Effect of silicone on the collagen fibrillogenesis and stability.

Collagen, the most abundant protein in mammals, is able to form fibrils, which have central role in tissue repair, fibrosis, and tumor invasion. As a component of skin, tendons, and cartilages, this protein contacts with any implanted materials. An inherent problem associated with implanted prostheses is their propensity to be coated with host proteins shortly after implantation. Also, silicone implants undergoing relatively long periods of contact with blood can lead to formation of thrombi and emboli. In this paper, we demonstrate the existence of interactions between siloxanes and collagen. Low-molecular-weight cyclic siloxane (hexamethylcyclotrisiloxane-D3) and polydimethylsiloxanes (PDMS) forming linear chains, ranging in viscosity from 20 to 12,000 cSt, were analyzed. We show that D3 as well as short-chain PDMS interact with collagen, resulting in a decrease in fibrillogenesis. However, loss of collagen native structure does not occur because of these interactions. Rather, collagen seems to be sequestered in its native form in an interlayer formed by collagen-siloxane complexes. On the other hand, silicone molecules with longer chains (i.e., PDMS with viscosity of 1000 and 12,000 cSt, the highest viscosity analyzed here) demonstrate little interaction with this protein and do not seem to affect collagen activity.

Biological and surface-active properties of double-chain cationic amino acid-based surfactants.

Cationic amino acid-based surfactants were synthesized via solid phase peptide synthesis and terminal acylation of their α and ε positions with saturated fatty acids. Five new lipopeptides, N-α-acyl-N-ε-acyl lysine analogues, were obtained. Minimum inhibitory concentration and minimum bactericidal (fungicidal) concentration were determined on reference strains of bacteria and fungi to evaluate the antimicrobial activity of the lipopeptides. Toxicity to eukaryotic cells was examined via determination of the haemolytic activities. The surface-active properties of these compounds were evaluated by measuring the surface tension and formation of micelles as a function of concentration in aqueous solution. The cationic surfactants demonstrated diverse antibacterial activities dependent on the length of the fatty acid chain. Gram-negative bacteria and fungi showed a higher resistance than Gram-positive bacterial strains. It was found that the haemolytic activities were also chain length-dependent values. The surface-active properties showed a linear correlation between the alkyl chain length and the critical micelle concentration.

Synthesis and antimicrobial activity of truncated fragments and analogs of citropin 1.1: The solution structure of the SDS micelle-bound citropin-like peptides.

Citropin 1.1 is a basic, highly hydrophobic, 16-amino acid peptide (GLFDVIKKVASVIGGL-NH(2)), displaying wide-spectrum antimicrobial activities. In this paper we describe the synthesis and antimicrobial properties of citropin 1.1 and its 18 analogs constituting mostly truncated fragments of citropin 1.1. Moreover, we examined conformational properties of citropin 1.1 and its two analogs, (1-12)citropin and (1-13)[Ala(4)]citropin, using FTIR, CD and NMR spectroscopies. Three-dimensional structures of the peptides were determined using molecular dynamics (MD) simulations with time-averaged (TAV) restraints obtained from NMR spectra measured in micellar concentration of sodium dodecyl sulfate (SDS). Earlier investigations showed that in TFE solution, citropin 1.1 is a single helix all along the backbone. However, this structure is not retained in the presence of SDS micelle. In H(2)O/SDS-d(25) solution, citropin 1.1 adopts two alpha-helices in the fragments 4-7 and 10-16, respectively, separated by betaIV-turn at position 8, 9. The (1-12)citropin adopts an alpha-helical structure along the entire backbone. In turn, (1-13)[Ala(4)]citropin demonstrates the tendency to adopt only a short alpha-helix in the middle part. Moreover, the conversion of alpha-helix to 3(10)-helix has been noticed in about 30% of conformations. The 3(10)-helical units could be thermodynamic intermediates during folding and unfolding of the alpha-helical segment of the peptide.

Serum selenium concentration in patients with Wilson's disease.

BACKGROUND/AIMS: Wilson's disease is a genetically determined disorder of copper metabolism in the liver. Due to the toxic accumulation of this trace element, body organs are damaged by free radical generation, lipid peroxidase and inhibition of synthesis of some proteins. Behavior of anti-oxidative factors in Wilson's disease has not been completely evaluated yet. The aim of the study was to assess blood serum concentrations of selenium in patients with Wilson's disease. METHODOLOGY: Twenty-five patients with Wilson's disease and 30 healthy volunteers, constituting a control group were included in the study. The patients were in good clinical condition. In all the subjects blood serum concentrations of selenium were tested using the atomic absorption spectroscopy, hydride generation method. RESULTS: Selenium concentrations in the blood serum of the patients and healthy controls did not show statistical differences between both groups. Correlations between selenium concentrations and biochemical parameters: activity of alanine and aspartate aminotransferase, alkaline phosphatase, gamma-glutamyltranspeptidase, concentration of bilirubin, albumin and gamma globulin, international normalized prothrombin index as well as serum copper, ceruloplasmine and 24-h urine copper excretion were assessed. Statistically significant correlation was found only between selenium concentration and aspartate aminotransferase activity. No statistically significant differences between selenium concentrations in the serum of patients with different forms of Wilson's disease were found. CONCLUSIONS: On the basis of the results obtained in the study it can be assumed that in treated patients with Wilson's disease the antioxidant status measured as serum selenium concentration is comparable to healthy controls.

Pretreatment with the protegrin IB-367 affects Gram-positive biofilm and enhances the therapeutic efficacy of linezolid in animal models of central venous catheter infection.

BACKGROUND: Biofilms play an important role in the pathogenesis of several chronic infections and nosocomial infections related to indwelling medical devices. METHODS: To assess the efficacy of IB-367 and linezolid (LZD) in the treatment of central venous catheter (CVC) infections using the antibiotic-lock technique, in vitro and in vivo studies were performed. The in vitro antibiotic susceptibility assay for Staphylococcus aureus and Enterococcus faecalis biofilms developed on 96-well polystyrene tissue culture plates was performed to determine the activity of the compounds. Efficacy studies were performed in rat models of Gram-positive CVC infection. Silastic catheters were implanted into the superior cava of adult male Wistar rats. Twenty-four hours after implantation, the catheters were pretreated by filling with IB-367. Thirty minutes later, rats were challenged via the CVC with 1.0 x 10(6) CFU (colony forming units) of S aureus strain diffuse Smith and clinical isolate of slime-producing E faecalis. Administration of LZD into the CVC at a concentration equal to the minimum bacteriocidal concentration observed using adherent cells or at a much higher concentration (1024 microg/mL) began 24 hours later. RESULTS: Both for S aureus and E faecalis, the killing activities of LZD against adherent bacteria were at least 4-fold to 8-fold lower than that against freely growing cells. For both strains, in IB-367-pretreated wells, LZD strongly increases its activity. The in vivo studies showed that when CVCs were pretreated with IB-367, Gram-positive biofilm bacterial load was further decreased to 10(1) CFU/mL and bacteremia was not detected. CONCLUSIONS: IB-367 has potential as an adjunctive agent to LZD in the treatment of Gram-positive biofilm infections such as CVC infections.

High magnesium or potassium hair accumulation is not associated with ischemic stroke risk reduction: a pilot study.

OBJECTIVES: Various studies suggest that deficiency of magnesium and potassium may be associated with increased risk of ischemic stroke. However, single time-point serum measurements may not be suitable for assessing long-term tissue levels. PATIENTS AND METHODS: We investigated Mg and K levels in hair of patients with acute ischemic stroke. The elements hair accumulation analysis might provide historical information on their concentrations over a longer period of time and probably reflects the corresponding nutritional condition. The concentrations of Mg and K in hair of 48 men with acute ischemic stroke and a control group were measured using spectroscopic methods. RESULTS: The mean Mg and K concentrations in hair of patients were significantly higher than in the controls. CONCLUSIONS: This analysis does not seem to confirm the results of the previous studies suggesting that Mg or K high levels (or their diet supplementation) might protect humans against ischemic stroke.

In vitro release of cisplatin from sol-gel processed organically modified silica xerogels.

SiO2, SiO2/PEG and SiO2/PDMS xerogels were examined as polymeric carriers for the controlled release of cisplatin--an antineoplasmic medicine. Drug/carrier systems were prepared by the sol-gel method. The effect of organic substitution of the silica xerogel matrix and drying conditions on the release of cisplatin was evaluated. Based on the presented results of the study it may be stated that sol-gel method is useful for entrapping a cisplatin in the pores of organically modified silica gels and for releasing cisplatin mainly in the way of diffusion from the pores of the lattice under the in vitro conditions. The use of organic impurities in silica gel increased the release of cisplatin from xerogel (from 62% to 97% within 7 days), and thermal treatment of all xerogels with cisplatin at the temperature of 80 degrees C resulted in the acceleration of the drug release (2 days) and increase of the released drug (89-98%).

Efficacy of tachyplesin III, colistin, and imipenem against a multiresistant Pseudomonas aeruginosa strain.

An experimental study has been performed to compare the in vitro activity and the in vivo efficacy of tachyplesin III, colistin, and imipenem against a multiresistant Pseudomonas aeruginosa strain. In vitro experiments included MIC determination, time-kill, and synergy studies. For in vivo studies, a mouse model of sepsis has been used. The main outcome measures were bacterial lethality, quantitative blood cultures, and plasma levels of lipopolysaccharide, tumor necrosis factor alpha, and interleukin-6. The combination of tachyplesin III or colistin with imipenem showed in vitro synergistic interaction. A significant increase in efficacy was also observed in vivo: combination-treated groups had significantly lower levels of bacteremia than did groups treated with a single agent. Tachyplesin III combined with imipenem exhibited the highest efficacy on all main outcome measurements. These results highlight the potential usefulness of these combinations and provide therapeutic alternatives for serious infections caused by gram-negative bacteria in the coming years.

In vitro activities of tachyplesin III against Pseudomonas aeruginosa.

The in vitro activities of tachyplesin III were investigated against 20 multidrug-resistant Pseudomonas aeruginosa clinical isolates. Methods included minimal inhibitory concentrations, minimal bactericidal concentrations, time-kill studies, checkerboard titration method, endotoxin-binding activity and cytotoxicity assay. Overall the organisms were susceptible to the peptide at concentrations of 0.50-4 mg/l. Tachyplesin III completely inhibits the endotoxin procoagulant activity at 22.36 mg/l concentration. Fractional inhibitory concentration indexes demonstrated synergy between the peptide and betalactams or colistin. In conclusion, the intrinsic antibacterial and antiendotoxin activities and the synergistic interactions demonstrated with clinically used antibiotics make tachyplesin III valuable as potential candidate for new therapeutic strategies aimed to treat P. aeruginosa infection.

In vitro activity of aurein 1.2 alone and in combination with antibiotics against gram-positive nosocomial cocci.

This study was performed to evaluate the in vitro activity of the amphibian peptide aurein 1.2 and to investigate its interaction with six antibiotics against nosocomial gram-positive cocci. All isolates were inhibited at concentrations of 1 to 16 mg/liter. Synergy was demonstrated when aurein 1.2 was combined with clarithromycin and minocycline.

[Classification of thyroid gland disease on the basis of selenium concentration in serum]. / Klasyfikacja schorzen tarczycy na podstawie stezenia selenu w surowicy krwi.

The aim of this study was to estimate the concentration of total selenium in serum women with thyroid gland disease. Selenium was determined by atomic absorption spectrometry using the hydride generation method (HG-AAS). Research was determined in 94 patients with thyroid gland disease and in 28 healthy controls. Selenium concentration of serum was variously in patients than in control group and patients with different thyroid gland diseases. Concentration in control group was 0.06231 microg/ml, in goitre group--0.05612 microg/ml, in hyperthyroidism--0.07149 microg/ml and in hypothyroidism--0.09088 microg/ml.

The effect of PEG concentration on the release rate of cisplatin from PEG-modified silica xerogels.

Cisplatin-an antineoplastic medicine-was incorporated into a polyethylene glycol (PEG)-modified silica xerogels received by the sol-gel method. The influence of PEG concentration and drying temperature on the release of cisplatin was studied. From our results we may state that addition of PEG (MW 600) and drying of silica xerogels at 80 degrees C augmented the release of cisplatin. The release of cisplatin from the matrices grows with the increase of PEG volume in xerogel (up to 74-97% within 7 days), whereas application of thermal drying resulted in both increased speed and amount of the drug released up to 91-97% within 2 days.

Amphibian peptides prevent endotoxemia and bacterial translocation in bile duct-ligated rats.

OBJECTIVE: To investigate the efficacy of amphibian antimicrobial peptides in preventing bacterial translocation and neutralizing endotoxins in bile duct-ligated rats. DESIGN: Prospective, randomized, controlled animal study. SETTING: Research laboratory in a university hospital. SUBJECTS: Adult male Wistar rats. INTERVENTIONS: Adult male Wistar rats underwent sham operation or bile duct ligation (BDL). Eight groups were studied: sham operation with saline treatment, sham operation with 120 mg/kg tazobactam-piperacillin, sham operation with 2 mg/kg uperin 3.6, sham operation with 2 mg/kg magainin2, BDL with saline treatment, BDL with 120 mg/kg tazobactam-piperacillin, BDL with 2 mg/kg uperin 3.6, and BDL with 2 mg/kg magainin2. MEASUREMENTS AND MAIN RESULTS: Main outcome measures were: endotoxin and tumor necrosis factor-alpha concentrations in plasma and evidence of bacterial translocation in blood, peritoneum, liver, and mesenteric lymph nodes. Endotoxin and tumor necrosis factor-alpha plasma levels were significantly higher in BDL rats compared with sham-operated animals. All amphibian peptides achieved a significant reduction of plasma endotoxin and tumor necrosis factor-alpha concentration when compared with saline- and tazobactam-piperacillin-treated groups. On the other hand, both tazobactam-piperacillin and peptides significantly reduced bacterial growth compared with the control. Tazobactam-piperacillin and magainin2 exerted the maximal inhibition of bacterial growth. CONCLUSION: In conclusion, because of their multifunctional properties, amphibian peptides could be interesting compounds to inhibit bacterial translocation and endotoxin release in obstructive jaundice.

Citropin 1.1-treated central venous catheters improve the efficacy of hydrophobic antibiotics in the treatment of experimental staphylococcal catheter-related infection.

An in vitro antibiotic susceptibility assay for Staphylococcus aureus biofilms developed on 96-well polystyrene tissue culture plates was performed to elucidate the activity of citropin 1.1, rifampin and minocycline. Efficacy studies were performed in a rat model of staphylococcal CVC infection. Silastic catheters were implanted into the superior cava. Twenty-four hours after implantation the catheters were filled with citropin 1.1 (10 microg/mL). Thirty minutes later the rats were challenged via the CVC with 1.0 x 10(6) CFU of S. aureus strain Smith diffuse. Administration of antibiotics into the CVC (the antibiotic lock technique) began 24 h later. The study included: one control group (no CVC infection), one contaminated group that did not receive any antibiotic prophylaxis, one contaminated group that received citropin 1.1-treated CVC, two contaminated groups that received citropin 1.1-treated CVC plus rifampin and minocycline at concentrations equal to MBCs for adherent cells and 1024 microg/mL in a volume of 0.1 mL that filled the CVC and two contaminated groups that received rifampin or minocycline at the same concentrations. All catheters were explanted 7 days after implantation. Main outcome measures were: minimal inhibitory concentration (MIC), minimal bactericidal concentration (MBC), synergy studies, quantitative culture of the biofilm formed on the catheters and surrounding venous tissues, and quantitative peripheral blood cultures. MICs of conventional antibiotics against the bacteria in a biofilm were at least four-fold higher than against the freely growing planktonic cells. In contrast, when antibiotics were used on citropin 1.1 pre-treated cells they showed comparable activity against both biofilm and planktonic organisms. The in vivo studies show that when CVCs were pre-treated with citropin 1.1 or with a high dose of antibiotics, biofilm bacterial load was reduced from 10(7) to 10(3) CFU/mL and bacteremia reduced from 10(3) to 10(1) CFU/mL. When CVCs were treated both with citropin 1.1 and antibiotics, biofilm bacterial load was further reduced to 10(1) CFU/mL and bacteremia was not detected, suggesting 100% elimination of bacteremia and a log 6 reduction in biofilm load. Citropin 1.1 significantly reduces bacterial load and enhances the effect of hydrophobic antibiotics in the treatment of CVC-associated S. aureus infections.

In vitro activity of synthetic antimicrobial peptides against Candida.

Yeast-like fungi are the most common cause of fungal infections in humans. Actually, in the age of opportunistic infections and increasing resistance, development of modern antifungal agents becomes a very important challenge. This paper describes synthesis and antimicrobial assay of four naturally occurring peptide antibiotics (aurein 1.2, citropin 1.1, temporin A, uperin 3.6) and three chemically engineered analogues actually passing clinical trials (iseganan, pexiganan, omiganan) against Candida strains isolated from patients with infections of the oral cavity or respiratory tract. The peptides were synthesized using solid-phase method and purified by high-performance liquid chromatography. Biological tests were performed using the broth microdilution method. The antifungal activity of the peptide antibiotics was compared to that of nystatin and amphotericin B. We found synthetic peptides to be generally less potent than amphotericin B or nystatin. However, some of the naturally occurring peptides still retained reasonable antifungal activities which were higher than these of iseganan, pexiganan or omiganan. We think that the naturally occurring peptide antibiotics included in our study can be a good matrix for development of novel antifungal compounds.

In vitro activity of amphibian peptides alone and in combination with antimicrobial agents against multidrug-resistant pathogens isolated from surgical wound infection.

The in vitro activities of three amphibian peptides magainin II amide, citropin 1.1 and temporin A alone and in combination with eight clinically used antimicrobial agents (imipenem, ceftazidime, clarithromycin, vancomycin, amikacin, polymyxin E, ciprofloxacin and linezolid) were investigated against several multidrug-resistant Pseudomonas aeruginosa and Staphylococcus aureus strains isolated from surgical wound infections. Antimicrobial activities were measured by MIC, MBC and time-kill studies. P. aeruginosa strains were more susceptible to magainin II amide and less susceptible to temporin A. S. aureus isolates were highly susceptible to temporin A and citropin 1.1. The combination studies showed synergy between citropin 1.1 and clarithromycin. Magainin II amide and temporin A showed synergism with imipenem and ceftazidime. Finally, all peptides showed synergistic effects with polymyxin E. These results provide evidence for the potential use of these antimicrobial peptides in the topical or systemic treatment of surgical wound infections.

Temporin A alone and in combination with imipenem reduces lethality in a mouse model of staphylococcal sepsis.

BACKGROUND: Morbidity and mortality from staphylococcal toxic shock remain high, despite the availability of antibiotics to which the microorganism is sensitive. METHODS: In in vitro experiments, the ability of temporin A to inhibit lipoteichoic acid-induced production of tumor necrosis factor (TNF)- alpha and nitric oxide (NO) was determined. Also, mouse models of staphylococcal sepsis were used to evaluate the efficacy of temporin A alone and in combination with imipenem. BALB/c mice were injected intravenously with live Staphylococcus aureus or heat-killed cells and then received either isotonic sodium chloride solution, 2 mg/kg temporin A, 7 mg/kg imipenem, or 2 mg/kg temporin A in combination with 7 mg/kg imipenem immediately and 6 h after challenge. The main outcome measures were lethality rates, plasma bacterial counts, and plasma TNF- alpha and interleukin (IL)-6 levels. RESULTS: The in vitro experiments showed that temporin A did not cause TNF- alpha or NO release. In the in vivo experiments with live bacteria, both compounds reduced lethality rates and bacterial growth. Imipenem exhibited the highest efficacy. The combination-treated group had significantly lower bacterial counts than did the singly-treated groups and the lowest lethality rates. In the experiments with heat-killed cells, only temporin A demonstrated significant efficacy with respect to lethality and reduction of plasma TNF- alpha and IL-6 levels. DISCUSSION: This study shows that temporin A can reduce the stimulatory effects of bacterial cell components and suggests that it may be beneficial in the treatment of severe staphylococcal sepsis.

In vitro activity of MSI-78 alone and in combination with antibiotics against bacteria responsible for bloodstream infections in neutropenic patients.

MSI-78 is a 22 amino acid amphipathic peptide with potent antimicrobial activity against Gram-positive and Gram-negative organisms, including antibiotic-resistant strains. In this study, we assessed the in vitro activity of MSI-78 alone and in combination with eight clinically used antimicrobial agents against several strains of Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli isolated from blood of neutropenic febrile patients. Antimicrobial activity of MSI-78 was measured by minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill studies and checkerboard titration method. The Gram-negative isolates were susceptible to the peptide at concentrations in the range 0.50-16 mg/L, while staphylococci showed lower susceptibility. MSI-78 demonstrated a higher antimicrobial activity than colistin against Gram-negative organisms. The checkerboard titration method demonstrated synergy when the peptide was combined with beta-lactams. These results provide evidence for the potential use of MSI-78 in the management of severe infections in neutropenic patients.

[Selenium concentration in serum of women with thyroid gland disease]. / Stezenie selenu w surowicy krwi u kobiet ze schorzeniami tarczycy.

The aim of this study was to estimate the concentration of total selenium in serum women with thyroid gland disease. Selenium was determined by atomic absorption spectrometry using the hydride generation technique (HG-AAS). Selenium was determined in 30 patients with thyroid gland disease and in 12 healthy controls. Selenium concentration of serum was variously in patients than in control group and patients with different thyroid gland disease. The average concentration of selenium in control group was 0.0694 microg/ml, in goiter group 0.0529 microg/ml, in hyperactivity group 0.0441 microg/ml, in hypofunction group 0.0520 microg/ml.g/ml.

In vitro activity and killing effect of uperin 3.6 against gram-positive cocci isolated from immunocompromised patients.

The in vitro activity of uperin 3.6, alone or combined with six antibiotics, against gram-positive cocci, including Rhodococcus equi, methicillin-resistant staphylococci, and vancomycin-resistant enterococci, was investigated. All isolates were inhibited at concentrations of 1 to 16 mg/liter. Synergy was demonstrated when uperin 3.6 was combined with clarithromycin and doxycycline.