Probing Kinetics and Mechanism of Formation of Mixed Metallic Nanoparticles in a Polymer Membrane by Galvanic Replacement between Two Immiscible Metals: Case Study of Nickel/Silver Nanoparticle Synthesis.

Galvanic replacement between metals has received notable research interest for the synthesis of heterometallic nanostructures. The growth pattern of the nanostructures depends on several factors such as extent of lattice mismatch, adhesive interaction between the metals, cohesive forces of the individual metals, etc. Due to the difficulties in probing ultrafast kinetics of the galvanic replacement reaction and particle growth in solution, real-time mechanistic investigations are often limited. As a result, the growth mechanism of one metal on the surface of another metal at the nanoscale is poorly understood so far. In the present work, we could successfully probe the galvanic replacement of silver ions with nickel nanoparticles, stabilized in a polymer membrane, using two complementary methods, namely, small-angle X-ray scattering (SAXS) and radiolabeling, and the results are supported by density functional theory (DFT) computations. The silver-nickel system has been chosen for the present investigation because of the high degree of bulk immiscibility caused by the large lattice mismatch (15.9%) and the weak adhesive interaction, which makes it a perfect model system for immiscible metal pairs. Membrane, as a host medium, plays a crucial role in retarding the kinetics of atomic and particle rearrangements (nucleation and growth) due to slower mobility of the atoms (monomers) and particles within the polymer network. This allowed us to examine the real-time concentration of silver monomers during galvanic replacement of silver ions with nickel nanoparticles and evolution of Ni/Ag nanoparticles. From combined experiment and DFT computations, it has been demonstrated, for the first time to the best of our knowledge, that the majority of silver atoms, which are produced on the nickel nanoparticle surface by galvanic reactions, do not form traditional core-shell nanostructures with nickel and undergo a self-governing sequential nucleation and growth of silver nanoparticles via formation of intermediate prenucleation silver clusters, leading to the formation of mixed metallic nanoparticles in the membrane. The surface of NiNPs has a heterogeneous effect on the silver nucleation pathway, which is evident from the reduced critical free energy barrier of nucleation (ΔGcrit). The present work establishes an original mechanistic pathway based on a sequential nucleation model for formation of mixed metallic nanoparticles by the galvanic replacement route, which opens up future possibilities for size-controlled synthesis in mixed systems.

Etanercept biosimilar associated with Guillain-Barré syndrome: insights from a case.

Anti-tumor necrosis factor drugs are used routinely according to treatment guidelines for several chronic rheumatologic problems. However, a rare and usually unpredictable adverse drug reaction namely peripheral nervous system demyelination is being increasingly recognized. Biosimilars are gaining momentum especially in countries like India. Hence, we report a case of Guillain-Barré syndrome secondary to an etanercept biosimilar, probably the first case reported so far.

Poncet's disease diagnostic criteria decodes conundrum: Poncet's vs pseudo Poncet's.

Poncet's disease is very important and yet a challenging diagnosis of importance in countries with high TB endemicity (e.g. India). In this case series, we present 5 patients with diagnosed as Poncet's disease and in our tertiary health care center over 12 months and examine the performance of the diagnostic criteria suggested by Sharma and Pinto. The majority (4/5) of the patients were subsequently diagnosed and responded to anti-tuberculous therapy. In the other patient, a diagnosis of atypical seropositive rheumatoid arthritis or Pseudo Poncet's disease was established on follow up.

Comorbidities and related factors in rheumatoid arthritis patients of south India- Karnataka Rheumatoid Arthritis Comorbidity (KRAC) study.

The aim was to study the prevalence of comorbidities in rheumatoid arthritis (RA) patients in everyday clinical practice and their association with disease-specific and demographic factors. The multi-center study recruited 3,247 (at 14 centers, and 265) were excluded due to incomplete data. The number of subjects considered for the analysis was 2982. The mean (±standard deviation) age was 48.98±12.64 years and the male-to-female ratio was 1:5. The data was collected based on a pre-structured pro forma by trained clinical research associates through interview and verification of charts and reports available in the patient records. The following comorbidities were studied: cardiovascular disease, hypertension, diabetes mellitus, hypercholesterolemia, thyroid disease, psychiatric diseases like depression, and pulmonary disease. Hypertension (20.7%), diabetes mellitus (14.4%) and thyroid disease (18.3%) were the most prevalent comorbidities. Hypercholesterolemia (5.3%), pulmonary diseases (2.1%), cardiovascular diseases (0.2%) and depression (0.03%) were prevalent in ≤5% of the study population. The overall presence of comorbidity increased with age and reduced with the duration of illness prior (DOIP). The age, gender, and DOIP differed significantly between groups with and without hypercholesterolemia. Females had a statistically increased prevalence of thyroid disease. The prevalence of comorbidities in RA patients from south India is around 40% and the incidence of comorbidity increased with age. As per the literature evidence, the prevalence in the current study subjects was higher when compared to prevalence of similar diseases occurring in the general south Indian population.

Dose Dependent Hepatic and Endothelial Changes in Rats Treated with Dexamethasone.

AIMS AND OBJECTIVES: To study the effect of dexamethasone on liver and endothelium, and to determine the optimum dose which induces the abnormal changes in liver and endothelium in Wistar rats. MATERIALS AND METHODS: Albino Wistar rats were divided into 7 groups (n=6). Control group rats received normal saline. Graded doses of dexamethasone (0.5,1,2,4,8 and 16mg/kg/ i.p.) was administered to the groups for six days. Liver and aorta were dissected at the end of the study and examined for histopathological changes under microscope. RESULTS: Intraperitoneal administration of dexamethasone (4,8 and 16mg/kg) for six days resulted in fatty changes in liver and same doses have shown thickening of endothelial layers in aorta, in comparison to control group. There were not much significant changes seen in low doses of dexamethasone (0.5, 1 and 2mg/kg). CONCLUSION: It is concluded that the acute high doses of dexamethasone (4,8 and 16mg/kg) for six days caused hepatic steatosis and showed mild to moderate arteriosclerosis in aorta. These changes may be secondary consequences of insulin resistance. Hence, it can be used as new animal model to screen the various plants and medicines in the treatment of insulin resistance.

Redox decomposition of silver citrate complex in nanoscale confinement: an unusual mechanism of formation and growth of silver nanoparticles.

We demonstrate for the first time the intrinsic role of nanoconfinement in facilitating the chemical reduction of metal ion precursors with a suitable reductant for the synthesis of metal nanoparticles, when the identical reaction does not occur in bulk solution. Taking the case of citrate reduction of silver ions under the unusual condition of [citrate]/[Ag(+)] ≫ 1, it has been observed that the silver citrate complex, stable in bulk solution, decomposes readily in confined nanodomains of charged and neutral matrices (ion-exchange film and porous polystyrene beads), leading to the formation of silver nanoparticles. The evolution of growth of silver nanoparticles in the ion-exchange films has been studied using a combination of (110m)Ag radiotracer, small-angle X-ray scattering (SAXS) experiments, and transmission electron microscopy (TEM). It has been observed that the nanoconfined redox decomposition of silver citrate complex is responsible for the formation of Ag seeds, which thereafter catalyze oxidation of citrate and act as electron sink for subsequent reduction of silver ions. Because of these parallel processes, the particle sizes are in the bimodal distribution at some stages of the reaction. A continuous seeding with parallel growth mechanism has been revealed. Based on the SAXS data and radiotracer kinetics, the growth mechanism has been elucidated as a combination of continuous autoreduction of silver ions on the nanoparticle surfaces and a sudden coalescence of nanoparticles at a critical number density. However, for a fixed period of reduction, the size, size distribution, and number density of thus-formed Ag nanoparticles have been found to be dependent on physical architecture and chemical composition of the matrix.

Evaluation of antiulcerogenic potential of antioxidant α-tocopherol in pylorus-ligated albino rats.

BACKGROUND: Oxidative free radicals and lipid peroxidation mediate gastric injury. α-Tocopherol is a redox agent with biological and antioxidant property, hence, may provide ulcer protection. METHODS: Pylorus-ligated Shay rats (n=6) were used as the experimental gastric ulcer animal model. The rats were divided into three groups. Group I received saline (5 mL/kg), Group II α-tocopherol (12.5 mg/kg), and Group III omeprazole (3.6 mg/kg), orally daily for 5 days prior to ulcerogenic challenge. Nineteen hours after the challenge, the rats were sacrificed and their stomachs isolated and studied for degree of gastric injury. Formed gastric juice was collected for measurement of volume, titrimetric estimation of free and total acidity, and total acid output by the conventional methods. The ulcer index and total acid outputs were calculated. RESULTS: α-Tocopherol exerted significant (p<0.05) antiulcer activity (the ulcer index was reduced to 7.4 ± 1.0 from the control value of 19.8 ± 4.1). α-Tocopherol also significantly reduced free and total acidity, gastric juice volume, and total acid output (p<0.01). The results were analyzed by ANOVA and Scheffe's multiple comparison test. CONCLUSIONS: The study demonstrates that α-tocopherol has significant antiulcer activity. It, perhaps, acts by decreasing hydrochloric acid output.

Failure of the Laryngeal Mask Airway Unique™ and Classic™ in the pediatric surgical patient: a study of clinical predictors and outcomes.

BACKGROUND: Although predictors of laryngeal mask airway failure in adults have been elucidated, there remains a paucity of data regarding laryngeal mask airway failure in children. METHODS: The authors performed a retrospective database review of all pediatric patients who received a laryngeal mask anesthetic at their institution from 2006 to 2010. Device brands were restricted to LMA Unique™ (Cardinal Health, Dublin, OH) and LMA Classic™ (LMA North America, San Diego, CA), and primary outcome was laryngeal mask failure, defined as any airway event requiring device removal and tracheal intubation. Potential risk factors were analyzed with both univariate and multivariate techniques and included medical history, physical examination, surgical, and anesthetic characteristics. RESULTS: Of the 11,910 anesthesia cases performed in the study, 102 cases (0.86%) experienced laryngeal mask failure. Common presenting features of laryngeal mask failures included leak (25%), obstruction (48%), and patient intolerance such as intractable coughing/bucking (11%). Failures occurred before incision in 57% of cases and after incision in 43%. Independent clinical associations included ear/nose/throat surgical procedure, nonoutpatient admission status, prolonged surgical duration, congenital/acquired airway abnormality, and patient transport. CONCLUSIONS: The findings of the study support the use of the LMA Unique™ and LMA Classic™ as reliable pediatric supraglottic airway devices, demonstrating relatively low failure rates. Predictors of laryngeal mask airway failure in the pediatric surgical population do not overlap with those in the adult population and should therefore be independently considered.

Add grace to psychiatric practice.

BACKGROUND: The uniqueness of mindset of an individual makes psychiatric practice interesting, sensitive, and at times subjective. The practice in setup of an organization makes the situation more complex in view of administrative regulations, existing work culture, and issues like confidentiality, etc., Dilemmas are often faced while balancing loyalty between an organization and the patients, values of the therapist and the patient, and different dimension of justice coming from different cultural backgrounds of the patients and the treating doctors. A lot of mental work needs to be put in by the practitioner to consistently adhere to medical ethics and professional approach for taking key decisions despite of contradictory external forces from within and without. AIMS: I thought of sharing my experiences especially in setup of an organization with my colleagues so that the decision-taking process becomes somewhat easy and balancing for them. SETTINGS AND DESIGN: I have to try to interpret my clinical experiences gathered while working with my patients from the Department of Atomic Energy as well as from my private practice. CONCLUSION: The need of psycho education to self and others from time to time never ceases simply to make the practice more objective, justified, and graceful.

Sunscreening agents: a review.

The increasing incidence of skin cancers and photodamaging effects caused by ultraviolet radiation has increased the use of sunscreening agents, which have shown beneficial effects in reducing the symptoms and reoccurrence of these problems. Many sunscreen compounds are in use, but their safety and efficacy are still in question. Efficacy is measured through indices, such as sun protection factor, persistent pigment darkening protection factor, and COLIPA guidelines. The United States Food and Drug Administration and European Union have incorporated changes in their guidelines to help consumers select products based on their sun protection factor and protection against ultraviolet radiation, whereas the Indian regulatory agency has not yet issued any special guidance on sunscreening agents, as they are classified under cosmetics. In this article, the authors discuss the pharmacological actions of sunscreening agents as well as the available formulations, their benefits, possible health hazards, safety, challenges, and proper application technique. New technologies and scope for the development of sunscreening agents are also discussed as well as the role of the physician in patient education about the use of these agents.

Outcomes of repeat endothelial keratoplasty in patients with failed Descemet stripping endothelial keratoplasty.

PURPOSE: To report the outcomes of repeat endothelial keratoplasty (EK) in patients with failed Descemet stripping endothelial keratoplasty (DSEK). METHODS: The clinical records of patients with failed DSEK who underwent repeat EK surgery at a single institution were reviewed. RESULTS: A total of 20 eyes of 20 patients (8 men and 12 women) were included. The mean age at initial DSEK surgery was 69.9 ± 11.9 years (range, 41-83 years). The causes of DSEK failure included progressive endothelial failure (8 eyes; 40%), primary graft failure (8 eyes; 40%), and endothelial rejection (4 eyes; 20%). The mean duration from primary DSEK to repeat EK was 13.1 ± 10.3 months (range, 2-33 months). Removal of the failed DSEK donor disc was performed in all eyes. Mean preoperative corrected distance visual acuity (logMAR) before repeat EK surgery was 1.76, and this improved to 0.5 (P < 0.001) at the final follow-up at 27 months. Three eyes had limited corrected distance visual acuity secondary to ocular comorbidities (age-related macular degeneration and advanced glaucomatous optic neuropathy). CONCLUSIONS: Repeat EK in patients with DSEK failure is an effective treatment modality. This is the preferred management option compared with penetrating keratoplasty because the advantages of EK surgery are maintained with repeat EK surgery.

Silymarin, an antioxidant bioflavonoid, inhibits experimentally-induced peptic ulcers in rats by dual mechanisms.

INTRODUCTION: Antioxidants are reported to have antiulcer activity. We investigated silymarin, a bioflavonoid antioxidant, for antiulcer potential. MATERIALS AND METHODS: Pylorus-ligated Shay rats (n=5) were used as the experimental gastric ulcer animal model. The rats, separated into three groups, were administrated silymarin (50 mg/kg), omeprazole (3.6 mg/kg), or saline (5 ml/kg) per orally daily for 5 days prior to ulcerogenic challenge. Nineteen hours after the challenge, the rats were sacrificed and their stomachs isolated. Formed gastric juice was collected for measurement of volume, titrimetric estimation of free and total acidity, and total acid output by the conventional methods. The ulcer index was calculated. Total acid output and free and combined acid quantities were calculated using the acidity value and the volume of formed gastric juice. RESULTS: Silymarin exerted significant (P<.05) antiulcer activity (the ulcer index was reduced to 7.4 ± 1.0 from the control value of 19.8 ± 4.1). Silymarin also significantly reduced free and total acidity, gastric juice volume, total acid output, and combined acid content. The results were analyzed by ANOVA and Newman-Keuls multiple comparison test. CONCLUSION: This study demonstrates that silymarin has significant antiulcer activity. It perhaps acts by decreasing hydrochloric acid output and increasing buffering power (combined acid).

Advancing the scope of nursing practice: hepatic arterial catheter removal.

A delay in hepatic artery infusion catheter removal may prolong patient discomfort and lead to additional complications. As a result, this article evaluated the effectiveness of shifting the responsibility of catheter removal from advanced practice or medical staff to nurses. Overall, patients were satisfied, felt comfortable, and experienced minimal pain irrespective of whether their catheter was removed by a nurse, physician, or advanced practice staff. Nurses also were satisfied and felt they had enhanced their ability to provide quality patient care.

Diffusional transport of ions in plasticized anion-exchange membranes.

Diffusional transport properties of hydrophobic anion-exchange membranes were studied using the polymer inclusion membrane (PIM). This class of membranes is extensively used in the chemical sensor and membrane based separation processes. The samples of PIM were prepared by physical containment of the trioctylmethylammonium chloride (Aliquat-336) in the plasticized matrix of cellulose triacetate (CTA). The plasticizers 2-nitrophenyl octyl ether, dioctyl phthalate, and tris(2-ethylhexyl)phosphate having different dielectric constant and viscosity were used to vary local environment of the membrane matrix. The morphological structure of the PIM was obtained by atomic force microscopy and transmission electron microscopy (TEM). For TEM, platinum nanoparticles (Pt nps) were formed in the PIM sample. The formation of Pt nps involved in situ reduction of PtCl(6)(2-) ions with BH(4)(-) ions in the membrane matrix. Since both the species are anions, Pt nps thus formed can provide information on spatial distribution of anion-exchanging molecules (Aliquat-336) in the membrane. The glass transitions in the membrane samples were measured to study the effects of plasticizer on physical structure of the membrane. The self-diffusion coefficients (D) of the I(-) ions and water in these membranes were obtained by analyzing the experimentally measured exchange rate profiles of (131)I(-) with (nat)I(-) and tritiated water with H(2)O, respectively, between the membrane and equilibrating solution using an analytical solution of Fick's second law. The values of D(I(-)) in membrane samples with a fixed proportion of CTA, plasticizer, and Aliquat-336 were found to vary significantly depending upon the nature of the plasticizer used. The comparison of values of D with properties of the plasticizers indicated that both dielectric constant and viscosity of the plasticizer affect the self-diffusion mobility of I(-) ions in the membrane. The value of D(I(-)) in the PIM samples did not vary significantly with concentration of Aliquat-336 up to 0.5 mequiv g(-1), and thereafter D(I(-)) increased linearly with Aliquat-336 concentration in the membrane. The self-diffusion coefficients of water D(H(2)O) in PIM samples were found to be 1 order of magnitude higher than the value of D(I(-)) and varied slightly depending upon the plasticizer present in the membrane. It was observed in electrochemical impedance spectroscopic studies of the PIM samples that diffusion mobility of NO(3)(-) ions was 1.66 times higher than that of I(-) ions, and diffusion mobility of SO(4)(2-) ions was half of that for I(-) ions. The theoretical interpretation of experimental counterions exchange rate profiles in terms of the Nernst-Planck equation for interdiffusion also showed higher diffusion mobility of NO(3)(-) ions in the PIM than Cl(-), I(-), and ClO(4)(-) ions, which have comparable diffusion mobility.

Galvanic reactions involving silver nanoparticles embedded in cation-exchange membrane.

Galvanic reactions of Hg(2+), Rh(3+), and AuCl(4)(-) ions with Ag nanoparticles positioned near the surface and throughout the matrix of host poly(perfluorosulfonic) acid membrane have been studied.

In situ formation of stable gold nanoparticles in polymer inclusion membranes.

Gold nanoparticles (Au nps) were synthesized in the matrix of a plasticized anion-exchange membrane. The membrane was prepared by solvent casting of the solution containing a liquid anion exchanger trioctylmethylammonium chloride (Aliquat-336), a matrix-forming polymer cellulose triacetate (CTA), and a plasticizer dioctyl phthalate (DOP) dissolved in CH(2)Cl(2). For in situ synthesis of Au nps, the membrane samples were equilibrated with a well-stirred solution containing 0.01 mol L(-1)HAuCl(4). AuCl(4)(-) ions were transferred to membrane matrix as an ion pair with Aliquat-336 by an ion-exchange mechanism. In a second step, AuCl(4)(-) ion-loaded membrane samples were placed in a well-stirred 0.1 mol L(-1) aqueous solution of NaBH(4) for reduction. It was observed that 80% of the anion-exchange sites were readily available for the exchange process after formation of the Au nps. The content of Au nps in the membrane was increased either by increasing the concentration of the Aliquat-336 in membrane or by repeating sequential cycles of loading of AuCl(4)(-) ions followed by reduction with BH(4)(-) in the membrane matrix. TEM images of a cross section of the membrane showed that Au nps were dispersed throughout the matrix of the membrane but excluded from the surface. The size distribution of the nps was found to be dependent on Au content in the membrane. For example, 7- to 16-nm Au nps with average size 10 nm were observed in the membrane after the first cycle of synthesis. On increasing the Au content in the membrane by repeating the cycle of synthesis, the size dispersion of nps broadened from 5 to 20 nm without affecting the average size. The lambda(max) (530 nm) and intensity of the surface plasmon band of Au nps embedded in the matrix of membrane were found to remain unaltered over a testing period of a month in the samples kept in water as well as in air under ambient conditions. This indicated that Au nps were quite stable in the membrane matrix. The experimental information obtained by the radiotracers and energy-dispersive X-ray fluorescence (EDXRF) analyses has been used to understand the process of Au nps formation in the membrane matrix.

Needle-free powder lidocaine delivery system provides rapid effective analgesia for venipuncture or cannulation pain in children: randomized, double-blind Comparison of Venipuncture and Venous Cannulation Pain After Fast-Onset Needle-Free Powder Lidocaine or Placebo Treatment trial.

OBJECTIVE: The Comparison of Venipuncture and Venous Cannulation Pain After Fast-Onset Needle-Free Powder Lidocaine or Placebo Treatment trial was a randomized, single-dose, double-blind, phase 3 study investigating whether a needle-free powder lidocaine delivery system (a sterile, prefilled, disposable system that delivers lidocaine powder into the epidermis) produces effective local analgesia within 1 to 3 minutes for venipuncture and peripheral venous cannulation procedures in children. METHODS: Pediatric patients (3-18 years of age) were randomly assigned to treatment with the needle-free powder lidocaine delivery system (0.5 mg of lidocaine and 21 +/- 1 bar of pressure; n = 292) or a sham placebo system (n = 287) at the antecubital fossa or the back of the hand 1 to 3 minutes before venipuncture or cannulation. All patients rated the administration comfort of the needle-free systems and the pain of the subsequent venous access procedures with the Wong-Baker Faces Pain Rating Scale (from 0 to 5). Patients 8 to 18 years of age also provided self-reports with a visual analog scale, and parents provided observational visual analog scale scores for their child's venous access pain. Safety also was assessed. RESULTS: Immediately after administration, mean Wong-Baker Faces scale scores were 0.54 and 0.24 in the active system and sham placebo system groups, respectively. After venipuncture or cannulation, mean Wong-Baker Faces scale scores were 1.77 +/- 0.09 and 2.10 +/- 0.09 and mean visual analog scale scores were 22.62 +/- 1.80 mm and 31.97 +/- 1.82 mm in the active system and sham placebo system groups, respectively. Parents' assessments of their child's procedural pain were also lower in the active system group (21.35 +/- 1.43 vs 28.67 +/- 1.66). Treatment-related adverse events were generally mild and resolved without sequelae. Erythema and petechiae were more frequent in the active system group. CONCLUSIONS: The needle-free powder lidocaine delivery system was well tolerated and produced significant analgesia within 1 to 3 minutes.

Dengue 2 virus inhibits in vitro megakaryocytic colony formation and induces apoptosis in thrombopoietin-inducible megakaryocytic differentiation from cord blood CD34+ cells.

Thrombocytopenia is frequently associated with dengue virus infection in humans. Although antiplatelet immunopathogenic processes have been implicated in the origin of dengue-associated thrombocytopenia, the effect of dengue viruses on megakaryocyte differentiation remains incompletely understood. In this study, we examined the effect of human dengue 2 virus isolates on the in vitro growth and differentiation of thrombopoietin-induced megakaryopoiesis of cord blood CD34+ cells. Dengue 2 viruses, but not Japanese encephalitis virus, showed a dose-dependent inhibition of CFU-Mk. Viral antigens could be detected by an immunohistochemical technique in 3-5% of the early megakaryocytic progenitors by the 5th postexposure day in liquid cultures with cell loss, increased annexin V binding and active caspase-3 expression. In summary, dengue 2 viruses can inhibit in vitro megakaryopoiesis, as well as infect and induce apoptotic cell death in a subpopulation of early megakaryocytic progenitors. These events might contribute towards the origin of thrombocytopenia in dengue disease.