirements. Due to promising basic research findings, there are high expectations by the society toward the therapeutic potential of ATMPs. It is of utmost importance to develop a scientifically sound preclinical and clinical development plan before entering into the first clinical trial. Due to the complex features of ATMPs, this development plan should be discussed early with the regulatory authorities to define the specifics and challenges of each individual product. For planning as well as operational realization of the initial clinical trial involving ATMPs, specific requirements that need to be addressed are discussed in this paper.

Human iliac vein replacement with a tissue-engineered graft.

The modification of a previously described technique to generate venous conduits in a lamb model from a decellularised matrix and autologous cells and its application to human tissue is described. A 49-year-old woman underwent surgery for a large malignant pelvic tumour (carcinoma of unknown primary) involving the right iliac artery and vein. The right iliac artery was reconstructed with a cryopreserved human arterial allograft. For iliac vein reconstruction a tissue-engineered neo-vein was developed utilising a decellularised cryopreserved vein allograft that was reseeded in a bioreactor with autologous endothelial cells derived from the recipient's great saphenous vein. Both interposition grafts were patent initially, after 3, 6, 12, and 24 months, but the tissue-engineered neo-vein had become obstructed due to evolving disease four month postoperatively. Tissue engineered neo-veins may be a therapeutic option in selected cases with symptomatic vein stenosis or obstruction not curable with interventional methods or standard prosthetic replacement.

Preclinical development of tissue-engineered vein valves and venous substitutes using re-endothelialised human vein matrix.

OBJECTIVE: The aim of the study was to evaluate the use of a decellularised scaffold and its re-endothelialisation in vitro in order to create human vascular substitutes containing venous valves. This research is clinically relevant particularly with regard to the development of venous (valve containing) transplants to replace a diseased femoral vein valve and/or obstructed veins. This technique may enable causal treatment of venous reflux and obstructions. MATERIALS AND METHODS: Valve-bearing segments of human allogeneic great saphenous veins (GSVs) were decellularised using sodium deoxycholic acid (SD) and treated with DNase I. Human venous endothelial cells (ECs) were enzymatically harvested from the GSV, expanded up to the 3rd passage using FCS (n=20) or human AB serum (hABS; n=8) supplemented media before used for re-seeding. In special bioreactors, 3D re-seeding of 28 decellularised GSV was performed with constant perfusion (A; n=8), bidirectional perfusion (B; n=8), bidirectional perfusion/reduced flow (C; n=2), static conditions (D; n=2), and bidirectional perfusion/reduced flow using hABS (E; n=8) instead of FCS. Decellularised GSV, scaled-up EC and 3D-seeded tissue-engineered valve containing neo-veins underwent immunohistochemical and PCR characterisation. RESULTS: Intact collagen and elastin networks as well as complete acellularity were shown after GSV decellularisation. In EC culture, supplementation with hABS led to a significantly higher expression of vWF compared to FCS (p=0.025). Additional EC markers such as CD 31, FLK-1 and VE-Cadherin were not altered. EC re-seeding using hABS supplemented medium (E) led to a confluent monolayer of cells that were immunohistochemically positive for FLK-1, CD 31, vWF and VE-Cadherin and by means of PCR after RNA preparation in 7 of 8 cases but was unsuccessful if FCS was used (A-D). In A-D cells presented as conglomerates positive for CD 31 and VE-Cadherin, suggesting sufficient intercellular contact but not cell-matrix contact. CONCLUSIONS: Treatment with SD and DNase enables complete decellularisation of human valve containing veins whereas 3D matrix components such as collagen and elastin remain preserved. The lumen of the scaffold including the valves can be successfully re-seeded with a human EC monolayer in a 3D bioreactor. There is substantial evidence that hABS and not FCS is essential for the completion of cell-matrix contacts in human veins.

Web-based cheminformatics and molecular property prediction tools supporting drug design and development at Novartis.

Web-based tools offer many advantages for processing chemical information, most notably ease of use and high interactivity. Therefore more and more pharmaceutical companies are using web technology to deliver sophisticated molecular processing tools directly to the desks of their chemists, to assist them in the process of designing and developing new drugs. In this paper, the web-based cheminformatics system developed at Novartis and currently used by more than thousand users is described. The system allows various molecular modeling and molecular processing tasks, including the calculation of molecular and substituent properties, property-based virtual screening, visualization of molecules, bioisosteric design, diversity analysis, and support of combinatorial chemistry. The methodology to calculate various molecular properties relevant to drug design is described, including the prediction of intestinal absorption, blood-brain barrier penetration, efflux, and water solubility. Information about the web technology used is also provided.

Fast calculation of molecular polar surface area as a sum of fragment-based contributions and its application to the prediction of drug transport properties.

Molecular polar surface area (PSA), i.e., surface belonging to polar atoms, is a descriptor that was shown to correlate well with passive molecular transport through membranes and, therefore, allows prediction of transport properties of drugs. The calculation of PSA, however, is rather time-consuming because of the necessity to generate a reasonable 3D molecular geometry and the calculation of the surface itself. A new approach for the calculation of the PSA is presented here, based on the summation of tabulated surface contributions of polar fragments. The method, termed topological PSA (TPSA), provides results which are practically identical with the 3D PSA (the correlation coefficient between 3D PSA and fragment-based TPSA for 34 810 molecules from the World Drug Index is 0.99), while the computation speed is 2-3 orders of magnitude faster. The new methodology may, therefore, be used for fast bioavailability screening of virtual libraries having millions of molecules. This article describes the new methodology and shows the results of validation studies based on sets of published absorption data, including intestinal absorption, Caco-2 monolayer penetration, and blood-brain barrier penetration.

Comparison of several approaches of therapeutic drug monitoring of cyclosporin A based on individual pharmacokinetics.

OBJECTIVE: The clinical outcome of patients after organ transplantation is correlated with cyclosporin A (CyA) exposure. It is generally accepted that the area under the concentration-time curve (AUC) provides a reliable means for drug exposure. However, in routine therapeutic drug monitoring (TDM) of CyA, trough levels are mostly used. Currently, a number of different new concepts of CyA-TDM, including approaches such as single, double or triple time-point and abbreviated AUC determinations, have been introduced. The purpose of this study was to compare the predictive value of the different strategies of TDM. METHODS: Calculations were based on 40 individual concentration time profiles after oral administration of CyA to patients who had been included into an ongoing prospective clinical trial. Non-compartmental analysis was used to calculate the AUC0-12h. Multiple linear regression was performed to describe the relationship between the different sets of blood concentrations and the respective AUC0-12h as well as to evaluate their predictive value regarding AUC. Predictive performance was assessed by prediction bias and prediction precision, which were estimated as the mean prediction error and root mean squared error, respectively. RESULTS: When comparing the various combinations of time points, it was found that one-point approaches showed the strongest differences with regard to the predictive value; the associated r2 values differed from 0.203 to 0.792. The two and three time-point approaches showed lower differences - r2 0.802-0.972. The four-point and five-point approaches (r2 0.942-0.982) were the strongest predictors for CyA AUC0-12h. Relative bias ranged from -27.7% to 63.8% and changed significantly when multiple-point predictors were used. In those cases, the predictive performance improved. Considering the predictive performance as well as the smallest bias and highest prediction precision, C3, C1 + C3, C1 + C3 + C6 and C1 + C2 + C3 + C6 were the best predictors. CONCLUSION: The results of this study indicate that in kidney transplant patients a clinically sufficient precise estimation of the CyA AUC is possible using two or three concentration time points.

Combinatorial approaches to inhibitors of VLA-4: piperazine-peptoid-bisarylureas.

A combinatorial approach towards identifying inhibitors of VALA-4 was investigated. A library of piperazine-peptoid-bisarylureas was assembled in solid phase and screening in the novel v-well assay enabled the identification of active compounds.

Thermoregulated expression and characterization of an NAD(P)H-dependent 2-cyclohexen-1-one reductase in the plant pathogenic bacterium Pseudomonas syringae pv. glycinea.

The phytopathogenic bacterium Pseudomonas syringae pv. glycinea PG4180.N9 causes bacterial blight of soybeans and preferably infects its host plant during periods of cold, humid weather conditions. To identify proteins differentially expressed at low temperatures, total cellular protein fractions derived from PG4180.N9 grown at 18 and 28 degreesC were separated by two-dimensional gel electrophoresis. Of several proteins which appeared to be preferentially present at 18 degreesC, a 40-kDa protein with an isoelectric point of approximately 5 revealed significant N-terminal sequence homology to morphinone reductase (MR) of Pseudomonas putida M10. The respective P. syringae gene was isolated from a genomic cosmid library of PG4180, and its nucleotide sequence was determined. It was designated ncr for NAD(P)H-dependent 2-cyclohexen-1-one reductase. Comparison of the 1,083-bp open reading frame with database entries revealed 48% identity and 52% similarity to the MR-encoding morB gene of P. putida M10. The ncr gene was overexpressed in Escherichia coli, and its gene product was used to generate polyclonal antisera. Purified recombinant Ncr protein was enzymatically characterized with NAD(P)H and various morphinone analogs as substrates. So far, only 2-cyclohexen-1-one and 3-penten-2-one were found to be substrates for Ncr. By high-pressure liquid chromatography analysis, flavin mononucleotide could be identified as the noncovalently bound prosthetic group of this enzyme. The distribution of the ncr gene in different Pseudomonas species and various strains of P. syringae was analyzed by PCR and Southern blot hybridization. The results indicated that the ncr gene is widespread among P. syringae pv. glycinea strains but not in other pathovars of P. syringae or in any of the other Pseudomonas strains tested.

Occurrence of thermoregulation of genes involved in coronatine biosynthesis among various Pseudomonas syringae strains.

Several pathovars of Pseudomonas syringae produce the polyketide phytotoxin coronatine (COR). In the bacterial blight pathogen of soybean, P. syringae pv. glycinea PG4180, COR is produced at high levels at 18 degrees C whereas no toxin is synthesized at 28 degrees C. Previously, activation of three promoters inside the COR biosynthetic gene cluster by a modified two-component regulatory system was shown to influence thermoregulation of COR biosynthesis. Using phenotypic determination of COR synthesis, a transcriptional reporter gene fusion, and Western blot analysis, we screened a representative number of natural isolates of P. syringae for effects of temperature on expression of cmaA, cmaB, and cmaT, which encode enzymes involved in the biosynthesis of COR. Thermoregulation of cmaABT expression was frequent among the tested strains. However, intensities of the temperature effects varied widely. Coronatine synsthesis was found to differ at up to six-fold among COR producing strains. There was no strain which synthesized COR at 28 degrees C although some of them showed increased basal cmaABT promoter activities at this temperature. Transcriptional fusions between the cmaABT promoter and a promoterless reporter gene were found to be down regulated at 28 degrees C only in COR producing strains but not in the non-producing strains tested. The geographic origin of the bacterial strains did not influence the occurrence of temperature-dependent gene expression.

Growth phase and temperature influence promoter activity, transcript abundance, and protein stability during biosynthesis of the Pseudomonas syringae phytotoxin coronatine.

The plant-pathogenic bacterium Pseudomonas syringae pv. glycinea PG4180.N9 synthesizes high levels of the polyketide phytotoxin coronatine (COR) at 18 degrees C, whereas no detectable toxin is produced at 28 degrees C. Previously, we reported that the temperature-sensitive activation of three promoters within the COR biosynthetic gene cluster might explain thermoregulation of COR biosynthesis. The present study was aimed at furthering our understanding of the transcriptional as well as the posttranslational effects of temperature on expression of cmaB, which encodes an enzyme involved in COR biosynthesis. Transcriptional fusions using a promoterless glucuronidase gene and Northern blot analyses were used to monitor promoter activities and transcript abundance for the cmaABT operon during bacterial growth at 18 and 28 degrees C. Promoter activity and transcription rates were maximal when cells were incubated at 18 degrees C and sampled at mid-logarithmic phase. Transcription declined moderately during the transition to stationary phase but remained higher at 18 C than at 28 degrees C. Western blot analysis indicated that CmaB accumulated in the late stationary phase of P. syringae cultures grown at 18 degrees C but not in cultures incubated at 28 degrees C. Temperature shift experiments indicated that CmaB stability was more pronounced at 18 degrees C than at 28 degrees C. Although temperature has a strong impact on transcription of COR biosynthetic genes, we propose that thermoregulation of protein stability might also control COR synthesis.

Pharmacokinetics of mezlocillin and sulbactam under continuous veno-venous hemodialysis (CVVHD) in intensive care patients with acute renal failure.

OBJECTIVE: In intensive care medicine, continuous detoxication methods, such as continuous veno-venous hemodialysis (CVVHD), are used for treating acute renal failure. However, in contrast to conventional hemodialysis, little is known about the pharmacokinetics of many drugs administered in this setting and guidelines for dosages of drugs often do not exist. This holds particularly true for broad-spectrum antibiotics, which are often required during intensive care. METHODS: In this study, we investigated the pharmacokinetics of the acylureidopenicillin mezlocillin and the beta-lactamase inhibitor sulbactam during CVVHD and deduced dosage recommendations from the kinetic parameters with the goal of maintaining trough levels of above 10 mg.l-1 for mezlocillin and 5 mg.l-1 for sulbactam. Six intensive care patients with acute renal failure, receiving mezlocillin (n = 5) and/or sulbactam (n = 4), were examined during CVVHD and during intervals between CVVHD. The serum concentrations and the amounts of the drugs excreted into the dialyzate and into the urine within one dosage interval were measured using high performance liquid chromatography (HPLC). Three of the patients were jaundiced, indicating functional impairment of the liver. RESULTS: The clearances by CVVHD (CLCVVHD) for mezlocillin ranged between 11.0 and 44.9 ml.min-1 and the half lives ranged between 1.12 and 8.84 h. Low CL and long half lives were observed in the patients with jaundice. For sulbactam, CLCVVHD ranged between 10.1 and 22.8 ml.min-1 and serum half lives were 4.25-6.11 h, independent of liver function. CONCLUSION: Due to high hepatobiliary clearance of mezlocillin, dosage adjustments in patients with acute renal failure, treated by CVVHD, are needed only with concurrent impaired liver function. For sulbactam, the optimal dose was found to be 0.5 g, administered every 12 h, regardless of liver function.

Relationship between serum and free interstitial concentrations of cefodizime and cefpirome in muscle and subcutaneous adipose tissue of healthy volunteers measured by microdialysis.

Microdialysis is a suitable method to monitor unbound concentrations of antimicrobial drugs in the interstitial tissue space which is the site of many infections. The aim of this investigation was to examine whether free tissue levels of cefodizime (81% plasma protein binding) and cefpirome (10% plasma protein binding) in muscle and subcutaneous adipose tissue of healthy volunteers obtained by microdialysis are consistent with the extent of their respective plasma protein binding. Healthy volunteers were given cefodizine and cefpirome at a single intravenous 2-g dose in a randomized crossover design. Microdialysis probes were inserted into a medial vastus muscle and into the periumbilical subcutaneous layer. After calibration of the probe, samples of serum and microdialysis fluid were obtained and drug concentrations were measured using a microagar diffusion-bioassay. There was a reasonable agreement between plasma protein binding data and the tissue penetration of both cephalosporins (AUC0-infinity tissue, free/AUC0-infinity serum, total-ratios) into the interstitial fluid of the muscle tissue, but not for the subcutaneous tissue layer. Furthermore, the serum and tissue concentrations of both drugs were fitted to an open two-compartment body model. The measured free-tissue concentrations were compared with calculated unbound concentrations in the peripheral compartment. Good agreement was observed for the free muscle concentrations, but unbound concentrations in the subcutaneous tissue was somewhat higher (cefpirome) or lower (cefodizime) than predicted. This may be due to the different lipophilicities of the two compounds.

Prediction of in vivo drug interaction from in vitro systems exemplified by interaction between verapamil and cimetidine using human liver microsomes and primary hepatocytes.

Emphasis on drug safety is increasing as newly developed drugs become more potent. Interest in the prediction and description of drug interactions is growing accordingly. The study of potential interactions at a very early stage of drug development requires suitable in vitro models that describe drug interactions both qualitatively and quantitatively. The purpose of the work described here was to help assess the predictive value of in vitro drug interaction tests with liver microsomes and hepatocytes by means of the interaction between verapamil and cimetidine. The in vitro inhibition of verapamil metabolism by cimetidine observed during the studies was quantitatively similar to the results reported in published clinical studies after intravenous application. Studies using liver microsome fractions showed that the intrinsic clearances for the formation of various metabolites could be used to predict drug interactions. In addition, work with hepatocyte cultures revealed that an in vitro system covering both phase I and phase II reactions should be included in such studies to permit quantitative prediction of the various metabolic pathways. Both human hepatocyte cultures and human microsomes offer certain advantages for predicting the degree of drug metabolism and interactions in humans at the biotransformation level. Therefore, it seems likely that the simultaneous application of both systems will yield conclusions that most closely approximate the situation in humans.

Use of C1300 neuroblastoma cells to evaluate the protective value of hexamethonium, trimethaphan, hemicholinium, and triethylcholine against diisopropyl phosphorofluoridate toxicity.

Our intent was to evaluate the C1300 neuroblastoma cell as an in vitro system for studying the mode of action and efficacy of drugs used to treat or prevent organophosphate intoxication. The anticholinergic drugs hexamethonium, trimethaphan, and hemocholinium and the triethylcholine and cholinesterase/reactivator 2-pyridine aldoxime methochloride (2-PAM) have been shown to be effective in preventing intoxication by diisopropyl phosphorofluoridate (also known as diisopropyl fluorophosphate, DFP) in vivo. We determined their efficacy in preventing cell death (as measured by trypan blue exclusion) of neuroblastoma cells alone or in combination. We also determined their efficacy in reversing the cytotoxic effects of DFP on cell DNA synthesis (as measured by [3H]-thymidine incorporation), cell RNA synthesis (as measured by [3H]uridine incorporation), and on cell protein synthesis (as measured by [3H]leucine incorporation). The maximal nontoxic doses of the drugs in vitro were determined. All anticholinergic agents studied reduced the cytotoxicity of DFP using one or more parameters. 2-PAM, the cholinesterase reactivator, enhanced the cytotoxicity of DFP on cultured cells at a high concentration (1 mg/mL) and reduced it at a lower concentration (0.3 mg/mL). All four anticholinergic agents were capable of enhancing the uptake of [3H]thymidine. Only hexamethonium and hemicholinium reversed DFP inhibition of DNA synthesis. RNA synthesis was not affected by any anticholinergic agent and no agent reversed DFP inhibition of RNA synthesis. Protein synthesis was enhanced by every anticholinergic agent except hemicholinium; the inhibition of protein synthesis by DFP was reversed by trimethaphan and triethylcholine.(ABSTRACT TRUNCATED AT 250 WORDS)