Vibrio infection in freshwater fish in Poland

Vibrio species are common inhabitants of aquatic environments and have been described in connection with fish and human diseases. Six Vibrio species were isolated from diseased freshwater and ornamental fish in Poland. The strains were identified based on morphological and biochemical characteristics and confirmed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) as V. albensis (n=3) from Gymnocephalus cernua, Sander lucioperca, Paracheirodon innesi, and Xiphophorus hellerii; V. mimicus (n=1) from Xiphophorus maculatus; and V. vulnificus (n=1) from Nematobrycon palmeri. This is the first time that Vibrio species have been isolated and described from ornamental fish in Poland. The isolates were resistant to ampicillin (83.3%), gentamicin (16.6%), ciprofloxacin (16.6%), sulfamethoxazole-trimethoprim (16.6%), and chloramphenicol (16.6%). The multiple antibiotic resistance (MAR) index was 0.00-0.08 for V. albensis, 0.17 for V. mimicus, and 0.33 for V. vulnificus. Our study confirmed the presence of potentially pathogenic Vibrio species in freshwater and ornamental fish. Therefore, further monitoring of the presence of Vibrio species, mainly in ornamental fish, is necessary.

Comparison of serum protein profiles of Borrelia burgdorferi-positive Bernese Mountain Dogs and dogs of other breeds using MALDI-TOF technique

The aim of the study was to compare the serum protein profile of Bernese Mountain Dogs (BMDs) reacting positive for Bb in snap testing with the serum protein profile of dogs of other breeds (healthy and with clinical borreliosis) using the MALDI time-of-flight (MALDI-TOF) technique. The observations included five groups of dogs. BMDs reacting positively to Bb in snap serological testing and showing symptoms of borreliosis (group 1), BMDs for which no borreliosis symptoms were determined but with seropositivity for Bb determined with snap serological tests (group 2), clinically healthy BMDs with no antibodies for Bb found in the serum (group 3), five dogs of different breeds, reacting positively in serological testing, in which borreliosis symptoms were observed (group 4), clinically healthy dogs of different breeds with negative reaction in tests towards Bb (group 5). A proteomic analysis demonstrated the presence of five identical protein fractions among all five groups. An additional two protein fractions of approximately 7.630 and 15.260 kDa were found in all the serum samples obtained from the dogs positive for borrelia in a snap test, both in those exhibiting symptoms of borreliosis, and seropositive BMDs not presenting symptoms of the disease. These two additional protein fractions may be used to differentiate between seropositive and seronegative B. burgdorferi dogs and may be considered a seropositivity marker, however, it cannot be used to differentiate between animals with the clinical form of the disease and those that are only seropositive.

Natural Phytochemicals as SIRT Activators-Focus on Potential Biochemical Mechanisms

Sirtuins are a family of proteins with enzymatic activity. There are seven mammalian sirtuins (SIRT1-SIRT7) that are found in different cellular compartments. They are a part of crucial cellular pathways and are regulated by many factors, such as chemicals, environmental stress, and phytochemicals. Several in vitro and in vivo studies have presented their involvement in anti-inflammatory, antioxidant, and antiapoptotic processes. Recent findings imply that phytochemicals such as resveratrol, curcumin, quercetin, fisetin, berberine, and kaempferol may regulate the activity of sirtuins. Resveratrol mainly activates SIRT1 and indirectly activates AMPK. Curcumin influences mainly SIRT1 and SIRT3, but its activity is broad, and many pathways in different cells are affected. Quercetin mainly modulates SIRT1, which triggers antioxidant and antiapoptotic responses. Fisetin, through SIRT1 regulation, modifies lipid metabolism and anti-inflammatory processes. Berberine has a wide spectrum of effects and a significant impact on SIRT1 signaling pathways. Finally, kaempferol triggers anti-inflammatory and antioxidant effects through SIRT1 induction. This review aims to summarize recent findings on the properties of phytochemicals in the modulation of sirtuin activity, with a particular focus on biochemical aspects.

Urinary proteome of dogs with kidney injury during babesiosis

Background

Acute kidney injury is the most frequent complication of babesiosis in dogs and may provide a natural model for identifying early and specific markers of kidney injury in this species. There are limited data on urine proteomics in dogs, and none of the effect of babesiosis on the urine proteome. This study aimed to identify urinary proteins of dogs with kidney injury during the natural course of babesiosis caused by Babesia canis, and to compare them with proteins in a control group to reveal any potential biomarkers predicting renal injury before the presence of azotemia.

Urine samples were collected from 10 dogs of various breeds and sex with naturally occurring babesiosis, and 10 healthy dogs. Pooled urine samples from both groups were separated by 2D (two-dimensional) electrophoresis, followed by protein identification using MALDI-TOF (matrix-assisted laser desorption ionization time of flight) mass spectrometry.

Results

In total, 176 proteins were identified in the urine samples from healthy dogs, and 403 proteins were identified in the urine samples from dogs with babesiosis. Of the 176 proteins, 146 were assigned exclusively to healthy dogs, and 373 of the 403 proteins were assigned exclusively to dogs with babesiosis; 30 proteins were common for both groups. Characteristic analysis of 373 proteins found in dogs with babesiosis led to the isolation of 8 proteins associated with 10 metabolic pathways involved in immune and inflammatory responses.

Conclusions

It was hypothesized that epithelial-mesenchymal transition might play an important role in the mechanisms underlying pathological changes in renal tissue during babesiosis, as indicated by a causal relationship network built by combining 5 of the 10 selected metabolic pathways, and 4 of the 8 proteins associated with these pathways; this network included cadherins, gonadotropin releasing hormone receptors, inflammatory responses mediated by chemokine and cytokine signalling pathways, integrins, interleukins, and TGF-β (transforming growth factor β) pathways. Those pathways were linked by interleukin-13, bone morphogenetic protein 7, α2(1) collagen, and tyrosine protein kinase Fer, which are potential biomarkers of damage during babesiosis in dogs, that might indicate early renal injury.

Cyclization of flavokawain B reduces its activity against human colon cancer cells

Chalcones are naturally occurring compounds exhibiting biological activity through multiple mechanisms. Flavokawain B is one of chalcones found in kava plant. In our studies, we focused on the anticancer activity of flavokawain B in colorectal cancer cells LoVo and its resistant to doxorubicin subline-LoVo/Dx. Strong cytotoxic activity of flavokawain B and its ability to inhibit the proliferation in both cell lines was detected. These effects accompanied with induction cell cycle arrest in G2/M phase and the presence of SubG1 fraction. Flavokawain B at low concentration led to increase of caspase-3 activity. The chalcone-induced apoptosis was also confirmed by DNA fragmentation. In our work, the conversion of flavokawain B to corresponding flavanone-5,7-dimetoxyflavanone-was shown to be more extensive in cancer than in non-cancer cells. We found that the cyclization of the chalcone was related to the significant decrease in the cytotoxicity. Cell proliferation and cell cycle progression were not impaired significantly in the studied cancer cells incubated with 5,7-dimethoxyflavanone. We did not observe apoptosis in the cells incubated with flavanone. The results from biological studies agreed with the theoretical activity that emerges from structural parameters.

In vitro biofilm formation and antibiotic susceptibility of Pseudomonas aeruginosa isolated from airways of patients with cystic fibrosis

Background: Pseudomonas aeruginosa is the predominant cause of airway infections in patients with cystic fibrosis (CF) as a result of its ability to form biofilm. Resistance to antimicrobial agents is the most important feature of biofilm infection. The aim of this study was to evaluate biofilm formation and to compare antibiotic susceptibility of P. aeruginosa living in two modes of growth: planktonic and biofilm, isolated from respiratory tract of CF patients. Methods: Biofilm formation and biofilm susceptibility to antibiotics were determined using modified microtitere plate method. For susceptibility testing of planktonic culture to antibiotics serial microdilution broth method were used.Results: More than 95% of isolates were capable to form biofilm. Isolates grown as biofilms were more resistant to tested antibiotics compared to those grown planktonically. Ciprofloxacin showed the highest activity against P. aeruginosa biofilm. In contrast, no bacteriostatic activity was obtain for the highest concentration of piperacillin tested against most of P. aeruginosa strains growing in a biofilm (BIC > 4096 mg/L).Conclusions: Our study indicates the need to develop a standardized susceptibility testing method for biofilm mode of growth of pathogens. It appears that it is appropriate to introduce a biofilm susceptibility testing to routinely performed tests, as the effect of antibiotics on biofilm eradication may be variable and unpredictable.

In vitro biofilm formation and antibiotic susceptibility of Pseudomonas aeruginosa isolated from airways of patients with cystic fibrosis

Background: Pseudomonas aeruginosa is the predominant cause of airway infections in patients with cystic fibrosis (CF) as a result of its ability to form biofilm. Resistance to antimicrobial agents is the most important feature of biofilm infection. The aim of this study was to evaluate biofilm formation and to compare antibiotic susceptibility of P. aeruginosa living in two modes of growth: planktonic and biofilm, isolated from respiratory tract of CF patients. Methods: Biofilm formation and biofilm susceptibility to antibiotics were determined using modified microtitere plate method. For susceptibility testing of planktonic culture to antibiotics serial microdilution broth method were used.Results: More than 95% of isolates were capable to form biofilm. Isolates grown as biofilms were more resistant to tested antibiotics compared to those grown planktonically. Ciprofloxacin showed the highest activity against P. aeruginosa biofilm. In contrast, no bacteriostatic activity was obtain for the highest concentration of piperacillin tested against most of P. aeruginosa strains growing in a biofilm (BIC > 4096 mg/L).Conclusions: Our study indicates the need to develop a standardized susceptibility testing method for biofilm mode of growth of pathogens. It appears that it is appropriate to introduce a biofilm susceptibility testing to routinely performed tests, as the effect of antibiotics on biofilm eradication may be variable and unpredictable.

Influence of the multidrug transporter inhibitors on the activity of Kv1.3 voltage-gated potassium channels

Using the whole-cell patch-clamp technique, the influence of selected multidrug resistance modulators, both plant-derived compounds and derivatives on the activity of voltage-gated potassium channels Kv1.3 was investigated. Twelve compounds with phenolic and terpenic structures were tested: the stilbenes piceatannol (1) and its tetramethoxy (2) and tetracetoxy (3) derivatives, the flavonoids naringenin (4) and its methylated derivatives: naringenin-4',7-dimethylether (5) and naringenin-7-methylether (6), and aromadendrin (7), the coumarins esculetin (8) and scopoletin (9) and ent-abietane diterpenes, helioscopinolide B (10) and its 3beta-acetoxy derivative (11) and helioscopinolide E (12). The studies were performed on a model system with Kv1.3 channels endogenously expressed in human T lymphocytes. Obtained data provide evidence that compounds 2, 5 and 6 applied at 30 microM inhibited the amplitude of recorded currents to 31%, 4% and 29% of its control value, respectively. On the other hand, compounds 3, 4, 7-12 (at 30 microM) and compound 1 (at 40 microM) did not affect significantly the channel activity. These results indicate that some methoxy-derivatives of the tested compounds are effective inhibitors of Kv1.3 channels. Since the inhibition of Kv1.3 channels may inhibit the proliferation of prostate, breast and colon cancer cells expressing these channels, the channel inhibitors may exert an antiproliferative action. This action combined with a simultaneous modulation of the multidrug resistance may be significant for a potential application of these compounds in cancer chemotherapy.

Interactions of Phenothiazines with Lipid Bilayer and their Role in Multidrug Resistance Reversal

The mechanism of multidrug resistance (MDR) reversal is not fully understood yet. Interaction of MDR modifiers with lipid bilayer of cell membranes and alterations of fluidity or other biophysical properties of plasma membrane might be an important factor in mechanism of MDR modulation and reversal. In this review we focus on phenothiazines which belong to the group of drugs known to modify MDR in different types of cells, from cancer cells up to various kinds of microorganisms. First, the aggregation properties of phenothiazines and their interactions with lipid bilayers are described. The localization of phenothazine derivative molecules in bilayers and alteration of membrane properties are discussed. Apart from the influence on model bilayers also the interactions of phenothiazines with cellular membranes (especially of erythrocytes) are reviewed. In subsequent sections the anti-MDR activity of phenothiazine derivatives observed in microorganisms and in cancer cells is described. The possible molecular mechanisms involved in MDR reversal by these compounds are presented. The direct interactions of phenothiazines with multidrug transporters and other effects of these modulators on plasma membranes are discussed. Finally, the structural features of phenothiazine derivatives essential for their optimal MDR reversal activity are described.

Genistein inhibits the activity of kv1.3 potassium channels in human T lymphocytes

In the present study, the whole-cell patch-clamp technique was applied to follow the inhibitory effect of genistein--a tyrosine kinase inhibitor and a natural anticancer agent--on the activity of voltage-gated potassium channels Kv1.3 expressed in human T lymphocytes (TL). Obtained data provide evidence that genistein application in the concentration range of 1-80 microM reversibly decreased the whole-cell potassium currents in TL in a concentration-dependent manner to about 0.23 of the control value. The half-blocking concentration range of genistein was from 10 to 40 microM. The current inhibition was correlated in time with a significant decrease of the current activation rate. The steady-state activation of the currents was unchanged upon application of genistein, as was the inactivation rate. The inhibitory effect of genistein on the current amplitude and activation kinetics was voltage-independent. The current inhibition was not changed significantly in the presence of 1 mM of sodium orthovanadate, a tyrosine phosphatase inhibitor. Application of daidzein, an inactive genistein analogue, did not affect significantly either the current amplitudes or the activation kinetics. Possible mechanisms of the observed phenomena and their significance for genistein-induced inhibition of cancer cell proliferation are discussed.

Lipids as a target for drugs modulating multidrug resistance of cancer cells

In this review we focus on the role of the membrane lipids in multidrug resistance and its modulation. Results of the research performed in recent years indicate the importance of lipid phase playing active role in many membrane processes. Along with the alterations of lipid membrane composition of cancer cells (with respect to the normal ones) the resulting changes of the biophysical membrane properties are discussed. Next we describe the general features of multidrug resistance phenomenon paying a special attention to the role of lipids and alterations of lipid membrane composition in MDR cells. Taking into account the phase separation properties of sphingolipids the importance of membrane heterogeneity (presence of caveole and lipid rafts) is emphasised. On the basis of vacuum cleaner hypothesis of drug transport proteins action we discuss the importance of lipid bilayer as medium in which diffusion of drugs takes place. Considering the membrane fluidity and its influence on the integral proteins activity, we underline the role of balance between the passive cellular influx and active efflux of the drug molecules. Finally the effects exerted on membranes by different kinds of multidrug resistance modulators (chemosensitizers) are described. In this part we discuss the influence of verapamil, phenothiazine derivatives, tamoxifen and chosen flavonoids on the biophysical properties of membrane lipids. Some further consequences of the alteration of membrane state are also considered.

Antioxidant status and proteolytic-antiproteolytic balance in colorectal cancer

Free radicals participate in the development of cancer. When the antioxidant defence system is not longer capable to destroy free radicals they may cause lipid and protein oxidation. Lipid peroxidation products also modify proteins. In such a situation the proteolytic-antiproteolytic balance existing in the blood may be changed. Therefore the aim of this study was to examine the correlation between antioxidant status and activity of proteolytic enzymes and their inhibitors in cases of colorectal cancer. This study included 55 patients with colorectal cancer. The blood was taken before surgery and plasma was collected. Total antioxidant status, the levels of lipid peroxidation products (malondialdehyde and 4-hydroxynonenal) and activity of cathepsin G, elastase and their inhibitors (alpha-1-antitrypsin and alpha-2-macroglobulin) were determined in plasma. It was shown that during the development of cancer total antioxidant status was signficantly decreased while lipid peroxidation products were increased. Activity of alpha-2-macroglobulin was decreased and activity of determined enzymes was not significantly changed. The observed changes indicate a shift in proteolytic-antiproteolytic balance which may enhance carcinogenesis.

Protective effect of green tea against lipid peroxidation in the rat liver, blood serum and the brain

This paper reports data on the effect of green tea on the lipid peroxidation products formation and parameters of antioxidative system of the liver, blood serum and central nervous tissue of healthy young rats drinking green tea for five weeks. The rats were permitted free access to solubilized extract of green tea. Bioactive ingredients of green tea extract caused in the liver an increase in the activity of glutathione peroxidase and glutathione reductase and in the content of reduced glutathione as well as marked decrease in lipid hydroperoxides (LOOH), 4-hydroksynonenal (4-HNE) and malondialdehyde (MDA). The concentration of vitamin A increased by about 40%. Minor changes in the measured parameters were observed in the blood serum. GSH content increased slightly, whereas the index of the total antioxidant status increased significantly. In contrast, the lipid peroxidation products, particularly MDA was significantly diminished. In the central nervous tissue the activity of superoxide dismutase and glutathione peroxidase decreased while the activity od glutathione reductase and catalase increased after drinking green tea. Moreover the level of LOOH, 4-HNE and MDA significantly decreased. The use of green tea extract appeared to be beneficial to rats in reducing lipid peroxidation products. These results support and substantiate traditional consumption of green tea as protection against lipid peroxidation in the liver, blood serum, and central nervous tissue.

Reaction of arylsulfonylhydrazones of aldehydes with alpha-magnesio sulfones. A novel olefin synthesis

Reactions of representative tosylhydrazones of aldehydes and ketones with alpha-metalated sulfones were examined in order to develop a practical olefination method. Treatment of aldehyde tosylhydrazone 2 with an excess of alpha-lithiated methyl phenyl or dimethyl sulfones yielded 3a. The reaction of 2 with sterically unhindered lithiated alkyl sulfones gave mixtures of the respective olefination products 3b-d along with the Shapiro fragmentation product 4. Sterically hindered lithiated sulfones afforded Shapiro products exclusively. In contrast, aldehyde tosylhydrazones 2 or 6 in reactions with a variety of alpha-magnesio primary or secondary alkyl sulfones gave olefination products 3a-j and 7a-c in high yields (Tables 1 and 2). beta-Branched alkyl sulfones afforded predominantly (E)-alkenes, whereas unhindered primary sulfones gave mixtures of (E)- and (Z)-alkenes with low selectivity. Reaction of the 2,4,6-triisopropylbenzenesulfonylhydrazone (trisylhydrazone) of cyclodecanone 11c with alpha-magnesio methyl phenyl sulfone afforded the methylidene derivative 12a contaminated with the Shapiro product 13. Tosylhydrazone 2 resisted reaction with i-PrMgCl and gave only a small amount of the addition product in reaction with Bu(2)Mg. Some mechanistic aspects of the reaction of tosylhydrazones with organomagnesium compounds are discussed.

Design, synthesis, and bioactivity of the first nonsteroidal mimetics of brassinolide

Ten novel compounds, each consisting of two subunits and a linker, were designed with the aid of molecular modeling to resemble the natural steroidal phytohormone brassinolide. The mimetics were synthesized and subjected to the rice leaf lamina inclination bioassay to test for brassinosteroid activity. Most of the mimetics displayed very weak or no bioactivity, but two were strongly active when coapplied with the auxin indole-3-acetic acid (IAA), which synergizes the activity of brassinosteroids. Thus, 1-(4,6 alpha,7 alpha-trihydroxy-5,6,7,8-tetrahydronaphthyl)-2-(6 alpha',7 alpha'-dihydroxy-5',6',7',8'-tetrahydronaphthyl)ethyne (4) and (E)-1,2-bis[trans-(4a alpha,8a beta)-4-oxo-6 alpha,7 alpha-dihydroxy-4a,5,6,7,8,8a-hexahydro-(3H)-naphthyl]ethylene (11) showed exceptional activity at doses as low as 0.01 ng and 0.001 ng/plant, respectively. These compounds are the first biologically active nonsteroidal brassinolide mimetics.

Design, synthesis, and bioactivity of the first nonsteroidal mimetics of brassinolide

Ten novel compounds, each consisting of two subunits and a linker, were designed with the aid of molecular modeling to resemble the natural steroidal phytohormone brassinolide. The mimetics were synthesized and subjected to the rice leaf lamina inclination bioassay to test for brassinosteroid activity. Most of the mimetics displayed very weak or no bioactivity, but two were strongly active when coapplied with the auxin indole-3-acetic acid (IAA), which synergizes the activity of brassinosteroids. Thus, 1-(4,6 alpha,7 alpha-trihydroxy-5,6,7,8-tetrahydronaphthyl)-2-(6 alpha',7 alpha'-dihydroxy-5',6',7',8'-tetrahydronaphthyl)ethyne (4) and (E)-1,2-bis[trans-(4a alpha,8a beta)-4-oxo-6 alpha,7 alpha-dihydroxy-4a,5,6,7,8,8a-hexahydro-(3H)-naphthyl]ethylene (11) showed exceptional activity at doses as low as 0.01 ng and 0.001 ng/plant, respectively. These compounds are the first biologically active nonsteroidal brassinolide mimetics.

Monitoring of MRP-like activity in human erythrocytes: inhibitory effect of isoflavones

A method to fluorometrically monitor efflux of 2',7'-bis-(carboxypropyl)-5(6)-carboxyfluorescein (BCPCF) from human erythrocytes was developed. Genistein, daidzein, sophoraisoflavone A, and licoisoflavone A induced 50% inhibition (IC(50)) of BCPCF efflux at 15-70 microM. The IC(50) value of the most efficient isoflavone, licoisoflavone A (15-25 microM), was comparable to that of indomethacin (approximately 10 microM) and markedly lower than for probenecid (100-200 microM), both known MRP1 inhibitors. Our results indicate that the human erythrocyte is a useful cell model in screening potential MRP inhibitors, that BCPCF is a good substrate for MRP, and that some isoflavones at low concentrations inhibit MRP-mediated efflux.

Trifluoperazine induces domain formation in zwitterionic phosphatidylcholine but not in charged phosphatidylglycerol bilayers

The interaction of trifluoperazine with the zwitterionic lipids dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine and with anionic dimyristoylphosphatidylglycerol was studied by means of microcalorimetry and fluorescence spectroscopy. Intercalation of drug molecules into the lipid bilayers was confirmed by the observed differential scanning calorimetry peak broadening and the decrease in chain-melting temperatures. For trifluoperazine:lipid mole ratios higher than 0.4 and 0.6 (for dipalmitoylphosphatidylcholine and dimyristoylphosphatidylcholine, respectively) the deconvolution of transition profiles into two Gaussian components was possible, which suggests phase separation in the studied mixtures. Deconvolution of the thermograms was not possible for any of the drug:dimyristoylphosphatidylglycerol mole ratios studied. To confirm the existence of phase separation in trifluoperazine-phosphatidylcholine mixtures fluorescence spectroscopy experiments were performed using Laurdan as a probe. From the generalised polarisation versus excitation wavelength dependences, recorded at different temperatures, we conclude that a phase separation occurs in the gel state of the studied trifluoperazine-phosphatidylcholine mixtures. We attribute the existence of domains in the bilayer to the dissimilar interactions of two protonation forms of trifluoperazine with phosphatidylcholine molecules. Structural defects present at domain boundaries could be related to the trifluoperazine induced increase of membrane permeability and fluidity. This may partially explain the mechanism of multidrug resistance modulation by trifluoperazine.

[Bland-White-Garland syndrome co-existing with ventricular septal defect and patent ductus arteriosus--diagnostic difficulties]

A case of a 14 month-old boy suffering from unrecognized Bland-White-Garland syndrome with no typical clinical and electrocardiological features was reported. Diagnostic difficulties were caused by ventricular septal defect and patent ductus arteriosus co-existing with the anomaly of left coronary artery. Death caused by myocardial ischemia occurred after surgical closure of VSD and PDA.

Chlorpromazine inhibits miniature GABAergic currents by reducing the binding and by increasing the unbinding rate of GABAA receptors

Recent studies have emphasized that nonequilibrium conditions of postsynaptic GABAA receptor (GABAAR) activation is a key factor in shaping the time course of IPSCs (Puia et al., 1994; Jones and Westbrook, 1995). Such nonequilibrium, resulting from extremely fast agonist time course, may affect the interaction between pharmacological agents and postsynaptic GABAARs. In the present study we found that chlorpromazine (CPZ), a widely used antipsychotic drug known to interfere with several ligand and voltage-gated channels, reduces the amplitude and accelerates the decay of miniature IPSCs (mIPSCs). A good qualitative reproduction of the effects of CPZ on mIPSCs was obtained when mIPSCs were mimicked by responses to ultrafast GABA applications to excised patches. Our experimental data and model simulations indicate that CPZ affects mIPSCs by decreasing the binding (kon) and by increasing the unbinding (koff) rates of GABAARs. Because of reduction of kon by CPZ, the binding reaction becomes rate-limiting, and agonist exposure of GABAARs during mIPSC is too short to activate the receptors to the same extent as in control conditions. The increase in unbinding rate is implicated as the mechanism underlying the acceleration of mIPSC decaying phase. The effect of CPZ on GABAAR binding rate, resulting in slower onset of GABA-evoked currents, provides a tool to estimate the speed of synaptic clearance of GABA. Moreover, the onset kinetics of recorded responses allowed the estimate the peak synaptic GABA concentration.

Mycobacterium tuberculosis infection as a zoonotic disease: transmission between humans and elephants

Between 1994 and 1996, three elephants from an exotic animal farm in Illinois died of pulmonary disease due to Mycobacterium tuberculosis. In October 1996, a fourth living elephant was culture-positive for M. tuberculosis. Twenty-two handlers at the farm were screened for tuberculosis (TB); eleven had positive reactions to intradermal injection with purified protein derivative. One had smear-negative, culture-positive active TB. DNA fingerprint comparison by IS6110 and TBN12 typing showed that the isolates from the four elephants and the handler with active TB were the same strain. This investigation indicates transmission of M. tuberculosis between humans and elephants.

Activity of 2-chlorodeoxyadenosine (Cladribine) in 2-hour intravenous infusion in 94 previously treated patients with low grade non-Hodgkin's lymphoma

The purpose of our study was to determine the efficacy of 2-chlorodeoxyadenosine (2-CdA) administered in 2-hour intravenous infusions in previously treated patients with low grade non-Hodgkin's lymphoma (LGNHL). We treated 94 LGNHL patients with 2-CdA at a dosage of 0.12 mg/kg/24h in 2-hour intravenous infusion for 5 consecutive days. The treatment consisted of from 1 to 7 courses (median 3), repeated usually at monthly intervals. All patients were refractory to or relapsed after standard chemotherapy. Of these 94 patients 78 (83%) had clinical stage IV of the disease. Complete response (CR) was obtained in 12 (12.8%) and partial response (PR) in 36 (38.3%) giving an overall response rate of 51.1%. In 12 (12.8%) grade 4 thrombocytopenia with haemorrhagic diathesis was noted, grade 4 neutropenia was observed in 12 (12.8%) and infections complicated the course of treatment in 38 (40.4%) patients. 2-CdA treatment was the cause of death of 3 patients. The results of our study show that 2-CdA given in 2-hour infusions is an effective agent in advanced, heavily pretreated patients with LGNHL.

Interaction of erythrocyte spectrin with some nonbilayer phospholipids

Bovine erythrocyte spectrin was found to interact with lysophosphatidylcholine and lysophospatidylserine what was detected by small changes of the intrinsic fluorescence of spectrin. Lysophosphatidylethanolamine in contrast to its diacyl, natural counterpart did not affect the intrinsic fluorescence of spectrin at all. Dioleoylphosphatidylethanolamine induced distinct changes in the intrinsic fluorescence from these induced by natural phosphatidylethanolamine suspensions. Our data may indicate an importance of the presence of both fatty acyl chains in phosphatidylethanolamine molecule and perhaps, its bilayer structure for the interaction of this phospholipid aggregates with spectrin.

Interaction of bovine erythrocyte spectrin with aminophospholipid liposomes

Interaction of bovine erythrocyte spectrin with aminophospholipid (phosphatidylethanolamine, phosphatidylserine and their mixture) vesicles was studied by means of intrinsic fluorescence quenching and fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. Similarly as human and pig erythrocyte spectrin, bovine red blood cell spectrin interacts with vesicles prepared from these phospholipids. In model membranes, spectrin induced an increase of order parameter while in natural, red blood cell membranes spectrin binding was rather connected with a decrease in this parameter. The interaction of spectrin with the PE/PS vesicles was not affected by high concentrations of urea. These vesicles also did not protect spectrin from being denatured by urea.

Temperature studies of glyceraldehyde-3-phosphate dehydrogenase binding to liposomes using fluorescence technique

Interaction of rabbit muscle glyceraldehyde-3-phosphate dehydrogenase with negatively charged liposomes was investigated as a function of temperature. This interaction affects the temperature-dependent conformational transition in the enzyme and exerts stabilizing effect on the protein structure. It can be seen from the fluorescence quenching experiments that the accessibility of tryptophanyl residues and isoindol probe fluorophores (covalently bound with the protein amino groups) for a dynamic quencher, acrylamide, is altered upon binding. This accessibility represented by effective quenching constant (Keff) strongly depends on temperature for unmodified enzyme and for the enzyme adsorbed on liposomes, it is nearly constant over a wide range of temperatures.

Effect of spectrin on structure properties of lipid bilayers formed from mixtures of phospholipids. Fluorescence and microcalorimetric studies

Effect of spectrin from human erythrocytes on structure properties of lipid bilayers formed from a mixture of phosphatidylethanolamine/phosphatidylserine (PE/PS) and/or phosphatidylethanolamine/phosphatidylcholine (PE/PC) was studied with the use of fluorescence and microcalorimetric methods. Spectrin did not affect the order parameter of lipids in PE/PS vesicles. However, spectrin binding to liposomes did influence temperature, half-width and enthalpy of phase transitions in mixtures of dimyristoylphosphatidylethanolamine (DMPE) and dimyristoylphosphatidylcholine (DMPC), and this effect was dependent on DMPE to DMPC weight ratio. A change in miscibility of the components in the presence of spectrin was observed and it might be due to spectrin-PE interactions.

Investigation of spectrin binding to phospholipid vesicles using isoindole fluorescent probe. Thermal properties of the bound and unbound protein

Fluorescence of isoindole probe covalently bound to spectrin from pig erythrocytes, and fluorescence of tryptophanyl residues were used to study spectrin interaction with phospholipid bilayers. Evidence would be provided for conformational changes of spectrin occurring upon its binding to lipid bilayers. Fluorescence quenching experiments allowed to determine thermal stability of the protein in bound and unbound state. Spectrin binding to lipids was shown to protect the protein against thermal denaturation.

Interaction of spectrin with phospholipids. Quenching of spectrin intrinsic fluorescence by phospholipid suspensions

Phospholipid suspensions prepared of phosphatidylethanolamine, phosphatidylserine and their mixtures are able to influence the intrinsic protein fluorescence of spectrin. In the case of phosphatidylethanolamine suspension up to 75% of protein fluorescence can be quenched. The interaction of phospholipid aggregates with spectrin is modulated by pH and ionic strength. Phospholipids, particularly phosphatidylethanolamine display a 'stabilizing' effect against the changes of protein fluorescence induced by increasing ionic strength and by thermal denaturation.

Fluorescent probe studies on binding of glyceraldehyde-3-phosphate dehydrogenase to phosphatidylinositol liposomes. Further evidence for conformational changes

Glyceraldehyde-3-phosphate dehydrogenase from rabbit muscle can be absorbed on charged lipid bilayers by electrostatic forces. Upon binding to phosphatidylinositol liposomes the enzyme modifies its conformational state as it is shown by resonance energy transfer experiments. In the presence of 2-mercaptoethanol o-phthaldialdehyde reacts with amino groups of the protein and the covalently bound fluorophore is an acceptor of excitation energy transferred from tryptophanyl residues of the protein. The observed decrease of energy transfer efficiency upon binding to phosphatidylinositol liposomes is compared with the influence of the urea on the fluorescence spectra of the labelled protein. Significance of conformational changes of the enzyme upon adsorption on liposomes in the regulating function of cell membranes is discussed.

Effects of atrial natriuretic factor on drinking responses to central angiotensin II

The present study examined the effects of ANF(4-28) [Wy-47,663], a synthetic 25 amino acid human atrial natriuretic factor, on the dipsogenic actions of centrally-administered angiotensin II in conscious rats. Bolus injection (100 ng) or continuous infusion (60 ng/min) of Wy-47,663 or vehicle into the lateral cerebroventricle had no effect on mean arterial pressure or heart rate. No obvious behavioral changes were observed after central administration of Wy-47,663 or vehicle. Central injection of angiotensin II (15 or 30 ng) promptly elicited prolonged drinking responses in vehicle-treated rats. In rats pretreated with Wy-47,663, the onset of the angiotensin II-induced drinking responses was significantly delayed compared to vehicle-treated animals. However, Wy-47,663 had no effect on the total volume consumed over 30 minutes after angiotensin II injection. Intravenous infusion of Wy-47,663 (2 micrograms/kg/min) failed to alter the dipsogenic action of centrally administered angiotensin II. These data indicate that atrial natriuretic factor found within the brain but not the peripheral circulation may participate in the regulation of extracellular fluid volume by modulating the dipsogenic actions of the central renin-angiotensin system.