Explorative Randomized Phase II Clinical Study of the Efficacy and Safety of Finafloxacin versus Ciprofloxacin for Treatment of Complicated Urinary Tract Infections.

The broad-spectrum C-8-cyano-fluoroquinolone finafloxacin displays enhanced activity under acidic conditions. This phase II clinical study compared the efficacies and safeties of finafloxacin and ciprofloxacin in patients with complicated urinary tract infection and/or pyelonephritis. A 5-day regimen with 800 mg finafloxacin once a day (q.d.) (FINA05) had results similar to those of a 10-day regimen with 800 mg finafloxacin q.d. (FINA10). Combined microbiological and clinical responses at the test-of-cure (TOC) visit were 70% for FINA05, 68% for FINA10, and 57% for a 10-day ciprofloxacin regimen (CIPRO10) in 193 patients (64 for FINA05, 68 for FINA10, and 61 for CIPRO10) of the microbiological intent-to-treat (mITT) population. Additionally, the clinical effects of ciprofloxacin on patients with an acidic urine pH (80% of patients) were reduced, whereas the effects of finafloxacin were unchanged. Finafloxacin was safe and well tolerated. Overall, 43.4% of the patients in the FINA05 group, 42.7% in the FINA10 group, and 54.2% in the CIPRO10 group experienced mostly mild and treatment-emergent but unrelated adverse events. A short-course regimen of 5 days of finafloxacin resulted in high eradication and improved clinical outcome rates compared to those for treatment with ciprofloxacin for 10 days. In contrast to those of ciprofloxacin, the clinical effects of finafloxacin were not reduced by acidic urine pH. Hospitalized adults were randomized 1:1:1 to finafloxacin treatment (800 mg q.d.) for either 5 or 10 days or to ciprofloxacin treatment (400 mg/500 mg b.i.d.) for 10 days with an optional switch from intravenous (i.v.) to oral administration at day 3. The primary endpoint was the combined microbiological and clinical response at the TOC visit in the microbiological intent-to-treat population. (This study has been registered at ClinicalTrials.gov under identifier NCT01928433.).

Ca(2+)- and metabolism-related changes of mitochondrial potential in voltage-clamped CA1 pyramidal neurons in situ.

In hippocampal slices from rats, dialysis with rhodamine-123 (Rh-123) and/or fura-2 via the patch electrode allowed monitoring of mitochondrial potential (DeltaPsi) changes and intracellular Ca(2+) ([Ca(2+)](i)) of CA1 pyramidal neurons. Plasmalemmal depolarization to 0 mV caused a mean [Ca(2+)](i) rise of 300 nM and increased Rh-123 fluorescence signal (RFS) by

Neuron-glia signaling via alpha(1) adrenoceptor-mediated Ca(2+) release in Bergmann glial cells in situ.

Adrenoceptors were among the first neurotransmitter receptors identified in glial cells, but it is not known whether these receptors meditate glial responses during neuronal activity. We show that repetitive nerve activity evoked a rise of intracellular calcium in Bergmann glia and neighboring Purkinje neurons of cerebellar slices of mice. The glial but not the neuronal calcium transient persisted during block of ionotropic and metabotropic glutamate receptors. In contrast, the glial calcium response was abolished by cyclopiazonic acid and prazosin; however, prazosin affected neither the inward current nor the resulting depolarization that accompanied the stimulus-induced glial calcium transients. The glial depolarization was attenuated by 38% by the mixture of glutamate receptor blockers, which abolished the evoked neuronal depolarization and afterhyperpolarization. Ba(2+) reduced the glial currents by 66% without affecting the concomitant calcium transients. In the presence of Ba(2+), the mixture of glutamate receptor blockers exerted no effect on the glial inward current or calcium rise. Furthermore, Ba(2+) greatly potentiated both the activity-related Purkinje cell inward current and the accompanying neuronal calcium rises. The results indicate that release of noradrenaline from afferent fibers activates a glial alpha(1) adrenoceptor that promotes calcium release from intracellular stores. Glial calcium rises are known to stimulate a diversity of processes such as transmitter release, energy metabolism, or proliferation. Thus the adrenoceptor-mediated mechanism described here is well suited for feedback modulation of neuronal function that is independent of glutamate.

GABA- and glycine-mediated fall of intracellular pH in rat medullary neurons in situ.

In the region of the ventral respiratory group in brain stem slices from neonatal rats, intracellular pH (pHi) and membrane currents (I(m)) or potentials were measured in neurons dialyzed with the pH-sensitive dye 2',7'-bis-carboxyethyl-5(6)-carboxyfluorescein. Currents and increases in membrane conductance (g(m)) during bath application of 0.1 or 1 mM gamma-aminobutyric acid (GABA) were accompanied by a delayed mean fall of pHi by 0.17 and 0.25 pH units, respectively, from a pHi baseline of 7.33. These effects were reversibly suppressed by 50-100 microM bicuculline. Similar effects on I(m), g(m), and pHi were revealed on administration of 0.1 or 1 mM glycine. These responses were abolished by 10-100 microM strychnine. Dialysis of the cells with 15-30 microM carbonic anhydrase led to an acceleration of the kinetics and a potentiation of the GABA-induced pHi decrease. GABA- and glycine-evoked pHi decreases were very similar during recordings with either high- or low-Cl- patch electrodes, although the reversal potential of the accompanying currents differed by approximately 60 mV. The GABA-induced pHi decrease, but not the accompanying I(m) and g(m) responses, was suppressed in CO2/HCO3(-)-free, N-2-hydroxy-ethylpiperazine-N'-2-ethane sulphonic acid pH-buffered solution. Depolarization from -60 to +30 mV resulted in a sustained fall of pHi by maximally 0.5 pH units. In this situation, the GABA-induced fall of pHi turned into an intracellular alkalosis of 0.09-0.15 pH units. The results confirm and extend previous findings obtained in vivo that GABA- or glycine-induced intracellular acidosis of respiratory neurons is due to efflux of HCO3- via the receptor-coupled Cl- channel.

Acidosis of rat dorsal vagal neurons in situ during spontaneous and evoked activity.

1. Rat brainstem slices were taken for simultaneous measurements of intracellular pH (pHi) and membrane currents or potentials in dorsal vagal neurons, dialysed with the pH-sensitive dye BCECF. 2. Intrinsic intracellular buffering power was 18 mM per pH unit, as determined by exposure to trimethylamine in CO2/HCO3(-)-free, Hepes-buffered saline. 3. Tonic spike activity led to a stable fall in pHi of 0.05-0.2 pH units from a baseline of 7.19 in current-clamp mode, whereas depolarization from -60 to 0 mV for 1 min in voltage-clamp mode produced an intracellular acidification of 0.3 pH units. The depolarization-evoked fall in pHi was suppressed by 1 mM Ni2+ or 0.2 mM Cd2+, but not by 0.5 microM TTX or CO2/HCO3(-)-free saline. 4. Kainate (100 microM) led to an an inward current of -620 pA and a threefold increase in membrane conductance, accompanied by a fall in pHi of 0.33 pH units. 5. GABA (1 mM) evoked a bicuculline-blockable conductance increase and fall in pHi of up to 0.5 pH units. The GABA-induced pHi decrease, but not the conductance increase, was suppressed in Hepes solution. 6. Neither tonic spike activity, nor resting current or conductance were markedly changed upon Hepes-induced intracellular alkalinizations of up to 0.35 pH units, or by an anoxia-induced fall in pHi of a maximum of 0.36 pH units. 7. The data show that neuronal activity produces profound changes in pHi. It appears that spontaneous spike discharge of dorsal vagal neurons is rather tolerant of major perturbations in pHi.

Acidosis of hippocampal neurones mediated by a plasmalemmal Ca2+/H+ pump.

Modulation of cytosolic calcium ([Ca2+]i) plays a key role in intracellular signalling. In neurones, intracellular Ca2+ transients are involved in the regulation of excitability as well as in synaptic transmission and plasticity. Here, we report that depolarization-induced elevation of [Ca2+]i evokes a prominent fall of intracellular pH (pHi) in voltage-clamped hippocampal pyramidal neurones dialysed with fluorescent indicators of H+ and Ca2+. This acidification is caused by exchange of internal calcium for extracellular protons via a vanadate- and eosin-sensitive plasmalemmal Ca2+/H+ pump. In view of the potent neuromodulatory actions of H+, these results raise the possibility that changes in excitability and synaptic plasticity, hitherto solely attributed to Ca2+ transients, may include a significant component mediated by pH shifts.