Weight Bands Research Articles

Pharmacokinetics of zidovudine dosed twice daily according to World Health Organization weight bands in Ugandan HIV-infected children.

Data on zidovudine pharmacokinetics in children dosed using World Health Organization weight bands are limited. About 45 HIV-infected, Ugandan children, 3.4 (2.6-6.2) years, had intensive pharmacokinetic sampling. Geometric mean zidovudine AUC0-12h was 3.0 h.mg/L, which is higher than previously observed in adults, and was independently higher in those receiving higher doses, younger and underweight children. Higher exposure was also marginally associated with lower hemoglobin.

Estimation of Atmospheric Dust Deposition on Plant Leaves Based on Spectral Features

ABSTRACT Urban atmospheric dust is a significant problem and becoming a considerable pollution source in many cities. This study was based on a comparison of spectral reflectance on the surfaces of dusty and clean leaves. A significant linear relationship (r = 0.811) correlation between the dust weight and near-infrared band region (700–1000 nm) was found through analysis of the spectral data. This relationship obtained from near-infrared band regions, based on the main effects and cluster and interval analysis, was more distinct and stable than that of blue, green, red, and middle-infrared band regions. Thus, the use of near-infrared band data is a reliable method to estimate the amount of dust deposition on plant leaves. A regression model (R2 = 64.3%) was constructed based on dust deposition on plant leaves and a near-infrared ratio. The model proved to be accurate as regards an estimation of dust weight, based on a comparison of residuals (normal distribution) and accuracy tests (slope = 0.8437). This model could provide a methodological basis for spatial dust distribution analysis and has the potential for evaluating air pollution levels.

Three-layer structure microwave absorbers based on nanocrystalline alpha-Fe, Fe0.2(Co0.2Ni0.8)0.8 and Ni0.5Zn0.5Fe2O4 porous microfibers.

The three-layer structure microwave absorbers with thickness of 2 mm were designed based on nanocrystalline alpha-Fe, Fe0.2(Co0.2Ni0.8)0.8 and Ni0.5Zno.sFe204 porous microfibers with diameters about 2-5 microm. The electromagnetic parameters and microwave absorption properties were investigated by vector network analyzer in the frequency range of 2-18 GHz. The results show that the three-layer structure microwave absorbers display stronger absorption properties in a wide frequency range than the single-layer and double-layer microwave absorber. For the three-layer structure, the microwave absorption properties are mainly influenced by the microfibers layer arrangement order, total thickness and each layer thickness. When the Ni0.5Zn0.5Fe2O4 porous microfibers layer is arranged as the impedance-matching surface layer, with a total thickness of 2 mm consisting of 0.7 mm thick alpha-Fe porous microfibers inner layer, 0.9 mm thick Fe0.2(Co0.2Ni0.8)0.8 porous microfibers medium layer and 0.4 mm thick impedance-matching surface layer, the three-layer structure has a strongest microwave absorption of 45.7 dB at 12.8 GHz, the absorption bandwidth (with RL < -10 dB ) of 10.2 GHz from 7.8 GHz to 18 GHz and bandwidth (with RL < -20 dB) of 4.4 GHz from 11.1 GHz to 15.5 GHz respectively. This three-layer structure is promising microwave absorbers to meet the requirements of thin thickness, light weight and wide band for military and civil applications.

(276) A novel marker of macrophage phenotype indicates immune monitoring of nociceptor activity in dorsal root ganglia

There is extensive evidence for interactions between peripheral sensory neurons and immune cells at sites of peripheral injury. However, there has been limited investigation of neuro-immune crosstalk within peripheral sensory ganglia. We report the identification of a novel marker of macrophage activation whose expression is rapidly suppressed in resident cells within dorsal root ganglia (DRG) in response to a distant noxious stimulus. SDS-PAGE analysis of the global protein banding profile from lumbar L2-5 DRG was visualized by silver stain. Samples were compared from mice with and without inflammation of the hindpaw induced by injection of complete Freund’s adjuvant 24 hours before sample collection. A striking difference was the loss of a high molecular weight band at 250 kD in samples from inflamed mice. This band was excised and analyzed by mass spectroscopy. A high confidence target (p<0.01) was identified as myosin-4 and validated by Western blot. Immunohistochemistry for myosin-4 in combination with F4/80, a macrophage marker, revealed a network of F4/80+ macrophages in naïve DRG and extensive colocalization with myosin-4, indicating expression of myosin-4 in resident macrophages. Staining was also seen in macrophage-like cells cultured from bone marrow, but not in neuronal cultures. Analysis of mouse and human peripheral tissues revealed labeled macrophage-like cells, suggesting that myosin-4 is a marker of resident macrophages in human as well as mouse. To confirm that this phenotypic switch was not due to a systemic inflammatory response to the adjuvant, the TRPV1 agonist capsaicin was injected into the hindpaw to selectively excite nociceptors. 24 hours later, Western blot analysis indicated a loss of myosin-4 protein in L2-5 DRG. We propose that resident immune cells within DRG monitor nociceptor activity and respond to noxious insult with a change in phenotype. The significance of the phenotypic switch for macrophage signaling, mobility and phagocytosis is under investigation.

Pharmacokinetics of Pediatric Lopinavir/Ritonavir Tablets in Children When Administered Twice Daily According to FDA Weight Bands

Lopinavir/ritonavir (LPV/r) pediatric tablets (100/25 mg) are approved by the United States Food and Drug Administration (FDA) and European Medicines Agency (EMA) as part of combination antiretroviral therapy. Dosing is based on body weight bands or body surface area under FDA approval and only body surface area by the EMA. This can lead to a different recommended dose. In addition, weight band-based dosing has not been formally studied in the target population. We evaluated the pharmacokinetics (PK) of LPV/r in children, administered twice daily according to the FDA weight bands, using pediatric tablets. Fifty-three HIV-infected children were included in the PK substudy of the Paediatric European Network for the Treatment of AIDS 18 trial (KONCERT). In this study, children were randomized to receive LPV/r twice or once daily, according to FDA weight bands. A PK assessment was performed in 17, 16 and 20 children in the 15-25 kg, ≥ 25-35 kg and >35 kg weight band, respectively, while children took the tablets twice daily. Rich sampling was performed, and PK parameters were calculated by noncompartmental analysis. Given the high percentage of Asian children, it was also tested whether there was a difference in PK parameters between Asian and non-Asian children. For the total group, LPV geometric mean AUC0-12, Cmax and C12 were 106.9 h × mg/L, 12.0 mg/L and 4.9 mg/L, respectively. There were no significant differences in LPV PK parameters between the weight bands. In addition, weight was not found to be associated with variability in Cmax, C12 or AUC0-12 for the LPV PK parameters. FDA weight band-based dosing recommendations provide adequate exposure to LPV when using LPV/r pediatric tablets.

Photosynthetic activity and protein overexpression found in Cr(III)-tolerant cells of the green algae Dictyosphaerium chlorelloides

Chromium is an important constituent in effluents obtained from chromium plating industries. Due to the highly toxic nature of Cr(VI), attention has been shifted to less hazardous Cr(III) electroplating processes. This study evaluated aquatic toxicity of Cr(III)-containing laboratory samples representative of effluents from chromium electroplating industries, on the photosynthetic activity exhibited by both Cr(III)-sensitive (Dc1Mwt) and tolerant (Dc1MCr(III)R30) Dictyosphaerium chlorelloides strains. Additionally, selected de novo-determined peptide sequences, obtained from Dc1MCr(III)R30, have been analyzed to evidence the possible Cr(III) toxic mechanism involved in the resistance of these cells to high Cr(III) levels in aquatic environments. Dc1MCr(III)R30 strain exhibited a gross photosynthetic balance of about five times lower than that exhibited by Dc1Mwt strain, demonstrating that Dc1MCr(III)R30 has a photosynthetic yield significantly lower than Dc1Mwt. SDS–PAGE of Dc1MCr(III)R30 samples showed the presence of at least two protein bands (23.05 and 153.46KDa, respectively) absent in wild-type strain samples. Although it has achieved a low coincidence between the lower molecular weight band and a GTPase identified from genome of the green alga Chlamydomonas reinhardtii, none of de novo peptide sequences obtained showed a significant MS-BLAST score, so that further studies will be required.

Allergy To Ferret

S U N D A Y 354 Characterization Of The Allergenic Activity Of Tropomyosin From Aedes Aegypti Mr. Jose F. Cantillo, Prof. Leonardo Puerta, Dr. Enrique FernandezCaldas, Dr. Sylvie Lafosse-Marin; Complutense University of Madrid, Spain; Inmunotek S.L., Alcal a de Henares, Spain, Institute for Immunological Research/University of Cartagena, Cartagena, Colombia, Inmunotek, S.L, Spain, Cabinet de Inmunoallergology, Fort de France, Martinique. RATIONALE: Mosquito bites are an important cause of skin lesions in allergic and non-allergic individuals worldwide. The inhalation of mosquito allergens may also be a cause of allergic respiratory diseases. It has been suggested that there may be cross-reactivity among mosquitoes and other arthropods such as mites, Chironomidae and shrimps. We hypothesized that the panallergen tropomyosin may be involved in this process. METHODS: Tropomyosin was purified from a whole body A. aegypti extract by size exclusion and anionic exchange chromatography. Specific IgE binding to the purified tropomyosin was evaluated by immunoblot and ELISA in allergic patients with positive ELISA to A. aegypti allergenic extract and control individuals. Cross-reactivitywas evaluated by immunoblotting and ELISA inhibitions using tropomyosin derived from the giant tiger prawn Penaeus monodon (nPen m 1) and from the whiteleg shrimp Litopenaeus vannamei (rLit v 1). RESULTS: A purified fraction from the allergenic A. aegypti extract showed four bands of several molecular weights with reactivity to antiPen m 1 rabbit serum, which showed also IgE reactivity to positive sera to mosquito extract. The IgE reactivity to these bands disappears when the sera where adsorbed with shrimps tropomyosin (nPen m 1 and rLit v 1). 25% of the mosquito allergic individuals had detectable specific IgE levels to this fraction. Inhibition of IgE reactivity higher than 90 % was demonstrated in a sera pool adsorded with nPen m 1 and rLit v 1. CONCLUSIONS: We have demonstrated the presence of tropomyosin in A. aegypti extract, which cross-react with shrimp tropomyosins.

Electrophoretic profile of serum proteins in dromedary camels

Electrophoretic pattern of serum protein and dialysed serum protein profiles were studied from apparently healthy camels on 10% and 15% SDS-PAGE in addition to total protein and immunoglobulin content. The electrophoretic pattern of camel serum protein revealed 7 prominent bands of molecular weights ranging from 28.21 kDa to 123.07 kDa on 10% SDS-PAGE and dialysed serum protein revealed 4 prominent bands of molecular weights ranging from 24.30 kDa to 110.87 kDa. The electrophoretic pattern of camel serum protein on 15% SDS PAGE revealed 8 prominent bands of molecular weights ranging from 0.005 to 121.04 kDa along with 5 bands of dialysed serum protein. There are about 7 lower molecular weight bands which may be of prealbumin and other lower molecular weight proteins. The lower molecular weight bands may be of pre albumin. The band with higher molecular weight may be of different globulin fractions including immunoglobulins. Total protein and immunoglobulin content were low in present study possibly due to very hot temperature and limited grazing facility during summer.

Deep Sequencing Insights in Therapeutic shRNA Processing and siRNA Target Cleavage Precision

TT-034 (PF-05095808) is a recombinant adeno-associated virus serotype 8 (AAV8) agent expressing three short hairpin RNA (shRNA) pro-drugs that target the hepatitis C virus (HCV) RNA genome. The cytosolic enzyme Dicer cleaves each shRNA into multiple, potentially active small interfering RNA (siRNA) drugs. Using next-generation sequencing (NGS) to identify and characterize active shRNAs maturation products, we observed that each TT-034–encoded shRNA could be processed into as many as 95 separate siRNA strands. Few of these appeared active as determined by Sanger 5′ RNA Ligase-Mediated Rapid Amplification of cDNA Ends (5-RACE) and through synthetic shRNA and siRNA analogue studies. Moreover, NGS scrutiny applied on 5-RACE products (RACE-seq) suggested that synthetic siRNAs could direct cleavage in not one, but up to five separate positions on targeted RNA, in a sequence-dependent manner. These data support an on-target mechanism of action for TT-034 without cytotoxicity and question the accepted precision of substrate processing by the key RNA interference (RNAi) enzymes Dicer and siRNA-induced silencing complex (siRISC).

Different sucrose-isomaltase response of Caco-2 cells to glucose and maltose suggests dietary maltose sensing

Using the small intestine enterocyte Caco-2 cell model, sucrase-isomaltase (SI, the mucosal α-glucosidase complex) expression and modification were examined relative to exposure to different mono- and disaccharide glycemic carbohydrates. Caco-2/TC7 cells were grown on porous supports to post-confluence for complete differentiation, and dietary carbohydrate molecules of glucose, sucrose (disaccharide of glucose and fructose), maltose (disaccharide of two glucoses α-1,4 linked), and isomaltose (disaccharide of two glucoses α-1,6 linked) were used to treat the cells. qRT-PCR results showed that all the carbohydrate molecules induced the expression of the SI gene, though maltose (and isomaltose) showed an incremental increase in mRNA levels over time that glucose did not. Western blot analysis of the SI protein revealed that only maltose treatment induced a higher molecular weight band (Mw ~245 kDa), also at higher expression level, suggesting post-translational processing of SI, and more importantly a sensing of maltose. Further work is warranted regarding this putative sensing response as a potential control point for starch digestion and glucose generation in the small intestine.

Mechanism of Transport Modulation by an Extracellular Loop in an Archaeal Excitatory Amino Acid Transporter (EAAT) Homolog

Secondary transporters in the excitatory amino acid transporter family terminate glutamatergic synaptic transmission by catalyzing Na(+)-dependent removal of glutamate from the synaptic cleft. Recent structural studies of the aspartate-specific archaeal homolog, Glt(Ph), suggest that transport is achieved by a rigid body, piston-like movement of the transport domain, which houses the substrate-binding site, between the extracellular and cytoplasmic sides of the membrane. This transport domain is connected to an immobile scaffold by three loops, one of which, the 3-4 loop (3L4), undergoes substrate-sensitive conformational change. Proteolytic cleavage of the 3L4 was found to abolish transport activity indicating an essential function for this loop in the transport mechanism. Here, we demonstrate that despite the presence of fully cleaved 3L4, Glt(Ph) is still able to sample conformations relevant for transport. Optimized reconstitution conditions reveal that fully cleaved Glt(Ph) retains some transport activity. Analysis of the kinetics and temperature dependence of transport accompanied by direct measurements of substrate binding reveal that this decreased transport activity is not due to alteration of the substrate binding characteristics but is caused by the significantly reduced turnover rate. By measuring solute counterflow activity and cross-link formation rates, we demonstrate that cleaving 3L4 severely and specifically compromises one or more steps contributing to the movement of the substrate-loaded transport domain between the outward- and inward-facing conformational states, sparing the equivalent step(s) during the movement of the empty transport domain. These results reveal a hitherto unknown role for the 3L4 in modulating an essential step in the transport process.

Laboratory Predictors Of Loss Of High Molecular Weight Multimers In Patients With Cardiovascular Disease-Associated Acquired Von Willebrand Syndrom

BackgroundAssociation of acquired von Willebrand syndrome (AVWS) with various cardiovascular (CV) disorders such as cardiac valve disease and hypertrophic cardiomyopathy (HCM) is well known and documented. The mechanism is thought to be related to shear stress induced loss of high molecular weight multimers (HMWM). The gold standard test to assess for loss of HMWM is von Willebrand protein electrophoresis and then visual assessment of loss of high molecular weight bands. This is both a costly and subjective test. Ratio of von Willebrand factor activity to antigen level is useful in patients with type IIA Von Willebrand Disease caused by loss of HMW multimer, but its sensitivity to detect CV-associated AVWS is unknown. AimOur aim was to test whether routine VWF laboratory tests could be used to predict which patients with CV conditions are going to have high molecular weight multimer loss. We also aimed to assess whether these tests could be used to predict bleeding risk in patients with CV disorders. MethodsWe prospectively collected laboratory data of 234 patients with cardiovascular disorders known to be associated with AVWS: aortic stenosis (66), aortic insufficiency(22), aortic and mitral valve prostheses(38), mitral valve regurgitation (51) and hypertrophic cardiomyopathy(57). All patients had Von Willebrand factor antigen (VWF:Ag), Von Willebrand factor activity by latex method (VWF:Ltx), platelet function testing via PFA-100 CADP as well as von Willebrand factor multimers tested. All patients also completed a bleeding questionnaire. We used logistic regression model to calculate the relationship between the VWF:Ltx/VWF:Ag ratio and loss of high molecular weight multimers. Same analysis was performed for PFA-100. We also tested these associations for bleeding risk. ResultsMean value for VWF:Ag was 142 IU/dL, VWF:Ltx 121%, PFA-100 151 seconds and 0.86 for the VWF:Ltx/Ag ratio. Over a half of patients (56%) had VWF multimer loss noted on protein electrophoresis testing and a quarter reported bleeding on bleeding questionnaire. The ratio of VWF:Ltx to VWF:Ag had strong correlation with HMW multimer loss (p<0.001) with AUC of 0.77. Correlation with PFA-100 was even stronger with AUC of 0.83. The ratio cut off value of 0.83 had sensitivity of 60% and specificity of 83% in predicting multimer loss. With the cut off of 0.77, specificity reached 95%. With PFA 100 value of 118 seconds, specificity was 76% and sensitivity was 80%. Increasing the cut off to 198 seconds improved the specificity to 95%. The association with bleeding was present for PFA-100 (p=0.01), but did not exist for the Ltx/Ag ratio. ConclusionsPFA-100 CADP as well as VWF:Ag and VWF:Ltx can be used to detect acquired Von Willebrand disease in patients with cardiovascular disorders and may decrease the need for costly and time consuming testing of multimers. PFA-100 CADP also correlates with the bleeding risk in these patients. Disclosures:No relevant conflicts of interest to declare.

Does thyroid peroxidase provide an antigenic link between thyroid autoimmunity and breast cancer?

Women with breast cancer (BC) and antithyroid peroxidase (TPO) autoantibodies (TPOAb) have a better prognosis than women lacking TPOAb. Sera from women with TPOAb displayed immunoreactivity to BC tissue by immunofluorescence that was not apparent in women without TPOAb. We hypothesize a BC/thyroid shared antigen that provides a target for humoral or cell-mediated immune activity; candidates include the sodium/iodide symporter (expressed in thyroid and BC), cross-reacting epitopes in TPO and lactoperoxidase (LPO) or TPO itself. As the association is with TPOAb, we investigated TPO expression in BC, breast peritumoral tissue (PT), other tissues (tumoral and not) and thyroid as positive control. Transcripts for known and novel TPO isoforms were detected in BC (n = 8) and PT (n = 8) but at approximately 10(4) -fold lower than in thyroid while in non-BC tumors (n = 5) they were at the limit of detection. TPO was expressed also in adipose tissue (n = 17), 10(3) -fold lower than in thyroid. Full length TPO (Mr 105-110 kDa) was detected in Western blots in the majority of examined tissues; preabsorption of the TPO antibody with recombinant TPO (but not LPO) reduced the signal, indicating specificity. The same occurred with some lower molecular weight bands, which could correspond to smaller TPO transcript isoforms, present in all samples. In conclusion, TPO is weakly expressed in BC and other tissues; this could partly explain the high frequency and protective role of TPOAb in BC patients. Further studies will investigate tissue specificity, function and immunogenicity of the novel TPO variants (some BC-specific) identified.

Leucine Zipper Motif Drives the Transmembrane Domain Dimerization of E-cadherin

E-cadherin is a transmembrane glycoprotein which is involved in the Ca2+-dependent cell–cell adhesion, and the adhesiveness is heavily dependent on the homodimerization of this molecule. Previous studies have shown that both the extracellular domain and cytoplasmic domain of E-cadherin contribute to its homodimerization. However, the roles of the transmembrane(TM) domain in the E-cadherin homodimerization have not been discussed in detail. In our experiments, SDS-PAGE showed higher molecular weight bands for the synthetic E-cadherin TM peptide, which indicated that the E-cadherin TM peptide is able to dimerize in the SDS micelle. The TOXCAT assay proved that the E-cadherin TM domain can form a moderate homo-oligomer in the Escherichia coli inner membrane. Furthermore, mutational analyses using the TOXCAT assays revealed that, instead of the common GxxxG dimerization motif, the leucine zipper motif is essential for the dimerization of the E-cadherin TM domain. Combining our experiment data and the computational simulation results, we provide insights for understanding the roles of the TM domain in the E-cadherin dimerization.

Biochemical characterization of stallion prostasomes and comparison to their human counterparts

Release of nanometer-sized prostasomes into human and equine semen suggests essential functions in their relationships with sperm cells and the fertilization process. The two types of prostasomes displayed ultrastructural similarities, albeit the human prostasomes were somewhat larger than the stallion prostasomes. A high ratio of saturated fatty acids was characteristic for the two prostasome types. Electrophoretic separation systems revealed an equine prostasomal pattern different from that of human. The 21 distinctive low molecular weight protein spots in the 2D-gel (with no counterparts in human prostasomes) were identified via peptide mass fingerprinting, several of which may be different isoforms. Out of the three high molecular weight bands characteristic for human prostasomes (CD10, CD13, and CD26), CD10 and CD13 were retrieved in equine prostasomes. We present some new proteins of horse prostasomes not found in their human counterparts. Further studies are warranted to reveal the function of these proteins.

Effects of rifampin-based antituberculosis therapy on plasma efavirenz concentrations in children vary by CYP2B6 genotype

An efavirenz-based antiretroviral therapy (ART) regimen is preferred for children more than 3 years of age with tuberculosis. However, rifampin, a key component of antituberculosis therapy, induces CYP2B6. An increased dose of efavirenz is recommended in adults weighing more than 50 kg who require rifampin, but there is scant information in children being treated for tuberculosis. Plasma efavirenz concentrations were compared in 40 children during concomitant treatment for tuberculosis and HIV-1, after stopping rifampicin, and in a control group of children without tuberculosis. Associations with antituberculosis treatment, metabolizer genotype (based on CYP2B6 516G→T, 983T→C, and 15582C→T), weight, and time after dose were evaluated. Compared to children with extensive metabolizer genotypes, efavirenz concentrations were increased 1.42-fold (95% confidence interval, CI 0.94–2.15) and 2.85-fold (95% CI 1.80–4.52) in children with intermediate and slow metabolizer genotypes, respectively. Concomitant antituberculosis treatment increased efavirenz concentrations 1.49-fold (95% CI 1.10–2.01) in children with slow metabolizer genotypes, but did not affect efavirenz concentrations in extensive or intermediate metabolizer genotypes. After adjustment for dose/kg, each kilogram of weight was associated with a 2.8% (95% CI 0.9–4.7) decrease in efavirenz concentrations. Despite higher milligram per kilogram doses, a higher proportion of children in the lowest weight band (10–13.9 kg) had efavirenz concentrations less than 1.0 mg/l than larger children. Antituberculosis treatment was not associated with reduced efavirenz concentrations in children, which does not support increased efavirenz doses. Children with slow metabolizer genotype have increased efavirenz concentrations during antituberculosis treatment, likely due to isoniazid inhibiting enzymes involved in accessory metabolic pathways for efavirenz.

Population Pharmacokinetics Study of Recommended Zidovudine Doses in HIV-1-Infected Children

The aims of this study were to describe the pharmacokinetics of zidovudine (ZDV) and its biotransformation to its metabolite, 3*-azido-3*-deoxy-5*-glucuronylthymidine (G-ZDV), in HIV-infected children, to identify factors that influence the pharmacokinetics of ZDV, and to compare and evaluate the doses recommended by the World Health Organization (WHO) and the Food and Drug Administration (FDA). ZDV concentrations in 782 samples and G-ZDV concentrations in 554 samples from 247 children ranging in age from 0.5 to 18 years were retrospectively measured. A population pharmacokinetic model was developed with NONMEM software (version 6.2), and the pharmacokinetics of ZDV were best described by a one-compartment model with first-order absorption and elimination. The effect of body weight on the apparent elimination clearance and volume of distribution was significant. The mean population parameter estimates were as follows: absorption rate, 2.86 h(-1); apparent elimination clearance, 89.7 liters · h(-1) (between-subject variability, 0.701 liters · h(-1)); apparent volume of distribution, 229 liters (between-subject variability, 0.807 liters); metabolic formation rate constant, 12.6 h(-1) (between-subject variability, 0.352 h(-1)); and elimination rate constant of G-ZDV, 2.27 h(-1). On the basis of simulations with FDA and WHO dosing recommendations, the probabilities of observing efficient exposures (doses resulting in exposures of between 3 and 5 mg/liter · h) with less adverse events (doses resulting in exposures below 8.4 mg/liter · h) were higher when the FDA recommendations than when the WHO recommendations were followed. In order to improve the FDA recommendations, ZDV doses should be reconsidered for the weight band (WB) of 20 to 40 kg. The most appropriate doses should be decreased from 9 to 8 mg/kg of body weight twice a day (BID) for the WB from 20 to 29.9 kg and from 300 to 250 mg BID for the WB from 30 to 39.9 kg. The highest dose, 300 mg BID, should be started from body weights of 40 kg.

Population pharmacokinetics of abacavir in infants, toddlers and children

To characterize the pharmacokinetics of abacavir in infants, toddlers and children and to assess the influence of covariates on drug disposition across these populations. Abacavir concentration data from three clinical studies in human immunodeficiency virus-infected children (n = 69) were used for model building. The children received either a weight-normalized dose of 16 mg kg(-1) day(-1) or the World Health Organization recommended dose based on weight bands. A population pharmacokinetic analysis was performed using nonlinear mixed effects modelling VI. The influence of age, gender, bodyweight and formulation was evaluated. The final model was selected according to graphical and statistical criteria. A two-compartmental model with first-order absorption and first-order elimination best described the pharmacokinetics of abacavir. Bodyweight was identified as significant covariate influencing the apparent oral clearance and volume of distribution. Predicted steady-state maximal plasma concentration and area under the concentration-time curve from 0 to 12 h of the standard twice daily regimen were 2.5 mg l(-1) and 6.1 mg h l(-1) for toddlers and infants, and 3.6 mg l(-1) and 8.7 mg h l(-1) for children, respectively. Model-based predictions showed that equivalent systemic exposure was achieved after once and twice daily dosing regimens. There were no pharmacokinetic differences between the two formulations (tablet and solution). The model demonstrated good predictive performance for dosing prediction in individual patients and, as such, can be used to support therapeutic drug monitoring in conjunction with sparse sampling. The disposition of abacavir in children appears to be affected only by differences in size, irrespective of the patient's age. Maturation processes of abacavir metabolism in younger infants should be evaluated in further studies to demonstrate the potential impact of ontogeny.

Standard concentration infusions and ‘smart’ pumps in PICU: the challenge of change

IntroductionArising from reviews of critical incidents, many leading organisations, such as the Institute of Safe Medical Practice in the US and the National Patient Safety Agency in the UK, have...

Role of C‐terminal domain of E‐cadherin in activating β‐catenin/TCF pathway in cancer cells under hypoxic conditions

E‐cadherin expression plays a predominant role in the development and homeostasis of epithelial architecture. Down‐regulation of transmembrane protein E‐cadherin is often considered as a marker for cancer malignancy and metastasis. In this study, the effect of hypoxia on E‐cadherin expression in different cancer cell lines was analyzed. We hypothesized that down‐regulation of E‐cadherin under hypoxia would lead to transmigration of its intracellular C‐terminal fragment to the nucleus and result in activation of ß‐catenin/ TCF pathway. Treatment of A549 lung cancer, SW480 and SW620 colon cancer, T47D breast cancer, and HEK293 cells with hypoxia, 1% oxygen for periods of two, three, or four days, resulted in a significant decrease in E‐cadherin expression, Under hypoxic conditions, E‐cadherin is highly degraded resulting in the generation of multiple bands of different molecular weights depending on cells and involved proteinases. This decrease in E‐cadherin is concomitant to an increase in Snail and Slug expression, well‐known E‐cadherin suppressors. Similarly, over‐expression of Snail and Slug in cancer cells resulted in an increase in TCF activity quantified by a luciferase assays. Finally, transient transfection of cancer cells with cloned soluble C‐terminal E‐cadherin resulted in high TCF activity compared to the control. These results suggest that in normoxia, E‐cadherin neutralizes ß‐catenin and prevent it from inducing nuclear TCF activity. However, following E‐cadherin degradation, C‐terminal E‐cadherin binds ß‐catenin and translocates to the nucleus to activate TCF.