Disruption of AKAP-PKA Interaction Induces Hypercontractility With Concomitant Increase in Proliferation Markers in Human Airway Smooth Muscle

With the ability to switch between proliferative and contractile phenotype, airway smooth muscle (ASM) cells can contribute to the progression of airway diseases such as asthma and chronic obstructive pulmonary disease (COPD), in which airway obstruction is associated with ASM hypertrophy and hypercontractility. A-kinase anchoring proteins (AKAPs) have emerged as important regulatory molecules in various tissues, including ASM cells. AKAPs can anchor the regulatory subunits of protein kinase A (PKA), and guide cellular localization via various targeting domains. Here we investigated whether disruption of the AKAP-PKA interaction, by the cell permeable peptide stearated (st)-Ht31, alters human ASM proliferation and contractility. Treatment of human ASM with st-Ht31 enhanced the expression of protein markers associated with cell proliferation in both cultured cells and intact tissue, although this was not accompanied by an increase in cell viability or cell-cycle progression, suggesting that disruption of AKAP-PKA interaction on its own is not sufficient to drive ASM cell proliferation. Strikingly, st-Ht31 enhanced contractile force generation in human ASM tissue with concomitant upregulation of the contractile protein α-sm-actin. This upregulation of α-sm-actin was independent of mRNA stability, transcription or translation, but was dependent on proteasome function, as the proteasome inhibitor MG-132 prevented the st-Ht31 effect. Collectively, the AKAP-PKA interaction appears to regulate markers of the multi-functional capabilities of ASM, and this alter the physiological function, such as contractility, suggesting potential to contribute to the pathophysiology of airway diseases

Profiling Dizziness in Older Primary Care Patients: An Empirical Study

The diagnostic approach to dizzy, older patients is not straightforward as many organ systems can be involved and evidence for diagnostic strategies is lacking. A first differentiation in diagnostic subtypes or profiles may guide the diagnostic process of dizziness and can serve as a classification system in future research. In the literature this has been done, but based on pathophysiological reasoning only

Prognosis and Survival of Older Patients With Dizziness in Primary Care:a 10-year prospective cohort study

Purpose: The prognosis of dizzy older patients in primary care is unknown. Our objective was to determine the prognosis and survival of patients with different subtypes and causes of dizziness. Methods: In a primary care prospective cohort study, 417 older adults with dizziness (mean age 75.5 years) received a full diagnostic workup in 2006-2008. A panel of physicians classified their dizziness subtype and primary cause of dizziness. Presyncope was the most common dizziness subtype (69.1%), followed by vertigo (41.0%), disequilibrium (39.8%), and other dizziness (1.7%). The most common primary causes of dizziness were cardiovascular disease (56.8%) and peripheral vestibular disease (14.4%). Main outcome measures were mortality and dizziness-related impairment assessed at 10-year follow-up.Results: At 10-year follow-up 169 patients (40.5%) had died. Multivariable adjusted Cox models showed a lower mortality rate for patients with the subtype vertigo compared to other subtypes (HR 0.62 (95% CI 0.40 to 0.96)), and for peripheral vestibular disease versus cardiovascular disease as primary cause of dizziness (HR 0.46 (95% CI 0.25 to 0.84)). After 10 years, 47.7% of patients who filled out the follow-up measurement experienced substantial dizziness-related impairment. No significant difference in substantial impairment was seen between different subtypes and primary causes of dizziness. Conclusions: The 10-year mortality rate was lower for the dizziness subtype vertigo compared to other subtypes. Patients with dizziness primarily caused by peripheral vestibular disease had a lower mortality rate than patients with cardiovascular disease. Substantial dizziness-related impairment in older dizzy patients 10 years later is high, and indicates that current treatment strategies by FPs may be suboptimal.<br/

Predictors of dizziness in older persons: a 10-year prospective cohort study in the community

BACKGROUND: The current diagnosis-oriented approach of dizziness does not suit older patients. Often, it is difficult to identify a single underlying cause, and when a diagnosis is made, therapeutic options may be limited. Identification of predictors of dizziness may provide new leads for the management of dizziness in older patients. The aim of the present study was to investigate long-term predictors of regular dizziness in older persons. METHODS: Population-based cohort study of 1,379 community-dwelling participants, aged ≥60 years, from the Longitudinal Aging Study Amsterdam (LASA). Regular dizziness was ascertained during face-to-face medical interviews during 7- and 10-year follow-up. We investigated 26 predictors at baseline from six domains: socio-demographic, medical history, medication, psychological, sensory, and balance/gait. We performed multivariate logistic regression analyses with presence of regular dizziness at 7- and 10-year follow-up as dependent variables. We assessed the performance of the models by calculating calibration and discrimination. RESULTS: Predictors of regular dizziness at 7-year follow-up were living alone, history of dizziness, history of osteo/rheumatoid arthritis, use of nitrates, presence of anxiety or depression, impaired vision, and impaired function of lower extremities. Predictors of regular dizziness at 10-year follow-up were history of dizziness and impaired function of lower extremities. Both models showed good calibration (Hosmer-Lemeshow P value of 0.36 and 0.31, respectively) and acceptable discrimination (adjusted AUC after bootstrapping of 0.77 and 0.71). CONCLUSIONS: Dizziness in older age was predicted by multiple factors. A multifactorial approach, targeting potentially modifiable predictors (e.g., physical exercise for impaired function of lower extremities), may add to the current diagnosis-oriented approach. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2318-14-133) contains supplementary material, which is available to authorized users

Internet based vestibular rehabilitation with and without physiotherapy support for adults aged 50 and older with a chronic vestibular syndrome in general practice:three armed randomised controlled trial

Objective: To investigate the clinical effectiveness and safety of stand alone and blended internet based vestibular rehabilitation (VR) in the management of chronic vestibular syndromes in general practice.Design: Pragmatic, three armed, parallel group, individually randomised controlled trial.Setting: 59 general practices in the Netherlands.Participants: 322 adults aged 50 and older with a chronic vestibular syndrome.Interventions: Stand alone VR comprising a six week, internet based intervention with weekly online sessions and daily exercises (10-20 minutes a day). In the blended VR group, the same internet based intervention was supplemented by face-to-face physiotherapy support (home visits in weeks 1 and 3). Participants in the usual care group received standard care from a general practitioner, without any restrictions.Main outcome measures: The primary outcome was vestibular symptoms after six months as measured by the vertigo symptom scale-short form (VSS-SF range 0-60, clinically relevant difference ≥3 points). Secondary outcomes were dizziness related impairment, anxiety, depressive symptoms, subjective improvement of vestibular symptoms after three and six months, and adverse events.Results: In the intention-to-treat analysis, participants in the stand alone and blended VR groups had lower VSS-SF scores at six months than participants in the usual care group (adjusted mean difference −4.1 points, 95% confidence interval −5.8 to −2.5; and −3.5 points, −5.1 to −1.9, respectively). Similar differences in VSS-SF scores were seen at three months follow-up. Participants in the stand alone and blended VR groups also experienced less dizziness related impairment, less anxiety, and more subjective improvement of vestibular symptoms at three and six months. No serious adverse events related to online VR occurred during the trial.Conclusion: Stand alone and blended internet based VR are clinically effective and safe interventions to treat adults aged 50 and older with a chronic vestibular syndrome. Online VR is an easily accessible form of treatment, with the potential to improve care for an undertreated group of patients in general practice.Trial registration: Netherlands Trial Register NTR5712

Internet based vestibular rehabilitation with and without physiotherapy support for adults aged 50 and older with a chronic vestibular syndrome in general practice:three armed randomised controlled trial

OBJECTIVE: To investigate the clinical effectiveness and safety of stand alone and blended internet based vestibular rehabilitation (VR) in the management of chronic vestibular syndromes in general practice. DESIGN: Pragmatic, three armed, parallel group, individually randomised controlled trial. SETTING: 59 general practices in the Netherlands. PARTICIPANTS: 322 adults aged 50 and older with a chronic vestibular syndrome. INTERVENTIONS: Stand alone VR comprising a six week, internet based intervention with weekly online sessions and daily exercises (10-20 minutes a day). In the blended VR group, the same internet based intervention was supplemented by face-to-face physiotherapy support (home visits in weeks 1 and 3). Participants in the usual care group received standard care from a general practitioner, without any restrictions. MAIN OUTCOME MEASURES: The primary outcome was vestibular symptoms after six months as measured by the vertigo symptom scale-short form (VSS-SF range 0-60, clinically relevant difference ≥3 points). Secondary outcomes were dizziness related impairment, anxiety, depressive symptoms, subjective improvement of vestibular symptoms after three and six months, and adverse events. RESULTS: In the intention-to-treat analysis, participants in the stand alone and blended VR groups had lower VSS-SF scores at six months than participants in the usual care group (adjusted mean difference -4.1 points, 95% confidence interval -5.8 to -2.5; and -3.5 points, -5.1 to -1.9, respectively). Similar differences in VSS-SF scores were seen at three months follow-up. Participants in the stand alone and blended VR groups also experienced less dizziness related impairment, less anxiety, and more subjective improvement of vestibular symptoms at three and six months. No serious adverse events related to online VR occurred during the trial. CONCLUSION: Stand alone and blended internet based VR are clinically effective and safe interventions to treat adults aged 50 and older with a chronic vestibular syndrome. Online VR is an easily accessible form of treatment, with the potential to improve care for an undertreated group of patients in general practice. TRIAL REGISTRATION: Netherlands Trial Register NTR5712

Augmentation of arginase 1 expression by exposure to air pollution exacerbates the airways hyperresponsiveness in murine models of asthma

Abstract Background Arginase overexpression contributes to airways hyperresponsiveness (AHR) in asthma. Arginase expression is further augmented in cigarette smoking asthmatics, suggesting that it may be upregulated by environmental pollution. Thus, we hypothesize that arginase contributes to the exacerbation of respiratory symptoms following exposure to air pollution, and that pharmacologic inhibition of arginase would abrogate the pollution-induced AHR. Methods To investigate the role of arginase in the air pollution-induced exacerbation of airways responsiveness, we employed two murine models of allergic airways inflammation. Mice were sensitized to ovalbumin (OVA) and challenged with nebulized PBS (OVA/PBS) or OVA (OVA/OVA) for three consecutive days (sub-acute model) or 12 weeks (chronic model), which exhibit inflammatory cell influx and remodeling/AHR, respectively. Twenty-four hours after the final challenge, mice were exposed to concentrated ambient fine particles plus ozone (CAP+O3), or HEPA-filtered air (FA), for 4 hours. After the CAP+O3 exposures, mice underwent tracheal cannulation and were treated with an aerosolized arginase inhibitor (S-boronoethyl-L-cysteine; BEC) or vehicle, immediately before determination of respiratory function and methacholine-responsiveness using the flexiVent®. Lungs were then collected for comparison of arginase activity, protein expression, and immunohistochemical localization. Results Compared to FA, arginase activity was significantly augmented in the lungs of CAP+O3-exposed OVA/OVA mice in both the sub-acute and chronic models. Western blotting and immunohistochemical staining revealed that the increased activity was due to arginase 1 expression in the area surrounding the airways in both models. Arginase inhibition significantly reduced the CAP+O3-induced increase in AHR in both models. Conclusions This study demonstrates that arginase is upregulated following environmental exposures in murine models of asthma, and contributes to the pollution-induced exacerbation of airways responsiveness. Thus arginase may be a therapeutic target to protect susceptible populations against the adverse health effects of air pollution, such as fine particles and ozone, which are two of the major contributors to smog

Arginase strongly impairs neuronal nitric oxide-mediated airway smooth muscle relaxation in allergic asthma

BACKGROUND: Using guinea pig tracheal preparations, we have recently shown that endogenous arginase activity attenuates inhibitory nonadrenergic noncholinergic (iNANC) nerve-mediated airway smooth muscle relaxation by reducing nitric oxide (NO) production – due to competition with neuronal NO-synthase (nNOS) for the common substrate, L-arginine. Furthermore, in a guinea pig model of allergic asthma, airway arginase activity is markedly increased after the early asthmatic reaction (EAR), leading to deficiency of agonist-induced, epithelium-derived NO and subsequent airway hyperreactivity. In this study, we investigated whether increased arginase activity after the EAR affects iNANC nerve-derived NO production and airway smooth muscle relaxation. METHODS: Electrical field stimulation (EFS; 150 mA, 4 ms, 4 s, 0.5 – 16 Hz)-induced relaxation was measured in tracheal open-ring preparations precontracted to 30% with histamine in the presence of 1 μM atropine and 3 μM indomethacin. The contribution of NO to EFS-induced relaxation was assessed by the nonselective NOS inhibitor N(ω)-nitro-L-arginine (L-NNA, 100 μM), while the involvement of arginase activity in the regulation of EFS-induced NO production and relaxation was investigated by the effect of the specific arginase inhibitor N(ω)-hydroxy-nor-L-arginine (nor-NOHA, 10 μM). Furthermore, the role of substrate availability to nNOS was measured in the presence of exogenous L-arginine (5.0 mM). RESULTS: At 6 h after ovalbumin-challenge (after the EAR), EFS-induced relaxation (ranging from 3.2 ± 1.1% at 0.5 Hz to 58.5 ± 2.2% at 16 Hz) was significantly decreased compared to unchallenged controls (7.1 ± 0.8% to 75.8 ± 0.7%; P < 0.05 all). In contrast to unchallenged controls, the NOS inhibitor L-NNA did not affect EFS-induced relaxation after allergen challenge, indicating that NO deficiency underlies the impaired relaxation. Remarkably, the specific arginase inhibitor nor-NOHA normalized the impaired relaxation to unchallenged control (P < 0.05 all), which effect was inhibited by L-NNA (P < 0.01 all). Moreover, the effect of nor-NOHA was mimicked by exogenous L-arginine. CONCLUSION: The results clearly demonstrate that increased arginase activity after the allergen-induced EAR contributes to a deficiency of iNANC nerve-derived NO and decreased airway smooth muscle relaxation, presumably via increased substrate competition with nNOS

Newly diagnosed incident dizziness of older patients: a follow-up study in primary care

<p>Abstract</p> <p>Background</p> <p>Dizziness is a common complaint of older patients in primary care, yet not much is known about the course of incident dizziness. The aim of the study was to follow-up symptoms, subjective impairments and needs of older patients (≥65) with incident dizziness and to determine predictors of chronic dizziness. Furthermore, we analysed general practitioners' (GPs') initial diagnoses, referrals and revised diagnoses after six months.</p> <p>Methods</p> <p>An observational study was performed in 21 primary care practices in Germany, including a four-week and six-month follow-up. A questionnaire comprising characteristic matters of dizziness and a series of validated instruments was completed by 66 participants during enrolment and follow-up (after 1 month and 6 months). After six months, chart reviews and face-to-face interviews were also performed with the GPs.</p> <p>Results</p> <p>Mean scores of dizziness handicap, depression and quality of life were not or only slightly affected, and did not deteriorate during follow-up; however, 24 patients (34.8%) showed a moderate or severe dizziness handicap, and 43 (62.3%) showed a certain disability in terms of quality of life at the time of enrolment. In multivariate analysis, n = 44 patients suffering from chronic dizziness (dependent variable, i.e. relapsing or persistent at six months) initially had a greater dizziness handicap (OR 1.42, 95%CI 1.05-1.47) than patients with transient dizziness. GPs referred 47.8% of the patients to specialists who detected two additional cases of benign paroxysmal positional vertigo (BPPV).</p> <p>Conclusions</p> <p>New-onset dizziness relapsed or persisted in a considerable number of patients within six months. This was difficult to predict due to the patients' heterogeneous complaints and characteristics. Symptom persistence does not seem to be associated with deterioration of the psychological status in older primary care patients. Management strategies should routinely consider BPPV as differential diagnosis.</p