High Target Concentrations Research Articles

MULTIPRED2: A computational system for large-scale identification of peptides predicted to bind to HLA supertypes and alleles

MULTIPRED2 is a computational system for facile prediction of peptide binding to multiple alleles belonging to human leukocyte antigen (HLA) class I and class II DR molecules. It enables prediction of peptide binding to products of individual HLA alleles, combination of alleles, or HLA supertypes. NetMHCpan and NetMHCIIpan are used as prediction engines. The 13 HLA Class I supertypes are A1, A2, A3, A24, B7, B8, B27, B44, B58, B62, C1, and C4. The 13 HLA Class II DR supertypes are DR1, DR3, DR4, DR6, DR7, DR8, DR9, DR11, DR12, DR13, DR14, DR15, and DR16. In total, MULTIPRED2 enables prediction of peptide binding to 1077 variants representing 26 HLA supertypes. MULTIPRED2 has visualization modules for mapping promiscuous T-cell epitopes as well as those regions of high target concentration – referred to as T-cell epitope hotspots. Novel graphic representations are employed to display the predicted binding peptides and immunological hotspots in an intuitive manner and also to provide a global view of results as heat maps. Another function of MULTIPRED2, which has direct relevance to vaccine design, is the calculation of population coverage. Currently it calculates population coverage in five major groups in North America. MULTIPRED2 is an important tool to complement wet-lab experimental methods for identification of T-cell epitopes. It is available at http://cvc.dfci.harvard.edu/multipred2/.

Online determination of viable biomass up to very high cell densities in Arxula adeninivorans fermentations using an impedance signal

Up to now biomass has been measured online by impedance analysis only at low cell densities in yeast fermentations. As industrial fermentation processes focus, for example, on producing high target concentrations of biocatalysts or pharmaceutical proteins, it is important to investigate cell growth under high cell-density conditions. Therefore, for the first time, biomass has been measured online using impedance analysis in a 50 L high-pressure stirred tank reactor. As model organism the yeast Arxula adeninivorans was cultivated in two chemically defined mineral media at a constant growth rate in fed-batch mode. To ensure aerobic culture conditions over the entire fermentation time, the fermentations were conducted at an elevated headspace overpressure of up to 9.5 bar. The highest oxygen transfer rate value of 0.56 mol L −1 h −1 ever reported for yeast fermentations was measured in these investigations. Unlike previous findings, in this study a linear correlation was found between capacitance and biomass up to concentrations of 174 g L −1 dry cell weight.

Metal-coordination-mediated sequential chelation-enhanced fluorescence (CHEF) and fluorescence resonance energy transfer (FRET) in a heteroditopic ligand system

Sequential fluorescence enhancement and fluorescence resonance energy transfer over a zinc ion gradient have been engineered in a two-fluorophore heteroditopic ligand platform. This is the first report that the strategies of metal-coordination modulated photoinduced electron transfer (PET), internal charge transfer (ICT), and fluorescence resonance energy transfer (FRET) are integrated in one synthetic fluoroionophore. Comparing to the previously reported single-fluorophore heteroditopic ligands (L. Zhang, R. J. Clark and L. Zhu, Chem. Eur. J. 2008, 14, 2894–2903), the resolution of two emission channels is greatly enhanced to almost 100 nm. This two-fluorophore heteroditopic platform lends promise to creating dual-emission fluorescent indicators where low- and high-target concentration regimes could be analyzed using independent emission filter sets.

Reusable, polyethylene glycol-structured microfluidic channel for particle immunoassays

A microfluidic channel made entirely out of polyethylene glycol (PEG), not PEG coating to silicon or polydimethylsiloxane (PDMS) surface, was fabricated and tested for its reusability in particle immunoassays and passive protein fouling, at relatively high target concentrations (1 mg ml-1). The PEG devices were reusable up to ten times while the oxygen-plasma-treated polydimethyl siloxane (PDMS) device could be reused up to four times and plain PDMS were not reusable. Liquid was delivered spontaneously via capillary action and complicated bonding procedure was not necessary. The contact angle analysis revealed that the water contact angle on microchannel surface should be lower than ~60°, which are comparable to those on dried protein films, to be reusable for particle immunoassays and passive protein fouling.

Impact of Cyclosporine a (CsA) Concentration on the Incidence of Severe Acute Graft-Versus-Host Disease (GVHD) after Allogeneic Stem Cell Transplantation (allo-SCT).

CsA is widely used as the backbone immunosuppressive agent for GVHD prevention after allo-SCT. Previous studies have demonstrated that the immunosuppressive effects of CsA (eg. inhibition of calcineurine in lymphocytes) may be correlated with CsA blood concentration, especially in the context of solid organ transplantation. This report aimed to investigate the impact of CsA concentrations in the early post allo- SCT period, on the incidence of severe acute GVHD, in 85 consecutive patients treated in a single centre between Jan. 2006 and Jan. 2008, and for whom CsA concentrations in the blood were monitored weekly after the start of infusion. 85 patients (45 males) received CsA (usually at 3 mg/Kg/d, 2 or 3 days prior to graft infusion) as a 24-h continuous infusion until hematopoietic recovery and switch to oral formulation. Dose modifications of CsA were performed to maintain adequate trough blood levels and to prevent nephrotoxicity. Patients' and donors characteristics were as follow: median age: 51 (range, 18–67), 46 (54%) female donors, 33 (39%) myeloid malignancies, 49 (58%) lymphoid malignancies, and 3 cases of SAA. The stem cell source was PBSC in 66 (78%) patients, while bone marrow was used in 19 (22%) patients. 37 (43.5%) were transplanted from a matched related donor, and 48 (56.5%) from a matched unrelated donor. A myeloablative conditioning regimen was used in 24 (28%) patients, and 61 (72%) received a reduced intensity regimen. The median concentrations of CsA in the blood at 1, 2, 3 and 4 weeks after allo-SCT were 348 (range, 172–733), 284 (range, 137–535), 274 (range, 107–649), and 247 (37–695) ng/mL respectively. All patients engrafted at a median of 17 (range, 0–42) days after allo-SCT. With a median follow-up of 16 (range, 5–29) months, grade 2–4 acute GVHD occurred in 36 patients (42%) at a median of 29 (range, 6–100) days after allo-SCT. The incidence of severe grade 3–4 acute GVHD was 23% (95%CI, 14–32%). In this cohort, all acute GVHD risk factors (age, donor-recipient gender, CMV serostatus, ABO compatibility, diagnosis, disease status, stem cell source, donor type, conditioning regimen type, GVHD prophylaxis regimen, CsA concentrations) were assessed. In multivariate analysis, we found that higher whole-blood CsA concentration in the first week following graft infusion, and before onset of acute GVHD was the strongest parameter significantly associated with a reduced the risk of severe grade 3–4 acute GVHD (P=0.01; RR=0.24; 95%CI, 0.08–0.73). Despite its retrospective nature, these data strongly indicate a close relationship between CsA trough blood concentration during the early post allo-SCT period and the severity of acute GVHD. Inadequate or insufficient early exposures of CsA can be a serious risk for developing severe acute GVHD. Therefore, precise monitoring of CsA concentrations and achievement of a high CsA target concentration may be an effective tool to prevent the onset of severe acute GVHD.

Performance characteristics of TCI devices implementing the Marsh model

There are several commercially available propofol target-controlled infusion (TCI) devices and pharmacokinetic simulation software packages. We compared the output of different simulation programs with eachother, and with the measured output of TCI devices. We used Stanpump, TIVATrainer and Rugloop to calculate the volumes required by the Marsh model to achieve target blood propofol concentrations of 0.5 and 6.0 μg.ml−1 for 120 min. The infusion devices were used to administer 1% propofol by TCI (at target blood propofol concentrations of 0.5 and 6.0 μg.ml−1 for 120 min). Devices used were: (i) Alaris Asena PK pump; (ii) Graseby 3500 pump; (iii) a Fresenius Orchestra Base Primea TCI infusion system; (iv) a PC running Stanpump software controlling a Graseby 3500 pump. For each device the propofol syringe was connected to a 200 cm long intravenous infusion administration set, which was in turn connected to a 22G intravenous cannula. The cannula was attached to and its tip directed into, a measuring flask placed on a high precision scale. At 10-min intervals, for each system, the cumulative mass of propofol delivered was recorded and used to calculate the administered volume for each 10-min epoch (Volmeas). We also recorded from the user interface the cumulative volume that the system estimated it had delivered (Volest). For each epoch, j, 10-min error was defined as: (Volmeas,j − Volest,j)/Volest,j × 100. Experiments were conducted under identical conditions; the flask was sealed to avoid evaporation during the experiment. The propofol volumes calculated by the different programs were almost identical. The infusion devices implemented infusion regimens very similar to those calculated by simulation programs. All pumps performed well at the high target concentration. Accuracy at low concentrations is shown in Fig. 1. Accuracy of pumps at low target concentration. All pumps performed sub-optimally at low infusion rates. At low target concentrations, the Fresenius and Graseby pumps significantly overestimated the volume of propofol administered during the early phases of the infusion. Fresenius Kabi kindly loaned the authors a Base Primea system. Cardinal Health provided RA with an unrestricted travel grant.

Chemotherapy for Colorectal Cancer Liver Metastases

Colorectal cancer (CRC) is a highly prevalent malignant disease in industrialized nations. The annual incidence of invasive CRC in the U.S. is among the highest in the world, and the liver is the only metastatic site in approximately one third of patients. Without treatment, patients with metastatic disease have a poor prognosis; however, long-term survival benefits and even cure have been reported in patients undergoing surgical resection of metastases. In addition, advances in chemotherapy, imaging, and surgical techniques have increased the proportion of patients who are eligible for resection. Combination therapy with fluorouracil and leucovorin has been the mainstay of treatment for metastatic CRC; however, the introduction of newer agents, such as oxaliplatin and irinotecan, and targeted agents, such as cetuximab and bevacizumab, has yielded improvements in response rates (RRs) and survival. Maximizing the exposure of hepatic metastases to high target concentrations of cytotoxic drugs using hepatic arterial infusion (HAI) increases RRs further than with systemic chemotherapy; however, the impact of HAI on survival is unclear. As the goals of chemotherapeutic treatment for metastatic CRC increasingly shift from palliation to prolongation of survival, improvement in RRs, and downsizing of tumors in order to enable or optimize resection, treatment in a multidisciplinary environment involving a medical oncologist, radiologist, and surgical oncologist with hepatobiliary expertise will become central to deciding the best course of therapy and timing of surgery.

Tacrolimus (FK506) for induction of remission in refractory ulcerative colitis

There are a limited number of treatment options for patients with refractory ulcerative colitis. Animal models of inflammatory bowel disease and uncontrolled studies in humans suggest that tacrolimus may be effective treatment for ulcerative colitis. This review aims to evaluate the efficacy of tacrolimus for induction of remission in patients with corticosteroid refractory ulcerative colitis. MEDLINE (PubMed), The Cochrane Central Register of Controlled Trials, the IBD/FBD review group specialized register and the ISI-Research Institute were searched (January 1997 to November 2007) to identify relevant studies all randomized trials. Each author independently reviewed potentially relevant studies to determine eligibility based on the pre-specified criteria. A data extraction form was developed and used to extract data from included studies. Two authors independently extracted data. Data were analyzed using Review Manager (RevMan 4.2.9). The primary outcomes were induction of remission and clinical improvement, as defined by the studies and expressed as a percentage of the patients randomized (intention to treat analysis). One randomized controlled trial comparing high target serum concentration and low target serum concentration tacrolimus versus placebo was identified and included in the review. Clinical remission was observed in 19% (4/21) of patients in the high target serum concentration group, in 9% (2/22) in the low target serum concentration group and in 5% (1/20) in the placebo group (OR 2.27; 95% CI 0.35 to 14.75). A statistically significant benefit for clinical improvement at two weeks was observed. Clinical improvement was observed in 62% (13/21) of patients in the high target serum concentration group, in 36% (8/22) in the low target serum concentration group and in 10% (2/20) in the placebo group (OR 8.66; 95% CI 1.79 to 42.00; RD 0.39; 95% CI 0.20 to 0.59; NNT = 3). Patients in the high serum target concentration group were significantly more likely than placebo patients to experience adverse events related to treatment (P = 0.043). Finger tremor (n = 6) was the most common adverse event in the tacrolimus group. Other adverse events included: gastroenteritis, sepsis, sleepiness, hot flush, headache, queasiness and stomach discomfort. Tacrolimus may be effective for short-term clinical improvement in patients with refractory ulcerative colitis. However, these results should be interpreted with caution due to the small number of patients enrolled in the trial and other study limitations. Insufficient treatment and follow-up intervals prevent any conclusions with regard to long term safety and efficacy. The use of tacrolimus in the clinical setting requires careful consideration of risks versus benefits as well as close monitoring for adverse events. More data from well designed and controlled studies are needed to determine the long-term efficacy and safety of tacrolimus.

Colorimetric Detection of Mercuric Ion (Hg2+) in Aqueous Media using DNA‐Functionalized Gold Nanoparticles

Mercury is a widespread pollutant with distinct toxicological profiles, and it exists in a variety of different forms (metallic, ionic, and as part of organic and inorganic salts and complexes). Solvated mercuric ion (Hg), one of the most stable inorganic forms of mercury, is a caustic and carcinogenic material with high cellular toxicity. The most common organic source of mercury, methyl mercury, can accumulate in the human body through the food chain and cause serious and permanent damage to the brain with both acute and chronic toxicity. Methyl mercury is generated by microbial biomethylation in aquatic sediments from water-soluble mercuric ion (Hg). Therefore, routine detection of Hg is central to the environmental monitoring of rivers and larger bodies of water and for evaluating the safety of aquatically derived food supplies. Several methods for the detection of Hg, based upon organic fluorophores or chromophores, semiconductor nanocrystals, cyclic voltammetry, polymeric materials, proteins, and microcantilevers, have been developed. Colorimetric methods, in particular, are extremely attractive because they can be easily read out with the naked eye, in some cases at the point of use. Although there are now several chromophoric colorimetric sensors for Hg, all of them are either limited with respect to sensitivity (current limit of detection 1 mm) and selectivity, kinetically unstable, or incompatible with aqueous environments. Recently, DNA-functionalized gold nanoparticles (DNA– Au NPs) have been used in a variety of forms for the detection of proteins, oligonucleotides, certain metal ions, and other small molecules. DNA–Au NPs have high extinction coefficients (3–5 orders of magnitude higher than those of organic dye molecules) and unique distancedependent optical properties that can be chemically programmed through the use of specific DNA interconnects, which allows one, in certain cases, to detect targets of interest through colorimetric means. Moreover, these structures, when hybridized to complementary particles, exhibit extremely sharp melting transitions, which have been used to enhance the selectivity of detection systems based upon them. By using such an approach, one can typically detect nucleic acid targets in the low nanomolar to high picomolar target concentration range in colorimetric format. The ability to use such particles to detect Hg in the nanomolar concentration range in colorimetric format would be a significant advance, especially when one considers that commercial systems for detecting Hg rely on cumbersome inductively coupled plasma approaches that are not suitable for point-of-use applications. Herein, we present a highly selective and sensitive colorimetric detection method for Hg that relies on thymidine–Hg–thymidine coordination chemistry and complementary DNA–Au NPs with deliberately designed T–T mismatches. When two complementary DNA–Au NPs are combined, they form DNA-linked aggregates that can dissociate reversibly with a concomitant purple-to-red color change. 28] For our novel colorimetric Hg assay, however, we prepared two types of Au NPs (designated as probe A and probe B, see the Supporting Information), each functionalized with different thiolated-DNA sequences (probe A: 5’HS-C10-A10-T-A103’, probe B: 5’HS-C10-T10-T-T103’), which are complementary except for a single thymidine–thymidine mismatch (shown in bold; Scheme 1). Importantly, these particles also form stable aggregates and exhibit the characteristic sharp melting transitions (full width at half maximum< 1 8C) associated with aggregates formed from perfectly complementary particles, but with a lower melting temperature Tm. [17, 18] Since it is known that Hg will coordinate selectively to the bases that make up a T–T mismatch, we hypothesized that Hg would

Kinetics of oligonucleotide hybridization to photolithographically patterned DNA arrays

The hybridization kinetics of oligonucleotide targets to oligonucleotide probe arrays synthesized using photolithographic fabrication methods developed by Affymetrix have been measured. Values for the fundamental adsorption parameters, k a, k d, and K, were determined at both room temperature and 45 °C by monitoring the hybridization of fluorescently labeled targets to the array. The values for these parameters and the adsorbed target density (⩽1 pmol/cm 2 at saturation) agree relatively well with published values for arrays fabricated by immobilizing intact probes. The isotherms can be fit well with the Sips model, a generalization of the Langmuir model that allows for multiple binding energies. However, binding to these arrays also displays certain characteristics that may result from the close spacing of probes on the array. At high target concentrations and 22 °C, an “overshoot” is observed, wherein a large amount of target binds rapidly and then desorbs to a final plateau. This binding mode may be a result of the unique nature of photolithographically patterned arrays given that targets initially can bind in lower stability binding modes by partially adsorbing to a probe and its neighbor(s), a process that can be viewed as a form of competitive hybridization for overlapping sites on a given probe. Using the values measured for k a and k d, an analytical model that accounts for this behavior is proposed. Alternatively, at 45 °C, the adsorption approaches an initial plateau, rather than an overshoot, and then undergoes a “secondary rise” to a final value. A potential explanation for this phenomenon that is compatible with the analysis at lower temperature is offered.

Application of a nifH oligonucleotide microarray for profiling diversity of N2‐fixing microorganisms in marine microbial mats

Diazotrophic community structure in microbial mats from Guerrero Negro (GN), Baja California, Mexico, was studied using polymerase chain reaction amplification of the nifH gene and a newly developed nifH oligonucleotide microarray. Ninety-six oligonucleotide probes designed for nifH sequences from cultivated isolates and the environment were printed on glass microarrays. Phylogenetic analysis showed that the probes represented all of the main nifH clusters. Specificity was tested by (i) evaluation of cross hybridization using individual targets, and (ii) comparison of the observed hybridization signals and those predicted from the sequences cloned from microbial mats. Signal intensity had a positive relationship with target concentration and the percentage identity between probe and target. Under moderate stringency and high target concentration, specificity of the probes varied from 77% to 100% with the individual targets tested. At the end of a 7-month long nutrient manipulation experiment in GN microbial mats, no expression of nitrogen fixation under nitrogen loading was detected, although a diverse community of diazotrophs was detected. The diversity in diazotrophic population present was higher than in the population expressing the nifH gene, and there were taxa specific differences in response to nutrients. The nifH microarray is a powerful tool for diazotroph community analysis in the marine environment.

Mono and bivalent binding of a scFv and covalent diabody to murine laminin-1 using radioiodinated proteins and SPR measurements: Effects on tissue retention in vivo

Phage display techniques identified a scFv, 15-9, which binds to murine laminin-1 and accumulated selectively in tumors. In this study, a covalent diabody was constructed by changing the amino acid residues at positions VH44 and VL100 to cysteine residues so that the diabody form could be stabilized via a disulfide bond. The covalent diabody was expressed in Pichia pastoris and purified by affinity chromatography. The binding properties were measured by surface plasmon resonance and solid phase binding of 125I diabody and scFv. Data from the plasmon resonance method yielded calculated K Ds of 4.4 × 10 − 10 M for the covalent diabody and 9.9 × 10 − 8 M for the scFv. K Ds calculated from solid phase binding of radioiodinated proteins were 1.7–2.1 × 10 − 10 M and 2.1–2.4 × 10 − 8 M respectively. The rate of dissociation of 125I scFv from solid phase laminin was independent of laminin concentration; however, the dissociation of the 125I diabody was dependent both on the concentration of laminin and on the concentration of the diabody. Specifically, high concentrations of laminin yielded very slow rates of diabody dissociation indicating that bivalent attachments had formed. When higher amounts of diabody were used that essentially saturated the laminin sites with univalent binding, the dissociation rate was similar to that for the scFv indicating univalent binding. Biodistribution studies in tumor-bearing SCID mice showed that the covalent diabody improved the ratio of tumor/muscle 2 fold over that obtained with the scFv, although the absolute amount of protein bound to the tumor site was not significantly different for the two forms. The data also showed that retention of the diabody in the tumor and kidney, sites where laminin is present in high concentration, was much longer compared to that of scFv. These data are consistent with the hypothesis that both scFv and diabody forms bind to available laminin in vivo with similar association kinetics, but that in situations of high target concentration, the diabody can bind bivalently and is thus retained at the binding site much longer than the scFv.

Loss of Outer Membrane Proteins without Inhibition of Lipid Export in an Escherichia coli YaeT Mutant

Escherichia coli yaeT encodes an essential, conserved outer membrane (OM) protein that is an ortholog of Neisseria meningitidis Omp85. Conflicting data with N. meningitidis indicate that Omp85 functions either in assembly of OM proteins or in export of OM lipids. The role of YaeT in E. coli was investigated with a new temperature-sensitive mutant harboring nine amino acid substitutions. The mutant stops growing after 60 min at 44 degrees C. After 30 min at 44 degrees C, incorporation of [35S]methionine into newly synthesized OM proteins is selectively inhibited. Synthesis and export of OM phospholipids and lipopolysaccharide are not impaired. OM protein levels are low, even at 30 degrees C, and the buoyant density of the OM is correspondingly lower. By Western blotting, we show that levels of the major OM protein OmpA are lower in the mutant in whole cells, membranes, and the growth medium. SecA functions as a multicopy suppressor of the temperature-sensitive phenotype and partially restores OM proteins. Our data are consistent with a critical role for YaeT in OM protein assembly in E. coli.

Reproducibility of HPV 16 and HPV 18 viral load quantitation using TaqMan real-time PCR assays

A reproducibility study was designed to assess within-assay, between-day, and interlaboratory variability of three real-time PCR assays targeting HPV 16, HPV 18, and the human glyceraldehyde-3-phosphate dehydrogenase (GAPDH) pseudogenes. Fifteen HPV 16 and fifteen HPV 18 cervical swab samples were amplified in triplicate by GAPDH and HPV 16 and by GAPDH and HPV 18 assays, respectively. All samples were amplified undiluted and at a 1:10 dilution on 2 separate days in the same laboratory, and the same samples were amplified in a separate laboratory. HPV 16 and HPV 18 normalized viral load is reported as the number of HPV genomes per 20 000 GAPDH copies. The analytic specificity of the HPV 16 and 18 assays was 100 and 97%, respectively. The intraclass correlation coefficients (ICC) were 0.99, 0.97, and 0.98 for HPV 16, HPV 18, and GAPDH, respectively, indicating that the variability due to experimental error was very low. Ten-fold differences in viral load could be readily discriminated across a six order of magnitude dynamic range (ca. 5–5×10 6 copies). Power of discrimination was increased at higher target concentrations (>5000 copies). The correlation of normalized HPV 16 and 18 viral load was high between the two laboratories (Spearman rho (ρ)=0.96 and 0.87, respectively). These HPV 16 and HPV 18 quantitative PCR assays with GAPDH normalization are reproducibly quantitative over a broad linear dynamic range allowing for application in epidemiologic studies for measurement of viral load.

Neuroprotection Is Unlikely to Be Effective in Humans Using Current Trial Designs: An Opposing View

To summarize recent neuroprotective trials, there has been no useful balance of benefit over risk.1 It is premature to shoot the messenger without evidence either that the results have been misleading or that we have missed trends. Confirmatory trials and/or meta-analysis support the validity of the results, and similar designs have successfully revealed the risks and benefits of thrombolysis. Trial designs have been imperfect, but the message is accurate: the drugs or doses we tried were inadequate. We need safer and better drugs, we need to know when and how to use them, and we need to maximize the efficiency of our trials. All are possible with current designs.2 Originally, limited efficacy data from a single laboratory and an acceptable toxicity profile were sufficient to proceed to clinical development. Choice of dose range, the optimal duration of therapy, patient subgroup selection, and the likely extent of benefit were all reserved for testing in clinical trials. The misplaced optimism of such an approach is now recognized, however, and guidance on preclinical testing has been elaborated.3 Rigorous external scrutiny of preclinical data now occurs in the more informed companies,4 and clinical development is deferred pending resolution of any deficiencies. This is the first role of the (now mandatory) trial steering committee. The drug classes under investigation are evolving, and new approaches are still being discovered. Glutamate antagonists have been widely studied.1 While effective in small animal models, their short time window in the laboratory, failure to protect …

Effects of targets impregnated with the chitin synthesis inhibitor triflumuron on the blowfly Lucilia sericata

AbstractThe effects of exposure of adults of the blowfly Lucilia sericata (Meigen) for 24 h to cloth targets impregnated with the chitin synthesis inhibitor triflumuron plus sucrose or sucrose only, were considered. When both male and female L. sericata were exposed to targets treated with sucrose only, the percentage egg hatch varied between 60–75%. When both sexes were exposed to targets treated with 10% triflumuron plus sucrose the percentage egg hatch varied between 3–7%. When females alone were exposed to triflumuron, prior to the introduction of unexposed males, egg hatch varied between 4–14%. The exposure of males alone to 10% triflumuron treated targets, prior to the introduction of unexposed virgin females, did not give any consistent significant decrease in the mean percentage egg hatch. However, repetition of this trial with males exposed to targets treated with 15 or 20% triflumuron, resulted in a percentage egg hatch of 3.1% and 10.3%, respectively. These results suggest that at relatively high target concentrations, males can transfer effective doses of triflumuron to unexposed virgin females.The exposure of adults to triflumuron treated targets did not significantly increase the mortality of either male or female L. sericata. Furthermore, bioassays showed that there was no significant decline in the ovicidal effectiveness of targets treated with 10% triflumuron and sucrose solution following exposure to sun and rain for up to 8 weeks in 1995 and 1996.The results suggest that targets treated with triflumuron suspension concentrate and sucrose may form the basis of an effective system for the control of L. sericata in the field. However, the relatively high concentrations of triflumuron required and the low efficiency with which males are able to transfer effective doses to unexposed females may diminish one of the main theoretical advantages of using a chitin synthesis inhibitor, such as triflumuron, over a conventional insecticide.