RESUMEN
BACKGROUND: Many vital components in bioprocess media are prone to photo-conversion or photo-degradation upon exposure to ambient light, with severe negative consequences for biomass yield and overall productivity. However, there is only limited awareness of light irradiation as a potential risk factor when working in transparent glass bioreactors, storage vessels or disposable bag systems. The chemical complexity of most media renders a root-cause analysis difficult. This study investigated in a novel, holistic approach how light-induced changes in media composition relate to alterations in radical burden, cell physiology, morphology, and product formation in industrial Chinese hamster ovary (CHO) bioprocesses. RESULTS: Two media formulations from proprietary and commercial sources were tested in a pre-hoc light exposure scenario prior to cultivation. Using fluorescence excitation/emission (EEM) matrix spectroscopy, a photo-sensitization of riboflavin was identified as a likely cause for drastically decreased IgG titers (up to -80%) and specific growth rates (-50% to -90%). Up to three-fold higher radical levels were observed in photo-degraded medium. On the biological side, this resulted in significant changes in cell morphology and aberrations in the normal IgG biosynthesis/secretion pathway. CONCLUSION: These findings clearly illustrate the underrated impact of room light after only short periods of exposure, occurring accidentally or knowingly during bioprocess development and scale- up. The detrimental effects, which may share a common mechanistic cause at the molecular level, correlate well with changes in spectroscopic properties. This offers new perspectives for online monitoring concepts, and improved detectability of such effects in future. © 2018 The Authors. Journal of Chemical Technology & Biotechnology published by JohnWiley & Sons Ltd on behalf of Society of Chemical Industry.
RESUMEN
Retigabine, currently used as antiepileptic drug, has a wide range of potential medical uses. Administration of the drug in patients can lead to QT interval prolongation in the electrocardiogram and to cardiac arrhythmias in rare cases. This suggests that the drug may perturb the electrical properties of the heart, and the underlying mechanisms were investigated here. Effects of retigabine on currents through human cardiac ion channels, heterologously expressed in tsA-201 cells, were studied in whole-cell patch-clamp experiments. In addition, the drug's impact on the cardiac action potential was tested. This was done using ventricular cardiomyocytes isolated from Langendorff-perfused guinea pig hearts and cardiomyocytes derived from human induced pluripotent stem cells. Further, to unravel potential indirect effects of retigabine on the heart which might involve the autonomic nervous system, membrane potential and noradrenaline release from sympathetic ganglionic neurons were measured in the absence and presence of the drug. Retigabine significantly inhibited currents through hKv11.1 potassium, hNav1.5 sodium, as well as hCav1.2 calcium channels, but only in supra-therapeutic concentrations. In a similar concentration range, the drug shortened the action potential in both guinea pig and human cardiomyocytes. Therapeutic concentrations of retigabine, on the other hand, were sufficient to inhibit the activity of sympathetic ganglionic neurons. We conclude that retigabine- induced QT interval prolongation, and the reported cases of cardiac arrhythmias after application of the drug in a typical daily dose range, cannot be explained by a direct modulatory effect on cardiac ion channels. They are rather mediated by indirect actions at the level of the autonomic nervous system.
Asunto(s)
Potenciales de Acción/efectos de los fármacos , Anticonvulsivantes/toxicidad , Arritmias Cardíacas/inducido químicamente , Carbamatos/toxicidad , Ganglios Simpáticos/efectos de los fármacos , Bloqueadores Ganglionares/toxicidad , Sistema de Conducción Cardíaco/efectos de los fármacos , Canales Iónicos/antagonistas & inhibidores , Miocitos Cardíacos/efectos de los fármacos , Fenilendiaminas/toxicidad , Animales , Arritmias Cardíacas/metabolismo , Arritmias Cardíacas/fisiopatología , Bloqueadores de los Canales de Calcio/toxicidad , Canales de Calcio Tipo L/efectos de los fármacos , Canales de Calcio Tipo L/metabolismo , Línea Celular , Relación Dosis-Respuesta a Droga , Canal de Potasio ERG1/antagonistas & inhibidores , Canal de Potasio ERG1/metabolismo , Ganglios Simpáticos/metabolismo , Ganglios Simpáticos/fisiopatología , Cobayas , Sistema de Conducción Cardíaco/metabolismo , Sistema de Conducción Cardíaco/fisiopatología , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Células Madre Pluripotentes Inducidas/efectos de los fármacos , Células Madre Pluripotentes Inducidas/metabolismo , Canales Iónicos/genética , Canales Iónicos/metabolismo , Preparación de Corazón Aislado , Miocitos Cardíacos/metabolismo , Canal de Sodio Activado por Voltaje NAV1.5/efectos de los fármacos , Canal de Sodio Activado por Voltaje NAV1.5/metabolismo , Norepinefrina/metabolismo , Bloqueadores de los Canales de Potasio/toxicidad , Ratas Sprague-Dawley , Medición de Riesgo , Factores de Tiempo , Transfección , Bloqueadores del Canal de Sodio Activado por Voltaje/toxicidadRESUMEN
Ibogaine, an alkaloid derived from the African shrub Tabernanthe iboga, has shown promising anti-addictive properties in animals. Anecdotal evidence suggests that ibogaine is also anti-addictive in humans. Thus, it alleviates drug craving and impedes relapse of drug use. Although not licensed as therapeutic drug, and despite evidence that ibogaine may disturb the rhythm of the heart, this alkaloid is currently used as an anti-addiction drug in alternative medicine. Here, we report that therapeutic concentrations of ibogaine reduce currents through human ether-a-go-go-related gene potassium channels. Thereby, we provide a mechanism by which ibogaine may generate life-threatening cardiac arrhythmias.
Asunto(s)
Arritmias Cardíacas/inducido químicamente , Conducta Adictiva/tratamiento farmacológico , Canales de Potasio Éter-A-Go-Go/antagonistas & inhibidores , Antagonistas de Aminoácidos Excitadores/farmacología , Ibogaína/farmacología , Adulto , Animales , Relación Dosis-Respuesta a Droga , Antagonistas de Aminoácidos Excitadores/efectos adversos , Femenino , Frecuencia Cardíaca/efectos de los fármacos , Humanos , Ibogaína/efectos adversos , Prevención SecundariaRESUMEN
The plant alkaloid ibogaine has promising anti-addictive properties. Albeit not licensed as a therapeutic drug, and despite hints that ibogaine may perturb the heart rhythm, this alkaloid is used to treat drug addicts. We have recently reported that ibogaine inhibits human ERG (hERG) potassium channels at concentrations similar to the drugs affinity for several of its known brain targets. Thereby the drug may disturb the heart's electrophysiology. Here, to assess the drug's cardiac ion channel profile in more detail, we studied the effects of ibogaine and its congener 18-Methoxycoronaridine (18-MC) on various cardiac voltage-gated ion channels. We confirmed that heterologously expressed hERG currents are reduced by ibogaine in low micromolar concentrations. Moreover, at higher concentrations, the drug also reduced human Nav1.5 sodium and Cav1.2 calcium currents. Ion currents were as well reduced by 18-MC, yet with diminished potency. Unexpectedly, although blocking hERG channels, ibogaine did not prolong the action potential (AP) in guinea pig cardiomyocytes at low micromolar concentrations. Higher concentrations (≥ 10 µM) even shortened the AP. These findings can be explained by the drug's calcium channel inhibition, which counteracts the AP-prolonging effect generated by hERG blockade. Implementation of ibogaine's inhibitory effects on human ion channels in a computer model of a ventricular cardiomyocyte, on the other hand, suggested that ibogaine does prolong the AP in the human heart. We conclude that therapeutic concentrations of ibogaine have the propensity to prolong the QT interval of the electrocardiogram in humans. In some cases this may lead to cardiac arrhythmias.
Asunto(s)
Conducta Adictiva , Canales de Potasio Éter-A-Go-Go/antagonistas & inhibidores , Ibogaína/farmacología , Miocitos Cardíacos/efectos de los fármacos , Bloqueadores de los Canales de Potasio/farmacología , Potenciales de Acción/efectos de los fármacos , Potenciales de Acción/fisiología , Animales , Conducta Adictiva/tratamiento farmacológico , Conducta Adictiva/metabolismo , Relación Dosis-Respuesta a Droga , Canales de Potasio Éter-A-Go-Go/fisiología , Femenino , Cobayas , Humanos , Ibogaína/química , Ibogaína/uso terapéutico , Canales Iónicos/antagonistas & inhibidores , Canales Iónicos/fisiología , Miocitos Cardíacos/fisiología , Bloqueadores de los Canales de Potasio/química , Bloqueadores de los Canales de Potasio/uso terapéuticoRESUMEN
To maintain or improve revenue streams under the Medicare outpatient prospective payment system (PPS), healthcare financial managers should use a process-oriented approach to assess the effectiveness of revenue capture in departments most affected by the PPS's use of ambulatory patient classifications, which typically include the radiology, cardiology, and emergency departments. Such an assessment should be conducted by a multidisciplinary team with senior management support. The team ideally should include the CFO, COO, and leaders from the departments to be assessed. Such an assessment process should consist of five basic phases: chargemaster/charge-capture analysis, revenue-capture process assessment, claims review, development of implementation strategies, and monitoring.