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  • 1
    ISSN: 1432-2013
    Keywords: Key words CO2/HCO3 ; NH3/NH4+ ; pHi ; [Ca2+]i ; Fura-2 ; BCECF ; Ca2+ store ; Ca2+ influx ; Inositol 1 ; 4 ; 5-trisphosphate ; Epithelia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  The influence of intracellular pH (pHi) on intracellular Ca2+ activity ([Ca2+]i) in HT29 cells was examined microspectrofluorometrically. pHi was changed by replacing phosphate buffer by the diffusible buffers CO2/HCO3 –or NH3/NH4 + (pH 7.4). CO2/HCO3 –buffers at 2,5 or 10% acidified pHi by 0.1, 0.32 and 0.38 pH units, respectively, and increased [Ca2+]i by 8–15 nmol/l. This effect was independent of the extracellular Ca2+ activity and the filling state of thapsigargin-sensitive Ca2+ stores. Removing the CO2/HCO3 –buffer alkalinized pHi by 0.14 (2%), 0.27 (5%), and 0.38 (10%) units and enhanced [Ca2+]i to a peak value of 20, 65, and 143 nmol/l, respectively. Experiments carried out with Ca2+-free solution and with thapsigargin showed that the [Ca2+]i transient was due to release from intracellular pools and stimulated Ca2+ entry. NH3/NH4 + (20 mmol/l) induced a transient intracellular alkalinization by 0.6 pHunits and increased [Ca2+]i to a peak (Δ [Ca2+]i = 164 nmol/l). The peak [Ca2+]i increase was not influenced by removal of external Ca2+, but the decline to basal [Ca2+]i was faster. Neither the phospholipase C inhibitor U73122 nor the inositol 1,4,5-trisphosphate (InsP 3) antagonist theophylline had any influence on the NH3/NH4 +-stimulated [Ca2+]i increase, whereas carbachol-induced [Ca2+]i transients were reduced by more than 80% and 30%, respectively. InsP 3 measurements showed no change of InsP 3 during exposure to NH3/NH4 +, whereas carbachol enhanced the InsP 3 concentration, and this effect was abolished by U73122. The pHi influence on ”capacitative” Ca2+ influx was also examined. An acid pHi attenuated, and an alkaline pHi enhanced, carbachol- and thapsigargin-induced [Ca2+]i influx. We conclude that: (1) an alkaline pHi releases Ca2+ from InsP 3-dependent intracellular stores; (2) the store release is InsP 3 independent and occurs via an as yet unknown mechanism; (3) the store release stimulates capacitative Ca2+ influx; (4) the capacitative Ca2+ influx activated by InsP 3 agonists is decreased by acidic and enhanced by alkaline pHi. The effects of pHi on [Ca2+]i should be of relevance under many physiological conditions.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Pflügers Archiv 428 (1994), S. 179-185 
    ISSN: 1432-2013
    Keywords: BCECF ; Na+/H+ exchanger ; HCO 3 − /Cl− exchanger ; Na+-dependent HCO 3 − transporter ; DIDS ; HOE-694
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The pH regulation in HT29 colon carcinoma cells has been investigated using the pH-sensitive fluorescent indicator 2′,7′-biscarboxyethyl-5(6)-carboxyfluorescein (BCECF). Under control conditions, intracellular pH (pHi) was 7.21±0.07 (n=22) in HCO 3 − -containing and 7.21±0.09 (n=12) in HCO 3 − -free solution. HOE-694 (10 μmol/l), a potent inhibitor of the Na+/H+ exchanger, did not affect control pHi. As a means to acidify cells we used the NH 4 + /NH3 (20 mmol/l) prepulse technique. The mean peak acidification was 0.37±0.07 pH units (n=6). In HCC 3 − -free solutions recovery from acid load was completely blocked by HOE-694 (1 μmol/l), whereas in HCO3 3 − -containing solutions a combination of HOE-694 and 4,4′-diisothiocyanatostilbene-2, 2′-disulphonate (DIDS, 0.5 mmol/l) was necessary to show the same effect. Recovery from acid load was Na+-dependent in HCO 3 − -containing and HCO 3 − -free solutions. Removal of external Cl− caused a rapid, DIDS-blockable alkalinization of 0.33±0.03 pH units (n=15) and of 0.20±0.006 pH units (n=5), when external Na+ was removed together with Cl−. This alkalinization was faster in HCO 3 − -containing than in HCO 3 − -free solutions. The present observations demonstrate three distinct mechanisms of pH regulation in HT29 cells: (a) a Na+/H+ exchanger, (b) a HCO 3 − /Cl− exchanger and (c) a Na+-dependent HCC 3 − transporter, probably the Na+-HCO 3 − /Cl− antiporter. Under HCO 3 − — free conditions the Na+/H+ exchanger fully accounts for recovery from acid load, whereas in HCO 3 − -containing solutions this is accomplished by the Na+/H+ exchanger and a Na+-dependent mechanism, which imports HCO 3 − . Recovery from alkaline load is caused by the HCO 3 − /Cl− exchanger.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 382 (1997), S. S5 
    ISSN: 1435-2451
    Keywords: Key words Peritonitis ; Candidiasis ; Mycosis ; Fungal infection ; Antifungal therapy ; Schlüsselwörter Peritonitis ; Candidiasis ; Mycosis ; Fungal-Infektion ; Antifungal-Therapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Obwohl 20% der Bevölkerung eine Pilzkolonisation des Gastrointestinaltrakts aufweisen, spielen Mykosen in der Initialphase der sekundären Peritonitis eine untergeordnete Rolle. Das Risiko für eine Pilzinfektion steigt nach ausgedehnten operativen Eingriffen, bei Breitspektrumantibiose, parenteraler Ernährung, Katheterismus, Immunsuppression etc. deutlich an. Innerhalb der letzten Jahre nahmen bei nosokomialen Infektionen Mykosen (überwiegend Candida spp.) deutlich zu. Intraabdominale Infektionen bei CAPD-Patienten werden in ca. 5% der Fälle durch Pilze verursacht. Bei Peritonitiden aufgrund Anastomoseninsuffizienz steigt die Inzidenz der Mykosen deutlich an, wobei die Letalität bis zu 80% beträgt. Im Verlauf der schweren Pankreatitis tritt bei bis zu 5% der Nekroseinfektionen eine invasive Mykose auf. Die Klinik der invasiven Pilzinfektion gleicht dem septischen Syndrom und ist in diesem Stadium mit einer Häufigkeit von bis zu 50% mit Fungämien vergesellschaftet. Da die meisten fakultativ pathogenen Pilze Teil der physiologischen Flora sind, ist die Interpretation kultureller Nachweise schwierig. Zur Diagnose einer invasiven Mykose können histopathologische Methoden sowie serologische Candidaantigen- und -antikörpernachweis hilfreich sein. Therapeutisch stehen mit Amphotericin B, Flucytosin und Fluconazol 3 hochwirksame Substanzen für die i.v.-Applikation zur Verfügung. Amphotericin B wird in einer Dosierung bis zu 1 mg/kg und Tag, in der liposomalen Galenik bis 3 mg/kg und Tag verabreicht. Flucytosin (0,15–0,2 g/kg und Tag) ist gut liquorgängig und hat in der Kombination mit Amphotericin B eine synergistische Wirkung. Fluconazol stellt bei empfindlichen Pilzen (Ausnahmen C. glabrata und C. krusei) in einer Dosierung von 200–800 mg/Tag eine ähnlich wirksame und nebenwirkungsärmere Alternative dar.
    Notes: Abstract Although there is a 20% yeast colonization in the gastrointestinal tract of the population, fungal infections appear only rarely in secondary peritonitis. The risk of severe mycosis increases after a major operation and when a patient is taking broad-spectrum antibiotics, is on total parenteral nutrition, is catheterized, and/or is immune-suppressed. In the past years the incidence of nosocomial fungal infections (usually Candida spp.) has risen significantly. Five percent of CAPD-related peritonitis is caused by fungi. In enteral anastomosis breakdown, invasive mycosis occurs more often, with an accompanying lethality of up to 80%. In severe pancreatitis, up to 5% of peripancreatic necrosis is infected with fungi. The clinical course of severe mycosis, like the septic syndrome, is associated with fungemia in up to 50% of cases. As most of the facultative pathogenic fungi are part of the physiological flora, it is difficult to interpret mycological cultures. In order to diagnose invasive fungal infections, histopathological techniques and serologic tests for antigens and antibodies are available. Three antifungal agents (amphotericin B, flucytosine, fluconazole) are available for intravenous administration. Amphotericin B is given at doses of up to 1 mg/kg per day, in liposomal galenism up to 3 mg/kg per day. Combining amphotericin B with flucytosine (150–200 mg/kg per day) a synergistic effect is reached. Fluconazole at a dosage of 200–800 mg per day represents an alternative with similar antifungal activity and lower side effects.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Langenbeck's archives of surgery 382 (1996), S. S5 
    ISSN: 1435-2451
    Keywords: Peritonitis ; Candidiasis ; Mycosis ; Fungal infection ; antifungal therapy ; Peritonitis ; Candidiasis ; Mycosis ; Fungal-Infektion ; Antifungal-Therapie
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Obwohl 20% der Bevölkerung eine Pilzkolonisation des Gastrointestinaltrakts aufweisen, spielen Mykosen in der Initialphase der sekund=:aren Peritonitis eine untergeordnete Rolle. Das Risiko für eine Pilzinfektion steigt nach ausgedehnten operativen Eingriffen, bei Breitspektrumantibiose, parenteraler Ernährung, Katheterismus, Immunsuppression etc. deutlich an. Innerhalb der letzten Jahre nahmen bei nosokomialen Infektionen Mykosen (überwiegendCandida spp.) deutlich zu. Intraabdominale Infektionen bei CAPD-Patienten werden in ca. 5% der Fälle durch Pilze verursacht. Bei Peritonitiden aufgrund Anastomoseninsuffizienz steigt die Inzidenz der Mykosen deutlich an, wobei die Letalität bis zu 80% beträgt. Im Verlauf der schweren Pankreatitis tritt bei bis zu 5% der Nekroseinfektionen eine invasive Mykose auf. Die Klinik der invasiven Pilzinfektion gleicht dem septischen Syndrom und ist in diesem Stadium mit einer Häufigkeit von bis zu 50% mit Fungämien vergesellschaftet. Da die meisten fakultativ pathogenen Pilze Teil der physiologischen Flora sind, ist die Interpretation kultureller Nachweise schwierig. Zur Diagnose einer invasiven Mykose können histopathologische Methoden sowie serologische Candidaantigen- und-antikörpernachweis hilfreich sein. Therapeutisch stehen mit Amphotericin B, Flucytosin und Fluconazol 3 hochwirksame Substanzen für die i.v.-Applikation zur Verfügung. amphotericin B wird in einer Dosierung bis zu 1 mg/kg und Tag, in der liposomalen Galenik bis 3 mg/kg und Tag verabreicht. Flucytosin (0,15–0,2 g/kg und Tag) ist gut liquorgängig und hat in der Kombination mit Amphotericin B eine synergistische Wirkung. Fluconazol stellt bei empfindlichen Pilzen (AusnahmenC. glabrata undC. krusei) in einer Dosierung von 200–800 mg/Tag eine ähnlich wirksame und nebenwirkungsärmere alternative dar.
    Notes: Abstract Although there is a 20% yeast colonization in the gastrointestinal tract of the population, fungal infections appear only rarely in secondary peritonitis. The risk of severe mycosis increases after a major operation and when a patient is taking broad-spectrum antibiotics, is on total parenteral nutrition, is catheterized, and/or is immune-suppressed. In the past years the incidence of nosocomial fungal infections (usuallyCandida spp.) has risen significantly. Five percent of CAPD-related peritonitis is caused by fungi. In enteral anastomosis breakdown, invasive mycosis occurs more often, with an accompanying lethality of up to 80%. In severe pancreatitis, up to 5% of peripancreatic necrosis in infected with fungi. The clinical course of severe mycosis, like the septic syndrome, is associated with fungemia in up to 50% of cases. As most of the facultative pathogenic fungi are part of the physiological flora, it is difficult to interpret mycological cultures. In order to diagnose invasive fungal infections, histopathological techniques and serologic tests for antigens and antibodies are available. Three antifungal agents (amphotericin B, flucytosine, fluconazole) are available for intravenous administration. Amphotericin B is given at doses of up to 1 mg/kg per day, in liposomal galenism up to 3 mg/kg per day. Combining amphotericin B with flucytosine (150–200 mg/kg per day) a synergistic effect is reached. Fluconazole at a dosage of 200–800 mg per day represents an alternative with similar antifungal activity and lower side effects.
    Type of Medium: Electronic Resource
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