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Primary prophylaxis of invasive fungal diseases in patients with haematological malignancies: 2022 update of the recommendations of the Infectious Diseases Working Party (AGIHO) of the German Society for Haematology and Medical Oncology (DGHO). J Antimicrob Chemother 2023:dkad143. [PMID: 37311136 PMCID: PMC10393896 DOI: 10.1093/jac/dkad143] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023] Open
Abstract
Patients with haematological malignancies (HM) are at high risk of developing invasive fungal disease (IFD) with high morbidity and attributable mortality. We reviewed data published until September 2021 to update the 2017 antifungal prophylaxis recommendations of the German Society of Haematology and Medical Oncology (DGHO). The strong recommendation to administer antifungal prophylaxis in patients with HM with long-lasting neutropenia, i.e. <500 cells/μL for >7 days remains unchanged. Posaconazole remains the drug of choice for mould-active prophylaxis in these patients. Novel treatment options in HM, such as CAR-T-cell treatment or novel targeted therapies for acute myeloid leukaemia (AML) were considered, however, data are insufficient to give general recommendations for routine antifungal prophylaxis in these patients. Major changes regarding specific recommendations compared to the 2017 edition are the now moderate instead of mild support for the recommendations of isavuconazole and voriconazole. Furthermore, published evidence on micafungin allows recommending it at moderate strength for its use in HM. For the first time we included recommendations for non-pharmaceutical measures regarding IFD, comprising the use of high-efficiency particulate air (HEPA) filters, smoking, measures during construction work and neutropenic diets. We reviewed the impact of antifungal prophylaxis with triazoles on drug-drug interactions with novel targeted therapies that are metabolized via cytochrome p450 where triazoles inhibit CYP3A4/5. The working group recommends reducing the dose of venetoclax when used concomitantly with strong CYP3A4 inhibiting antifungals. Furthermore, we reviewed data on the prophylactic use of novel antifungal agents. Currently there is no evidence to support their use in a prophylactic setting in clinical practice.
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An unusual case of a multiple myeloma with thyroid involvement at primary diagnosis. Blood 2023; 141:1092. [PMID: 36862432 DOI: 10.1182/blood.2022018243] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/03/2023] Open
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Impact of single-room contact precautions on acquisition and transmission of vancomycin-resistant enterococci on haematological and oncological wards, multicentre cohort-study, Germany, January-December 2016. Euro Surveill 2022; 27:2001876. [PMID: 35027104 PMCID: PMC8759111 DOI: 10.2807/1560-7917.es.2022.27.2.2001876] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 08/18/2021] [Indexed: 06/14/2023] Open
Abstract
BackgroundEvidence supporting the effectiveness of single-room contact precautions (SCP) in preventing in-hospital acquisition of vancomycin-resistant enterococci (haVRE) is limited.AimWe assessed the impact of SCP on haVRE and their transmission.MethodsWe conducted a prospective, multicentre cohort study in German haematological/oncological departments during 2016. Two sites performed SCP for VRE patients and two did not (NCP). We defined a 5% haVRE-risk difference as non-inferiority margin, screened patients for VRE, and characterised isolates by whole genome sequencing and core genome MLST (cgMLST). Potential confounders were assessed by competing risk regression analysis.ResultsWe included 1,397 patients at NCP and 1,531 patients at SCP sites. Not performing SCP was associated with a significantly higher proportion of haVRE; 12.2% (170/1,397) patients at NCP and 7.4% (113/1,531) patients at SCP sites (relative risk (RR) 1.74; 95% confidence interval (CI): 1.35-2.23). The difference (4.8%) was below the non-inferiority margin. Competing risk regression analysis indicated a stronger impact of antimicrobial exposure (subdistribution hazard ratio (SHR) 7.46; 95% CI: 4.59-12.12) and underlying disease (SHR for acute leukaemia 2.34; 95% CI: 1.46-3.75) on haVRE than NCP (SHR 1.60; 95% CI: 1.14-2.25). Based on cgMLST and patient movement data, we observed 131 patient-to-patient VRE transmissions at NCP and 85 at SCP sites (RR 1.76; 95% CI: 1.33-2.34).ConclusionsWe show a positive impact of SCP on haVRE in a high-risk population, although the observed difference was below the pre-specified non-inferiority margin. Importantly, other factors including antimicrobial exposure seem to be more influential.
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Digital Monitoring and Management of Patients With Advanced or Metastatic Non-Small Cell Lung Cancer Treated With Cancer Immunotherapy and Its Impact on Quality of Clinical Care: Interview and Survey Study Among Health Care Professionals and Patients. J Med Internet Res 2020; 22:e18655. [PMID: 33346738 PMCID: PMC7781800 DOI: 10.2196/18655] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2020] [Revised: 06/01/2020] [Accepted: 11/02/2020] [Indexed: 02/06/2023] Open
Abstract
Background Cancer immunotherapy (CIT), as a monotherapy or in combination with chemotherapy, has been shown to extend overall survival in patients with locally advanced or metastatic non-small cell lung cancer (NSCLC). However, patients experience treatment-related symptoms that they are required to recall between hospital visits. Digital patient monitoring and management (DPMM) tools may improve clinical practice by allowing real-time symptom reporting. Objective This proof-of-concept pilot study assessed patient and health care professional (HCP) adoption of our DPMM tool, which was designed specifically for patients with advanced or metastatic NSCLC treated with CIT, and the tool’s impact on clinical care. Methods Four advisory boards were assembled in order to co-develop a drug- and indication-specific CIT (CIT+) module, based on a generic CIT DPMM tool from Kaiku Health, Helsinki, Finland. A total of 45 patients treated with second-line single-agent CIT (ie, atezolizumab or otherwise) for advanced or metastatic NSCLC, as well as HCPs, whose exact number was decided by the clinics, were recruited from 10 clinics in Germany, Finland, and Switzerland between February and May 2019. All clinics were provided with the Kaiku Health generic CIT DPMM tool, including our CIT+ module. Data on user experience, overall satisfaction, and impact of the tool on clinical practice were collected using anonymized surveys—answers ranged from 1 (low agreement) to 5 (high agreement)—and HCP interviews; surveys and interviews consisted of closed-ended Likert scales and open-ended questions, respectively. The first survey was conducted after 2 months of DPMM use, and a second survey and HCP interviews were conducted at study end (ie, after ≥3 months of DPMM use); only a subgroup of HCPs from each clinic responded to the surveys and interviews. Survey data were analyzed quantitatively; interviews were recorded, transcribed verbatim, and translated into English, where applicable, for coding and qualitative thematic analysis. Results Among interim survey respondents (N=51: 13 [25%] nurses, 11 [22%] physicians, and 27 [53%] patients), mean rankings of the tool’s seven usability attributes ranged from 3.2 to 4.4 (nurses), 3.7 to 4.5 (physicians), and 3.7 to 4.2 (patients). At the end-of-study survey (N=48: 19 [40%] nurses, 8 [17%] physicians, and 21 [44%] patients), most respondents agreed that the tool facilitated more efficient and focused discussions between patients and HCPs (nurses and patients: mean rating 4.2, SD 0.8; physicians: mean rating 4.4, SD 0.8) and allowed HCPs to tailor discussions with patients (mean rating 4.35, SD 0.65). The standalone tool was well integrated into HCP daily clinical workflow (mean rating 3.80, SD 0.75), enabled workflow optimization between physicians and nurses (mean rating 3.75, SD 0.80), and saved time by decreasing phone consultations (mean rating 3.75, SD 1.00) and patient visits (mean rating 3.45, SD 1.20). Workload was the most common challenge of tool use among respondents (12/19, 63%). Conclusions Our results demonstrate high user satisfaction and acceptance of DPMM tools by HCPs and patients, and highlight the improvements to clinical care in patients with advanced or metastatic NSCLC treated with CIT monotherapy. However, further integration of the tool into the clinical information technology data flow is required. Future studies or registries using our DPMM tool may provide insights into significant effects on patient quality of life or health-economic benefits.
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Impact of digital patient monitoring (DPM) on quality of clinical care of cancer immunotherapy (CIT)-treated patients (pts) with advanced/metastatic non-small cell lung cancer (a/mNSCLC). Ann Oncol 2019. [DOI: 10.1093/annonc/mdz449.039] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Anti-infective vaccination strategies in patients with hematologic malignancies or solid tumors-Guideline of the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO). Ann Oncol 2019; 29:1354-1365. [PMID: 29688266 PMCID: PMC6005139 DOI: 10.1093/annonc/mdy117] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Infectious complications are a significant cause of morbidity and mortality in patients with malignancies specifically when receiving anticancer treatments. Prevention of infection through vaccines is an important aspect of clinical care of cancer patients. Immunocompromising effects of the underlying disease as well as of antineoplastic therapies need to be considered when devising vaccination strategies. This guideline provides clinical recommendations on vaccine use in cancer patients including autologous stem cell transplant recipients, while allogeneic stem cell transplantation is subject of a separate guideline. The document was prepared by the Infectious Diseases Working Party (AGIHO) of the German Society for Hematology and Medical Oncology (DGHO) by reviewing currently available data and applying evidence-based medicine criteria.
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FungiScope ™ -Global Emerging Fungal Infection Registry. Mycoses 2018; 60:508-516. [PMID: 28730644 DOI: 10.1111/myc.12631] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 12/18/2022]
Abstract
Rare invasive fungal diseases (IFD) are challenging for the treating physicians because of their unspecific clinical presentation, as well as the lack of standardised diagnostic and effective treatment strategies. Late onset of treatment and inappropriate medication is associated with high mortality, thus, urging the need for a better understanding of these diseases. The purpose of FungiScope™ is to continuously collect clinical information and specimens to improve the knowledge on epidemiology and eventually improve patient management of these orphan diseases. FungiScope™ was founded in 2003, and today, collaborators from 66 countries support the registry. So far, clinical data of 794 cases have been entered using a web-based approach. Within the growing network of experts, new collaborations developed, leading to several publications of comprehensive analyses of patient subgroups identified from the registry. Data extracted from FungiScope™ have also been used as the sole control group for the approval of a new antifungal drug. Due to the rarity of these diseases, a global registry is an appropriate method of pooling the scarce and scattered information. Joining efforts across medical specialities and geographical borders is key for researching rare IFD. Here, we describe the structure and management of the FungiScope™ registry.
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Invasive Mucormycosis in Patients With Hematological Diseases Identified in the Global FungiScope Registry. Open Forum Infect Dis 2016. [DOI: 10.1093/ofid/ofw194.38] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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FungiScope: Global Emerging Fungal Infection Registry. Open Forum Infect Dis 2016. [DOI: 10.1093/ofid/ofw172.1284] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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1,3-β-d-Glucan contamination of common antimicrobials—authors' response. J Antimicrob Chemother 2016; 71:2997-9. [DOI: 10.1093/jac/dkw299] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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A cohort study on breakthrough invasive fungal infections in high-risk patients receiving antifungal prophylaxis. J Antimicrob Chemother 2016; 71:2634-41. [DOI: 10.1093/jac/dkw199] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2016] [Accepted: 04/26/2016] [Indexed: 12/15/2022] Open
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Domestic mould exposure and invasive aspergillosis—air sampling ofAspergillusspp. spores in homes of hematological patients, a pilot study. Med Mycol 2016; 54:576-83. [DOI: 10.1093/mmy/myw007] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 01/13/2016] [Indexed: 11/14/2022] Open
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1,3-β-d-Glucan contamination of common antimicrobials: Table 1. J Antimicrob Chemother 2015; 71:913-5. [DOI: 10.1093/jac/dkv419] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2015] [Accepted: 11/05/2015] [Indexed: 11/13/2022] Open
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1,3-ß-D-glucan concentrations in blood products predict false positive post-transfusion results. Mycoses 2015; 59:39-42. [DOI: 10.1111/myc.12432] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Revised: 10/20/2015] [Accepted: 10/20/2015] [Indexed: 11/28/2022]
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Our 2015 approach to invasive pulmonary aspergillosis. Mycoses 2015; 58:375-82. [DOI: 10.1111/myc.12319] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 03/09/2015] [Accepted: 03/09/2015] [Indexed: 12/13/2022]
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Colonization and infection with extended spectrum beta-lactamase producing Enterobacteriaceae in high-risk patients – Review of the literature from a clinical perspective. Crit Rev Microbiol 2014; 42:1-16. [DOI: 10.3109/1040841x.2013.875515] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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A neuroprotective phase precedes striatal degeneration upon nucleolar stress. Cell Death Differ 2013; 20:1455-64. [PMID: 23764776 PMCID: PMC3792439 DOI: 10.1038/cdd.2013.66] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2012] [Revised: 05/03/2013] [Accepted: 05/16/2013] [Indexed: 01/17/2023] Open
Abstract
The nucleolus is implicated in sensing and responding to cellular stress by stabilizing p53. The pro-apoptotic effect of p53 is associated with several neurodegenerative disorders, including Huntington's disease (HD), which is characterized by the progressive loss of medium spiny neurons (MSNs) in the striatum. Here we show that disruption of nucleolar integrity and function causes nucleolar stress and is an early event in MSNs of R6/2 mice, a transgenic model of HD. Targeted perturbation of nucleolar function in MSNs by conditional knockout of the RNA polymerase I-specific transcription initiation factor IA (TIF-IA) leads to late progressive striatal degeneration, HD-like motor abnormalities and molecular signatures. Significantly, p53 prolongs neuronal survival in TIF-IA-deficient MSNs by transient upregulation of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor that inhibits mammalian target of rapamycin signaling and induces autophagy. The results emphasize the initial role of nucleolar stress in neurodegeneration and uncover a p53/PTEN-dependent neuroprotective response.
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Abstract
Mucormycosis is an emerging invasive fungal infection, primarily affecting immunocompromised patients. The disease is difficult to diagnose and mortality reaches 40% even if treated adequately. Depending on site of infection and risk factors, surgical debridement in combination with systemically active antifungal drugs are the mainstay treatment strategies. Lipid-based amphotericin B is the treatment of choice for first-line therapy while posaconazole may be a promising alternative. We performed a PubMed search on reports of patients with mucormycosis treated with posaconazole. From 2003 to 2011, 96 cases have been published. Diagnosis was based on histology alone in 2 (2.1%) and microbiological evidence in 67 (69.8%), while no data on the diagnostic approach was reported in 27 (28.1%) patients. The most frequent pathogens were Rhizopus spp. (31.2%), followed by Mucor spp. (14.6%). The site of infection was predominantly rhino-orbital (38.5%, of which 43% also had central nervous system [CNS] involvement), followed by disseminated disease (22.1%). A complete response was achieved in 62 (64.6%), partial response in 7 (7.3%) patients, and stable disease in 1 (1%). Overall mortality was 24% (lacking data for three patients). In published case reports on posaconazole treatment for mucormycosis, the drug was frequently and successfully used in combination or as second line therapy.
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Behavioral phenotyping of mice lacking the K ATP channel subunit Kir6.2. Physiol Behav 2006; 87:723-33. [PMID: 16530794 DOI: 10.1016/j.physbeh.2006.01.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2005] [Revised: 12/19/2005] [Accepted: 01/19/2006] [Indexed: 01/27/2023]
Abstract
ATP-sensitive potassium (K(ATP)) channels are expressed in various tissues and cell-types where they act as so-called metabolic sensors that couple metabolic state to cellular excitability. The pore of most K(ATP) channel types is built by Kir6.2 subunits. Analysis of a general Kir6.2 knockout (KO) mouse has identified a variety of different functional roles for central and peripheral K(ATP) channels in situations of metabolic demand. However, the widespread distribution of these channels suggests that they might influence cellular physiology and animal behavior under metabolic control conditions. As a comprehensive behavioral description of Kir6.2 KO mice under physiological control conditions has not yet been carried out, we subjected Kir6.2 KO and corresponding wild-type (WT) mice to a test battery to assess emotional behavior, motor activity and coordination, species-typical behaviors and cognition. The results indicated that in these test situations Kir6.2 KO mice were less active, had impaired motor coordination, and appeared to differ from controls in their emotional reactivity. Differences between KO and WT mice were generally attenuated in test situations that resembled the home cage environment. Moreover, in their home cages KO mice were more active than WT mice. Thus, our results suggest that loss of Kir6.2-containing K(ATP) channels does affect animal behavior under metabolic control conditions, especially in novel situations. These findings assign novel functional roles to K(ATP) channels beyond those previously described. However, according to the widespread expression of K(ATP) channels, these effects are complex, being dependent on details of test apparatus, procedure and prior experience.
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KATP channels control the differential vulnerability of dopaminergic midbrain neurons in a chronic MPTP-model of Parkinson's disease. AKTUELLE NEUROLOGIE 2005. [DOI: 10.1055/s-2005-916300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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A role for neuronal K(ATP) channels in metabolic control of the seizure gate. Trends Pharmacol Sci 2001; 22:599-601; discussion 601-2. [PMID: 11730952 DOI: 10.1016/s0165-6147(00)01861-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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ATP-sensitive potassium channels in dopaminergic neurons: transducers of mitochondrial dysfunction. NEWS IN PHYSIOLOGICAL SCIENCES : AN INTERNATIONAL JOURNAL OF PHYSIOLOGY PRODUCED JOINTLY BY THE INTERNATIONAL UNION OF PHYSIOLOGICAL SCIENCES AND THE AMERICAN PHYSIOLOGICAL SOCIETY 2001; 16:214-7. [PMID: 11572924 DOI: 10.1152/physiologyonline.2001.16.5.214] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
ATP-sensitive potassium (K(ATP)) channels directly couple the metabolic state of a cell to its electrical activity. Dopaminergic midbrain neurons express alternative types of K(ATP) channels mediating their differential response to mitochondrial complex I inhibition. Because reduced complex I activity is present in Parkinson's Disease, differential K(ATP) channel expression suggests a novel candidate mechanism for selective dopaminergic degeneration.
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ATP-sensitive K+ channels in the hypothalamus are essential for the maintenance of glucose homeostasis. Nat Neurosci 2001; 4:507-12. [PMID: 11319559 DOI: 10.1038/87455] [Citation(s) in RCA: 417] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Glucose-responsive (GR) neurons in the hypothalamus are thought to be critical in glucose homeostasis, but it is not known how they function in this context. Kir6.2 is the pore-forming subunit of K(ATP) channels in many cell types, including pancreatic beta-cells and heart. Here we show the complete absence of both functional ATP-sensitive K+ (K(ATP)) channels and glucose responsiveness in the neurons of the ventromedial hypothalamus (VMH) in Kir6.2-/- mice. Although pancreatic alpha-cells were functional in Kir6.2-/-, the mice exhibited a severe defect in glucagon secretion in response to systemic hypoglycemia. In addition, they showed a complete loss of glucagon secretion, together with reduced food intake in response to neuroglycopenia. Thus, our results demonstrate that KATP channels are important in glucose sensing in VMH GR neurons, and are essential for the maintenance of glucose homeostasis.
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Molecular physiology of neuronal K-ATP channels (review). Mol Membr Biol 2001; 18:117-27. [PMID: 11463204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023]
Abstract
ATP sensitive potassium (K-ATP) channels are widely expressed in many cell types including neurons. K-ATP channels are heteromeric membrane proteins that consist of two very different subunits: the pore-forming, two-transmembrane spanning potassium channel subunit (Kir6) and the regulatory, 17 transmembrane spanning sulphonylurea receptor (SUR). This ensemble--joined together in a 4:4 stoichiometry--endows this channel with a unique combination of functional properties. The open probability of K-ATP channels directly depends on the intracellular ATP/ADP levels allowing the channels to directly couple the metabolic state of a cell to its electrical activity. Here, recent progress on the molecular composition and functional diversity of neuronal K-ATP channels is reviewed. One is particular concerned with single-cell mRNA expression studies that give insight to the coexpression patterns of Kir6 and SUR isoforms in identified neurons. In addition, the physiological roles of neuronal K-ATP channels in glucose sensing and adapting neuronal activity to metabolic demands are discussed, as well as their emerging pathophysiological functions in acute brain ischemia and chronic neurodegenerative diseases.
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Single-cell mRNA expression of HCN1 correlates with a fast gating phenotype of hyperpolarization-activated cyclic nucleotide-gated ion channels (Ih) in central neurons. Eur J Neurosci 2000; 12:2685-93. [PMID: 10971612 DOI: 10.1046/j.1460-9568.2000.00151.x] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hyperpolarization-activated currents (Ih) are key players in shaping rhythmic neuronal activity. Although candidate genes for Ih channels have been cloned (HCN1-HCN4), the subunit composition of different native Ih channels is unknown. We used a combined patch-clamp and qualitative single-cell reverse transcription multiplex polymerase chain reaction (RT-mPCR) approach to analyse HCN1-4 coexpression profiles in four neuronal populations in mouse CNS. Coexpression of HCN2, HCN3 and HCN4 mRNA was detected in single neurons of all four neuronal cell types analysed. In contrast, HCN1 mRNA was detected in neocortical and hippocampal pyramidal neurons but not in dopaminergic midbrain and thalamocortical neurons. HCN1 expression was correlated with significantly faster activation kinetics on the level of individual neurons. Semiquantitative single-cell RT-mPCR analysis demonstrated that HCN1 mRNA expression is at least eightfold higher in cortical neurons than subcortical neurons. We show that single neurons possess complex coexpression patterns of Ih candidate genes. Alternative expression of HCN1 is likely to be an important molecular determinant to generate the different neuronal Ih channel species adapted to tune either subcortical or cortical network activity.
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Abstract
1. ATP-sensitive potassium (KATP) channels are composed of pore-forming (Kir6.x) and regulatory sulphonylurea receptor (SURx) subunits. We have isolated a novel SUR variant (SUR1bDelta33) from a hypothalamic cDNA library. This variant lacked exon 33 and introduced a frameshift that produced a truncated protein lacking the second nucleotide binding domain (NBD2). It was expressed at low levels in hypothalamus, midbrain, heart and the insulin-secreting beta-cell line MIN6. 2. We examined the properties of KATP channels composed of Kir6.2 and SUR1bDelta33 by recording macroscopic currents in membrane patches excised from Xenopus oocytes expressing these subunits. We also investigated the effect of truncating SUR1 at either the start (SUR1bT1) or end (SUR1bT2) of exon 33 on KATP channel properties. 3. Kir6.2/SUR1bDelta33 showed an enhanced open probability (Po = 0.6 at -60 mV) and a reduced ATP sensitivity (Ki, 86 microM), when compared with wild-type channels (Po = 0.3; Ki, 22 microM). However, Kir6.2/SUR1bT1 and Kir6.2/SUR1bT2 resembled the wild-type channel in their Po and ATP sensitivity. 4. Neither MgADP, nor the K+ channel opener diazoxide, enhanced Kir6.2/SUR1bDelta33, Kir6.2/SUR1bT1 or Kir6.2/SUR1bT2 currents, consistent with the idea that these agents require an intact NBD2 for their action. Sulphonylureas blocked KATP channels containing any of the three SUR variants, but in excised patches the extent of block was less than that for the wild-type channel. In intact cells, the extent of sulphonylurea block of Kir6.2/SUR1bDelta33 was greater than that in excised patches and was comparable to that found for wild-type channels. 5. Our results demonstrate that NBD2 is not essential for functional expression or sulphonylurea block, but is required for KATP channel activation by K+ channel openers and nucleotides. Some of the unusual properties of Kir6.2/SUR1bDelta33 resemble those reported for the KATP channel of ventromedial hypothalamic (VMH) neurones, but the fact that this mRNA is expressed at low levels in many other tissues makes it less likely that SUR1bDelta33 serves as the SUR subunit for the VMH KATP channel.
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The weaver mouse gain-of-function phenotype of dopaminergic midbrain neurons is determined by coactivation of wvGirk2 and K-ATP channels. J Neurosci 1999; 19:8839-48. [PMID: 10516303 PMCID: PMC6782762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/14/2023] Open
Abstract
The phenotype of substantia nigra (SN) neurons in homozygous weaver (wv/wv) mice was studied by combining patch-clamp and single-cell RT-multiplex PCR techniques in midbrain slices of 14-d-old mice. In contrast to GABAergic SN neurons, which were unaffected in homozygous weaver mice (wv/wv), dopaminergic SN neurons possessed a dramatically altered phenotype with a depolarized membrane potential and complete loss of spontaneous pacemaker activity. The gain-of-function phenotype was mediated by a large, nonselective membrane conductance exclusively present in (wv/wv) dopaminergic SN neurons. This constitutively activated conductance displayed a sensitivity to external QX-314 (IC(50) = 10.6 microM) very similar to that of heterologously expressed wvGirk2 channels and was not further activated by G-protein stimulation. Single-cell Girk1-4 expression profiling suggested that homomeric Girk2 channels were present in most dopaminergic SN neurons, whereas Girk2 was always coexpressed with other Girk family members in GABAergic SN neurons. Surprisingly, acute QX-314 inhibition of wvGirk2 channels did not induce wild-type-like pacemaker activity but instead caused membrane hyperpolarization. Additional application of a blocker of ATP-sensitive potassium channels (100 microM tolbutamide) induced wild-type-like pacemaker activity. We conclude that the gain-of-function weaver phenotype of dopaminergic substantia nigra neurons is mediated by coactivation of wvGirk2 and SUR1/Kir6. 2-mediated ATP-sensitive K(+) channels. We also show that in contrast to wild-type neurons, all (wv/wv) dopaminergic SN neurons expressed calbindin, a calcium-binding protein that marks dopaminergic SN neurons resistant to neurodegeneration. The identification of two ion channels that in concert determine the weaver phenotype of surviving calbindin-positive dopaminergic SN neurons will help to understand the molecular mechanisms of selective neurodegeneration of dopaminergic SN neurons in the weaver mouse and might be important in Parkinson's disease.
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Alternative sulfonylurea receptor expression defines metabolic sensitivity of K-ATP channels in dopaminergic midbrain neurons. EMBO J 1999; 18:833-46. [PMID: 10022826 PMCID: PMC1171176 DOI: 10.1093/emboj/18.4.833] [Citation(s) in RCA: 189] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
ATP-sensitive potassium (K-ATP) channels couple the metabolic state to cellular excitability in various tissues. Several isoforms of the K-ATP channel subunits, the sulfonylurea receptor (SUR) and inwardly rectifying K channel (Kir6.X), have been cloned, but the molecular composition and functional diversity of native neuronal K-ATP channels remain unresolved. We combined functional analysis of K-ATP channels with expression profiling of K-ATP subunits at the level of single substantia nigra (SN) neurons in mouse brain slices using an RT-multiplex PCR protocol. In contrast to GABAergic neurons, single dopaminergic SN neurons displayed alternative co-expression of either SUR1, SUR2B or both SUR isoforms with Kir6.2. Dopaminergic SN neurons expressed alternative K-ATP channel species distinguished by significant differences in sulfonylurea affinity and metabolic sensitivity. In single dopaminergic SN neurons, co-expression of SUR1 + Kir6.2, but not of SUR2B + Kir6.2, correlated with functional K-ATP channels highly sensitive to metabolic inhibition. In contrast to wild-type, surviving dopaminergic SN neurons of homozygous weaver mouse exclusively expressed SUR1 + Kir6.2 during the active period of dopaminergic neurodegeneration. Therefore, alternative expression of K-ATP channel subunits defines the differential response to metabolic stress and constitutes a novel candidate mechanism for the differential vulnerability of dopaminergic neurons in response to respiratory chain dysfunction in Parkinson's disease.
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Physiological and therapeutic effects of high frequency electrical pulses. INTEGRATIVE PHYSIOLOGICAL AND BEHAVIORAL SCIENCE : THE OFFICIAL JOURNAL OF THE PAVLOVIAN SOCIETY 1996; 31:88-95. [PMID: 8809593 DOI: 10.1007/bf02699781] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The results of stimulating human subjects with the LISS Cranial Stimulator (LCS) and the LISS Body Stimulator (LBS) include an increase or decrease in the activities of certain neurotransmitters and neurohormones and the reduction of associated pain, insomnia, depression, and spasticity. The effects were documented in human subjects with measurements of the serum concentration of the various agents and assessments of the symptoms being performed before and after stimulation. The stimulators had a carrier frequency of 15,000 hz, which utilizes the bulk capacitance of the body, and a 15 hz modulating bioactive frequency. The second modulating frequency presently used, 500 hz, reduces the energy input to the patient by half. Significant increases in levels of CSF serotonin and beta endorphin were recorded post stimulation. There were also elevations in the levels of plasma serotonin, beta endorphin, GABA and DHEA together with diminished levels of cortisol and tryptophan. Concomitant with these changes were significant improvements in the symptoms of pain, insomnia, spasticity, depression, and headache.
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