Association of Biofilm Inducer with bla VIM, bla IMP, and bla NDM in Pseudomonas aeruginosa Isolates.

Pseudomonas aeruginosa (P. aeruginosa) is a ubiquitous opportunistic organism that is hard to treat. This study aimed to investigate the association of bla VIM, bla IMP, and bla NDM prevalence with Cyclic di-GMP (c-di-GMP) in P. aeruginosa. To this end, 27 clinical isolates of P. aeruginosa were obtained from different hospitals in Baghdad, Iraq. The phenotypic detection of carbapenem and biofilm assays was performed by the M63 minimal medium, supplemented with glucose, magnesium sulfate. The polymerase chain reaction was utilized to detect carbapenem genes. The results showed that the isolates were highly resistant to Imipenem (37%) and Meropenem (63%). Imipenem (37%) and Meropenem (63%) demonstrated a moderate sensitivity against P. aeruginosa. The P. aeruginosa No.5 showed high resistance to carbapenem by bla VIM +, bla IMP +, and bla NDM +, followed by a robust biofilm confirmed with c-di-GMP levels and the twitching motility ability. Upon these findings, the use of antibiotics should be restricted to severe bacterial infections to avoid the rapid emergence of new resistant isolates, which leads to the hard treatment of infection with P. aeruginosa. It is highly recommended that these findings be notified for infectious control. Future studies can investigate the link between transferable resistant genes and c-di-GMP values.

A Novel Phage Cocktail Therapy of the Urinary Tract Infection in a Mouse Model.

Escherichia coli (E. coli) is a major bacterial pathogen associated with many cases of serious infections, such as urinary tract infections (UTI) and meningitis intestinal. The rapid emergence of antimicrobial multidrug-resistant bacteria occurring worldwide has been attributed to the overuse of antibiotics. Alternative strategies must be developed to overcome antibiotic resistance. A promising alternative for the treatment of infections is the use of phages as antibacterial agents. A total of 90 female albino mice were randomly divided into three groups (n=30) and used for the induction of UTI. The animals were acclimatized in their cages for 24 h before inoculation and allowed to access chow and water freely. For UTI induction, the peri-urethral area was sterilized with 70% ethanol, and bacterial inoculation was then injected into the bladder through the urethra using a 24-gauge sterile Teflon catheter with an outer diameter of 0.7 mm and length of 19 mm. A single phage and a phage cocktail preparation have been evaluated for their therapeutic activity in the mouse model of chronic UTI induced by transurethral injection of two isolates of the uropathogenic E. coli 8 and E. coli 302. The results of the transurethral and intra-peritoneal injection of phage(s) that prepared on day 10 after the establishment of the mouse chronic model showed no effect of a single phage PEC80 in the treatment of UTI, whereas both administration routes of the phage cocktail preparation resulted in the clearance of bacteria from mice urine and homogenates of the urinary bladders and kidneys of the sacrificed mice after 24 h following the administration of phage cocktail dose. The high activity of the phage cocktail in the treatment of mouse chronic model of UTI is attributed to the broader host range of the phage cocktail, compared to the very narrow host range of the phage PEC80. It is concluded that the phage therapy by using phage preparations as the 25 phages cocktail evaluated in this study is a highly promising and potential alternative therapy for human UTIs.

Nanosilver-PMMA composite coating optimized to provide robust antibacterial efficacy while minimizing human bone marrow stromal cell toxicity.

Porous PMMA is a versatile biomaterial with good biocompatibility but high susceptibility to bacterial colonization, which we mitigated by utilizing immobilized antimicrobial silver nanoparticles (AgNPs). A uniform porous thin film was deposited onto silicon wafers by simultaneously ablating PMMA and silver (Ag) using pulsed laser deposition (PLD) optimized for minimal human cell toxicity and antibacterial efficacy. PMMA without Ag became heavily colonized by E. coli in simulated dynamic conditions, while Ag-containing samples prevented all colonization. ICP-MS analysis demonstrated that the amount of leached Ag after 24h under simulated in vivo conditions (with serum media at 37°C and 5% CO2) increased in proportion to film thickness (and total silver content). 10,000, 14,000, and 20,000 laser pulse-deposited films released 0.76, 1.05, and 1.67µg/mL Ag, respectively, after 24h. Human bone marrow stromal cells (hBMSCs) grown directly on 10,000-pulse films (0.76µg/mL Ag released) for 24-h exhibited no cytotoxicity. Exposure to the remaining films produced cytotoxicity, necrosis, and apoptosis detected using flow cytometry. Examining both leachates and direct cell contact allowed us to develop an in vitro cytotoxicity test method and optimize a novel device material and coating to be nontoxic and bactericidal during both potential initial implantation and external use.

Nanosecond laser switching of surface wettability and epitaxial integration of c-axis ZnO thin films with Si(111) substrates.

We have achieved integration of polar ZnO[0001] epitaxial thin films with Si(111) substrates where cubic yttria-stabilized zirconia (c-YSZ) was used as a template on a Si(111) substrate. Using XRD (θ-2θ and φ scans) and HRTEM techniques, the epitaxial relationship between the ZnO and the c-YSZ layers was shown to be [0001]ZnO || [111]YSZ and [21¯1¯0]ZnO || [1¯01](c-YSZ), where the [21¯1¯0] direction lies in the (0001) plane, and the [1¯01] direction lies in the (111) plane. Similar studies on the c-YSZ/Si interface revealed epitaxy as (111)YSZ || (111)Si and in-plane (110)YSZ || (110)Si. HRTEM micrographs revealed atomically sharp and crystallographically continuous interfaces. The ZnO epilayers were subsequently laser annealed by a single pulse of a nanosecond excimer KrF laser. It was shown that the hydrophobic behavior of the pristine sample became hydrophilic after laser treatment. XPS was employed to study the effect of laser treatment on surface stoichiometry of the ZnO epilayers. The results revealed the formation of oxygen vacancies, which are envisaged to control the observed hydrophilic behavior. Our AFM studies showed surface smoothing due to the coupling of the high energy laser beam with the surface. The importance of integration of c-axis ZnO with Si(111) substrates is emphasized using the paradigm of domain matching epitaxy on the c-YSZ[111] buffer platform along with their out-of-plane orientation, which leads to improvement of the performance of the solid-state devices. The observed ultrafast response and switching in photochemical characteristics provide new opportunities for application of ZnO in smart catalysts, sensors, membranes, DNA self-assembly and multifunctional devices.

Defect mediated photocatalytic decomposition of 4-chlorophenol on epitaxial rutile thin films under visible and UV illumination.

We show that pure rutile TiO(2) can be photo-responsive even under low energy visible light after annealing in vacuum where we envisage that the point defects, i.e. oxygen vacancies and titanium interstitials, serve an important role. In this study, single crystal rutile films were grown by the pulsed laser deposition technique and then vacuum annealed under different oxygen pressures to introduce defects into their lattices. 4-chlorophenol was selected as a model material and decomposed by the annealed TiO(2) films where the maximum photocatalytic reaction rate constants were determined as 0.0107 and 0.0072 min(-1) under UV and visible illumination. Epitaxial growth along the [200] direction was confirmed by φ-scan and 2θ-scan XRD and the epitaxial relationship between the rutile film and the c-sapphire substrate was explained as (100)[010](R) [parallel] (0001)[12[combining overline]10](S). The formation of atomically sharp interfaces and the epitaxial growth were ascertained by annular dark-field STEM imaging. Based on the XPS, UV-vis and PL spectroscopy results, it was found that the defect concentration increased after annealing under lower pressures, e.g. 5 × 10(-6) Torr. In contrast, more perfect crystals were obtained when the films were annealed under high oxygen pressures, namely 5 × 10(1) Torr. The morphology of the films was also investigated by employing an AFM technique. It was observed that increase of the annealing pressure results in the formation of larger grains. It was also found that the electrical resistivity of the rutile films strongly increased by about three orders of magnitude when the annealing pressure increased from 5 × 10(-4) to 5 × 10(1) Torr.

Effect of synaptic plasticity on the structure and dynamics of disordered networks of coupled neurons.

In an all-to-all network of integrate-and-fire neurons in which there is a disorder in the intrinsic oscillatory frequencies of the neurons, we show that through spike-timing-dependent plasticity the synapses which have the high-frequency neurons as presynaptic tend to be potentiated while the links originated from the low-frequency neurons are weakened. The emergent effective flow of directed connections introduces the high-frequency neurons as the more influential elements in the network and facilitates synchronization by decreasing the synaptic cost for onset of synchronization.

An innovative technique to simply fabricate ZrO2-HA-TiO2 nanostructured layers.

For the first time, ZrO2-HA-TiO2 layers were synthesized through EPD-Enhanced MAO (EEMAO) technique in only one step where no supplementary treatment was required. SEM, XRD, EDX, and XPS techniques were employed to propose a correlation between the growth parameters and the physical and chemical properties of the layers. The layers revealed a porous structure where applying higher voltages and/or utilizing higher concentrated electrolytes resulted in formation of wider pores and increasing the zirconium concentration in the layers; meanwhile, prolonging the growth time had the same effects. The layers mainly consisted of anatase, hydroxyapatite, monoclinic ZrO2, and tetragonal ZrO2 phases. Increasing the voltage, electrolyte concentration, and time, hydroxyapatite as well as tetragonal ZrO2 was decomposed to α-TCP, monoclinic ZrO2, and ZrO. The nanosized zirconia particles (d = 20-60 nm) were further accumulated on the vicinity of the layers when thicker electrolytes were utilized or higher voltages were applied. Emphasizing on the chemical and electrochemical foundations, a probable formation mechanism was finally put forward.

Statistical mechanics of steiner trees.

The minimum weight Steiner tree (MST) is an important combinatorial optimization problem over networks that has applications in a wide range of fields. Here we discuss a general technique to translate the imposed global connectivity constrain into many local ones that can be analyzed with cavity equation techniques. This approach leads to a new optimization algorithm for MST and allows us to analyze the statistical mechanics properties of MST on random graphs of various types.

Fullerene-linked Pt nanoparticle assemblies.

Fullerene-Pt nanoparticle assemblies were prepared by attachment and immobilisation of different Pt nanoparticles on a gold electrode using molecular layers of C60 as a linker system. These assemblies were active for the methanol oxidation following treatment with CO.

Development of partition coefficients, Vmax and Km values, and allometric relationships.

A knowledge of the methods used to obtain partition coefficients, Vmax, and Km values, and the use of allometric relationships is essential to understanding their role in physiologically based pharmacokinetic (PBPK) models. Vial equilibration methods for obtaining the partition coefficients of volatile and nonvolatile compounds were presented using the results from studies with p-chlorobenzotrifluoride (PCBTF) and isofenphos, respectively. Partition coefficients for volatile and nonvolatile compounds from published studies were included. Several published in vivo inhalation (gas uptake) studies and in vitro enzyme studies were presented to demonstrate several methods for obtaining Vmax and Km values. Allometric equations used in PBPK models for body weight scaling of respiration and cardiac rates between species were presented along with equations for within species body weight scaling of Vmax.

Development of in vitro Vmax and Km values for the metabolism of isofenphos by P-450 liver enzymes in animals and human.

The rate of metabolism of [14C]isofenphos (IFP) to isofenphos oxon (IFP-oxon), des N-isofenphos (d-N-IFP), and des N-isofenphos oxon (d-N-IFP-oxon) by rat, guinea pig, monkey, dog, and human liver microsomal P-450 enzymes was studied to obtain Vmax and Km values for Michaelis-Menten kinetics. The monkey had the highest Vmax value for the conversion of IFP to IFP-oxon (desulfuration), 162 nmol isofenphos hr-1 per 1.3 nanomoles P-450, followed by guinea pig (98), rat (66), dog (43), and human (14). The Km values for the desulfuration of isofenphos were 19.2, 7.4, 14.1, 23.3, and 18.4 microM, respectively, for the monkey, guinea pig, rat, dog, and human. The Vmax values for the dealkylation process (conversion of IFP to d-N-IFP) were 64.6, 17.2, 9.7, and 7.3 nmol isofenphos hr-1 per 1.3 nanomoles P-450 for the monkey, rat, dog, and human, respectively. For the dealkylation process, monkey had the highest Km value, 16.3 microM IFP, followed by human (11.2), rat (9.9), and dog (9.3). The rate of metabolism of IFP-oxon and d-N-IFP to d-N-IFP-oxon were separately studied. The Vmax and Km values obtained in this study for animal and human liver P-450 enzymes will be used to develop a PB-PK/PB-PD model to predict the fate and toxicity of isofenphos in animals and man.

Effect of inhaled dimethylselenide in the Fischer 344 male rat.

In this project, a total of 60 adult Fischer 344 male rats were exposed to dimethylselenide (DMSe) vapor at 1607, 4499, or 8034 ppm for 1 h (20 rats/group). In addition, 26 unexposed rats were used as controls. The exposed rats were observed frequently during the 7 d following exposure and appeared normal. The animals were sacrificed at either 1 or 7 d after inhalation and the major tissues were grossly examined and weighed. Selenium levels were found to be elevated only in the lung at d 1. At d 1, significant changes in organ weights were an increase in the lung weight at exposure levels of 1607 and 8034 ppm of DMSe and in liver weight at 4499 and 8034 ppm. At d 1, significant changes in the lung were an increase in protein at 1607 and 8034 ppm of DMSe, and an increase in RNA and a reduction in DNA at 4499 ppm DMSe. The only change in the liver was a reduction in DNA at 4499 ppm. At 7 d, the protein content and RNA content of spleen were increased. Lung, liver, kidney, spleen, thymus, lymph nodes, pancreas, and adrenal gland were examined microscopically and found to be normal. All of these observed responses were minor and did not severely impact the health of the rats. Overall, the data indicate that the inhalation of DMSe for 1 h has relatively low toxicity in rats even at high concentrations.

The lymphotoxic action of vanadate.

The acute toxicity of ammonium metavanadate (15.5 mg/kg) in mice was investigated to examine the induction of lymphoid necrosis to (1) verify the reproducibility of the lesions in the thymus, lymph nodes, and spleen; (2) determine whether the necrosis of lymphoid tissue previously observed during the first 3 days post-treatment but absent at 14 days was the result of differences in sensitivity of the mice or the result of recovery from the effects of vanadium; and (3) determine whether differences in the presence and the degree of necrosis between thymus and spleen were correlated with differences in the uptake of vanadium in these tissues. A timed sacrificed study was conducted in conjunction with a 48V tracer. In this study, BALB/C mice were injected subcutaneously (s.c.) with ammonium metavanadate solution (15.5 mg/kg). Groups of mice were sacrificed at 0.5, 1, 2, 3, 4, 6, 8, 10, 12, 14, 21, and 28 days postexposure. Lymphoid necrosis was found in the thymus, spleen, lymph nodes, and bone marrow, with the necrosis being most severe in the thymus. The necrosis was moderate at 0.5 days, most severe at 2 to 3 days, with recovery beginning at 4 days, and proceeding to full recovery at 14 to 28 days. At 0.5 days post-treatment, the concentration of vanadium in thymus and spleen was 4.4 and 8.3 micrograms/g, respectively. At all post-treatment periods, with the exception of the 1- and the 4-day periods, the concentration of vanadium in spleen was significantly higher than in the thymus, p less than 0.05. The treated animals showed neurological signs (ataxia, convulsion, dyspnea, and paralysis of hind legs) between 5 min and 54 hr post-treatment, but the concentration of vanadium in the brain was very low during this period (less than 5.2% of blood concentration).

Time and dose-response study of the effects of vanadate in rats: changes in blood cells, serum enzymes, protein, cholesterol, glucose, calcium, and inorganic phosphate.

A daily dosage of vanadate (0.9 mgV/kg) injected subcutaneously for 16 days to adult rats produced significant changes in blood cells and serum elements. The hematological changes included an increase in white blood cell count at two days after the last injection. At five days, red blood cell count (RBC), hemoglobin, and packed cell volume (PCV) were low. At 12 days, there were reductions in RBC, hemoglobin, PCV, and lymphocyte counts and an increase in polymorphonuclear cell (PMN) counts. At 25 days, RBC, hemoglobin, and PCV were still low. At 40 days, the only change was a reduction in RBC. Changes in the serum at two days posttreatment were a reduction in lactic dehydrogenase activity (LDH), alkaline phosphatase activity (AP), calcium, albumin, and total protein and an increase in cholesterol. At five days, glutamic-oxalacetic transaminase (GOT), lactic dehydrogenase (LDH), inorganic phosphate, and total protein were low and calcium was high. At 12 days, GOT, glutamic-pyruvic transaminase (GPT), and LDH were reduced, and the levels of calcium and cholesterol were elevated. At 25 days, there was a reduction in GPT and LDH and an increase in glucose, calcium, and albumin. At 40 days, the levels of GOT, LDH, AP, and inorganic phosphate were still low. Vanadate at lower dosage levels (0.3-0.6 mg V/kg per day for 16 days) also produced significant changes in blood cellular and serum elements but at lesser degrees of severity. These findings show that the exposure of rats repeatedly to low levels of Vanadate caused anemia, elevation in blood cholesterol levels, and a reduction in serum enzymes activities.

Time and dose-response study of the effects of vanadate on rats: morphological and biochemical changes in organs.

Vanadate at a dosage level of 0.9 mg V/kg per day produced acute toxic signs in rats when injected subcutaneously for 16 days. These signs were weakness, loss of appetite, dehydration, significant reduction in body weight, nose bleeding, and death. The pathological and biochemical changes were most severe in kidney tissue. The kidney lesions were bilateral and multifocal. At two days, degenerative and necrotic changes of the tubular and glomerular epithelium, thickening of glomerular membrane, vascular congestion, and edema were observed. At five days, proliferation of tubular epithelial and interstitial cells was observed. At 12 days, the cellular proliferation in both cortex and medulla was significantly greater. Fibrosis was observed at glomerular tuft, preglomeruli, pretubules, and interstitium (cortex and medulla). At 25 days, the collagen deposition reached the highest level in all regions, cellular proliferation decreased, and thickening of the arteriolar wall became prominent. The renal lesions were coupled with changes in the levels of protein, RNA, DNA, and hydroxyproline. At 40 days, the kidney showed signs of recovery. Blood urea nitrogen levels were significantly elevated at 2-25 days post-treatment. Stained tissue sections from liver, lung, heart, spleen, thymus, lymph nodes, testes, and adrenal glands of the treated rats were examined microscopically and appeared normal. Biochemically, significant changes (p less than .05) in protein, RNA, DNA, and hydroxyproline were also observed in these organs. At lower dosage (0.6 mg V/kg per day for 16 days), similar but less severe pathological and biochemical changes in kidneys and other organs were observed. At 0.3 mg V/kg per day for 16 days, the changes in the tissues were detected only at the biochemical level. These results indicate that the toxic effects of vanadium are cumulative and that vanadium-produced fibrosis in tissues is dose-dependent.

Acute toxicity of ammonium metavanadate in mice.

Acute toxicity of ammonium metavanadate solutions in normal saline (pH 6.7) or 0.1 M Tris-HCl-NaCl buffers (pH 7.2 or pH 7.8) was studied in BALB/c mice at 20 mg V/kg. Animals receiving these solutions subcutaneously started to show severe clinical signs 10-15 min postinjection and high mortality rates (45-73%) during the first 3 d. Animals dying because of vanadium toxicity did so only within the first 3 d after injection. NH4VO3-treated animals showed a tendency to increase their liver and spleen weights as compared to those receiving control solutions. Severe necrosis in lymphoid tissues (thymus, spleen, lymph nodes, and Peyer's patch), pulmonary hemorrhage, and renal acute tubular necrosis were commonly demonstrated in vanadium-treated animals. Toxicity of NH4VO3 solution in 0.1 M Tris-HCl-NaCl buffer (pH 7.8) was greatly reduced upon acidification with HCl to pH 6.1 or following boiling for 15 min (final pH of 7.7). Acidification of the solution reduced the mortality rate to 20 from 68%; however, the clinical signs were still severe. Boiling of the solution reduced the mortality rate to zero and moderated the severity of the clinical signs.