Interesting anticandidal effects of anisic aldehydes on growth and proton-pumping-ATPase-targeted activity

Attention has been drawn to evaluate the antifungal activity of p-anisaldehyde (1), o-anisaldehyde (2) and m-anisaldehyde (3). To put forward this approach, antifungal activity has been assessed in thirty six fluconazole-sensitive and eleven fluconazole-resistant Candida isolates. Growth and sensitivity of the organisms were significantly effected by test compounds at different concentrations. The rapid irreversible action of compound-1, compound-2 and compound-3 on fungal cells suggested a membrane-located target for their action. We investigated their effect on H⁺ ATPase mediated H⁺-pumping by various Candida species. All the compounds inhibit H⁺- ATPase activity at their respective MIC₉₀ values. Inhibition of H⁺ ATPase leads to intracellular acidification and cell death. Scanning electron microscopy analysis revealed deep wrinkles, deformity and flowed content. Furthermore, it was also observed that position of methoxy group attached to the benzene ring decides antifungal activity of the compound. The present study indicates that compound-1, compound-2 and compound-3 have significant antifungal activity against Candida, including azole-resistant strains, advocating further investigation for clinical applications in the treatment of fungal infections.     

In Vitro Activity of the New Echinocandin Antifungal, MK-0991, against Common and Uncommon Clinical Isolates of Candida Species

 A broth macrodilution method, performed as recommended by the National Committee for Clinical Laboratory Standards, was used for comparative testing of the new echinocandin antifungal agent MK-0991 and fluconazole against 50 yeast isolates belonging to 12 species of Candida. MK-0991 was shown to be highly effective against both fluconazole-susceptible and -resistant Candida spp., yielding minimum inhibitory concentrations ranging from ≤0.19 to 0.78 μg/ml. Fungicidal activity was exerted at ≤1.5 μg/ml for 73% of the isolates tested. This study suggests that MK-0991 has significant potential for clinical development.     

Species distribution and antifungal susceptibility of Candida bloodstream isolates in a tertiary medical center in Israel

To evaluate the species distribution and antifungal susceptibility of Candida isolates in a tertiary institution in Israel, all consecutive isolates of Candida spp. recovered from blood during the last 2 years were studied. The isolates were identified by the germ tube test and the API ID 32C test (bioMérieux, Marcy l'Etoile, France). MICs of antifungal agents were determined by the E test. Candida albicans was the most commonly isolated species, accounting for 44% (63/142) of the isolates, followed by Candida tropicalis (25%; 35/142), Candida parapsilosis (20%; 29/142), Candida glabrata (10%; 14/142), and Candida krusei (0.7%; 1/142). All isolates were sensitive to amphotericin B and voriconazole. Resistance to fluconazole (using a high MIC of ≥256 μg/ml) was found in 1.6% of C. albicans isolates, in 3.4% of C. parapsilosis isolates, and in 21.4% of C. glabrata isolates. Resistance to itraconazole was detected in 3.2% of C. albicans isolates, in 2.9% of C. tropicalis isolates, in 3.4% of C. parapsilosis isolates, and in 93% of C. glabrata isolates. Disparities in species distribution and antifungal susceptibility of Candida isolates from the institute studied versus Candida isolates from other centers and countries are described. The findings emphasize the need for continuous surveillance and further clinical investigational studies.     

A continuous-flow technique for analysis of stoichiometry and transport kinetics of gastric H,K-ATPase

A continuous-flow method was developed for determining the stoichiometry of the gastric proton pump H, K-ATPase (EC 3.6.1.36) in its hydrolysis of ATP and translocation of H⁺ and the K⁺ congener “Rb⁺. H, K-ATPase-containing vesicles which had been isolated from pig gastric mucosa were incubated at 37 °C for 2 h in 150 mM ⁸⁶RbCl, 0.5 mM ethylenebis(oxyethylenenitrilo)tetra-acetic acid and J mM 2–(N-morpholino)ethane sulphonic acid (Mes) adjusted to pH 6.1 with Tris, and then applied onto a 0.45 μm pore size cellulose acetate filter. The immobilized vesicles were perfused with 0.15 mM Mes/Tris buffer, pH 6.1, containing 150 mcholine chloride and 0.2 mM MgCl₂., After changing to a medium containing 0.1 mM ATP, the amounts and rates of H⁺ uptake, ⁸⁶Rb⁺ efflux and ATP hydrolysis were measured. The initial ratio of Rb⁺ transported to ATP hydrolysed gave values of 0.96 ± 0.26 (mean f SD, n= 28). The initial ratio of ATP-dependent Rb⁺ efflux to H⁺ uptake gave values of 0.92 + 0.28 (mean f SD, n= 28). The Mg-ATPase activity was measured in vesicles which had been incubated with choline chloride instead of RbC1. This activity was 15.8 f 8.7% (mean + SD) of the total ATPase activity in the initial fractions used for calculation of the stoichiometry. It is argued that this Mg-ATPase may be an intrinsic activity of the H, K-ATPase and that the relation between these activities is dependent on the amount of K⁺ (or Rb⁺) present in the assay. However, whether corrections were made for this Mg-ATPase or not, it had only marginal effects on the calculations of the stoichiometry of the pump. Thus simultaneous measurements of ⁸⁶Rb⁺ efflux, H⁺ uptake and ATP hydrolysis in immobilized gastric vesicles gave a stoichiometry of the pump close to a 1:1:1 ratio. These results indicate that the pump is non-electrogenic.     

In vitro comparison of cilofungin alone and in combination with other antifungal agents against clinical isolates ofCandida species

Cilofungin, a lipopeptide antifungal agent, was tested for in vitro activity alone and in combination with ketoconazole, itraconazole, flucytosine and amphotericin B against 102 clinical isolates ofCandida species. At 48 hours all isolates ofCandida albicans, Candida tropicalis, Candida paratropicalis andCandida glabrata were inhibited by 5 mcg/ml of cilofungin. In contrast, the MIC90 forCandida krusei was 10 mcg/ml and forCandida parapsilosis >40 mcg/ml. The interaction of combinations of cilofungin with amphotericin B, itraconazole, ketoconazole and flucytosine was additive or indifferent at 48 hours for 100 %, 88 %, 78 % and 70 % of allCandida species isolates, respectively. Overall, cilofungin demonstrated good activity in vitro against mostCandida species isolates.     

Regional intestinal adaptations in Na+,K+‐ATPase in experimental colitis and the contrasting effects of interferon‐γ

Aims: This study evaluated Na⁺,K⁺‐ATPase activity and the abundance of α₁ subunit Na⁺,K⁺‐ATPase in experimental colitis and gathered evidence on the effects of interferon‐γ (IFN‐γ) on intestinal Na⁺,K⁺‐ATPase. Methods: Colitis was induced by the intrarectal administration of 2,4,6‐trinitrobenzene sulphonic acid (TNBS, 30 mg/250 μL). Na⁺,K⁺‐ATPase activity was determined as the difference between total and ouabain‐insensitive ATPase. The abundance of Na⁺,K⁺‐ATPase was analysed by immunoblotting. Results: Na⁺,K⁺‐ATPase activity was markedly reduced in the proximal colonic mucosa of TNBS‐treated rats, whereas upstream in the terminal ileal mucosa a marked increase in sodium pump activity was observed. At the jejunal level no significant changes in Na⁺,K⁺‐ATPase activity were observed between TNBS‐treated rats and corresponding controls (ethanol‐treated rats). No changes were observed in the abundance of α₁ subunit Na⁺,K⁺‐ATPase in the proximal colon, terminal ileum and jejunum. The administration of IFN‐γ (50 000 U) 48 h before sacrifice reduced both Na⁺,K⁺‐ATPase activity and the abundance of α₁ subunit Na⁺,K⁺‐ATPase in the proximal colon. Dexamethasone prevented colonic inflammation and decreases in proximal colonic Na⁺,K⁺‐ATPase activity in TNBS‐treated rats, but did not affect the INF‐γ‐induced decrease in colonic Na⁺,K⁺‐ATPase activity. Conclusions: The increase in ileal Na⁺,K⁺‐ATPase activity upstream to the lesioned colonic mucosa, where Na⁺,K⁺‐ATPase activity was markedly reduced, might indicate a compensatory process to counteract the decrease in water and electrolyte absorption at the colonic level. This decrease in colonic Na⁺,K⁺‐ATPase activity is likely not related to INF‐γ‐induced downregulation of Na⁺,K⁺‐ATPase.     

Sevoflurane reduces severity of acute lung injury possibly by impairing formation of alveolar oedema

Pulmonary oedema is a hallmark of acute lung injury (ALI), consisting of various degrees of water and proteins. Physiologically, sodium enters through apical sodium channels (ENaC) and is extruded basolaterally by a sodium–potassium–adenosine–triphosphatase pump (Na⁺/K⁺‐ATPase). Water follows to maintain iso‐osmolar conditions and to keep alveoli dry. We postulated that the volatile anaesthetic sevoflurane would impact oedema resolution positively in an in‐vitro and in‐vivo model of ALI. Alveolar epithelial type II cells (AECII) and mixed alveolar epithelial cells (mAEC) were stimulated with 20 µg/ml lipopolysaccharide (LPS) and co‐exposed to sevoflurane for 8 h. In‐vitro active sodium transport via ENaC and Na⁺/K⁺‐ATPase was determined, assessing ²²sodium and ⁸⁶rubidium influx, respectively. Intratracheally applied LPS (150 µg) was used for the ALI in rats under sevoflurane or propofol anaesthesia (8 h). Oxygenation index (PaO₂/FiO₂) was calculated and lung oedema assessed determining lung wet/dry ratio. In AECII LPS decreased activity of ENaC and Na⁺/K⁺‐ATPase by 17·4% ± 13·3% standard deviation and 16·2% ± 13·1%, respectively. These effects were reversible in the presence of sevoflurane. Significant better oxygenation was observed with an increase of PaO₂/FiO₂ from 189 ± 142 mmHg to 454 ± 25 mmHg after 8 h in the sevoflurane/LPS compared to the propofol/LPS group. The wet/dry ratio in sevoflurane/LPS was reduced by 21·6% ± 2·3% in comparison to propofol/LPS‐treated animals. Sevoflurane has a stimulating effect on ENaC and Na⁺/K⁺‐ATPase in vitro in LPS‐injured AECII. In‐vivo experiments, however, give strong evidence that sevoflurane does not affect water reabsorption and oedema resolution, but possibly oedema formation.     

Comparative in Vitro Activity of Voriconazole and Itraconazole Against Fluconazole-Susceptible and Fluconazole-Resistant Clinical Isolates of Candida Species from Spain

 The in vitro activity of voriconazole was compared with that of itraconazole against 299 fluconazole-susceptible (MIC≤8 μg/ml) and 130 fluconazole-resistant (MIC≥16 μg/ml) clinical isolates of Candida spp. An adaptation of the National Committee for Clinical Laboratory Standards reference method was employed for determination of MICs. Voriconazole showed more potent activity than either fluconazole and itraconazole, even against some Candida albicans, Candida glabrata, and Candida krusei isolates resistant to fluconazole. However, for fluconazole-resistant isolates, the MICs of itraconazole and voriconazole were proportionally higher than for fluconazole-susceptible isolates. These data may indicate cross-resistance.     

Prevalence and role of efflux pump activity in ciprofloxacin resistance in clinical isolates of <Emphasis Type="Italic">Klebsiella pneumoniae</Emphasis>

We investigated the prevalence and role of efflux pump activity and possible drug influx resistance in ciprofloxacin susceptibility amongst 26 distinct clinical isolates of Klebsiella pneumoniae of varying ciprofloxacin susceptibilities and known quinolone resistance-determining region (QRDR) genotypes. Cellular [¹⁴C]ciprofloxacin accumulation patterns and the amount of cell-associated [¹⁴C]ciprofloxacin of mid-logarithmic phase cells were determined before and after challenging with the efflux pump inhibitor carbonyl cyanide 3-chlorophenylhydrazone (CCCP). Most isolates (24/26), and all with ciprofloxacin minimum inhibitory concentrations (MICs) >1 μg/ml, had efflux activity that could extrude up to 90% of cell-associated [¹⁴C]ciprofloxacin; none had significant influx resistance. In isolates with no QRDR mutations, efflux alone reduced ciprofloxacin susceptibility. In isolates with QRDR mutations, the efflux activity varied: in one isolate with no efflux activity, the most common fluoroquinolone resistance-causing QRDR mutation did not bring about clinically significant ciprofloxacin resistance; isolates with multiple mutations had high MICs and, usually, high levels of efflux activity. Fluoroquinolone efflux activity is much more common in clinical isolates of K. pneumoniae than previously reported and it can contribute to decreased ciprofloxacin susceptibility.     

Dopamine‐induced inhibition of Na+‐K+‐ATPase activity requires integrity of actin cytoskeleton in opossum kidney cells

The present study evaluated the importance of the association between Na⁺‐K⁺‐ATPase and the actin cytoskeleton on dopamine‐induced inhibition of Na⁺‐K⁺‐ATPase activity. The approach used measures the transepithelial transport of Na⁺ in monolayers of opossum kidney (OK) cells, when the Na⁺ delivered to Na⁺‐K⁺‐ATPase was increased at the saturating level by amphotericin B. The maximal amphotericin B (1.0 μg mL^–1) induced increase in short‐circuit current (I_sc) was prevented by ouabain (100 μM ) or removal of apical Na⁺. Dopamine (1 μM ) applied from the apical side significantly decreased (29 ± 5% reduction) the amphotericin B‐induced increase in I_sc, this being prevented by the D₁‐like receptor antagonist SKF 83566 (1 μM ) and the protein kinase C (PKC) inhibitor chelerythrine (1 μM ). Exposure of OK cells to cytochalasin B (1 μM ) or cytochalasin D (1 μM ), inhibitors of actin polymerization, from both cell sides reduced by 31 ± 4% and 36 ± 3% the amphotericin B‐induced increase in I_sc and abolished the inhibitory effect of apical dopamine (1 μM ), but not that of the PKC activator phorbol‐12,13‐dibutyrate (PDBu; 100 nM ). Colchicine (1 μM ) failed to alter the inhibitory effects of dopamine. The relationship between Na⁺‐K⁺‐ATPase and the concentration of extracellular Na⁺ showed a Michaelis–Menten constant (K_m) of 44.1 ± 13.7 mM and a V_max of 49.6 ± 4.8 μA cm^–2 in control monolayers. In the presence of apical dopamine (1 μM ) or cytochalasin B (1 μM ) V_max values were significantly (P < 0.05) reduced without changes in K_m values. These results are the first, obtained in live cells, showing that the PKC‐dependent inhibition of Na⁺‐K⁺‐ATPase activity by dopamine requires the integrity of the association between actin cytoskeleton and Na⁺‐K⁺‐ATPase.     

In vitro antifungal and antibiofilm activities of novel sulfonyl hydrazone derivatives against Candida spp.

BackgroundThe aim of this study was to investigate the antifungal and antibiofilm activity of the new sulfonyl hydrazones compound derived from sulphonamides.MethodsIn this study, new sulfonyl hydrazone series were synthesized via a green chemistry method. The structures of the synthesized compounds were characterized by elemental analyses and spectroscopic methods. The antifungal activities of the Anaf compounds against Candida strains under planktonic conditions were tested. The biofilm-forming ability of Candida strains was determined and the inhibitory effects of Anaf compounds on Candida biofilms compared with fluconazole were measured by MTT assay. Expression analysis of biofilm-related genes was investigated with qRT-PCR. The statistical analysis was performed using a one-way ANOVA test.Candidastrains was determined and the inhibitory effects of Anaf compounds on Candida biofilms compared with fluconazole were measured by MTT assay. Expression analysis of biofilm-related genes was investigated with qRT-PCR. The statistical analysis was performed using a one-way ANOVA test.ResultsA total of 16 (45.7%) out of 35 Candida isolates were determined as strong biofilm producers in this study. C. albicans was the most biofilm producer, followed by C. krusei and C. lusitaniae. The Anaf compounds had a broad spectrum of activity with MIC values ranging from 4 μg/ml to 64 μg/ml. Our data indicated that the Anaf compound had a significant effect on inhibiting biofilm formation in both fluconazole-susceptible and -resistant strains. The expression levels of hypha-specific genes als3, hwp1, ece1 and sap5 were downregulated by Anaf compounds.ConclusionsOur study revealed that the Anaf compounds had antifungal activity and inhibited fungal biofilms, which may be related to the suppression of C. albicans adherence and hyphal formation. These results suggest that Anaf compounds may have therapeutic potential for the treatment and prevention of biofilm-associated Candida infections.     

Antifungal drug susceptibility profile of clinically important dermatophytes and determination of point mutations in terbinafine-resistant isolates

With regard to increasing number of antifungal-resistant dermatophytes, antifungal susceptibility testing of dermatophytes serves as a useful tool in managing clinical dermatophytosis. This study aimed to determine antifungal susceptibility profile of clinically important dermatophytes and determination of point mutations in terbinafine-resistant isolates. Based on our results, dermatophytosis was confirmed in 97 cases by direct microscopic examination, culture, and sequencing of ITS region. Antifungal susceptibility of 97 dermatophyte isolates distributed in four species including Trichophyton interdigitale (26 isolates), T. rubrum (19 isolates), T. tonsurans (29 isolates), and Epidermophyton floccosum (21 isolates) was assessed to nine antifungal agents using CLSI M38-A2 guidelines. Minimum inhibitory concentration range (MIC range) for luliconazole and terbinafine was 0.001–0.008 μg/ml and 0.003–> 32 μg/ml, compared to 0.03–64 μg/ml for griseofulvin, 0.01–16 μg/ml for itraconazole and voriconazole, 0.03–8 μg/ml for ketoconazole, 0.03–32 μg/ml for econazole, 0.03–1 μg/ml for lanoconazole, and 0.01–4 μg/ml for butenafine. Trichophyton tonsurans was the most susceptible (MIC = 0.006 μg/ml) and E. floccosum was the most resistant (MIC = 0.02 μg/ml) species to terbinafine. Terbinafine resistance was reported for two species, i.e., T. rubrum and T. tonsurans at the total rate of 2% which was due to Leu393Phe substitution in both species. Taken together, our results assist clinicians and prompt the current knowledge about the necessity of antifungal susceptibility testing to select effective strategies for management of clinical cases of dermatophytosis.     

Blood pressure in essential hypertension correlates with the concentration of a circulating inhibitor of the sodium pump

Summary The influence of serum from patients with essential hypertension on the sodium efflux rate constants of human lymphocytes and on the activity of isolated (Na⁺+K⁺)-ATPase was investigated. The ouabain-sensitive sodium efflux rate constant was significantly decreased (p<0.001) in the sera of 19 hypertensives (1.92±0.11 h^–1) compared with the sera of 30 normotensives (2.44±0.07 h^–1). The ouabain-insensitive sodium efflux was unaffected. These results corresponded with a significant difference (p<0.005) of (Na⁺+K⁺)-ATPase activity (1.03±0.04 mU/ml and 0.079±0.06 mU/ml), when an isolated (Na⁺+K⁺)-ATPase was incubated with the sera of 22 normotensives or 18 hypertensives. Both the rate constant of ouabain-sensitive sodium efflux and the (Na⁺+K⁺)-ATPase activity correlated significantly with the diastolic and systolic blood pressure (p<0.001). These data, therefore, demonstrated the close relationship between essential hypertension and the concentration of a circulating inhibitor of the sodium pump.Abbreviations ATP Adenosine triphosphate - EGTA Ethyleneglycol bis(2-aminoethyl)-N,N,N,N-tetraacetic acid This paper contains an essential part of the thesis of K.M. presented to the Fachbereich Veterinärmedizin, GiessenThis work was supported by the Deutsche Forschungsgemeinschaft, Bonn-Bad Godesberg (Scho 139/16-2) and by the Fonds der Chemischen Industrie, Frankfurt/Main     

Absence of a significant linkage between Na+,K+‐ATPase subunit (ATP1A3 and ATP1B3) genotypes and bipolar affective disorder in the old‐order Amish

Previous studies provide evidence for a genetic component for susceptibility to bipolar affective disorder (BPAD) in the old‐order Amish population. El‐Mallakh and Wyatt [ 1995 : Biol Psychiatry 37:235–244] have suggested that the Na⁺,K⁺‐ATPase may be a candidate gene for BPAD. This study examines the relationship between BPAD in the old‐order Amish cohort and the Na⁺,K⁺‐ATPase α1 and β3 subunit genes (ATP1A3, ATP1B3). A total of 166 sibling pairs were analyzed for linkage via nonparametric methods. Suggestive levels of statistical significance were not reached in any stratification model for affective illness. Overall, the results do not support linkage of bipolar disorder to the Na⁺,K⁺‐ATPase alpha subunit gene (ATP1A3) and beta subunit gene (ATP1B3) in these old‐order Amish families and they show that these Na⁺,K⁺‐ATPase subunit genes are not major effect genes (≥fourfold increased genetic risk of disease) for BPAD in the old‐order Amish pedigrees. We cannot exclude other genetic variants of the Na⁺,K⁺‐ATPase hypothesis for BPAD, whereby other loci may modifying Na⁺,K⁺‐ATPase activity. © 2001 Wiley‐Liss, Inc.     

Effects of hexosamines and omega-3/omega-6 fatty acids on pH regulation by interleukin 1-treated isolated bovine articular chondrocytes

Previous work has shown that interleukin 1 (IL-1) increases the activity of acid extruders in articular chondrocytes, while the H⁺-adenosine triphosphatase (ATPase) inhibitor bafilomycin can prevent aggrecanase-mediated cartilage degradation. The H⁺ transport induced by IL-1 may therefore be required for proteinase activity. In the present study, the effects of hexosamines and fish oils on H⁺-ATPase activity have been characterised for isolated bovine articular chondrocytes. Cells isolated in the presence of IL-1 were acidified, and the fraction of acid extrusion mediated by Na⁺–H⁺ exchange and an H⁺-ATPase were determined using specific inhibitors. Exposure to IL-1 significantly enhanced both components of acid extrusion. Co-incubation with glucosamine or mannosamine attenuated the H⁺-ATPase fraction of efflux. The addition of glucosamine at 9 h after exposure to IL-1—when H⁺-ATPase activation is already apparent—was also able to abolish H⁺-ATPase activity, implying that hexosamines do not exert effects at the level of protein synthesis. Co-incubation with the glucose transport inhibitor phloretin elicited similar effects to the hexosamines, suggesting that modulation of adenosine triphosphate levels may underlie their effects on H⁺-ATPase function. The omega-3 fish oil linolenic acid but not the omega-6 fish oil linoleic acid reduced H⁺-ATPase activity to levels seen in IL-1-untreated cells, although total efflux remained elevated, as a result of an enhanced H⁺ leak. These observations support a model whereby IL-1 stimulates an H⁺-ATPase-dependent system, possibly involved in aggrecanase activation, which appears to be one of the target mechanisms interrupted by dietary supplements reported to have symptom-modifying effects on osteoarthritis.     

Epidemiology and antifungal susceptibility of Candida species isolated from hospitalized patients

ObjectiveVoricanozole and caspofungin are new antifungal agents used in the treatment of Candida infections. However, the susceptibility of Candida species to these antifungal agents could be variable. The aim of this study was to investigate the distribution of the Candida species isolated from hospitalized patients and to determine their susceptibilities to some antifungal agents including voriconazole, caspofungin, fluconazole and amphotericin B.Material and MethodsA total of 164 Candida strains were isolated from clinical specimens obtained during the study period. Of 164 strains, 103 (62%) were C. albicans, followed by C. tropicalis (11%) and C. glabrata (8%). Other Candida species less frequently identified were C. parapsilosis, C. lusitaniae, C. kefyr, C. pelliculosa and C. norvegensis. Antifungal susceptibility testing of these isolates were performed according to the CLSI (formerly NCCLS) M27-A2 broth microdilution method and the results were read after 24 h.ResultsFluconazole resistance was seen in 21 (13%) isolates. All fluconazole-resistant isolates showed low MICs to caspofungin and amphotericin B. MIC values of voriconazole for Candida isolates were between 0.125 and 4 μg/ml.ConclusionAmphotericin B is still the major therapeutic agent for azole resistant Candida strains and caspofungin seems to be a good alternative.     

Intracellular sodium modulates the state of protein kinase C phosphorylation of rat proximal tubule Na+,K+‐ATPase

The natriuretic hormone dopamine and the antinatriuretic hormone noradrenaline, acting on α‐adrenergic receptors, have been shown to bidirectionally modulate the activity of renal tubular Na⁺,K⁺‐adenosine triphosphate (ATPase). Here we have examined whether intracellular sodium concentration influences the effects of these bidirectional forces on the state of phosphorylation of Na⁺,K⁺‐ATPase. Proximal tubules dissected from rat kidney were incubated with dopamine or the α‐adrenergic agonist, oxymetazoline, and transiently permeabilized in a medium where sodium concentration ranged between 5 and 70 mM . The variations of sodium concentration in the medium had a proportional effect on intracellular sodium. Dopamine and protein kinase C (PKC) phosphorylate the catalytic subunit of rat Na⁺,K⁺‐ATPase on the Ser23 residue. The level of PKC induced Na⁺,K⁺‐ATPase phosphorylation was determined using an antibody that only recognizes Na⁺,K⁺‐ATPase, which is not phosphorylated on its PKC site. Under basal conditions Na⁺,K⁺‐ATPase was predominantly in its phosphorylated state. When intracellular sodium was increased, Na⁺,K⁺‐ATPase was predominantly in its dephosphorylated state. Phosphorylation of Na⁺,K⁺‐ATPase by dopamine was most pronounced when intracellular sodium was high, and dephosphorylation by oxymetazoline was most pronounced when intracellular sodium was low. The oxymetazoline effect was mimicked by the calcium ionophore A23187. An inhibitor of the calcium‐dependent protein phosphatase, calcineurin, increased the state of Na⁺,K⁺‐ATPase phosphorylation. The results imply that phosphorylation of renal Na⁺,K⁺‐ATPase activity is modulated by the level of intracellular sodium and that this effect involves PKC and calcium signalling pathways. The findings may have implication for the regulation of salt excretion and sodium homeostasis.     

Antifungal properties of Salvadora persica and Juglans regia L. extracts against oral Candida strains

We report in this work, and for the first time, the potent antifungal activities of Salvadora persica and Juglans regia L. on different Candida species. Methanol, ethyl acetate, and diluted acetone extracts of S. persica (fresh and dry plant) and J. regia L. were screened for in vitro activity against some Candida species. These plants were selected due to their traditional use for the treatment of oral infections. Plant preparations were screened for antifungal activity using a standard agar disc diffusion assay. Following study of the antifungal activity of plant extracts, their minimal inhibitory concentration (MIC) and minimal fungicidal concentration (MFC) values were determined using broth microdilution assay. Among S. persica and J. regia L. extracts, ethyl acetate J. regia L. extract had potent antifungal activity against all Candida strains. The MIC values of the J. regia L. against Candida strains ranged from 0.006 to 0.195 mg/ml. Two C. albicans strains showed a high MIC value (3.125 mg/ml). These results indicate that extracts can contain compounds with therapeutic potential against Candida strains and, hence, their possible use as therapeutic agents.