Effect of intracranial bleeds on the neurocognitive, academic, behavioural and adaptive functioning of boys with haemophilia

Brain insults are a risk factor for neuropsychological and academic deficits across several paediatric conditions. However, little is known about the specific effects of intracranial haemorrhage (ICH) in boys with haemophilia. The study compared neurocognitive, academic and socio-emotional/behavioural outcomes of boys with haemophilia with and without a history of ICH. Of 172 consecutive patients seen at a Pediatric Comprehensive Care Hemophila Centre, 18 had a history of ICH. Sixteen boys between the ages of 3 and 17 years were available for study and were matched to controls with haemophilia of the same age and disease severity and on the basis of maternal education. Groups were compared on neuropsychological and academic outcomes. Attention, socio-emotional function and executive skills were compared using data from parent questionnaires. Differences were found in intellectual function, visual-spatial skill, fine motor dexterity and particularly language-related skills, including vocabulary, word reading and applied math problem solving. Despite these group differences, outcomes were within the average range for most boys with ICH. No group differences were found in behavioural and socio-emotional functioning. Although ICH in haemophilia is not benign, it was not associated with significant cognitive and academic consequences for most boys. Early neuropsychological assessment may be indicated when there is a history of ICH. Investigation of age at ICH and quantitative measures of brain in relation to neurocognitive outcomes in larger groups of boys with ICH would be useful.

A new species of myxosporean (Sphaeromyxidae), a parasite of lined seahorses, Hippocampus erectus, from the Gulf of Mexico

Sphaeromyxa cannolii sp. n. is described from the bile ducts of aquaria-maintained lined seahorses (Hippocampus erectus) from the Gulf of Mexico. Spores of the new species are linear, 17-18 µm long and 5-6 µm wide, with flattened tips; polar capsules measure 4 × 3 µm. Routine necropsies of H. erectus following planned death revealed liver inflammation, bile duct obstruction, bile accumulation, and myxozoan parasites in the bile ducts of 11 of 40 animals sampled (27.5%). The presence of S. cannolii in an aquaculture setting should prompt keepers to carefully quarantine new animals and exclude annelid fauna, a potential intermediate host of myxozoans.

Abstract 2734: Genome-wide analysis of direct Nkx3.1 target genes

NKX3.1 is an androgen-regulated, prostate-specific tumor suppressor gene that is essential for development and maintenance of the prostate gland. Loss of Nkx3.1 expression results in the formation of premalignant lesions called prostatic intraepithelial neoplasia lesions (PIN). With additional mutations, these PIN lesions will progress to invasive carcinoma and eventually to metastatic disease in which there is currently no effective treatment. The specific mechanism(s) by which Nkx3.1 suppresses prostate tumorigenesis remains unknown. Previous gene expression profiling studies in Nkx3.1-deficient mouse prostates have shown aberrant expression of many genes that may be involved in prostate tumorigenesis. However, it is unknown whether these genes are direct targets of Nkx3.1 in vivo. To identify direct Nkx3.1 target gens, we used chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-Seq) to identify Nkx3.1 binding sites in the genomes of a human prostate cancer cell line (LNCaP) as well as the normal mouse prostate. We obtained 7 to 15 million uniquely mapped tags each from Nkx3.1 ChIP-seq using LNCaP cells or Nkx3.1+/+, Nkx3.1+/−, and Nkx3.1−/− mouse prostates. This led to the identification of about 8000 Nkx3.1 binding sites in the genome (the Nkx3.1 cistrome). The binding site data were integrated with gene expression profiling results from Nkx3.1 mutant mice to yield a core set of “direct” Nkx3.1 target genes. One gene in particular that is upregulated in Nkx3.1 mutant mice and in human prostate tumors and bound by Nkx3.1 in our ChIP-Seq studies is the receptor activity modifying protein 1 (RAMP1) gene. Ramp1 is a single transmembrane protein that is required for trafficking of the calcitonin gene-related peptide (CGRP) receptor to the plasma membrane. The CGRP receptor binds CGRP, a neuropeptide that has been shown to promote cancer progression. Current studies are focused on whether RAMP1 expression in human prostate cancer cells function to promote tumorigenesis. Given that Ramp1 is localized to the plasma membrane, data from my project may provide support for investigating Ramp1 as a therapeutic target for prostate cancer or for imaging prostate lesions.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2734. doi:10.1158/1538-7445.AM2011-2734

Importance of inhaler-device satisfaction in asthma treatment: real-world observations of physician-observed compliance and clinical/patient-reported outcomes

INTRODUCTION

It is hypothesized that health and patient-reported outcomes in asthma are positively influenced by the level of patient satisfaction with their inhaler device. This paper uses data from a real-world observational study to investigate the extent of the relationship between inhaler satisfaction and patient compliance, and the influence this has on health and patient-reported outcomes.

METHODS

Data were drawn from the Adelphi Respiratory Disease Specific Programme® (Adelphi, Macclesfield, UK), a cross-sectional study of consulting patients in five European countries undertaken between June and September 2009. A range of clinical and patient-reported outcomes were observed allowing analysis of these and their relationship with patient-reported inhaler satisfaction and patient compliance.

RESULTS

The analysis demonstrates that for the majority of patients the higher the level of satisfaction that the patient reports for their device the more likely the patient is observed to be compliant and to experience better outcomes including quality of life (as measured by EuroQol 5 Dimensions [EQ-5D] utility score, P<0.001), fewer exacerbations (P<0.001), fewer hospital visits (P=0.011), fewer healthcare visits (P=0.001), fewer primary care physician visits (P=0.001), and fewer sleep disturbances (P<0.001).

CONCLUSION

The level of patient satisfaction with their inhaler device is observed to have a positive influence on the treatment goals for asthma through its association with improved compliance.

Characterization of Conductive Anodic Filament (Caf) by X-Ray Microtomography and by Serial Sectioning

X-ray microtomography is used to nondestructively section printed wiring boards in which conductive anodic filaments (CAFs) had grown, Quantification of the spatial distribution of copper is compared for microtomography and for serial sections obtained in SEM with backscattered electrons. The agreement between the techniques is excellent and indicates that microtomography may be used confidently to follow the subsurface growth of CAFs.

Design and quality of ICF-compatible data items for national disability support services

PURPOSE

To examine the structure, distribution and interrelationships of International Classification of Functioning, Disability and Health (ICF)-compatible items in Australia's national data collection about disability support services.

METHOD

Rasch analyses were carried out on 93,000 records relating to people aged 15 to 64 years, receiving disability support services in Australia in 2003. The range of disabilities and services received was diverse. 'Support needs', in all nine life areas based on the ICF Activities and Participation domains, are recorded in the national data collection in one of the following three categories: 'needs no help/supervision in this life area'; 'sometimes needs help/supervision'; or 'always needs help/supervision or unable to do activity'.

RESULTS

The results of the analysis demonstrate the value of the 'support needs' questions. The three categories of need for support were distinct and widely separated; the ICF domains were also found to be distinct. The results also showed that 'support needs' in one subset of ICF Activities and Participation domains could not be used to predict values in another subset.

CONCLUSIONS

The two-dimensional question about 'support needs' offers promise as a general data capture tool for indicating 'extent' of disability. Caution should be exercised in the omission of any ICF Activities and Participation life areas for measurement in diverse populations.

The patient-physician partnership in asthma: real-world observations associated with clinical and patient-reported outcomes

INTRODUCTION

It is hypothesized that a good partnership between asthma patients and their physicians has a direct and positive influence on the patients' clinical and patient-reported outcomes. Conversely, poor partnership has a detrimental effect on clinical and patient-reported outcomes. This paper uses data from a real-world observational study to define partnership through matched physician and patient data and correlate the quality of partnership with observed clinical and patient-reported outcomes.

METHODS

Data were drawn from Adelphi's Respiratory Disease Specific Programme, a cross-sectional study of consulting patients in five European countries undertaken between June and September 2009. A range of clinical and patient-reported outcomes were observed allowing analysis of the partnership between 2251 asthma patients and their physicians.

RESULTS

Analysis demonstrates that the better the partnership between patient and physician, the more likely the patient is to have their asthma condition controlled (P<0.001), to experience fewer exacerbations (P<0.001), to have better quality of life (P<0.001), to have fewer sleep disturbances (P<0.001), and to have fewer patient-reported symptoms (P<0.001). Partnership is also associated with lower impact on lifestyle (P<0.01) and reduced days lost at work/school (P<0.05), and with patient satisfaction with their inhaler device (P<0.05).

CONCLUSION

The patient-physician partnership is a contributory factor in the improvement of asthma treatment, and patient education may lead to improvement in a patient's ability to contribute to this. Device satisfaction is one of the markers of good partnership.

Sensitivity and Resistance to Spectinomycin in Escherichia coli

Inhibition of growth and division of Escherichia coli by spectinomycin is reversible, and the kinetics of its interference with deoxyribonucleic and ribonucleic acid synthesis may be interpreted as secondary effects of inhibition of protein synthesis on the ribosome. Spontaneous mutations to spectinomycin resistance occur in E. coli K-12 at a rate of about 2 x 10(-10). Resistance is transducible with a discrete lag in phenotypic expression, and the kinetics of its development is about the same as that for streptomycin resistance. All spectinomycin-resistant mutants tested contain resistant ribosomes, and all map in a locus (spc) counterclockwise to and 70% cotransducible with the classical str locus. Differences in the residual drug sensitivity of various spectinomycin-resistant mutants, and of their ribosomes, indicate the existence of more than one phenotypic class of resistance.

Lysis of halobacteria in bacto-peptone by bile acids

All tested strains of halophilic archaebacteria of the genera Halobacterium, Haloarcula, Haloferax, and Natronobacterium lysed in 1% Bacto-Peptone (Difco) containing 25% NaCl, whereas no lysis was observed with other strains belonging to archaebacteria of the genera Halococcus, Natronococcus, and Sulfolobus, methanogenic bacteria, and moderately halophilic eubacteria. Substances in Bacto-Peptone which caused lysis of halobacteria were purified and identified as taurocholic acid and glycocholic acid. High-performance liquid chromatography analyses of peptones revealed that Bacto-Peptone contained nine different bile acids, with a total content of 9.53 mg/g, whereas much lower amounts were found in Peptone Bacteriological Technical (Difco) and Oxoid Peptone. Different kinds of peptones can be used to distinguish halophilic eubacteria and archaebacteria in mixed cultures from hypersaline environments.

Paradigm shift or annoying distraction: emerging implications of web 2.0 for clinical practice

Web 2.0 technologies, known as social media, social technologies or Web 2.0, have emerged into the mainstream. As they grow, these new technologies have the opportunity to influence the methods and procedures of many fields. This paper focuses on the clinical implications of the growing Web 2.0 technologies. Five developing trends are explored: information channels, augmented reality, location-based mobile social computing, virtual worlds and serious gaming, and collaborative research networks. Each trend is discussed based on their utilization and pattern of use by healthcare providers or healthcare organizations. In addition to explorative research for each trend, a vignette is presented which provides a future example of adoption. Lastly each trend lists several research challenge questions for applied clinical informatics.

AAA+ proteins RUVBL1 and RUVBL2 coordinate PIKK activity and function in nonsense-mediated mRNA decay

Phosphatidylinositol 3-kinase-related protein kinase (PIKK) family proteins play essential roles in DNA-based and RNA-based processes, such as the response to DNA damage, messenger RNA (mRNA) quality control, transcription, and translation, where they contribute to the maintenance of genome integrity and accurate gene expression. The adenosine triphosphatases associated with diverse cellular activities (AAA+) family proteins RuvB-like 1 (RUVBL1) and RUVBL2 are involved in various cellular processes, including transcription, RNA modification, DNA repair, and telomere maintenance. We show that RUVBL1 and RUVBL2 associate with each PIKK family member. We also show that RUVBL1 and RUVBL2 control PIKK abundance at least at the mRNA level. Knockdown of RUVBL1 or RUVBL2 decreased PIKK abundance and impaired PIKK-mediated signaling. Analysis of SMG-1, a PIKK family member involved in nonsense-mediated mRNA decay (NMD), revealed an essential role for RUVBL1 and RUVBL2 in NMD. RUVBL1 and RUVBL2 associated with SMG-1 and the messenger ribonucleoproteins in the cytoplasm and promoted the formation of mRNA surveillance complexes during NMD. Thus, RUVBL1 and RUVBL2 regulate PIKK functions on two different levels: They control the abundance of PIKKs, and they stimulate the formation of PIKK-containing molecular complexes, such as those involved in NMD.

Adenovirus-mediated leptin expression normalises hypertension associated with diet-induced obesity

In our previous study, moderate increases in plasma leptin levels achieved via administration of recombinant adenovirus containing the rat leptin cDNA were shown to correct the abnormal metabolic profile in rats with diet-induced obesity, suggesting that these animals had developed resistance to the metabolic effects of leptin, which could be reversed by leptin gene over-expression. However, the effect of this therapeutic strategy on blood pressure was not investigated. The present study aimed to determine whether a moderate increase of endogenous plasma leptin levels affected arterial blood pressure in rats with diet-induced obesity and hypertension. The major finding from the present study was that the natural rise in plasma leptin with weight-gain is insufficient to counterbalance high blood pressure associated with obesity, additional increases of circulating leptin levels with adenoviral leptin gene therapy led to normalisation of blood pressure in high-fat diet-induced obese and hypertensive rats. Mechanistically, the reduction of blood pressure by leptin in obese rats was likely independent of alpha-adrenergic and acetylcholinergic receptor mediation. This is the first study to demonstrate that further increases in circulating leptin levels by leptin gene transfer during obesity could reduce blood pressure.

Costs and outcomes associated with IVF using recombinant FSH

Cost and outcome estimates based on clinical trial data may not reflect usual clinical practice, yet they are often used to inform service provision and budget decisions. To expand understanding of assisted reproduction treatment in clinical practice, an economic evaluation of IVF/intracytoplasmic sperm injection (ICSI) data from a single assisted conception unit (ACU) in England was performed. A total of 1418 IVF/ICSI cycles undertaken there between October 2001 and January 2006 in 1001 women were analysed. The overall live birth rate was 22% (95% CI: 19.7-24.2), with the 30- to 34-year age group achieving the highest rate (28%). The average recombinant FSH (rFSH) dose/cycle prescribed was 1855 IU. Average cost of rFSH/cycle was 646 pound(SD: 219 pound), and average total cost/cycle was 2932 pound (SD: 422 pound). Economic data based on clinical trials informing current UK guidance assumes higher doses of rFSH dose/cycle (1750-2625 IU), higher average cost of drugs/cycle (1179 pound), and higher average total cost/cycle (3266 pound). While the outcomes in this study matched UK averages, total cost/cycle was lower than those cited in UK guidelines. Utilizing the protocols and (lower) rFSH dosages reported in this study may enable other ACU to provide a greater number of IVF/ICSI cycles to patients within given budgets.

Human adult stem cells derived from adipose tissue protect against experimental colitis and sepsis

BACKGROUND AND AIMS

Inflammatory bowel diseases (IBDs) are associated with uncontrolled innate and adaptive immunity against normal constituents, including commensal bacteria and microbial products. Mesenchymal stem cells (MSCs) suppress effector T cell responses and have beneficial effects in various immune disorders. This work investigates the therapeutic effects of human adipose-derived MSCs (hASCs) in various models of IBD and sepsis.

METHODS

Acute and chronic colitis was induced in mice with dextran sulfate sodium. Sepsis was induced by caecal ligation and puncture or by endotoxin injection. Colitic and septic mice were treated intraperitoneally with hASCs or murine ASCs, and diverse disease clinical signs and mortality were determined. The levels of various inflammatory cytokines and chemokines, T helper 1(Th1)-type response and generation of regulatory T cells (Treg) were determined in affected organs.

RESULTS

Systemic infusion of ASCs significantly ameliorated the clinical and histopathological severity of colitis, abrogating weight loss, diarrhoea and inflammation, and increasing survival. The therapeutic effect was associated with downregulation of the Th1-driven inflammatory responses. ASCs decreased a wide panel of inflammatory cytokines and chemokines and increased interleukin 10 (IL10), acting on macrophages. hASCs also impaired Th1 cell activation in both colonic mucosa and draining lymph nodes. The induction of IL10-secreting Treg was partially involved in the therapeutic effect of hASCs. Moreover, ASCs protected from severe sepsis by reducing the infiltration of inflammatory cells in various target organs and by downregulating the production of various inflammatory mediators.

CONCLUSIONS

hASCs emerge as key regulators of immune/inflammatory responses in vivo and as attractive candidates for cell-based treatments for IBD and sepsis.

Randomized controlled trial of general practitioner intervention in women with excessive alcohol consumption

Seventy two women drinking 21 units (210g) or more of alcohol per week were recruited from an opportunistic screening programme in eight English general practices. The women were randomized into control and treatment groups. Women in the treatment group received ten minutes advice from their general practitioner to reduce alcohol consumption. At one year follow-up, when analyzed by intention to treat, women in the treatment group had reduced their alcohol consumption from an average of 35-24 units per week. Similar reductions were found in the control group (from 37-27 units per week). The lack of evidence for a treatment effect may be explained by contamination of the control group by informal interventions.

SMG-8 and SMG-9, two novel subunits of the SMG-1 complex, regulate remodeling of the mRNA surveillance complex during nonsense-mediated mRNA decay

Nonsense-mediated mRNA decay (NMD) is a surveillance mechanism that detects and degrades mRNAs containing premature translation termination codons (PTCs). SMG-1 and Upf1 transiently form a surveillance complex termed "SURF" that includes eRF1 and eRF3 on post-spliced mRNAs during recognition of PTC. If an exon junction complex (EJC) exists downstream from the SURF complex, SMG-1 phosphorylates Upf1, the step that is a rate-limiting for NMD. We provide evidence of an association between the SURF complex and the ribosome in association with mRNPs, and we suggest that the SURF complex functions as a translation termination complex during NMD. We identified SMG-8 and SMG-9 as novel subunits of the SMG-1 complex. SMG-8 and SMG-9 suppress SMG-1 kinase activity in the isolated SMG-1 complex and are involved in NMD in both mammals and nematodes. SMG-8 recruits SMG-1 to the mRNA surveillance complex, and inactivation of SMG-8 induces accumulation of a ribosome:Upf1:eRF1:eRF3:EJC complex on mRNP, which physically bridges the ribosome and EJC through eRF1, eRF3, and Upf1. These results not only reveal the regulatory mechanism of SMG-1 kinase but also reveal the sequential remodeling of the ribosome:SURF complex to the predicted DECID (DECay InDucing) complex, a ribosome:SURF:EJC complex, as a mechanism of in vivo PTC discrimination.

Absorption and side-effects after peroral administration of sustained release iron tablets. Ferro-Retard compared with Ferronicum and Duroferon Duretter

Study I. In 13 iron deficient patients the absorption from 100 mg ferrous sulphate (Ferro-Retard) after 3 and 5 hours was comparable to the absorption from 176 mg ferrous gluconate in rapidly disintegrating tablets (Ferronicum). Study II. (a) The serum iron elevation in 14 blood donors with normal Hb after administration of ferrous sulphate (100 mg Fe2+) in Ferro-Retard or Duroferon Duretter seemed to be equal when tested on the 4th day after donation of 450 ml blood. (b) The iron absorption, measured by the elevation of serum iron 5 and 8 hours after administration of sustained release tablets, proved to be better on the 11th and especially on the 16th day than on the 4th day after donation. Study III (side-effects). In a study on 113 subjects the total number of complaints was unusually high both before and after administration of placebo, rapidly disintegrating and sustained release ferrous sulphate tablets. The selection of participants and other methodological factors have probably been of importance. Hence, comparisons between different studies of side-effects should always be carried out with caution.

The C. elegans sex determination gene laf-1 encodes a putative DEAD-box RNA helicase

The Caenorhabditis elegans gene laf-1 is critical for both embryonic development and sex determination. Laf-1 is thought to promote male cell fates by negatively regulating expression of tra-2 in both hermaphrodites and males. We cloned laf-1 and established that it encodes a putative DEAD-box RNA helicase related to Saccharomycescerevisiae Ded1p and Drosophila Vasa. Three sequenced laf-1 mutations are missense alleles affecting a small region of the protein in or near helicase motif III. We demonstrate that the phenotypes resulting from laf-1 mutations are due to loss or reduction of laf-1 function, and that both laf-1 and a related helicase vbh-1 function in germline sex determination. Laf-1 mRNA is expressed in both males and hermaphrodites and in both the germline and soma of hermaphrodites. It is expressed at all developmental stages and is most abundant in embryos. LAF-1 is predominantly, if not exclusively, cytoplasmic and colocalizes with PGL-1 in P granules of germline precursor cells. Previous results suggest that laf-1 functions to negatively regulate expression of the sex determination protein TRA-2, and we find that the abundance of TRA-2 is modestly elevated in laf-1/+ females. We discuss potential functions of LAF-1 as a helicase and its roles in sex determination.

Pharmacokinetics of calcium channel blocking agents

Verapamil and nifedipine are the most frequently used calcium channel blocking agents in Sweden at present time. The pharmacokinetics of verapamil has been described both in healthy volunteers as well as in patients with supraventricular arrhythmias, angina pectoris, liver cirrhosis, hypertrophic cardiomyopathy or hypertension. Intravenous pharmacokinetics of nifedipine has been investigated in healthy volunteers and oral pharmacokinetics in healthy volunteers as well as in patients with hypertension. The pharmacokinetics of verapamil and of one of its metabolites, norverapamil, is changed after multiple oral dosing as has been described in patients with supraventricular tachyarrhythmias, angina pectoris or in patients with essential hypertension. Plasma concentration-effect relationships have been established for verapamil in different clinical situations and in a few cases also for nifedipine. An update of the pharmacokinetics of these two important calcium channel blocking agents is presented.

Real-world physician and patient behaviour across countries: Disease-Specific Programmes - a means to understand

BACKGROUND/OBJECTIVES

Treatment guidelines and strategies are often based on data from randomized controlled trials and observational clinical studies. These sources drive treatment decisions, yet the data they provide may have limited relevance to the wider population in real-world clinical practice due to the narrow selection criteria applied to patients in trials. Information used to inform clinical practice and improve patient outcomes can, therefore, be unreflective of real-world clinical situations. The purpose of this article is to assess the value of Adelphi Disease Specific Programmes (DSPs) as sources of real world data.

METHODS

DSPs are large, multinational, observational studies of clinical practice for a range of common chronic diseases. Treatment practice data are collected by physicians (n = 700) who are asked to provide information for the next 10 patients consulting for a specific condition. These patients (n = 7000) are also invited to fill out a self-completion form providing their own assessment of symptoms, expectations and quality of life.

ANALYSES

This article provides examples of the statistical techniques that have been employed to analyse the data in terms of cost/burden of illness, quality of life, disease severity and progression, compliance and adherence to therapy, impact of treatment guidelines and analyses of unmet need.

CONCLUSIONS

DSPs can support clinical understanding of how diseases are managed including rationale for doctor decision-making and patient attitudes to their condition. Comparisons with other data sources and limitations of the programmes are discussed (including the fact that, unlike claims databases and registries, the DSPs are cross-sectional and not longitudinal).

Glucose lowers the threshold for human aortic vascular smooth muscle cell migration: inhibition by protein phosphatase-2A

AIMS/HYPOTHESIS

Atherosclerosis, which occurs prematurely in individuals with diabetes, incorporates vascular smooth muscle cell (VSMC) chemotaxis. Glucose, through protein kinase C-beta(II) signalling, increases chemotaxis to low concentrations of platelet-derived growth factor (PDGF)-BB. In VSMC, a biphasic response in PDGF-beta receptor (PDGF-betaR) level occurs as PDGF-BB concentrations increase. The purpose of this study was to determine whether increased concentrations of PDGF-BB and raised glucose level had a modulatory effect on the mitogen-activated protein kinase/extracellular-regulated protein kinase pathway, control of PDGF-betaR level and chemotaxis.

METHODS

Cultured aortic VSMC, exposed to normal glucose (NG) (5 mmol/l) or high glucose (HG) (25 mmol/l) in the presence of PDGF-BB, were assessed for migration (chemotaxis chamber) or else extracted and immunoblotted.

RESULTS

At concentrations of PDGF-BB <540 pmol/l, HG caused an increase in the level of PDGF-betaR in VSMC (immunoblotting) versus NG, an effect that was abrogated by inhibition of aldose reductase or protein kinase C-beta(II). At higher concentrations of PDGF-BB (>540 pmol/l) in HG, receptor level was reduced but in the presence of aldose reductase or protein kinase C-beta(II) inhibitors the receptor levels increased. It is known that phosphatases may be activated at high concentrations of growth factors. At high concentrations of PDGF-BB, the protein phosphatase (PP)2A inhibitor, endothall, caused an increase in PDGF-betaR levels and a loss of biphasicity in receptor levels in HG. At higher concentrations of PDGF-BB in HG, the chemoattractant effect of PDGF-BB was lost (chemotaxis chamber). Under these conditions inhibition of PP2A was associated with a restoration of chemotaxis to high concentrations of PDGF-BB.

CONCLUSION/INTERPRETATION

The biphasic response in PDGF-betaR level and in chemotaxis to PDGF-BB in HG is due to PP2A activation.