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1.
Pneumologie ; 74(6): 358-365, 2020 Jun.
Article in German | MEDLINE | ID: mdl-32294763

ABSTRACT

The enormous increase in patients with severe respiratory distress due to the COVID-19 pandemic outbreak requires a systematic approach to optimize ventilated patient at risk flow. A standardised algorithm called "SAVE" was developed to distribute patients with COVID-19 respiratory distress syndrome requiring invasive ventilation. This program is established by now in Berlin. An instrumental bottleneck of this approach is the vacant slot assignment in the intensive care unit to guarantee constant patient flow. The transfer of the patients after acute care treatment is needed urgently to facilitate the weaning process. In a next step we developed a triage algorithm to identify patients at SAVE intensive care units with potential to wean and transfer to weaning institutions - we called POST SAVE. This manuscript highlights the algorithms including the use of a standardised digital evaluation tool, the use of trained navigators to facilitate the communication between SAVE intensive care units and weaning institutions and the establishment of a prospective data registry for patient assignment and reevaluation of the weaning potential in the future.


Subject(s)
Intensive Care Units/organization & administration , Practice Guidelines as Topic , Ventilator Weaning , Berlin , Betacoronavirus , COVID-19 , Coronavirus , Coronavirus Infections/epidemiology , Coronavirus Infections/therapy , Disease Outbreaks/prevention & control , Humans , Pandemics , Pneumonia, Viral/epidemiology , Pneumonia, Viral/therapy , Prospective Studies , SARS-CoV-2
2.
Pneumologie ; 73(4): 225-232, 2019 Apr.
Article in German | MEDLINE | ID: mdl-30895591

ABSTRACT

There is a paucity of data about the at home monitoring and the outpatient setting and care of patients with non-invasive ventilation. We here show, in a prospective study, that both standardized outpatient care visits as well as quality of life monitoring at home are safe and feasible. Monitoring and managing the quality of care at home did not lead to an increase of non-elective hospitalisations or deterioration of respiratory disease burden.


Subject(s)
Ambulatory Care , Home Care Services , Noninvasive Ventilation/statistics & numerical data , Respiration, Artificial , Respiratory Insufficiency/therapy , Humans , Prospective Studies , Quality of Health Care , Quality of Life
5.
Internist (Berl) ; 51(7): 909-13, 2010 Jul.
Article in German | MEDLINE | ID: mdl-20458459

ABSTRACT

A 25-year-old female patient from India suffered from diffuse pain in the upper and lower abdomen, caused by infiltrative changes of the ovaries and intraabdominal fluid. The patient refused further examinations. 11 months later she endured additional pain of the thorax and the left shoulder. An opacity in the left lung and costal destruction was diagnosed. Puncture of the lung process showed a granulomatous inflammation including Langerhans cells. The puncture of a peritoneal thickening also showed inflammation. Microscopic examination was negative for mycobacteria, but PCR and the culture for Mycobacterium tuberculosis after 8 weeks were positive, with full sensibility, so treatment with RMP, INH, PZA and EMB was initiated. The lung process improved but the abdominal complaints were progressive due to a pyosyalpinx requiring surgical removal. The further course was uneventful. Two years after diagnosis the patient is in a good condition now.


Subject(s)
Abdominal Pain/etiology , Abdominal Pain/prevention & control , Antitubercular Agents/therapeutic use , Tuberculosis/complications , Tuberculosis/diagnosis , Abdominal Pain/diagnosis , Adult , Female , Humans , Treatment Outcome , Tuberculosis/drug therapy
6.
Pneumologie ; 64(1): 7-17, 2010 Jan.
Article in German | MEDLINE | ID: mdl-20091440

ABSTRACT

During the first half of its 100-year history, tuberculosis was predominant in the German Society of Pneumology (DGP). This led largely to the separation of pneumology from internal medicine, particularly in the universities. Since the 1960s, the spectrum of respiratory diseases has changed considerably. Asthma, COPD, lung cancer, and pneumonia today rank among the most widespread diseases. Numerous new diagnostic and therapeutic methods have induced dramatic changes in the field of pneumology. Today, pneumology, together with cardiology and gastroenterology, belongs to the major specialties of internal medicine. One of the most urgent tasks of the DGP is to improve the insufficient representation at German universities, and thus promote teaching and research in respiratory medicine.


Subject(s)
Pulmonary Medicine/history , Societies, Medical/history , Anniversaries and Special Events , Germany , History, 20th Century , History, 21st Century
8.
Leukemia ; 22(8): 1587-94, 2008 Aug.
Article in English | MEDLINE | ID: mdl-18449208

ABSTRACT

Plasticity of committed mouse B cells has been demonstrated by inactivation of the B-cell commitment transcription factor PAX5, resulting in loss of the B-cell phenotype and differentiation into various hematopoietic lineages. Furthermore, mature mouse B cells could be reprogrammed into macrophages by overexpression of myeloid-specific transcription factors. Here, we report that aberrant activity of the transmembrane receptor, Notch1, interferes with the B-lymphoid phenotype of mature human germinal center-derived B cells in Hodgkin lymphoma, so called Hodgkin and Reed-Sternberg cells. They have lost the B-cell phenotype despite their mature B-cell origin. Notch1 remodels the B-cell transcription factor network by antagonizing the key transcription factors E2A and early B-cell factor (EBF). Through this mechanism, B lineage-specific genes were suppressed and B lineage-inappropriate genes were induced. We provide evidence that absence of the Notch inhibitor Deltex1 contributes to deregulated Notch activity in Hodgkin and Reed-Sternberg cells. These data suggest that Notch activation interferes with dedifferentiation of neoplastic B cells in Hodgkin lymphoma.


Subject(s)
B-Lymphocytes/immunology , Hodgkin Disease/pathology , Receptor, Notch1/metabolism , B-Lymphocytes/cytology , Base Sequence , Cell Differentiation , Cell Line, Tumor , Cell Lineage , DNA Primers , Hodgkin Disease/immunology , Hodgkin Disease/metabolism , Humans , Immunohistochemistry , In Situ Hybridization , PAX5 Transcription Factor/metabolism , Phenotype , Reverse Transcriptase Polymerase Chain Reaction
9.
Clin Lab ; 52(11-12): 639-54, 2006.
Article in English | MEDLINE | ID: mdl-17175896

ABSTRACT

This communication deals with a longitudinal evaluation of C-reactive protein (CRP) analysis during a one-year period using a single lot of liquid control sera (3 levels) (BIOREF-CRP levels 1, 2 and 3) in different laboratories. A total of 652 sets of data were returned from 20 participating laboratories using 13 different reagent-measuring device combinations. The use of the control materials was defined in a standard operating procedure. Data was returned to the organizers on a monthly basis and questions could be asked or problems presented during the evaluation period. Although the performance of different reagents varied, the control materials were shown to be stable over the whole of the evaluation period when stored at 4-7 degrees C in a refrigerator/cold room. Typical problems were encountered, examples of which are presented here in graphical and tabular form.


Subject(s)
C-Reactive Protein/analysis , Humans , Indicators and Reagents , Longitudinal Studies , Nephelometry and Turbidimetry/methods , Reproducibility of Results
10.
Praxis (Bern 1994) ; 95(10): 369-73, 2006 Mar 08.
Article in German | MEDLINE | ID: mdl-16550711

ABSTRACT

A pneumomediastinum is characterized by free air within the mediastinum. In most cases it is caused by an injury of the thorax. A spontaneous pneumomediastinum (sPM) occurred without any recognizable cause. By a sudden intraalveolar hypertension (caused by cough or physical exertion) a damage of alveoli is followed by diffusion of air along the bronchovascular sheats to the mediastinal soft tissue. sPM is a rare complication of asthma especially in young men. We demonstrate a young asthmatic patient with sPM first diagnosed as an allergic reaction to draw the attention to this rare but differential diagnostic important entity. sPM is reported in connection with drug inhalation abuse as a more frequent problem within the last years.


Subject(s)
Asthma/complications , Mediastinal Emphysema/etiology , Subcutaneous Emphysema/etiology , Adult , Asthma/diagnostic imaging , Cough/complications , Diagnosis, Differential , Humans , Male , Mediastinal Emphysema/diagnostic imaging , Subcutaneous Emphysema/diagnostic imaging , Tomography, Spiral Computed
11.
Reproduction ; 126(4): 517-25, 2003 Oct.
Article in English | MEDLINE | ID: mdl-14525534

ABSTRACT

The effect of energy metabolism on intracellular pH was studied in boar spermatozoa using nuclear magnetic resonance (NMR) spectroscopy and confocal microscopy with the pH-sensitive dye seminaphthorhodafluor (SNARF-1). Freshly ejaculated spermatozoa had a high adenylate energy charge (AEC=0.8), which decreased to 0.6 under aerobic conditions and to 0.2 under anaerobic conditions. Correspondingly, no ATP resonances but high AMP resonance were visible in (31)P-NMR-spectra of the spermatozoa. When an artificial oxygen buffer (Fluosol) and a purpose-built air supply system were used during (31)P-NMR data acquisition, ATP resonances reappeared whereas the AMP resonance disappeared. Boar spermatozoa kept under aerobic conditions have intracellular compartments that differ markedly in pH, as demonstrated by both (31)P-NMR spectroscopy and confocal microscopy. Using confocal microscopy, the midpiece of the flagellum in which all mitochondria are located was identified as an acidic compartment (pH(i-mp) 6.7). The intracellular pH of both the head (pH(i-h)) and the long principal piece of the flagellum (pH(i-pp)) were 7.2 and, thus, only slightly below the extracellular pH (pH(e) 7.3). Storage of spermatozoa in a glucose-free medium at 15 degrees C when they are immotile slowly shifted the pH(i-mp) from 6.7 to 6.9 within 20 h, whereas pH(i-h) and pH(i-pp) remained unchanged (pH 7.1-7.2). When glucose was present in the medium, all visible compartments of the spermatozoa as well as the medium were acidified to pH 6.2 within 20 h. Under these conditions a resonance at 4.8 mg kg(-1) appeared representing glycerol 3-phosphate.


Subject(s)
Energy Metabolism , Intracellular Fluid/physiology , Spermatozoa/metabolism , Swine/metabolism , Adenosine Diphosphate/metabolism , Adenosine Monophosphate/metabolism , Adenosine Triphosphate/metabolism , Animals , Culture Media , Glucose , Hydrogen-Ion Concentration , Inositol , Lactic Acid/metabolism , Magnetic Resonance Spectroscopy , Male , Microscopy, Confocal , Oxygen/metabolism , Spermatozoa/ultrastructure
12.
Pneumologie ; 57(8): 439-43, 2003 Aug.
Article in German | MEDLINE | ID: mdl-12928984

ABSTRACT

Pulmonary varicosity is a very rare entity. Beside congenital varices, most combined with other malformations of the pulmonary vessels, varicosities are described above all in connection with mitral insufficiency. Most cases with pulmonary varicosity are diagnosed by chance, because of absence of any symptoms or only slight symptoms respectively. We demonstrate our own case with respect to the diagnostic requirements (computerized tomography, multi-slice CT) and the differential diagnostic aspects.


Subject(s)
Lung Neoplasms/diagnostic imaging , Pulmonary Veno-Occlusive Disease/diagnostic imaging , Varicose Veins/etiology , Aged , Diagnosis, Differential , Female , Humans , Radiography, Thoracic , Tomography, X-Ray Computed
13.
Andrologia ; 35(1): 44-54, 2003 Feb.
Article in English | MEDLINE | ID: mdl-12558528

ABSTRACT

Effects of kinins, mainly bradykinin (Bk), and other components of the kallikrein-kinin system on sperm motility and further fertility-related functions have been described repeatedly. However, reported data are in part controversial and the mechanism of kinin effects on sperm motility is not yet understood. In the present report we describe a significant promoting effect of Bk on sperm motility at subnanomolar concentrations. This effect was stabilized and even increased by suppression of Bk hydrolysis in semen samples. As sperm membrane-bound angiotensin-converting enzyme and neutral metalloendopeptidase are mainly involved in Bk hydrolysis, an effective cocktail of enzyme inhibitors promoting the sperm motility consists of phosphoramidon and lisinopril (both at 10-7 m). The effects of Bk on sperm cells are not mediated by the B2 Bk receptor. Using several biochemical, molecular and genetic methods we could not detect any Bk receptor on spermatozoa.


Subject(s)
Bradykinin/pharmacology , Peptide Hydrolases/metabolism , Sperm Motility/drug effects , Spermatozoa/drug effects , Angiotensin-Converting Enzyme Inhibitors/pharmacology , Animals , Bradykinin/metabolism , Calcium/analysis , Cattle , Glycopeptides/pharmacology , Humans , Hydrolysis , Lisinopril/pharmacology , Male , Mice , Mice, Knockout , Neprilysin/antagonists & inhibitors , Neprilysin/metabolism , Peptidyl-Dipeptidase A/metabolism , Protease Inhibitors/pharmacology , RNA, Messenger , Rats , Rats, Wistar , Receptor, Bradykinin B2 , Receptors, Bradykinin/deficiency , Receptors, Bradykinin/genetics , Receptors, Bradykinin/physiology
14.
Eur J Biochem ; 269(16): 4025-32, 2002 Aug.
Article in English | MEDLINE | ID: mdl-12180979

ABSTRACT

The uptake by mammalian cells of phosphorothioate oligonucleotides was compared with that of their respective complexes or conjugates with cationic, cell-penetrating model peptides of varying helix-forming propensity and amphipathicity. An HPLC-based protocol for the synthesis and purification of disulfide bridged conjugates in the 10-100 nmol range was developed. Confocal laser scanning microscopy (CLSM) in combination with gel-capillary electrophoresis and laser induced fluorescence detection (GCE-LIF) revealed cytoplasmic and nuclear accumulationin all cases. The uptake differences between naked oligonucleotides and their respective peptide complexes or conjugates were generally confined to one order of magnitude. No significant influence of the structural properties of the peptide components upon cellular uptake was found. Our results question the common belief that the increased biological activity of oligonucleotides after derivatization with membrane permeable peptides may be primarily due to improved membrane translocation.


Subject(s)
Oligodeoxyribonucleotides, Antisense/metabolism , Peptides/metabolism , Thionucleotides/metabolism , Amino Acid Sequence , Animals , Aorta , CHO Cells , Cell Membrane Permeability , Cell Nucleus/metabolism , Chromatography, High Pressure Liquid , Cricetinae , Cricetulus , Cystine/chemistry , Cytoplasm/metabolism , Dogs , Electrophoresis, Capillary , Endothelium, Vascular/cytology , Endothelium, Vascular/metabolism , Fluorometry , Microfilament Proteins/genetics , Microscopy, Confocal , Molecular Sequence Data , Peptides/chemical synthesis , Peptides/chemistry
15.
Neuroreport ; 12(11): 2513-7, 2001 Aug 08.
Article in English | MEDLINE | ID: mdl-11496140

ABSTRACT

Astrocytes induce blood-brain barrier (BBB) properties in brain endothelial cells (EC)*O(2)*, generated in blood and EC, opens the BBB. Hence, high activity of superoxide dismutase (SOD) is a prerequisite for normal BBB function. Therefore, the influence of rat astrocytes on the expression of manganese (Mn)SOD in rat EC was investigated in two coculture models of the BBB, allowing either exchange of soluble factors or additionally cellular contacts. Activity, protein content and mRNA expression of endothelial MnSOD were significantly increased in both coculture models in comparison to monoculture by soluble astrocytic factors, such as cytokines. High activity of endothelial MnSOD may be considered as a further essential property of the BBB, which is induced and maintained by astrocytes.


Subject(s)
Astrocytes/metabolism , Endothelium, Vascular/enzymology , Superoxide Dismutase/metabolism , Animals , Astrocytes/cytology , Blood-Brain Barrier/physiology , Brain/cytology , Cell Line, Transformed , Coculture Techniques , Endothelium, Vascular/cytology , Free Radicals/metabolism , Gene Expression Regulation, Enzymologic , Interleukin-1/metabolism , RNA, Messenger/analysis , Rats , Superoxide Dismutase/genetics , Tumor Necrosis Factor-alpha/metabolism
16.
Biophys J ; 80(4): 1783-90, 2001 Apr.
Article in English | MEDLINE | ID: mdl-11259291

ABSTRACT

The water channel aquaporin-2 (AQP2), a key component of the antidiuretic machinery in the kidney, is rapidly regulated by the antidiuretic hormone vasopressin. The hormone exerts its action by inducing a translocation of AQP2 from intracellular vesicles to the cell membrane. This step requires the elevation of intracellular cyclic AMP. We describe here a new method, laser scanning reflection microscopy (LSRM), suitable for determining cellular osmotic water permeability coefficient changes in primary cultured inner medullary collecting duct (IMCD) cells. The recording of vertical-reflection-mode x-z-scan section areas of unstained, living IMCD cells proved useful and valid for the investigation of osmotic water permeability changes. The time-dependent increases of reflection-mode x-z-scan section areas of swelling cells were fitted to a single-exponential equation. The analysis of the time constants of these processes indicates a twofold increase in osmotic water permeability of IMCD cells after treatment of the cells both with forskolin, a cyclic AMP-elevating agent, and with Clostridium difficile toxin B, an inhibitor of Rho proteins that leads to depolymerization of F-actin-containing stress fibers. This indicates that both agents lead to the functional insertion of AQP2 into the cell membrane. Thus, we have established a new functional assay for the study of the regulation of the water permeability at the cellular level.


Subject(s)
Bacterial Proteins , Kidney/cytology , Microscopy, Confocal/methods , Water/metabolism , Actins/metabolism , Animals , Bacterial Toxins/pharmacology , Cell Line , Colforsin/pharmacology , Cyclic AMP/metabolism , Dogs , Kinetics , Microscopy, Fluorescence , Osmosis , Protein Structure, Tertiary , Protein Transport/drug effects , Rats , Rats, Wistar , Time Factors
17.
J Biol Chem ; 276(23): 20451-7, 2001 Jun 08.
Article in English | MEDLINE | ID: mdl-11278652

ABSTRACT

Vasopressin regulates water reabsorption in renal collecting duct principal cells by a cAMP-dependent translocation of the water channel aquaporin-2 (AQP2) from intracellular vesicles into the cell membrane. In the present work primary cultured inner medullary collecting duct cells were used to study the role of the proteins of the Rho family in the translocation of AQP2. Clostridium difficile toxin B, which inhibits all members of the Rho family, Clostridium limosum C3 toxin, which inactivates only Rho, and the Rho kinase inhibitor, Y-27632, induced both depolymerization of actin stress fibers and AQP2 translocation in the absence of vasopressin. The data suggest an inhibitory role of Rho in this process, whereby constitutive membrane localization is prevented in resting cells. Expression of constitutively active RhoA induced formation of actin stress fibers and abolished AQP2 translocation in response to elevation of intracellular cAMP, confirming the inhibitory role of Rho. Cytochalasin D induced both depolymerization of the F-actin cytoskeleton and AQP2 translocation, indicating that depolymerization of F-actin is sufficient to induce AQP2 translocation. Thus Rho is likely to control the intracellular localization of AQP2 via regulation of the F-actin cytoskeleton.


Subject(s)
Aquaporins/metabolism , Kidney Medulla/metabolism , Vasopressins/physiology , rho GTP-Binding Proteins/physiology , Amides/pharmacology , Animals , Aquaporin 2 , Aquaporin 6 , Bacterial Toxins/pharmacology , Cell Membrane/metabolism , Cells, Cultured , Cyclic AMP/antagonists & inhibitors , Enzyme Inhibitors/pharmacology , Protein Transport , Pyridines/pharmacology , Rats , rho GTP-Binding Proteins/antagonists & inhibitors
18.
Eur J Biochem ; 267(19): 6043-50, 2000 Oct.
Article in English | MEDLINE | ID: mdl-10998065

ABSTRACT

The cellular uptake of a peptide set derived from membrane-permeable alpha-helical amphipathic peptides by stepwise alterations of structure forming propensity and charge was studied by confocal laser scanning microscopy (CLSM) combined with HPLC. For CLSM monitoring, an online protocol was employed that avoided bias of the uptake results by washout. Using this protocol, extensive fluorescence, approaching the intensity of the external peptide, was observed in the cytosol and nucleus within minutes in all cases, irrespective of the degree of amphipathicity. HPLC analyses of the cell lysates revealed the unmetabolized peptides to be the predominant source of the intracellular fluorescence. Significant amphipathicity-dependent differences became apparent only after washing the peptide-loaded cells, reflecting the effects of amphipathicity on resistance to wash out. Exposure of the cells to the peptides at 37 and 0 degrees C led to similar results, indicating the nonendocytic character of the uptake. With a view to practical applications, the results of the present study open the possibility of exploiting nonamphipathic peptides as vectors for translocating polar compounds into the cell interior, which would circumvent substantial obstacles currently connected with the use of amphipathic vector peptides, such as membrane toxicity and low solubility. Moreover, differences in the uptake of several members of the investigated peptide series into different cell types present a promising basis for the design of cell-type specific vector peptides.


Subject(s)
Cell Membrane Permeability , Peptides/metabolism , Amino Acid Sequence , Animals , Aorta/cytology , Biological Transport , Cattle , Chemical Phenomena , Chemistry, Physical , Chromatography, High Pressure Liquid , Endothelium, Vascular/cytology , Endothelium, Vascular/metabolism , Humans , Microscopy, Confocal , Microscopy, Fluorescence , Molecular Sequence Data , Peptides/chemical synthesis
19.
Br J Cancer ; 80(12): 1987-94, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10471051

ABSTRACT

The oncogene product epidermal growth factor receptor (EGF-R), the tumour suppressor gene product p53 and anti-p53 antibodies are detectable in the serum of certain cancer patients. Increased levels of some of these products were reported in lung cancer patients after occupational asbestos exposure and after exposure to polycyclic aromatic hydrocarbons or vinylchloride. In the first step, this study investigated the possible diagnostic value of serum EGF-R, p53-protein and anti-p53 antibodies, measured by an enzyme-linked immunosorbent assay, in lung tumour patients. In addition to being investigated on a molecular epidemiological basis, these parameters were examined as biomarkers of carcinogenesis, especially with regard to asbestos incorporation effects or of radon-induced lung cancers. Also, a possible effect of cigarette smoking and age dependence were studied. A total of 116 male patients with lung or pleural tumours were examined. The histological classification was four small-cell cancers, six large-cell cancers, 32 adenocarcinomas, 47 squamous carcinomas, 12 mixed lung carcinomas, five diffuse malignant mesotheliomas and ten lung metastasis of extrapulmonary tumours. Twenty-two lung cancers and all mesotheliomas were related to asbestos, 22 lung cancers were related to ionizing radiation and 61 patients had cigarette smoke-related lung cancer. Besides these patients 50 male patients with non-malignant lung or pleural diseases were included; of the latter eight subjects suffered from asbestosis. Controls were 129 male subjects without any lung disease. No significantly elevated or decreased serum values for p53 protein, EGF-R, or anti-p53 antibodies as a function of histological tumour type, age, or degree and type of exposure (asbestos, smoking, ionizing radiation) could be found. The utility of p53-protein, EGF-R and anti-p53 antibodies as routine biomarkers for screening occupationally derived lung cancers is limited.


Subject(s)
Autoantibodies/blood , Biomarkers, Tumor/blood , ErbB Receptors/blood , Lung Diseases/blood , Lung Neoplasms/blood , Occupational Exposure , Pleural Effusion/blood , Tumor Suppressor Protein p53/blood , Adenocarcinoma/blood , Adenocarcinoma/etiology , Aged , Carcinoma, Large Cell/blood , Carcinoma, Large Cell/etiology , Carcinoma, Small Cell/blood , Carcinoma, Small Cell/etiology , Carcinoma, Squamous Cell/blood , Carcinoma, Squamous Cell/etiology , Humans , Lung Diseases/etiology , Lung Neoplasms/etiology , Lung Neoplasms/secondary , Male , Mesothelioma/blood , Mesothelioma/etiology , Middle Aged , Pleural Effusion/etiology , Pleural Neoplasms/blood , Pleural Neoplasms/etiology , Pulmonary Fibrosis/blood , Pulmonary Fibrosis/etiology , Reference Values , Tumor Suppressor Protein p53/immunology
20.
Kidney Int ; 56(2): 517-27, 1999 Aug.
Article in English | MEDLINE | ID: mdl-10432391

ABSTRACT

BACKGROUND: The vasopressin V2 receptor is expressed in the polarized principal cell of the renal collecting duct. Inactivating mutations of the vasopressin V2 receptor gene cause X-linked nephrogenic diabetes insipidus (NDI). Most of the mutant V2 receptors show transport defects, as analyzed in non-polarized cells, but data pertaining to polarized cells have not previously been presented. METHODS: Madin-Darby canine kidney cell (MDCK) II clones stably expressing c-myc-tagged human V2 receptors were characterized for [3H]-arginine vasopressin (AVP)-binding and AVP-sensitive adenylyl cyclase activity. The V2 receptors were immunocytochemically localized using the tyramide signal amplification technique in conjunction with an anti-c-myc antibody. RESULTS: The introduction of the c-myc epitope at the N- or C-terminus did not affect the functional properties of the V2 receptor expressed in MDCK II clones. However, the use of standard immunofluorescence methodology for these MDCK II clones yielded only weak signals. With the tyramide signal amplification technique, strong signals were obtained, showing the V2 receptor to be mainly localized within the lateral and, to a minor extent, apical membrane. In MDCK II clones stably expressing the c-myc-tagged V2 receptor NDI mutant L44P, fluorescent signals were found exclusively within the cell. CONCLUSION: The wild-type V2 receptor is expressed mainly in the lateral membrane, whereas the L44P mutant is completely retained within the cell. In conjunction with tyramide signal amplification, MDCK II cells constitute a suitable model for the analysis of transport-defective mutants of the V2 receptor.


Subject(s)
Kidney Tubules, Distal/chemistry , Kidney Tubules, Distal/cytology , Receptors, Vasopressin/genetics , Adenylyl Cyclases/metabolism , Animals , Biological Transport/physiology , Cell Line , Cell Membrane/chemistry , Cell Membrane/metabolism , DNA Probes , Diabetic Nephropathies/genetics , Diabetic Nephropathies/physiopathology , Dogs , Gene Expression/physiology , Humans , Kidney Tubules, Distal/enzymology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Mutagenesis, Site-Directed/physiology , Proto-Oncogene Proteins c-myc/genetics , RNA, Messenger/analysis , Receptors, Vasopressin/metabolism , Recombinant Proteins/analysis , Recombinant Proteins/genetics , Transfection , Tritium , X Chromosome
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