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1.
Int J Infect Dis ; 81: 210-214, 2019 Apr.
Article in English | MEDLINE | ID: mdl-30794940

ABSTRACT

Dalbavancin, a lipoglycopeptide with prolonged half-life approved for the treatment of acute bacterial skin and soft tissue infections, can be used for the treatment of infections caused by gram-positive bacteria requiring long term treatment such as endocarditis, prosthetic joint infections (PJI) or osteomyelitis. Clinical data are limited in these settings. OBJECTIVES: To evaluate indications, safety, tolerability and long-term outcomes of dalbavancin-treated patients. Patients and methods Our multicenter, retrospective study includes patients who received dalbavancin in Austria from September 2016 to March 2018. 90-day outcomes and tolerability were determined. RESULTS: A total of 101 patients were included in 3 centers (57% male, median age 65 years). The treated infections were PJI (31%), osteomyelitis (29%), endocarditis (25%) and acute bacterial skin and soft tissue infections (12%). Concomitant use of other antimicrobial substances was common (63%). The mean total cumulative dose of dalbavancin was 3,357mg (±2,283mg). Clinical success rate was 89%. Side effects occurred in 3/101 patients. CONCLUSION: In this real-life study dalbavancin was primarily used in off-label indications for treatment of PJI, osteomyelitis and endocarditis. Success rate was high (89%), tolerability and safety were excellent in this setting. Dalbavancin may therefore be used in these off-label indications as alternative treatment approach.


Subject(s)
Anti-Bacterial Agents/administration & dosage , Gram-Positive Bacteria/drug effects , Gram-Positive Bacterial Infections/drug therapy , Teicoplanin/analogs & derivatives , Adolescent , Adult , Aged , Aged, 80 and over , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/therapeutic use , Austria , Child , Female , Gram-Positive Bacteria/genetics , Gram-Positive Bacteria/isolation & purification , Gram-Positive Bacteria/physiology , Gram-Positive Bacterial Infections/microbiology , Humans , Male , Middle Aged , Osteomyelitis/microbiology , Retrospective Studies , Soft Tissue Infections/drug therapy , Soft Tissue Infections/microbiology , Teicoplanin/administration & dosage , Teicoplanin/adverse effects , Young Adult
2.
Phys Rev Lett ; 113(9): 094801, 2014 Aug 29.
Article in English | MEDLINE | ID: mdl-25215987

ABSTRACT

Relativistic electron bunches circulating in accelerators are subjected to a dynamical instability leading to microstructures at millimeter to centimeter scale. Although this is a well-known fact, direct experimental observations of the structures, or the field that they emit, remained up to now an open problem. Here, we report the direct, shot-by-shot, time-resolved recording of the shapes (including envelope and carrier) of the pulses of coherent synchrotron radiation that are emitted, and that are a "signature" of the electron bunch microstructure. The experiments are performed on the UVSOR-III storage ring, using electrical field sensitive YBa2Cu3O(7-x) thin-film ultrafast detectors. The observed patterns are subjected to permanent drifts, that can be explained from a reasoning in phase space, using macroparticle simulations.

3.
Phys Rev Lett ; 110(15): 157001, 2013 Apr 12.
Article in English | MEDLINE | ID: mdl-25167299

ABSTRACT

Interfacing photonic and solid-state qubits within a hybrid quantum architecture offers a promising route towards large scale distributed quantum computing. Ideal candidates for coherent qubit interconversion are optically active spins, magnetically coupled to a superconducting resonator. We report on an on-chip cavity QED experiment with magnetically anisotropic Er(3+)∶Y2SiO5 crystals and demonstrate collective strong coupling of rare-earth spins to a lumped element resonator. Moreover, the electron spin resonance and relaxation dynamics of the erbium spins are detected via direct microwave absorption, without the aid of a cavity.

4.
Article in English | MEDLINE | ID: mdl-19724152

ABSTRACT

The objective of this investigation was to test the effects of different intensities (1000, 1500, 2000, 3000, and 4000 microstrain) of a physiological loading signal (jumping) on trabecular bone stiffness and osteoid thickness using the ZETOS culture and loading system. Fourty eight bovine bone samples were randomised equally across 6 groups: 5 loading groups and 1 control group. The bone samples were cultured for 26 days (DMEM high glucose medium) and subjected to mechanical stress on 23 days. The stiffness of the samples was determined each day before loading in the loading groups and every 3rd day in the control group. The stiffness measurements in the loaded groups were significantly higher than in the control group. The degree of stiffness increased continuously throughout the observation period in the 1500, 2000, and 3000 microstrain groups. Maximum stiffness was achieved in the 4000 microstrain after a very short time (8th loading day) and then remained constant to the end of the investigation. The osteoid thickness in this group was, however, not higher than in the 2000 and 3000 microstrain groups. The 2000 microstrain group showed the highest proportion of newly formed osteoid. The amounts of osteoid deposited in the 2000, 3000 and 4000 microstrain groups were significantly greater than in the control group. Moreover, a correlation between increasing intensity of the signal and increase in osteoid deposition was observed. Histological investigations were conducted on non-decalcified bone and showed a well-preserved trabecular architecture and cell morphology.


Subject(s)
Biomechanical Phenomena/physiology , Bioreactors , Bone and Bones/physiology , Models, Anatomic , Animals , Bone Development/physiology , Bone Remodeling/physiology , Bone and Bones/cytology , Cattle , Female , Organ Culture Techniques/methods , Osteocytes/cytology , Osteocytes/physiology , Signal Processing, Computer-Assisted , Stress, Mechanical , Weight-Bearing/physiology
5.
Rehabilitation (Stuttg) ; 48(6): 354-60, 2009 Dec.
Article in German | MEDLINE | ID: mdl-20069519

ABSTRACT

AIM: The pivotal role of optimizing pharmacotherapy is generally accepted in somatic rehabilitation of various specialities like cardiopulmonary rehabilitation. No data exist as to whether significant modifications of pharmacotherapy occur during gastroenterological rehabilitation of Crohn's Disease (CD) patients. METHODS: A single centre chart review was performed including patients with International Classification of Disease Codes for CD (ICD K50). The Harvey-Bradshaw activity index (HBI) and CD medications were protocolled at the beginning and end of in-patient rehabilitation. RESULTS: 337 of 355 patients with ICD K50 fulfilled the predefined diagnostic criteria of mild to moderate CD (250 female, 87 male, average age of 40 (95% confidenceinterval, 29-51)). Disease activity decreased from 4.9 to 3.7 by 1.2 (0.75-1.37) Units during 23 (20-35) days. On admission, 120 (36%) patients received one and 158 (47%) received two to five CD drugs. CD drug prescriptions changed in 162 (48%) patients. Overall, 116 (34%) patients received systemic steroids which were stopped in 14 patients (p<0.05). In the remaining 102 patients the cortisol equivalence doses decreased from 77 to 56 mg by 21 (14-28) mg. The number of patients on azathioprine (AZT) increased from 98 to 108 (p<0.05). The average AZT dose increased from 1.81 to 1.99 mg/kg in 97 rehabilitants continuously treated. CONCLUSION: Our results describe an association between rehabilitation and significant changes of CD-specific pharmacotherapy in line with current treatment guidelines. This supports the concept that future studies on effects of gastroenterological rehabilitation should control for changes in pharmacotherapy.


Subject(s)
Adrenal Cortex Hormones/administration & dosage , Anti-Inflammatory Agents, Non-Steroidal/administration & dosage , Anti-Inflammatory Agents/administration & dosage , Crohn Disease/rehabilitation , Immunosuppressive Agents/administration & dosage , Adult , Azathioprine/administration & dosage , Biological Products/administration & dosage , Combined Modality Therapy , Crohn Disease/diagnosis , Dose-Response Relationship, Drug , Drug Therapy, Combination , Female , Germany , Guideline Adherence , Humans , Male , Mercaptopurine/administration & dosage , Methotrexate/administration & dosage , Middle Aged
6.
Phys Rev Lett ; 95(22): 225001, 2005 Nov 25.
Article in English | MEDLINE | ID: mdl-16384228

ABSTRACT

Three-dimensional perturbations have been seeded in wire-array z pinches by etching 15 microm diameter aluminum wires to introduce 20% modulations in radius with a controlled axial wavelength. These perturbations seed additional three-dimensional imploding structures that are studied experimentally and with magnetohydrodynamics calculations, highlighting the role of current path nonuniformity in perturbation-induced magnetic bubble formation.

7.
Free Radic Biol Med ; 31(11): 1456-64, 2001 Dec 01.
Article in English | MEDLINE | ID: mdl-11728818

ABSTRACT

In different cardiovascular disease states, oxidative stress decreases the bioavailability of endothelial NO, resulting in endothelial dysfunction. An important molecular source of reactive oxygen species is the enzyme family of NAD(P)H oxidases (Nox). Here we provide evidence that the vascular Nox isoforms Nox1 and Nox4 appear to be involved in vascular oxidative stress in response to risk factors like angiotensin II (Ang II) in vitro as well as in vivo. Nox mRNA and protein levels were quantified by real-time RT-PCR and Western blotting, respectively. Nox1 and Nox4 were expressed in the vascular smooth muscle cell (VSMC) line A7r5 and aortas and kidneys of rats. Upon exposure of A7r5 cells to Ang II (1 microM, 4 h), Nox1 and Nox4 mRNA levels were increased 6-fold and 4-fold, respectively. Neither the vasoconstrictor endothelin 1 (up to 500 nM, 1-24 h) nor lipopolysaccharide (up to 100 ng/ml, 1-24 h) had any effect on Nox1 and Nox4 expression in these cells. Consistent with these observations made in vitro, aortas and kidneys of transgenic hypertensive rats overexpressing the Ren2 gene [TGR(mRen2)27] had significantly higher amounts of Nox1 and Nox4 mRNA and of Nox4 protein compared to tissues from normotensive wild-type animals. In conclusion, Nox4 and Nox1 are upregulated by the renin-angiotensin system. Increased superoxide production by upregulated vascular Nox isoforms may diminish the effectiveness of NO and thus contribute to the development of vascular diseases. Nox1 and Nox4 could be targeted therapeutically to reduce vascular reactive oxygen species production and thereby increase the bioavailability of NO.


Subject(s)
Gene Expression Regulation, Enzymologic , NADH, NADPH Oxidoreductases/genetics , NADPH Oxidases/genetics , Renin-Angiotensin System/physiology , Angiotensin II/pharmacology , Animals , Animals, Genetically Modified , Aorta , Blotting, Western , Cell Line , Endothelin-1/pharmacology , Male , Muscle, Smooth, Vascular , NADH, NADPH Oxidoreductases/analysis , NADPH Oxidase 1 , NADPH Oxidase 4 , NADPH Oxidases/analysis , RNA, Messenger/analysis , Rats , Renin/genetics , Reverse Transcriptase Polymerase Chain Reaction
8.
Am J Physiol Heart Circ Physiol ; 279(4): H1715-23, 2000 Oct.
Article in English | MEDLINE | ID: mdl-11009459

ABSTRACT

At the onset of dynamic exercise, muscle blood flow increases within 1-2 s. It has been postulated that local vasodilatory agents produced by the vascular endothelium or the muscle itself contribute to this response. We hypothesized that only vasodilators that act directly on the vascular smooth muscle could produce vasodilation of skeletal muscle arterioles in <2 s. To test this hypothesis, we determined the time course of the vasodilatory response of isolated skeletal muscle arterioles to direct application of potassium chloride, adenosine, acetylcholine, and sodium nitroprusside. Soleus and gastrocnemius muscles were dissected from the hindlimbs of male Sprague-Dawley rats. First-order arterioles (100-200 microm) were isolated, cannulated on micropipettes, and pressurized to 60 cmH(2)O in an organ bath. Vasodilatory agents were added directly to the bath, and diameter responses of the arterioles were recorded in real time on a videotape recorder. Frame-by-frame analysis of the diameter responses indicated that none of the vasodilator agents tested produced significant diameter increases in <4 s in either soleus or gastrocnemius muscle arterioles. These results indicate that, although these local vasodilators produce significant vasodilation of skeletal muscle resistance arterioles, these responses are not rapid enough (within 1-2 s) to contribute to the initiation of the exercise hyperemic response at the onset of dynamic exercise.


Subject(s)
Hyperemia/physiopathology , Motor Activity/physiology , Muscle, Skeletal/blood supply , Vasodilation , Acetylcholine/pharmacology , Adenosine/pharmacology , Animals , Arterioles/drug effects , Arterioles/physiopathology , Male , Nitroprusside/pharmacology , Potassium Chloride/pharmacology , Rats , Rats, Sprague-Dawley , Time Factors , Vasodilator Agents/pharmacology
9.
Parasitol Today ; 15(5): 198-200, 1999 May.
Article in English | MEDLINE | ID: mdl-10322354

ABSTRACT

Rapid progress has been made in the study of intracellular ion activities of eukaryotic cells through the recent combination of high-resolution microscopy with fluorimetric ion-specific probes. This technique allows a specific ion concentration within a single living cell to be monitored on-line with high temporal and spatial resolution. In this report, Stefan Wünsch, Paul Horrocks, Michael Gekle and Michael Lanzer evaluate the application of single-cell fluorimetry to the study of transport processes in Plasmodium falciparum.


Subject(s)
Erythrocytes/parasitology , Fluorometry/methods , Plasmodium falciparum/metabolism , Sodium/metabolism , Animals , Biological Transport , Cations, Monovalent/metabolism , Hydrogen-Ion Concentration
10.
J Physiol ; 511 ( Pt 1): 255-63, 1998 Aug 15.
Article in English | MEDLINE | ID: mdl-9679179

ABSTRACT

1. The mineralocorticoid aldosterone is essential for the regulation of electrolyte homeostasis, extracellular volume and blood pressure. As a steroid hormone the classical way of action is genomic. Previously we reported a non-genomic action of aldosterone on cytosolic Ca2+ and pH in renal epithelial (MDCK) cells. In parallel, aldosterone induces Zn2+-sensitive cytosolic acidification when extracellular Na+ is absent. 2. We now show that aldosterone (EC50, 7 x 10-11 mol l-1) induces a non-genomic increase in cytosolic sodium in MDCK cells. The membrane-impermeable aldosterone-bovine serum albumin (BSA) conjugate exerted the same effect. The effect of aldosterone was completely abolished by inhibition of Na+-H+ exchange with ethyl-isopropanol amiloride (EIPA). Aldosterone-induced Na+ influx exceeded H+ efflux more than 10-fold. 3. Omission of extracellular Ca2+, inhibition of protein kinase C or pretreatment with pertussis toxin reduced the effect of aldosterone significantly. Zn2+ (IC50, 3.3 x 10-6 mol l-1), but not ouabain, abolished the increase in Na+ almost completely. 4. The aldosterone-induced increase in cytosolic sodium was accompanied by an EIPA- and Zn2+-sensitive cell swelling. 5. Thus, physiological concentrations of aldosterone induce a non-genomic increase in cytosolic sodium concentration by activation of Na+-H+ exchange. Aldosterone exerts its effect, at least in part, at the plasma membrane via interaction with a G-protein-coupled mechanism. 6. The simultaneous activation of the acidification mechanism and Na+-H+ exchange by aldosterone allows a dramatic sodium influx without excessive changes in cytosolic pH and leads to changes in cell volume.


Subject(s)
Aldosterone/pharmacology , Epithelial Cells/physiology , Sodium/metabolism , Amiloride/analogs & derivatives , Amiloride/pharmacology , Animals , Cell Line , Cell Membrane/drug effects , Cell Membrane/physiology , Cytosol/metabolism , Dogs , Epithelial Cells/cytology , Epithelial Cells/drug effects , Hydrogen-Ion Concentration , Kidney , Kinetics , Models, Biological , Ouabain/pharmacology , Zinc/pharmacology
11.
J Cell Biol ; 140(2): 335-45, 1998 Jan 26.
Article in English | MEDLINE | ID: mdl-9442109

ABSTRACT

Here we describe the identification and characterization of a physiological marker that is associated with the chloroquine-resistant (CQR) phenotype in the human malarial parasite Plasmodium falciparum. Single cell in vivo pH measurements revealed that CQR parasites consistently have an elevated cytoplasmic pH compared to that of chloroquine-sensitive (CQS) parasites because of a constitutively activated Na+/H+ exchanger (NHE). Together, biochemical and physiological data suggest that chloroquine activates the plasmodial NHE of CQS parasites, resulting in a transitory phase of rapid sodium/hydrogen ion exchange during which chloroquine is taken up by this protein. The constitutively stimulated NHE of CQR parasites are capable of little or no further activation by chloroquine. We propose that the inability of chloroquine to stimulate its own uptake through the constitutively activated NHE of resistant parasites constitutes a minimal and necessary event in the generation of the chloroquine-resistant phenotype.


Subject(s)
Antimalarials/pharmacokinetics , Chloroquine/pharmacokinetics , Plasmodium falciparum/metabolism , Sodium-Hydrogen Exchangers/metabolism , Amiloride/analogs & derivatives , Amiloride/pharmacology , Animals , Cytoplasm/metabolism , Drug Resistance , Fluorometry , Humans , Hydrogen-Ion Concentration , Phenotype , Plasmodium falciparum/drug effects , Sodium-Hydrogen Exchangers/antagonists & inhibitors
12.
Mol Cell Biol ; 17(7): 3679-86, 1997 Jul.
Article in English | MEDLINE | ID: mdl-9199301

ABSTRACT

Plasmodium falciparum var genes encode a diverse family of proteins, located on the surfaces of infected erythrocytes, which are implicated in the pathology of human malaria through antigenic variation and adhesion of infected erythrocytes to the microvasculature. We have constructed a complete representative telomere-to-telomere yeast artificial chromosome (YAC) contig map of the P. falciparum chromosome 8 for studies on the chromosomal organization, distribution, and expression of var genes. Three var gene loci were identified on chromosome 8, two of which map close to the telomeres at either end of the chromosome. Analysis of the previously described chromosome 2 contig map and random P. falciparum telomeric YAC clones revealed that most, if not all, 14 P. falciparum chromosomes contain var genes in a subtelomeric location. Mapping the chromosomal location of var genes expressed in a long-term culture of the P. falciparum isolate Dd2 revealed that four of the five different expressed var genes identified map within subtelomeric locations. Expression of var genes from a chromosomal domain known for frequent rearrangements has important implications for the mechanism of var gene switching and the generation of novel antigenic and adhesive phenotypes.


Subject(s)
Blood Proteins/genetics , Chromosomes/ultrastructure , DNA, Protozoan/genetics , Gene Expression Regulation , Genes, Protozoan , Plasmodium falciparum/genetics , Protozoan Proteins/genetics , Animals , Base Sequence , Chromosomes, Artificial, Yeast , Molecular Sequence Data , Multigene Family , Recombination, Genetic , Restriction Mapping , Telomere , Transcription, Genetic
13.
Mol Biochem Parasitol ; 85(1): 67-76, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9108549

ABSTRACT

The spliced leader (SL) RNA plays a key role in mRNA maturation in trypanosomatid protozoa by providing the SL sequence, which is joined to the 5' end of every mRNA. As a first step towards a better understanding of the biogenesis and function of the SL RNA, we expressed a tagged SL RNA gene in a cell-free system of procyclic Trypanosoma brucei cells. Transcription initiates at + 1 can be detected as early as 1 min after addition of extract. Transcription of the SL RNA gene in vitro, as well as in permeable cells, is mediated by an alpha-amanitin/tagetitoxin resistant complex, suggesting a promoter that is intermediate between a classical RNA polymerase II and RNA polymerase III promoter. An analysis of the promoter architecture of the SL RNA gene revealed that regulatory elements are located upstream of the coding region and that the SL sequence, in contrast to the nematode SL sequence, is not required for T. brucei SL RNA gene transcription.


Subject(s)
Promoter Regions, Genetic , RNA, Messenger/genetics , RNA, Protozoan/genetics , Transcription, Genetic , Trypanosoma brucei brucei/genetics , Amanitins/pharmacology , Animals , Base Sequence , Dicarboxylic Acids/pharmacology , Genes, Protozoan , Molecular Sequence Data , Mutation , Nucleic Acid Synthesis Inhibitors/pharmacology , Organophosphorus Compounds/pharmacology , RNA Splicing , RNA, Messenger/biosynthesis , RNA, Protozoan/biosynthesis
14.
Behring Inst Mitt ; (99): 44-50, 1997 Mar.
Article in English | MEDLINE | ID: mdl-9303201

ABSTRACT

Here we describe a novel methodology for the investigation of the intracellular pH of P. falciparum. This method is based on a fluorescent dye with pH-dependent spectral properties, which can be monitored using a digital imaging system. This non-invasive method allows the cytoplasmic pH of single, living P. falciparum parasites to be measured while still within the host erythrocyte. It was found that schizonts from the P. falciparum clone D10 have a cytoplasmic pH of 7.18 to 7.23, differing slightly on the buffering system used. The pH of uninfected erythrocytes is 7.10 +/- 0.05. This method offers an opportunity to study the parasite's physiology and define transport mechanisms essential for parasite growth.


Subject(s)
Hydrogen-Ion Concentration , Plasmodium falciparum/physiology , Animals , Cytoplasm/physiology , Erythrocytes/parasitology , Fluoresceins , Fluorescent Dyes , Host-Parasite Interactions , Humans , Kinetics , Spectrometry, Fluorescence/methods
15.
J Biol Chem ; 272(5): 2652-8, 1997 Jan 31.
Article in English | MEDLINE | ID: mdl-9006900

ABSTRACT

We demonstrate that uptake of the antimalarial drug chloroquine is temperature-dependent, saturable, and inhibitable in Plasmodium falciparum. These features are indicative of carrier-mediated transport and suggest that a P. falciparum-encoded protein facilitates chloroquine import. Although both chloroquine-resistant and susceptible parasite isolates exhibit facilitated chloroquine uptake, the kinetics differ. Chloroquine-resistant parasite isolates consistently have an import mechanism with a lower transport activity and a reduced affinity for chloroquine. These differences in uptake kinetics are linked with chloroquine resistance in a genetic cross. These data suggest that changes in chloroquine import kinetics constitute a minimal and necessary event in the generation of the resistant phenotype. Competitive inhibition of chloroquine uptake by amiloride derivatives further suggests that chloroquine import is mediated by a plasmodial Na+/H+ exchanger.


Subject(s)
Chloroquine/metabolism , Chloroquine/toxicity , Drug Resistance/genetics , Plasmodium falciparum/metabolism , Sodium-Hydrogen Exchangers/metabolism , Amiloride/analogs & derivatives , Amiloride/pharmacology , Animals , Binding, Competitive , Biological Transport/drug effects , Crosses, Genetic , Erythrocytes/metabolism , Humans , Kinetics , Phenotype , Plasmodium falciparum/drug effects , Plasmodium falciparum/genetics , Temperature
16.
Mol Cell Endocrinol ; 116(1): 73-9, 1996 Jan 15.
Article in English | MEDLINE | ID: mdl-8822267

ABSTRACT

Ecdysteroids play an important role in the larval moulting process of insects. 20-Hydroxyecdysone (20E) causes the induction of specific 'puffs' in polytene chromosomes of Drosophila melanogaster salivary gland cells. Although it is known that inorganic ions control pretranscriptional processes in the cell nucleus, the intracellular mechanisms of gene activation are still unclear. Therefore, we examined the effects of 20E on plasma membrane ion transport of Drosophila melanogaster salivary gland cells. Isolated glands of the third larval stage were superfused with a solution mimicking the haemolymph. The relative K+ conductance of the cell membrane (tK+) was measured with microelectrodes by performing ion substitution experiments. Under control conditions tK+ averaged to 0.16 + 0.02 (n = 15). Addition of 5 x 10(-6) M 20E increased tK+ within 2 min by 19.1 +/- 4.2% (n = 15). This rapid response to 20E was elicited only in the presence of calcium. Moreover, starting from a steady-state intracellular pH of 7.20-7.60, 20E induced a rise in cytoplasmic pH by 0.27 +/- 0.06 (n = 6) within minutes. Amiloride (10(-3) M), a blocker of plasma membrane Na+/H+ exchange, prevented the 20E-induced intracellular alkalinization. We conclude that 20E activates a calcium-sensitive plasma membrane Na+/H+ exchange leading to a rise of plasma membrane K+ conductance and intracellular alkalinization both being prerequisites for steroid hormone induced gene activation.


Subject(s)
Calcium/metabolism , Drosophila melanogaster/metabolism , Ecdysterone/pharmacology , Salivary Glands/drug effects , Salivary Glands/metabolism , Sodium/metabolism , Amiloride/pharmacology , Animals , Cell Membrane/drug effects , Cell Membrane/metabolism , Drosophila melanogaster/drug effects , Drosophila melanogaster/growth & development , Ecdysterone/physiology , Hydrogen-Ion Concentration , Ion Transport/drug effects , Larva/metabolism , Membrane Potentials , Protons , Salivary Glands/growth & development , Sodium-Hydrogen Exchangers/metabolism
17.
J Cell Physiol ; 164(1): 164-71, 1995 Jul.
Article in English | MEDLINE | ID: mdl-7790388

ABSTRACT

We isolated two cell clones from the wild-type Madin-Darby canine kidney cell line (MDCK) that resembles renal collecting duct epithelium. Morphology and karyotypes of the two cell clones were evaluated. The MDCK-C7 cell clone morphologically resembles principal cells (polygonal cell shape, flat), while the MDCK-C11 clone resembles intercalated cells (cuboidal cell shape, high). The diploid chromosome number of MDCK-C7 cells is 83.1 +/- 0.2 (n = 139); that for MDCK-C11 cells is 78.8 +/- 0.1 (n = 128). Culture of MDCK-C7 cells in alkaline medium (pH 7.7) induced irreversible phenotypical and genotypical alterations. Transformed MDCK-C7F cells are characterized by two abnormal (biarmed) chromosomes. In contrast, MDCK-C11 cells are not phenotypically altered by alkaline stress. In order to elucidate the role of intracellular pH (pHi) in the transformation process, we measured pHi under control conditions (pH 7.4), after 5 min exposure to alkaline stress ("acute experiment," pH 7.7) and after incubation of the cells in alkaline medium for two weeks ("chronic experiment," pH 7.7). Under control conditions, MDCK-C7 cells maintained pHi at 7.14 +/- 0.01 (n = 154) and MDCK-C11 cells at 7.01 +/- 0.01 (n = 147). Acute alkaline stress increased pHi of both cell types to similar steady-state values. Under chronic alkaline stress, MDCK-C7 cells were unable to maintain intracellular pH within normal limits exhibiting sustained alkalinization, whereas MDCK-C11 cells could successfully regulate pHi. We conclude that wild-type MDCK cells consist of two genetically distinct subpopulations with different morphology and function. Only the MDCK-C7 clone that resembles the principle cell type of renal collecting duct can be transformed by alkaline stress while the MDCK-C11 clone resists this treatment, due to efficient pHi control mechanisms.


Subject(s)
Alkalies , Kidney/pathology , Kidney/physiopathology , Stress, Physiological/pathology , Stress, Physiological/physiopathology , Animals , Calcium/metabolism , Cell Division , Cell Line , Clone Cells , Dogs , Hydrogen-Ion Concentration , Karyotyping , Membrane Potentials , Oscillometry , Phenotype , Stress, Physiological/chemically induced
18.
Pflugers Arch ; 428(2): 157-62, 1994 Sep.
Article in English | MEDLINE | ID: mdl-7971172

ABSTRACT

Madin-Darby canine kidney (MDCK) cells originate from the renal collecting duct and consist of different cell subtypes. We cloned two MDCK cell subtypes denominated as C7 and C11 with different morphology and different function. The two clones maintained their functional differences after cloning. C7 monolayers exhibit a high transepithelial resistance (Rte = 5648 +/- 206 omega.cm2, n = 20) and secrete K+ (delta K+ = 1.31 +/- 0.08 mmol/l, n = 10) into the apical medium. C11 monolayers display a low Rte (330 +/- 52 omega.cm2, n = 20) and secrete Cl- (delta Cl- = 16.9 +/- 1.8 mmol/l, n = 10) into the apical medium. Aldosterone (1 mumol/l) stimulates K+ secretion (delta K+ of 3.58 +/- 0.11 mmol/l, n = 7) in C7 cells and H+ secretion in C11 cells (delta pH = 0.060 +/- 0.007, n = 10). Aldosterone-induced stimulation of K+ secretion is inhibited by apical application of amiloride (1 mumol/l). cAMP stimulates H+ secretion in C11 cells (delta pH = -0.068 +/- 0.004, n = 10). Furthermore, C7 cells are peanut-lectin(PNA)-negative and exhibit an intracellular pH of 7.39 +/- 0.05 (n = 7), whereas C11 cells maintain intracellular pH at 7.16 +/- 0.05 (n = 8) and a major fraction of cells is PNA positive. We conclude that we have cloned two subtypes of MDCK cells which stably express different functional characteristics. The C7 subtype resembles principal cells (PC) of the renal collecting duct, whereas the C11 subtype resembles intercalated cells (ICC) of the renal collecting duct.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Ion Transport , Kidney Tubules, Collecting/cytology , Aldosterone/pharmacology , Amiloride/pharmacology , Animals , Bucladesine/pharmacology , Cell Line , Chlorides/metabolism , Clone Cells , Dogs , Epithelial Cells , Epithelium/metabolism , Hydrogen-Ion Concentration , Ion Transport/drug effects , Kidney Tubules, Collecting/drug effects , Kidney Tubules, Collecting/metabolism , Lectins/metabolism , Membrane Potentials/drug effects , Peanut Agglutinin , Potassium/metabolism , Sodium/metabolism
19.
Cell Tissue Res ; 274(1): 145-51, 1993 Oct.
Article in English | MEDLINE | ID: mdl-8242702

ABSTRACT

Ecdysteroids play an important role in the larval moulting process of insects. Ecdysone-induced stimulation causes specific "puffs" in polytene chromosomes of salivary gland cells resulting in nuclear swelling. During this process, changes of intracellular ion composition are thought to act as an early regulatory mechanism of gene activation. By use of video-imaging analysis and electrophysiological techniques, we examined ecdysone-induced nuclear swelling in Drosophila salivary glands in situ and its dependence on pH and calcium. Isolated glands of the third larval stage were superfused with a solution mimicking the haemolymph. Addition of 5 x 10(-6) mol/1 20-OH-ecdysone led, after a lag period of 50 min, to a sustained Ca(2+)-dependent increase of nuclear volume by 23.0 +/- 2.3%. Amiloride, a blocker of plasma membrane Na+/H+ exchange, prevented 20-OH-ecdysone-induced nuclear swelling. Decreasing pH in the superfusate from 7.15 to 6.8 led to nuclear shrinkage by 16.9 +/- 3.9%. Measurements of pH in salivary gland cells with ion-sensitive microelectrodes disclosed an alkalinization of 0.23 +/- 0.05 pH units after stimulation with 20-OH-ecdysone. We postulate that 20-OH-ecdysone activates the amiloride-sensitive plasma membrane Na+/H+ exchanger. This leads to intracellular alkalinization and concomitant decondensation of the nuclear chromatin visible as nuclear swelling. Thus, cell alkalinization could be a potentially important stimulatory mechanism in mediating ecdysteroid-induced activation of the cell nucleus.


Subject(s)
Cell Nucleus/drug effects , Drosophila melanogaster/drug effects , Ecdysterone/pharmacology , Salivary Glands/drug effects , Alkalies , Amiloride/pharmacology , Animals , Cell Nucleus/metabolism , Cell Nucleus/ultrastructure , Drosophila melanogaster/metabolism , Drosophila melanogaster/ultrastructure , Hydrogen-Ion Concentration , Intracellular Fluid/metabolism , Ion Transport/drug effects , Larva/drug effects , Larva/metabolism , Larva/ultrastructure , Salivary Glands/metabolism , Salivary Glands/ultrastructure , Sodium-Hydrogen Exchangers/metabolism
20.
J Clin Invest ; 92(1): 218-23, 1993 Jul.
Article in English | MEDLINE | ID: mdl-8325988

ABSTRACT

Intracellular alkalinization is known to be associated with tumorigenic transformation. Besides phenotypical alterations alkali-transformed Madin-Darby canine kidney (MDCK) cells exhibit a spontaneously oscillating cell membrane potential (PD). Using single-channel patch clamp techniques, it was the aim of this study to identify the ion channel underlying the rhythmic hyperpolarizations of the PD. In the cell-attached patch configuration, we found that channel activity was oscillating. The frequency of channel oscillations is 1.1 +/- 0.1 min-1. At the peak of oscillatory channel activity, single-channel current was -2.7 +/- 0.05 pA, and in the resting state it was -1.95 +/- 0.05 pA. Given the single-channel conductance of 53 +/- 3 pS for inward (and of 27 +/- 5 pS for outward) current the difference of single-channel current amplitude corresponded to a hyperpolarization of approximately 14 mV. The channel is selective for K+ over Na+. Channel kinetics are characterized by one open and by three closed time constants. The channel is Ca2+ sensitive. Half maximal activation in the inside-out patch mode is achieved at a Ca2+ concentration of 10 mumol/liter. In addition, we also found a 13-pS K+ channel that shows no oscillatory activity in the cell-attached patch configuration and that was not Ca2+ sensitive. We conclude that the Ca(2+)-sensitive 53-pS K+ channel is underlying spontaneous oscillations of the PD. It has virtually identical biophysical properties as a Ca(2+)-sensitive K+ channel in nontransformed parent MDCK cells. Hence, alkali-induced transformation of MDCK cells did not affect the channel protein itself but its regulators thereby causing spontaneous fluctuations of the PD.


Subject(s)
Cell Transformation, Neoplastic , Ion Channel Gating , Potassium Channels/physiology , Animals , Calcium/physiology , Cell Line , Dogs , Hydrogen-Ion Concentration , Periodicity
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