A quick balance assessment tool for all clinical settings: validity and reliability of the Hungarian version of the activities-specific balance confidence scale.

BACKGROUND: The Activities-specific Balance Confidence Scale was developed for testing the balance confidence of elderly individuals, and it has been used extensively for evaluating various patients. No such scale has been adapted for the Hungarian population. OBJECTIVE: To translate and culturally adapt the Activities-specific Balance Confidence Scale and test the reliability and validity of the Hungarian version. METHODS: The study included 167 independently mobile subjects, of whom 39 filled in the questionnaire twice, 1 week apart. Beaton's six-step principle was applied for cross-cultural adaptation. Reliability was assessed by internal consistency measured by Cronbach's alpha and through test-retest analysis. Types of validity evaluated were concurrent validity using the Berg Balance Scale and cross-cultural validity. RESULTS: Excellent internal consistency was shown by Cronbach's alpha = 0.977. Test-retest analysis resulted in an Intra-Class Correlation Coefficient of 0.962 (0.865-0.961, 95% CI, p < .001) for the whole test; no floor or ceiling effects were found. The convergent validity of the scale was tested by Spearman's rank correlation analysis using the Berg Balance scale for external validation and showed a strong positive correlation (Rho = 0.755, p < .001). Receiver Operating Characteristic curve analysis showed an Area Under the Curve of 0.821 (CI 95% 0.75, 0.892). Mean detectable change based on the 95% confidence interval was 10.49% on the scale ranging from 0 to 100%. CONCLUSIONS: The Hungarian version of the Activities-Specific Balance Confidence Scale provides a valid and reliable picture of the patients' self-assessed balance. It is recommended both for clinicians and for clinical studies.

Genetic Polymorphisms in Exon 5 and Intron 5 and 7 of AIRE Are Associated with Rheumatoid Arthritis Risk in a Hungarian Population.

BACKGROUND: Rheumatoid arthritis (RA) is chronically persistent synovitis and systemic inflammation. Although multiple contributors are detected, only one is pivotal in the neonatal period: the negative selection of autoimmune naïve T-cells by the autoimmune regulator (AIRE) transcriptional factor. METHODS: Single-nucleotide polymorphisms (SNPs) in the DNA-binding site of AIRE may determine its function and expression. We intended to analyse site-specific allelic polymorphisms in two exon (rs878081 and rs1055311) and three intron (rs1003853, rs2075876, and rs1003854) loci with an RA risk. Our analytical case-control study analysed 270 RA patients and 322 control subjects in five different genetic models using quantitative real-time PCR (qPCR) with TaqMan® assays. RESULTS: Statistically significant differences were found between the odds of allelic polymorphisms in the loci of rs878081, rs1003854, and rs1003853 among the controls and RA patients, and the disease activity seemed to be significantly associated with the genotypic subgroups of rs878081 and rs1055311. Our in silico analysis supported this, suggesting that allele-specific alterations in the binding affinity of transcriptional factor families might determine RA activity. CONCLUSION: Our findings highlight the involvement of neonatal self-tolerance in RA pathogenesis, providing novel insights into disease development and paving the way for an analysis of further site-specific genetic polymorphisms in AIRE to expand the intervention time for RA.

Association Between AIRE Polymorphisms rs870881(C>T), rs1003854(T>C) and Rheumatoid Arthritis Risk: A Hungarian Case-control Study.

BACKGROUND/AIM: Autoimmune regulator (AIRE) is a transcription factor that plays pivotal role in controlling autoimmunity. In the thymus, it supports the presentation of peripheral tissue antigens to developing T cells, where recognition of these self-antigens negatively selects the autoimmune naïve T-cells by central tolerance. Studies demonstrated that single-nucleotide polymorphisms (SNPs) in AIRE alter transcription and propagate clonal survival of autoimmune T cells, therefore increase susceptibility to autoimmune diseases. This study intended to identify SNPs in exon and intron sequences that determine AIRE transcription, where their genotypes are associated with rheumatoid arthritis (RA) risk and clinical parameters. PATIENTS AND METHODS: After a thorough in silico research, we enrolled 100 patients with RA and 100 healthy controls to analyze the association of SNP rs870881(C>T) and rs1003854(T>C) in AIRE coding sequence with RA risk by using five different genetic models and selected clinical parameters. Multiplex quantitative polymerase chain reaction was used to determine allelic discrimination of SNPs. RA risk was assessed by odds ratios (ORs) and confidence intervals (CIs). RESULTS: In a recessive model of rs878081, minor allele TT homozygotes were associated with RA (p=0.032, OR=5.44, 95%CI=1.16-25.52); in a recessive model of rs1003854, minor allele CC homozygotes were associated with RA (p=0.047, OR=4.84, 95%CI=1.02-23.02). Higher C-reactive protein (CRP) levels in patients with RA were significantly associated with minor allele homozygotes in recessive and codominant genetic models (p=0.029 and p=0.043, respectively) of rs1003854. CONCLUSION: Genotypes for minor alleles of rs878081 and rs1003854 might be involved in RA pathogenesis and risk prediction.

Is Balneotherapy Protective Against Oxidative Stress? A Pilot Study.

BACKGROUND/AIM: This study aimed to research the effects of Harkány healing water on oxidative stress. The study was performed in a randomized, placebo-controlled, double-blind setup. PATIENTS AND METHODS: Twenty patients with psoriasis who underwent a 3-week-long inward balneotherapy-based rehabilitation were enrolled. Psoriasis Area and Severity Index (PASI) score and Malondialdehyde (MDA) - a marker of oxidative stress - were determined, on admission and before discharge. Patients were treated with dithranol. RESULTS: The mean PASI score - determined on admission and before discharge - decreased significantly after the 3-week-long rehabilitation 8.17 vs. 3.51 (p<0.001). The baseline MDA value of patients with psoriasis was significantly higher compared to controls (3.0±3.5 vs. 8.4±7.4) (p=0.018). MDA levels of patients receiving placebo water increased significantly compared to MDA levels of patients receiving healing water (p=0.049). CONCLUSION: The effectiveness of dithranol resides in the formation of reactive oxygen species. No increased oxidative stress was found in the patients treated with healing water, thus healing water seems to be protective against oxidative stress. However, further research is needed to confirm these preliminary results.

Effect of single end-range and not end-range Maitland mobilization on pressure pain threshold and functional measures in knee osteoarthritis: randomised, controlled clinical trial.

BACKGROUND: Hyperalgesia is attributed to peripheral and central sensitization in knee osteoarthritis (OA). Pressure pain threshold (PPT) is a relevant method for evaluating pain sensitivity in knee OA. The effect of end-range and not end-range Maitland mobilization for certain time-period on pain sensitivity has not been investigated in knee OA. AIM: The aim of this study was to investigate the effect of end-range and not end-range Maitland mobilization compared to sham manual therapy technique on PPT and functional measures. DESIGN: Randomised, controlled clinical trial. SETTING: Outpatient setting. POPULATION: Sixty-six patients with mild-to-severe knee OA. METHODS: Twenty-one patients (N.=21) received end-range Maitland mobilization (EMGr), twenty patients (N.=20) received not end-range Maitland mobilization (nEMGr) and twenty-two patients (N.=22) received sham manual therapy technique (CG). All interventions were performed once. Evaluation was conducted pre-, postintervention and on the following consecutive second days within a 6-day period. Outcomes were local and distant PPT, Timed Up and Go Test (TUG) and strength of passive resistance of knee at onset of pain. RESULTS: Local and distant PPT increased, TUG time and strength of passive resistance decreased immediately, local and distant PPT remained decreased in 6-day and 4-day period, TUG time remained decreased in 6-day period in EMGr (all changes P≤0.017). Local PPT increased immediately compared to baseline in nEMGr. In between group comparison, increase of local, distant PPT and strength of passive resistance endures on 2nd day, 4th day and postintervention, respectively, in EMGr compared to CG. EMGr compared to nEMGr presented significant difference on 6th day and 4th day in local and distant PPT, respectively (all changes P≤0.021). NEMGr presented no significant difference compared to CG on either follow-up. CONCLUSIONS: Single end-range Maitland mobilization is effective immediately and in 4-day period on pain sensitization and immediately on physical function compared to not end-range Maitland mobilization and sham manual therapy technique in knee OA. CLINICAL REHABILITATION IMPACT: Based on the present results, applying end-range Maitland mobilization is suggested on every second day to maintain alleviation of pain sensitization and increasing passive knee joint mobility effectively in knee OA.

Effect of HEAT therapy in patiEnts with type 2 Diabetes mellitus (HEATED): protocol for a randomised controlled trial.

INTRODUCTION: The burden of type 2 diabetes mellitus (T2DM) is increasing worldwide. Heat therapy has been found effective in improving glycaemic control. However, to date, there is a lack of randomised controlled studies investigating the efficacy of heat therapy in T2DM. Therefore, we aim to investigate whether heat therapy with natural thermal mineral water can improve glycaemic control in patients with T2DM. METHODS AND ANALYSIS: The HEAT therapy in patiEnts with type 2 Diabetes mellitus (HEATED) Study is a single-centre, two-arm randomised controlled trial being conducted at Harkány Thermal Rehabilitation Centre in Hungary. Patients with T2DM will be randomly assigned to group A (bath sessions in 38°C natural thermal mineral water) and group B (baths in thermoneutral water (30°C-32°C)). Both groups will complete a maximum of 5 weekly visits, averaging 50-60 visits over the 12-week study. Each session will last 30 min, with a physical check-up before the bath. At baseline, patients' T2DM status will be investigated thoroughly. Possible microvascular and macrovascular complications of T2DM will be assessed with physical and laboratory examinations. The short form-36 questionnaire will assess the quality of life. Patients will also be evaluated at weeks 4, 8 and 12. The primary endpoint will be the change of glycated haemoglobin from baseline to week 12. An estimated 65 patients will be enrolled per group, with a sample size re-estimation at the enrolment of 50% of the calculated sample size. ETHICS AND DISSEMINATION: The study has been approved by the Scientific and Research Ethics Committee of the Hungarian Medical Research Council (818-2/2022/EÜIG). Written informed consent is required from all participants. We will disseminate our results to the medical community and will publish our results in peer-reviewed journals. TRIAL REGISTRATION NUMBER: ClinicalTrials.gov, NCT05237219.

Overview of Registered Clinical Trials on Manual Therapy: Possible Implications of Genetic Testing for Personalized Treatment.

BACKGROUND/AIM: Manual therapy (MT) is a frequently applied intervention offering individualized treatment in the clinic. In addition to the traditional approaches of MT, measuring molecular response to MT may offer better understanding of MT outcomes in order to provide specific personalized treatment. The aim of this study was to summarize MT-related registered clinical trials, as well as to search for any evidence on MT and genetics. PATIENTS AND METHODS: A comprehensive search was conducted within the Clinical Trials database with predefined keywords mining for all types of MT-related clinical trials. RESULTS: From the 47 trials, 20 had results and 27 had no results. MT alleviated pain and improved function almost in all trials. One registered clinical trial had investigated molecular outcomes of MT. CONCLUSION: MT is an effective and individualized treatment offering option in the management of several conditions. Interestingly, a clinical trial was found investigating molecular genetics and MT pinpointing an already existing link between genetics and MT. Therefore, further clinical trials may focus on genetics and MT for providing specific personalized treatment in future.

End-range Maitland mobilization decreasing pain sensitivity in knee osteoarthritis: randomized, controlled clinical trial.

BACKGROUND: Pressure pain threshold (PPT) is a widely applied method for measuring the magnitude of increased peripheral and central pain sensitivity causing hyperalgesia in knee osteoarthritis (OA). Although manual therapy techniques effects positively PPT, the effect of end-range Maitland mobilization has not been evaluated in knee OA. AIM: The aim of this study was to investigate the effect of end-range Maitland mobilization compared to sham manual therapy technique on PPT and function-related measures. DESIGN: The design of the study was of a randomized, controlled clinical trial. SETTING: Outpatient setting. POPULATION: Forty women with moderate-to-severe knee OA. METHODS: Twenty patients (N.=20) were randomly assigned to Maitland group (MG) and twenty patients (N.=20) to control group (CG). Patients in MG received single end-range Maitland mobilization while patients in CG received sham manual therapy technique. Assessment was performed at baseline, 30 minutes and after 1-week period. Outcome measures were PPT locally at knee and distant at ipsilateral extensor carpi radialis longus muscle, general pain during the previous week using the Visual Analogue Scale (VAS), Timed Up and Go Test (TUG) time associated with pain measured with Numerating Pain Rating Scale (NPRS) and strength of passive resistance of knee at onset of pain. RESULTS: Despite all outcome measures improved significantly postintervention, no changes were detected after 1-week period compared to postintervention in MG. No change of outcome measures was found also postintervention and after 1-week period compared to postintervention in CG. All postintervention results showed significant improvement in between-group comparison in favor of MG. However, after 1-week period, only strength of passive resistance revealed significant difference in between-group comparison in favor of MG (P<0.001). CONCLUSIONS: Although end-range Maitland mobilization has an immediate effect on decreasing peripheral and central pain sensitivity and improving function-related measures in knee OA, these changes may not cause clinically relevant effect based on data measured after 1-week period. CLINICAL REHABILITATION IMPACT: Investigating the time-course of end-range Maitland mobilization for determining the optimal treatment frequency during rehabilitation is suggested in knee OA.

Effects of various types of ultrasound therapy in hip osteoarthritis - a double-blind, randomized, controlled, follow-up study.

PURPOSE: To compare the effects of various types of ultrasound therapy (UST) on pain, function, and quality of life in patients with hip osteoarthritis. METHODS: Seventy-one patients receiving conventional physiotherapy (exercise, massage, and balneotherapy), were randomly allocated into four treatment groups: (1) continuous UST, (2) pulsed UST, (3) UST combined with transcutaneous electrical nerve stimulation (TENS), (4) placebo UST. We evaluated the hip pain (Visual Analog Scale), medication use, functional impairment (Western Ontario and McMaster Universities Arthritis Index; 6-minute walking test) and quality of life (SF-36) before, right after the treatments, and at 3 months follow-up. RESULTS: Resting pain improved significantly in all treatment groups at the follow-up visit compared to baseline (p (group1-4) ≤0.002). The proportion of patients achieving Minimal Clinically Important Improvement (MCII) in function at month 3 was the highest in group 3 (73%). The 6-minute walking test significantly improved in each group during the follow-up period (p (group1-4) ≤ 0.025). Pain (p (group1-4) ≤ 0.014) and general health domains of the SF-36 showed the greatest improvement (p (group 2-4) ≤ 0.018). CONCLUSIONS: There was no difference among the effects of various types of UST on pain, function, and quality of life in the treatment of hip osteoarthritis. Additional ultrasound treatment is not likely to increase the effect of the conventional therapy on pain and function in hip osteoarthritis.

Cross-sectional study of female pelvic floor dysfunction in a Hungarian population / Noi kismedencei funkciózavarok keresztmetszeti vizsgálata magyarországi populáción.

Összefoglaló. Bevezetés és célkituzés: A noi kismedencei funkciózavarok változatos tünetekkel jelentkezhetnek, és jelentosen befolyásolják az érintettek életminoségét. Vizsgálatunk célja volt felmérni a medencefenék-diszfunkciós tüneteket és azok hatását az egyén életminoségére. Módszer: Vizsgálatunkba 203 not vontunk be. Az adatgyujtést két kérdoív, egy általunk összeállított és az Australian Pelvic Floor Questionnaire segítségével végeztük. Az adatok statisztikai elemzéséhez SPSS 20.0 rendszert használtunk. Spearman-korrelációt, khi-négyzet-próbát, Mann-Whitney-féle U-tesztet, Kruskal-Wallis-próbát és többváltozós lineáris regressziót alkalmaztunk. A szignifikanciaszintet p≤0,05 határnál állapítottuk meg. Eredmények: A hólyagdiszfunkciók gyakorisága (56,2%) szignifikáns kapcsolatot mutatott az életkor növekedésével (p<0,001), az obesitassal (p<0,001), a szülésszámmal és -móddal (p<0,001; p<0,001), az episiotomiával (p<0,001) és a prolapsusmutétekkel (p = 0,010). A süllyedéses kismedencei kórképek gyakorisága (27,1%) szignifikáns kapcsolatot mutatott az életkor növekedésével (p = 0,002), a szülésszámmal és -móddal (p<0,001; p<0,001) és a korábbi episiotomiával (p<0,001). Az analis incontinentia gyakorisága (58,9%) a magasabb testtömegindexszel (p = 0,029) volt szignifikáns kapcsolatban. Szexuális diszfunkciót (53,2%) allergia és tüdobetegségek (p = 0,048) jelenlétével kapcsolatban találtunk. A többes diszfunkció elofordulási gyakorisága az életkor növekedésével (p<0,001), az obesitassal (p = 0,043), a korábbi hysterectomiával (p = 0,046) és prolapsusmutétekkel (p<0,001) mutatott szignifikáns kapcsolatot. Minden diszfunkció esetén kimutatható volt az életminoség-romlás (hólyagfunkciók: p<0,001; bél- és székletürítési funkciók: p<0,001, hüvelyfali süllyedés: p<0,001, szexuális funkciók: p<0,001). Következtetés: Az általunk vizsgált noi populációban nagy arányban találtunk kismedencei funkciózavarokat, melyek kedvezotlen hatással voltak az érintettek életminoségére. Orv Hetil. 2021; 162(43): 1724-1731. INTRODUCTION AND OBJECTIVE: Pelvic floor dysfunction (PFD) can cause several complaints in women and has an adverse effect on the quality of life (Qol). The aim of our study was to evaluate the prevalence of pelvic floor dysfunction and its effect on Qol. METHOD: 203 women were included. We used two questionnaires, a self-constructed and the Australian Pelvic Floor Questionnaire. Statistical analysis was performed by SPSS 20.0. Spearman's correlation, chi-square, Mann-Whitney U, Kruskal-Wallis tests and multivariate linear regression were used. Statistical significance was set at p≤0.05. RESULTS: There was a significant association between the prevalence of urinary incontinence (56.2%) and age (p<0.001), obesity (p<0.001), number and mode of deliveries (p<0.001; p<0.001), episiotomy (p<0.001) and pelvic organ prolapse (POP) surgery (p = 0.010); between the occurrence of POP (27.1%) and age (p = 0.002), the number and mode of deliveries (p<0.001; p<0.001) and episiotomy (p<0.001); between the prevalence of anal incontinence (58.9%) and obesity (p = 0.029); between sexual dysfunction (SD) (53.2%) and respiratory disease and allergy (p = 0.048). Multiple PFD was significantly associated with age (p<0.001), obesity (p = 0.043), hysterectomy (p = 0.046) and POP surgery (p = 0.010). There was a significant difference between women having more severe PFD than milder complaints regarding Qol (bladder p<0.001; bowel p<0.001; SD p<0.001 and POP p<0.001). CONCLUSION: Pelvic floor dysfunction was common in our study population and had a great adverse effect on Qol. Orv Hetil. 2021; 162(43): 1724-1731.

Clinical Effect of End-range Maitland Mobilization in the Management of Knee Osteoarthritis - A Pilot Study.

BACKGROUND/AIM: Different manual therapy techniques and conservative therapy have been used separately for alleviation of pain and improvement of physical function in patients with knee osteoarthritis (KOA). However, no study has reported the effect of combination of these treatment modalities in the management of KOA. Our aim was to test the feasibility of the study design and to compare the effect of end-range Maitland mobilization to conservative therapy in KOA. PATIENTS AND METHODS: Fifteen patients (conservative therapy group: CG) received conservative therapy alone, fifteen patients (Maitland plus conservative therapy group: M+CG) received additionally end-range Maitland mobilization during the 3-week study period. Outcomes were pain intensity, measured with visual analogue scale (VAS) in general and during functional activities, passive range of motion (PROM) and peak muscle force during knee flexion and extension, Timed Up and Go test and 6-Minute Walk Test (6MWT). RESULTS: All outcomes improved significantly in both groups. Magnitude of changes was significantly greater in M+CG compared to CG regarding all VAS pain scores, flexion PROM of both knees, right hamstring peak muscle force and 6MWT. CONCLUSION: With few modifications, this study design seems feasible for the comparison of end-range Maitland mobilization with conservative therapy in KOA. Moreover, end-range Maitland mobilization in addition to conservative therapy appeared more effective in relief of pain and improvement of functional status than conservative therapy alone in KOA.

Virtual screening for LPA2-specific agonists identifies a nonlipid compound with antiapoptotic actions.

Lysophosphatidic acid (LPA) is a highly potent endogenous lipid mediator that protects and rescues cells from programmed cell death. Earlier work identified the LPA2 G protein-coupled receptor subtype as an important molecular target of LPA mediating antiapoptotic signaling. Here we describe the results of a virtual screen using single-reference similarity searching that yielded compounds 2-((9-oxo-9H-fluoren-2-yl)carbamoyl)benzoic acid (NSC12404), 2-((3-(1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)propyl)thio)benzoic acid (GRI977143), 4,5-dichloro-2-((9-oxo-9H-fluoren-2-yl)carbamoyl)benzoic acid (H2L5547924), and 2-((9,10-dioxo-9,10-dihydroanthracen-2-yl)carbamoyl) benzoic acid (H2L5828102), novel nonlipid and drug-like compounds that are specific for the LPA2 receptor subtype. We characterized the antiapoptotic action of one of these compounds, GRI977143, which was effective in reducing activation of caspases 3, 7, 8, and 9 and inhibited poly(ADP-ribose)polymerase 1 cleavage and DNA fragmentation in different extrinsic and intrinsic models of apoptosis in vitro. Furthermore, GRI977143 promoted carcinoma cell invasion of human umbilical vein endothelial cell monolayers and fibroblast proliferation. The antiapoptotic cellular signaling responses were present selectively in mouse embryonic fibroblast cells derived from LPA(1&2) double-knockout mice reconstituted with the LPA2 receptor and were absent in vector-transduced control cells. GRI977143 was an effective stimulator of extracellular signal-regulated kinase 1/2 activation and promoted the assembly of a macromolecular signaling complex consisting of LPA2, Na⁺ - H⁺ exchange regulatory factor 2, and thyroid receptor interacting protein 6, which has been shown previously to be a required step in LPA-induced antiapoptotic signaling. The present findings indicate that nonlipid LPA2-specific agonists represent an excellent starting point for development of lead compounds with potential therapeutic utility for preventing the programmed cell death involved in many types of degenerative and inflammatory diseases.

Serine phosphorylation differentially affects RhoA binding to effectors: implications to NGF-induced neurite outgrowth.

Activation of RhoA prevents NGF-induced outgrowth and causes retraction of neurites in neuronal cells, including PC12 cells. Despite its inhibitory effect on neurite outgrowth, NGF activates GTP loading of and effector binding to RhoA, setting up an apparent contradiction. According to the molecular switch hypothesis of GTPase function GTP-loading of RhoA should be sufficient to activate its effectors uniformly. However, when monitoring NGF-induced binding of GTP-RhoA to multiple targets, we noted differential interactions with its effectors. We found that NGF elicits a protein kinase A-mediated phosphorylation of RhoA on serine(188), which renders it unable to bind to Rho-associated kinase (ROK), whereas it retains the ability to interact with other RhoA targets including rhotekin, mDia-1 and PKN. We show in vitro and in vivo that phosphorylation of serine(188) represents an additional switch, capable of directing signals among effector pathways. In the context of PC12 cell differentiation, NGF-induced phosphorylation of RhoA on serine(188) prevents it from interacting with ROK, which would otherwise block neurite outgrowth. Transfection of RhoA(S188A) mutant into PC12 cells prevents NGF-induced neurite outgrowth, just like constitutively activated RhoA(14V) does, indicating the requirement of this phosphorylation site. Replacement of serine(188) with the phosphomimetic glutamate residue in RhoA(V14/S188E) selectively impairs interaction with ROK and when transfected into PC12 cells restores NGF-induced neurite outgrowth. Therefore, phosphorylation of serine(188) may serve as a novel secondary switch of RhoA capable of overriding GTP-binding-elicited effector activation to a subset of targets such as ROK, which interact with the C-terminus of RhoA.

Nerve growth factor signals through TrkA, phosphatidylinositol 3-kinase, and Rac1 to inactivate RhoA during the initiation of neuronal differentiation of PC12 cells.

In PC12 rat pheochromocytoma cells, nerve growth factor (NGF)-induced neuronal differentiation is blocked by constitutively active dominant mutants of RhoA but augmented by negative ones, suggesting a not yet elucidated inhibitory signaling link between NGF receptors and RhoA. Here we show that NGF treatment rapidly translocates RhoA from the plasma membrane to the cytosol and simultaneously decreases RhoA affinity to its target Rho-associated kinase (ROK), a key mediator of neurite outgrowth. This effect was transient, because after 2 days of NGF treatment, RhoA relocated from the cytosol to the plasma membrane, and its GTP loading returned to a level found in undifferentiated cells. Inhibition of RhoA is mediated by activation of the TrkA receptor, because NGF failed to induce RhoA translocation and inhibition of ROK binding in nnr5 cells that lack TrkA, whereas the inhibition was reconstituted in receptor add-back B5 cells. In MM17-26 cells, which due to expression of dominant negative Ras do not differentiate, NGF-stimulated transient RhoA inhibition was unaffected. The inhibitory pathway from TrkA to RhoA involves phosphatidylinositol-3-kinase (PI3K), because the inhibitors LY294002 or wortmannin prevented NGF-induced RhoA translocation and increased RhoA association with ROK. Furthermore, inhibition of PI3K significantly reduced NGF- mediated Rac1 activation, whereas dominant negative Rac1 abolished the inhibitory signaling to RhoA. Taken together, these data indicate that NGF-mediated activation of TrkA receptor stimulates PI3K, which in turn increases Rac1 activity to induce transient RhoA inactivation during the initial phase of neurite outgrowth.

Molecular basis for lysophosphatidic acid receptor antagonist selectivity.

Recent characterization of lysophosphatidic acid (LPA) receptors has made possible studies elucidating the structure-activity relationships (SAR) for agonist activity at individual receptors. Additionally, the availability of these receptors has allowed the identification of antagonists of LPA-induced effects. Two receptor-subtype selective LPA receptor antagonists, one selective for the LPA1/EDG2 receptor (a benzyl-4-oxybenzyl N-acyl ethanolamide phosphate, NAEPA, derivative) and the other selective for the LPA3/EDG7 receptor (diacylglycerol pyrophosphate, DGPP, 8:0), have recently been reported. The receptor SAR for both agonists and antagonists are reviewed, and the molecular basis for the difference between agonism and antagonism as well as for receptor-subtype antagonist selectivity identified by molecular modeling is described. The implications of the newly available receptor-subtype selective antagonists are also discussed.