[Vigilance for veterinary medicinal products: Reports of adverse reactions in the year 2017]

INTRODUCTION

A total of 306 reports of adverse reactions to veterinary medicinal products were received during the year 2017 representing an increase of 21% compared to the previous year. The majority of these reports described reactions concerning companion animals (180 dogs and 59 cats) as well as cattle (38 reports) and horses (14 reports). Most of the reported reactions were linked to the use of antiparasitics (158 reports), hormone products (30 reports) and anti-inflammatory products (25 reports). 40 reports were generated from consultations with Tox Info Suisse in Zürich and mainly involved the excessive intake of flavoured tablets and, in some cases, the use of products under the cascade regulation (applied to another species than that authorized). Nine signals were identified from the reports, resulting in revisions of the product information in the sections addressing contra-indications or adverse reactions.

[Vigilance for veterinary medicinal products: Reports of adverse reactions in the year 2016]

INTRODUCTION

A total of 253 reports of adverse reactions to veterinary medicinal products were received during the year 2016 representing a decrease of 13% compared to the previous year (292 reports). The majority of the reports described reactions affecting companion animals (178 dogs and 32 cats) as well as cattle (17 reports) and horses (10 reports). Most of the reactions reported were linked to the use of antiparasitics (145 reports), hormone products (26 reports) and antiinfectives (10 reports). 32 reports were generated from consultations with Tox Info Suisse in Zürich and involved mainly the excessive intake of flavoured tablets and, in some cases, the use of reconverted products (applied to another species than that authorized). Five signals were identified from the reports, which resulted in revisions of the product information in the sections addressing contraindications or adverse reactions.

[Vigilance for veterinary medicinal products: Reports of adverse reactions in the year 2015]

INTRODUCTION

A total of 292 adverse reactions to veterinary medicinal products were reported during the year 2015. This represents an increase of 9% compared to the previous year (268 reports). Similar to previous years, most of the reactions reported were linked to the use of antiparasitics (55.1%), non-steroidal anti-inflammatory products (8.9%) or antiinfectives (9.3%). The affected animal species were primarily dogs (198 reports) and cats (42 reports), followed by cattle (31 reports) and horses (8 reports). Additional 42 reports were provided within the frame of consultations with Tox Info Suisse in Zürich and involved mainly the excessive intake of flavored tablets. Eight signals were identified from the reports received or the periodic safety update reports. They resulted in revisions of the product information in sections addressing contraindications, adverse reactions or withdrawal times.

[Calculation of therapeutic intensity for piglets and fattening pigs during the use of antibiotics in feed]

Oral treatments for groups of pigs via medicated feed must be prescribed on specific forms submitted to veterinary authorities. We analyzed 869 such prescription forms for the year 2009 representing the treatment of 69'863 piglets and 31'506 fattening pigs. Parameters under investigation were indication and quantity of antimicrobials prescribed. Most of the treatments took place at weaning with 10 - 14 kg and again at the beginning of the fattening period with 20 - 29 kg body weight. The average body weights at treatment were 16 kg (piglets) and 29 kg (fatteners). In analogy with the indicator DID of human medicine, we developed PIDvet describing the prescribed dose per 1000 individuals on given day in veterinary medicine. Calculated PIDvet on a given day was 180.9 for the whole population, 297.6 for piglets and 83.2 for fatteners. This shows PIDvet to be useful to stratify therapeutic intensity in different age classes and could represent a new tool to monitor the use of antibiotics.

Aldosterone-controlled linkage between Na+/H+ exchange and K+ channels in fused renal epithelial cells

Aldosterone maintains acid-base balance and K+ homeostasis by controlling H+ and K+ secretion in renal epithelial cells. We have shown recently in the amphibian distal nephron that aldosterone activates a Na+/H+ exchange system in the luminal cell membrane, leading to transepithelial H+ secretion and cytoplasmic alkalinization. Since H+ secretory fluxes are paralleled by K+ secretion, it was postulated that the hormone-induced increase of intracellular pH activates the luminally located K+ channels. In 'giant' cells fused from individual cells of the distal nephron, we measured simultaneously cytoplasmic pH and cell membrane K+ conductance during acidification of the cell cytoplasm. The experiments demonstrate that cell membrane K+ conductance is half-maximal at an intracellular pH of 7.42, and that a positive cooperative interaction exists between K+ channel proteins and H+ ions (Hill coefficient = 6.5). Moreover, the cellular K+ conductance is most sensitive to cytoplasmic pH in the range modified by aldosterone. This supports the hypothesis that intracellular H+ activity, regulated by the Na+/H+ exchanger, serves as the signal to couple aldosterone-induced K+ secretory flux to H+ secretion in renal tubules.

[Reported adverse reactions of veterinary drugs and vaccines in 2005]

We received 105 reports of suspected adverse events (SARs) following the use of veterinary drugs for the year 2005. This corresponds to a 35% increase compared to 2004. Practicing veterinarians sent most of these declarations. 73% of these concerned drugs used on companion animals. Antiparasitic drugs approved for topical use were the most frequently represented group with 48%, followed by drugs used to treat gastrointestinal disorders (11%) and drugs used off-label (14%; other target species or other indication). For the first time 2 declarations concerning the application of permethrin containing spot-on preparations used by mistake on cats were received. An overview of 20 declarations about adverse reactions following application of different vaccines is also presented with emphasis on the problem of fibrosarcoma in cats. We are pleased by the growing interest shown by practicing veterinarians for the vigilance system and hope to further develop this collaboration in the future.

[Swiss veterinary drug compendium as a tool for reconversions]

The new Swiss ordinance on veterinary drugs poses a new challenge to the veterinarians, specially those working with farm animals. A complete overview about the registered veterinary drugs and immunobiologicals is absolutely necessary to cope with these new tasks: the internet version of the Swiss Veterinary Drug Compendium is a versatile tool to satisfy this needs (http://www.tierarzneimittel.ch). Due to the frequent updates and powerful search possibilities, this database is a reliable and comprehensive information system regarding Swiss veterinary drugs. We will demonstrate how this system can be used as a valuable help in the case of reconversions of drugs (e.g. use of small animal drugs in farm animals).

Functional role of Na+-HCO3- cotransport in migration of transformed renal epithelial cells

Cell migration is crucial for immune defence, wound healing or formation of tumour metastases. It has been shown that the activity of the Na(+)-H(+) exchanger (NHE1) plays an important role in cell migration. However, so far it is unknown whether Na(+)- HCO(3)(-) cotransport (NBC), which has similar functions in the regulation of intracellular pH (pH(i)) as NHE1, is also involved in cell migration. We therefore isolated NHE-deficient Madin-Darby canine kidney (MDCK-F) cells and tested whether NBC compensates for NHE in pH(i) and cell volume regulation as well as in migration. Intracellular pH was measured with the fluorescent pH indicator 2'7'-bis(carboxyethyl)-5-carboxyfluorescein (BCECF). The expression of NBC isoforms was determined with semiquantitative PCR. Migration was monitored with time-lapse video microscopy and quantified as the displacement of the cell centre. We found that MDCK-F cells express the isoform NBC1 (SLCA4A gene product) at a much higher level than the isoform kNBC3 (SLCA4A8 gene product). This difference is even more pronounced in NHE-deficient cells so that NBC1 is likely to be the major acid extruder in these cells and the major mediator of propionate-induced cell volume increase. NHE-deficient MDCK-F cells migrate more slowly than normal MDCK-F cells. NBC activity promotes migration during an acute intracellular acid load and increases migratory speed and displacement on a short timescale (< 30 min) whereas it has no effect on the long-term behaviour of migrating MDCK-F cells. Taken together, our results show that NBC actvity, despite many functional similarities, does not have the same importance for cell migration as NHE1 activity.

[Suspected adverse drug reactions in 2004]

We received 62 reports of suspected adverse events (SARs) for the year 2004. Their number and repartition according to affected animals and active substances were comparable with the previous year. The distributors or manufacturers submitted most of the declarations, but the proportion submitted by practicing veterinarians is slowly growing. 72% of the declarations dealt with adverse reactions in small animals (cats and dogs), followed by cattle and horses. Antiparasitics, anti-inflammatory drugs and immunologicals were the most frequently mentioned therapeutic classes, which are listed here according to the international ATCvet classification. A report from abroad about a fatality following injection of an antibiotic preparation for cattle prompted Swissmedic to review the security of this medication also sold on the Swiss market. It was decided to modify the package insert to warn about the danger of inadvertent self-injection in humans, to reduce the risk of similar accidents in Switzerland. We hope that the pharmacovigilance system will enjoy an increasing awareness by the practicing veterinarians.

[Pharmacovigilance for veterinary drugs in Switzerland]

Pharmacovigilance is a system concerned with the acquisition, evaluation and classification of informations about suspected adverse drug reactions (SADR). Such a system was developed in Switzerland under the supervision of Swissmedic after the introduction of the federal law on therapeutic products on January 1st 2002. By sending declarations about SADRs, veterinary practitioners play a central role in this scheme. The reports are processed according to international standards (ABON) and provide useful hints to enhance the safety of drug usage by both patients and owners. The system acquired 58 reports in its first complete year of operation (2003). Analysis of these reveals that trends observed in foreign countries are also applicable to Switzerland: most of the reports concerned the use of antiparasitic or antibiotic drugs in small animals. The first year also revealed a high percentage of declarations coming from the pharmaceutical companies and the authors would therefore like to encourage practitioners to take a more active part in this scheme.

Inhibition of Na superset+/H superset+ exchange decreases albumin-induced NF-kappaB activation in renal proximal tubular cell lines (OK and LLC-PK1 cells)

Filtered proteins play a role in the pathogenesis of renal interstitial inflammation and fibrosis. At least part of these effects are mediated by the nuclear factor kappaB (NF-kappaB). Receptor-mediated endocytosis of proteins like albumin in renal proximal tubular cells is in part dependent on Na superset+/H superset+ exchanger (NHE) isoform 3. We tested the hypothesis that pharmacological inhibition of NHE-3 reduces albumin-induced NF-kappaB activation - and therefore albumin-induced renal interstitial inflammation and fibrosis - using established proximal tubular cell lines (OK and LLC-PK1). 5-(N-ethyl-N-isopropyl)-amiloride (EIPA) or HOE694 were used to inhibit NHE. Albumin endocytosis was determined by fluorometric analysis of FITC-BSA uptake. Electromobility gel shift assays were performed in order to determine the NF-kappaB-specific DNA-binding activity. EIPA reduced albumin uptake in OK and LLC-PK1 cells and HOE694 decreased albumin uptake in LLC-PK1 cells, with IC subset50 values corresponding to NHE-3 inhibition. Furthermore, albumin-induced increases in NF-kappaB DNA-binding activity were partially inhibited by EIPA in OK and LLC-PK1 cells. HOE694 at a concentration of 100 micromol/l similarly decreased albumin-induced NF-kappaB DNA-binding activity. Cytosolic acidification by propionic acid did not prevent BSA-induced activation of NF-kappaB. Inhibition of BSA endocytosis by chlorpromazine decreased NF-kappaB activation. NHE-dependent albumin endocytosis induces an increase in NF-kappaB-specific protein activity in renal proximal tubular cells in culture, which is decreased by EIPA and HOE694. Thus, inhibition of albumin uptake might be a therapeutical strategy to prevent albumin-induced NF-kappaB activation and albumin-associated inflammatory or fibrotic renal pathomechanisms in vivo.

Albumin in the mg/l-range activates NF-kappaB in renal proximal tubule-derived cell lines via tyrosine kinases and protein kinase C

Albuminuria represents one of the most unfavourable diagnostic factors for the prognosis of nephropathies. We investigated albumin-induced NF-kappaB activation and the potential contribution of tyrosine kinase and protein kinase C. Therefore we exposed proximal tubule-derived human (IHKE-1), opossum (OK) and porcine (LLC-PK1) cell lines to serum albumin at concentrations of 10 - 500 mg/l. DNA-binding activity of NF-kappaB increased concentration-dependently in the presence of albumin. In OK and LLC-PK1 cells, NF-kappaB activity increased during the first 45 min and reached a plateau thereafter. In IHKE-1, cells NF-kappaB activity reached a plateau after 90 min with a maximum at 180 min exposure to albumin. The albumin-induced increase in NF-kappaB DNA-binding activity was inhibited by herbimycin A (tyrosine kinase inhibitor) and BIM (protein kinase C inhibitor). Reporter gene assays demonstrated that albumin stimulates NF-kappaB mediated reporter gene activation in LLC-PK1 cells, which was partially inhibited by herbimycin A and BIM. Our data indicate, that albumin exposure induces a rapid increase in NF-kappaB protein activity in renal proximal tubule cells of different species via a tyrosine kinase- and protein kinase C-dependent pathway, at concentrations occurring during mild glomerular injury.

K(+) channel-dependent migration of fibroblasts and human melanoma cells

Previously, we showed that migration of transformed renal epithelial cells (MDCK-F cells) is a K(+) channel-dependent process [J Clin Invest 1994;93:1631]. In order to determine whether K(+) channel activity is a general requirement for locomotion, we extended our observations to NIH3T3 fibroblasts and human melanoma cells. Migration of both cell types and its dependence on K(+) channel activity was measured at the single cell level by time lapse photography in the absence and presence of the specific K(+) channel blocker charybdotoxin (CTX). Locomotion of both cell types is inhibited by K(+) channel blockade. CTX slows down migration of fibroblasts and of melanoma cells dose-dependently by up to 61 +/- 11%. These findings suggest that K(+) channel activity is a general prerequisite for migration. To determine whether CTX-induced inhibition of migration of fibroblasts and melanoma cells involves quantitative changes of actin filaments, we indirectly measured filamentous actin by quantitating binding of fluorescently labeled phalloidin. Whereas CTX elicits a decrease of bound phalloidin in fibroblasts there is an increase in melanoma cells. Since migration of tumor cells is required for invading surrounding tissue, we developed an assay to test whether CTX-induced inhibition of migration also impairs invasion of melanoma cells. Melanoma cells were seeded on a layer of high resistance renal epithelial cells (MDCK cells clone C7; transepithelial resistance R(te) >3,000 Omegacm(2)) and R(te) was measured daily. R(te) starts to decrease 2 days after seeding of melanoma cells onto MDCK-C7 cells. By day 7, R(te) has dropped to 24 +/- 1.5% of control. K(+) channel blockade with CTX (10 nmol/l) cannot prevent or delay this drop of R(te). R(te) reaches the same level with or without CTX. These results indicate that the disruption of an epithelial layer, unlike migration of melanoma cells, cannot be modulated by K(+) channel blockade.

Inhibition of Na+-H+ exchange impairs receptor-mediated albumin endocytosis in renal proximal tubule-derived epithelial cells from opossum

1. Receptor-mediated endocytosis is an important mechanism for transport of macromolecules and regulation of cell-surface receptor expression. In renal proximal tubules, receptor-mediated endocytosis mediates the reabsorption of filtered albumin. Acidification of the endocytic compartments is essential because it interferes with ligand-receptor dissociation, vesicle trafficking, fusion events and coat formation. 2. Here we show that the activity of Na+-H+ exchanger isoform 3 (NHE3) is important for proper receptor-mediated endocytosis of albumin and endosomal pH homeostasis in a renal proximal tubular cell line (opossum kidney cells) which expresses NHE3 only. 3. Depending on their inhibitory potency with respect to NHE3 and their lipophilicity, the NHE inhibitors EIPA, amiloride and HOE694 differentially reduced albumin endocytosis. The hydrophilic inhibitor HOE642 had no effect. 4. Inhibition of NHE3 led to an alkalinization of early endosomes and to an acidification of the cytoplasm, indicating that Na+-H+ exchange contributes to the acidification of the early endosomal compartment due to the existence of a sufficient Na+ gradient across the endosomal membrane. 5. Exclusive acidification of the cytoplasm with propionic acid or by removal of Na+ induced a significantly smaller reduction in endocytosis than that induced by inhibition of Na+-H+ exchange. 6. Analysis of the inhibitory profiles indicates that in early endosomes and endocytic vesicles NHE3 is of major importance, whereas plasma membrane NHE3 plays a minor role. 7. Thus, NHE3-mediated acidification along the first part of the endocytic pathway plays an important role in receptor-mediated endocytosis. Furthermore, the involvement of NHE3 offers new ways to explain the regulation of receptor-mediated endocytosis.

Characterization of an ochratoxin-A-dedifferentiated and cloned renal epithelial cell line

Ochratoxin A (OTA) is a ubiquitous fungal metabolite with predominant nephrotoxic action. OTA impairs postproximal renal electrolyte handling and increases the incidence of renal adenoma and carcinoma. Furthermore, it is supposed to be involved in the pathogenesis of different forms of human renal diseases. Previously we have shown that OTA activates extracellular signal-regulated kinase 1 (ERK1) and ERK2 in the C7 clone but not in the C11 clone of renal epithelial MDCK cells. Here we show that nanomolar concentrations of OTA lead to stable and irreversible phenotypical and genotypical alterations, resulting in sustained dedifferentiation of MDCK-C7 cells but not of MDCK-C11 cells. Dedifferentiated MDCK-C7 cells (OTA-C7 cells) display a distinct morphology from the parent cell line (spindle-shape, pleiomorphic, narrow intercellular spaces, increased cell size) and show a reduced proliferation rate and numerical chromosomal aberrations. Functionally, OTA-C7 cells are characterized by a dramatic reduction of transepithelial electrolyte transport and the complete loss of responsiveness to the mineralocorticoid hormone aldosterone. Our data provide further evidence that OTA can lead to cell dedifferentiation and eventually to transformation of cloned quiescent cells. The changes in phenotype due to this dedifferentiation could explain some of the OTA-induced changes in renal function.

Topical application of synthetic pyrethroids to cattle as a source of persistent environmental contamination

Following the application of permethrin or cyhalothrin to cattle for the control of ectoparasites, the occurrence and persistence of these chemicals was assessed on the animals and in their environment. The release of permethrin from ear tags containing 1 g of the drug on cattle was followed for 65 days and lead to concentrations of 5 to 35 micrograms of permethrin per gram of hair on the shoulders. On the flanks of the animals, the corresponding values were 10 times lower. Across the 1.5 acre pasture, high concentrations of permethrin were measured at various locations and long after treatment: 6 micrograms/g on bark of a birch after one week, 5 micrograms/g on a pole of the fence after two weeks, 1 microgram/g in grass from a resting site of the animal after six weeks, and 0.5 microgram/g in bark of a pine tree after three month and two weeks after the animals had left the pasture. In similar assays, cyhalothrin applied to milk cows as a pour-on preparation was monitored. One week following treatment with 0.2 g/animal, hair cut from the shoulders contained 5 micrograms/g of the insecticide, which disappeared with a half-life of 12 days. Dust collected two weeks after the pour-on treatment from the milk barn where the cows were milked twice daily contained 47 micrograms/g of cyhalothrin, which disappeared with a half-life of 44 days. These results show that synthetic pyrethroids used on farm animals can be the source of widespread and persistent contamination.

The pyrethroids permethrin and cyhalothrin are potent inhibitors of the mitochondrial complex I

The synthetic pyrethroid derivatives permethrin and cyhalothrin are widely used insecticides that are considered to be relatively nontoxic to higher animals. However, a variety of toxic effects on mammals have been reported. We investigated the effect of these drugs on energy coupling by mitochondria and on the activity of the individual respiratory complexes. Using isolated rat liver mitochondria, a concentration-dependent inhibition of glutamate and succinate sustained state 3 respiration was found for both compounds in the micromolar range. The effect of pyrethroids on the activities of the complexes I to V were assessed individually in submitochondrial particles (complex I) and in freeze-thawed mitochondria (complexes II-V). Complex I (EC 1.6.5.3) was found to be the most sensitive link within the electron transport chain. Half-maximal inhibition was observed at 0.73 microM permethrin and 0.57 microM cyhalothrin, respectively, and exhibited sigmoidal inhibition kinetics. Complexes II, III, IV and V (EC 1.3.5.1, 1.10.2.2, 1.9.3.1, 3.6.1.34) were not significantly inhibited by up to 50 microM of these drugs. Thus, our results reveal a model of action of synthetic pyrethroid insecticides not previously reported.

Extracellular detection of K+ release during migration of transformed Madin-Darby canine kidney cells

Madin Darby canine kidney cells transformed by alkaline stress (MDCK-F cells) constitutively migrate at a rate of about 1 microm.min-1. Migration depends on the intermittent activity of a Ca2+-stimulated, 53-pS K+ channel (KCa channel) that is inhibitable by charybdotoxin. In the present study we examined whether this intermittent KCa channel activity results in a significant K+ loss across the plasma membrane. K+ efflux from MDCK-F cells should result in a transient increase of extracellular K+ ([K+]e) in the close vicinity of a migrating cell. However, due to the rapid diffusion of K+ ions into the virtually infinite extracellular space, such a transient increase in [K+]e was too small to be detected by conventional K+-selective electrodes. Therefore, we developed a "shielded ion-sensitive microelectrode" (SIM) that limited diffusion to a small compartment, formed by a shielding pipette which surrounded the tip of the K+-sensitive microelectrode. The SIM improved the signal to noise ratio by a factor of at least three, thus transient increases of [K+]e in the vicinity of MDCK-F cells became detectable. They occurred at a rate of 1.3 min-1. The cell releases 40 fmol K+ during each burst of intermittent KCa channel activity, which corresponds to about 15% of the total cellular K+ content. Since transmembrane K+ loss must be accompanied by anion loss and therefore leads to a decrease of cell volume, these findings support the hypothesis that intermittent volume changes are a prerequisite for the migration of MDCK-F cells.

Pharmacokinetic and toxicological aspects of the medication of beef-type calves with an oral formulation of chloramphenicol palmitate

Chloramphenicol (CAP) plasma levels were determined after oral administration of four doses of CAP palmitate (each dose corresponding to CAP 25 mg/kg/12 h) to four ruminating beef-type calves. Steady-state plasma concentrations of CAP were reached after the fourth oral dose and varied between 5 and 6 micrograms/ml. Half-life of elimination of CAP was 4.5 h. In addition to CAP, dehydrochloramphenicol (DH-CAP), a metabolite of chloramphenicol, was detected in plasma at concentrations between 3 and 7 ng/ml. DH-CAP is known to be produced from CAP by intestinal bacteria. This is significant since DH-CAP is suspected of being involved in the development of fatal aplastic anaemia, which occurs in man after exposure to CAP. Thus, it cannot be excluded that DH-CAP residues may occur in edible tissues. A risk arising from DH-CAP can neither be excluded for the animals being treated with CAP nor for consumers.

Endothelin-1 blunts transepithelial transport and differentiation of Madin-Darby canine kidney cells

We investigated the effects of endothelin-1 (ET-1) on Madin-Darby canine kidney (MDCK) cells, a cell line originating from the renal collecting duct. The activity of transepithelial transport was assessed as the rate of dome formation in monolayers grown on solid support. The pH value of the dome fluid (dome pH) was measured by means of pH-selective microelectrodes. Differentiation of monolayer cells was estimated as the peanut-lectin(PNA)-binding capacity of the apical membrane. Confluent monolayers were incubated for 12-72 h in serum-free medium at various concentrations of ET-1. Exposure to 1 nmol/l ET-1 reduced dome formation by a maximum of 41 +/- 8% (n = 4; P less than 0.02) after 24 h. ET-1 (10 nmol/l; 24 h) decreased dome pH from 7.52 +/- 0.02 (n = 53) to 7.36 +/- 0.03 (n = 51; P less than 0.02). Apical application of amiloride (1 mmol/l) reduced dome pH in both ET-1-treated and non-treated domes to essentially the same level, 7.25 +/- 0.03 (n = 19) and 7.23 +/- 0.03 (n = 17) respectively. ET-1 (10 nmol/l; 24 h) reduced PNA-binding capacity by 19 +/- 3% (n = 5; P less than 0.02). Moreover, ET-1 prevented the increase in PNA binding (+ 53 +/- 7%; n = 5) induced by 0.1 mumol/l aldosterone. We conclude that ET-1 inhibits transepithelial transport and PNA binding via inhibition of apical Na+/H+ exchange, thus antagonizing aldosterone action in MDCK cells.

Alkaline stress transforms Madin-Darby canine kidney cells

Similar to growth factors aldosterone stimulates Na+/H+ exchange in renal target cells leading to cytoplasmic alkalinization. An alkaline intracellular pH reduces the H+ bonds between repressor proteins and DNA leading to the destabilization of the nuclear chromatin. We observed that sustained alkaline stress "per se" can lead to malignant transformation of Madin-Darby canine kidney (MDCK) cells. Cells grown for two weeks in alkaline culture medium (pH 7.8) developed multiple "foci" composed of spindle-shaped pleomorphic cells lacking contact inhibition and exhibiting poor adhesion to the culture support, typical characteristics of dedifferentiated tumor cells. "Focus" cells were cloned and grown in standard medium (pH 7.4). Cells maintained their abnormal growth pattern, indicating stable pH-induced genetic transformation. Cells were fused with polyethylene glycol to giant cells and impaled with microelectrodes. In contrast to non-transformed giant MDCK cells the plasma membrane potential showed spontaneous oscillations that could be virtually abolished by the omission of extracellular Ca2+ or by the addition of the K+ channel blocker Ba2+. We conclude that sustained alkaline stress can induce malignant transformation in MDCK cells indicated by an abnormal growth pattern and by membrane potential oscillations most likely due to Ca2+ activated K+ channels in the plasma membrane.

Fusion of cultured dog kidney (MDCK) cells: I. Technique, fate of plasma membranes and of cell nuclei

The evaluation of the intracellular signal train and its regulatory function in controlling transepithelial transport with electrophysiological methods often requires intracellular measurements with microelectrodes. However, multiple impalements in epithelial cells are hampered by the small size of the cells. In an attempt to avoid these problems we fused cells of an established cell line. Madin Darby canine kidney cells, originally derived from dog kidney, to "giant" cells by applying a modified polyethylene glycol method. During trypsin-induced detachment from the ground of the petri dish, individual cells grown in a monolayer incorporate volume and mainly lose basolateral plasma membrane by extrusion. By isovolumetric cell-to-cell fusion, spherical "giant" cells are formed within 2 hr. During this process a major part of the individual cell plasma membranes is internalized. Over three weeks following cell plasma membrane fusion degradation of single cell nuclei and cell nuclear fusion occurs. We conclude that this experimental approach opens the possibility to investigate ion transport of epithelia in culture by somatic cell genetic techniques.

Dependence of the red blood cell calcium pump on the membrane potential

(1) It is shown that the rate of calcium extrusion from intact human red cells is faster at a membrane potential of approximately +50 mV (inside) than at approximately -50 mV. (2) The positive potential applied was the chloride potential of KCl cells in a K-gluconate medium when the Ca2+ sensitive K+ channel was blocked by 0.3mM quinidine. The negative potential resulted from the high K+ permeability in Ca2+ loaded cells (the cells were loaded to a Ca2+ activity in the cell water of about 50 microM). (3) It is further demonstrated that the Ca2+ affinity of the pump ATPase is decreased both at the internal (high affinity) and external (low affinity) site by increasing the proton concentration. Acidification thus inhibits internally and stimulates externally. (4) An indirect effect of the membrane potential on the pump activity via the accompanying pH shifts on either side of the membrane could be ruled out by choosing Ca2+ concentrations which are fully activating at the internal Ca2+ binding site at pH 6.5 and not yet inhibitory at the external Ca2+ binding site at pH 8. (5) The result is compatible with the assumption that the human red cell Ca-pump is exchanging Ca2+ for protons, yet is electrogenic by virtue of a stoichiometry of 1H+:1Ca2+ for this exchange.

[Clinical aspects and therapy of acute poisoning by the drug combination melitracen-flupenthixol (Deanxit)]

From 1975 to 1982, the Austrian Poison Information Centre gave medical advice in forty cases of acute melitracenee-flupenthixol poisoning. The case reports were reviewed and analysed in retrospect. 13 patients who either had ingested less than 20 pills (n = 5) or who underwent early gastric lavage (n = 8) showed no symptoms. In 19 patients who had swallowed 20 to 60 (n = 11), 60 to 100 (n = 3) pills respectively, or an unknown dose (n = 5) atropine like symptoms predominated. Five patients developed atropine like and extrapyramidal symptoms. The number of pills taken by these patients ranged from 20 to 60 (n = 4) and in one up to 100. Extrapyramidal reactions were encountered as predominant symptoms in three patients one of which had taken 20, the other 60 and the third an unknown number of pills. Additionally, five patients were unconscious. 21 patients developed ECG changes, 19 of which showing sinus tachycardia. The remaining two patients who had ingested 600 to 1000 mg melitracen atrial premature beats or T-wave inversions were observed. All 40 patients recovered.