Inhibition of biofilm formation and antibacterial properties of a silver nano-coating on human dentine

The survival of pathogenic bacteria in the oral cavity depends on their successful adhesion to dental surfaces and their ability to develop into biofilms, known as dental plaque. Bacteria from the dental plaque are responsible for the development of dental caries, gingivitis, periodontitis, stomatitis and peri-implantitis. Certain metal nanoparticles have been suggested for infection control and the management of the oral biofilm. Here, it is shown that application of a silver nano-coating directly on dentine can successfully prevent the biofilm formation on dentine surfaces as well as inhibit bacterial growth in the surrounding media. This silver nano-coating was found to be stable (>98.8%) and to maintain its integrity in biological fluids. Its antibacterial activity was compared to silver nitrate and the widely used clinical antiseptic, chlorhexidine. The bacterial growth and cell viability were quantitatively assessed by measuring the turbidity, proportion of live and dead cells and lactate production. All three bioassays showed that silver nanoparticles and silver nitrate dentine coatings were equally highly bactericidal (>99.5%), while inhibiting bacterial adhesion. However, the latter caused significant dentine discolouration (ΔE* = 50.3). The chlorhexidine coating showed no antibacterial effect. Thus, silver nanoparticles may be a viable alternative to both chlorhexidine and silver nitrate, protecting from dental plaque and secondary caries when applied as a dentine coating, while they may provide the platform for creating anti-biofilm surfaces in medical devices and other biomedical applications.     

Effects of local anesthetics on human platelets: filopodial suppression and endogenous proteolysis

Agents that affect platelet shape may be useful in understanding the mechanism of shape change; for this reason the effects of local anesthetics are worthy of further study. Local anesthetics cause platelets to retract filopodia. At short time intervals (up to about 30 min) and low concentrations of the drugs, the filopodia are reextended when the platelets are gel filtered with eluant free of anesthetic. At longer time intervals (1-2 hr) or higher drug concentrations, the retraction becomes irreversible. When the polypeptide composition of the total platelet lysate was examined on SDS gels, proteolysis of two high molecular weight bands was seen when the suppression became irreversible. These polypeptides, estimated as 250,000 and 230,000 daltons, were major components of a precipitate that formed when platelets were lysed at low ionic strength and were also enriched in a "cytoskeletal" preparation made by lysing platelets attached to glass beads and analyzing the adherent residue. Electron micrographs of platelets lysed on surfaces showed an intermeshed network of filaments to be a major component of the residue. The results suggest that the proteins comprised of these bands may be part of the cytoskeletal system and that their integrity may be necessary for the platelet to reextend filopodia following suppression.     

希拉里的宽恕

希拉里·克林顿在丈夫性丑闻阴影袭来时,所表现出的愤怒、痛苦、挣扎让世界看到了这位坚强女性的另一面。通过坚强的信念和爱,希拉里最终做出了抉择。让我们回到那个夏天,一探这位杰出女性的心路历程。     

C3bi/CR3 is a Main Ligand-Receptor Interaction in Attachment and Phagocytosis of C3-Coated Particles by Mouse Peritoneal Macrophages

We investigated the relative role of C3bi-CR3 interaction in the binding and phagocytosis of EAC43 by mouse peritoneal macrophages. Anti-Mac-1 F(ab')2 markedly inhibited the binding and lymphokine-induced phagocytosis of both EAC43b and EAC43bi. Fifty per cent inhibition of attachment and phagocytosis occurred at 1 microgram/ml of anti-Mac-1 F(ab')2 in the incubation media. On the other hand, EIgG binding and phagocytosis were not inhibited at all even at a concentration of 10 micrograms/ml. Depletion of divalent cations from the incubation media abolished EAC43b and EAC43bi rosettes but not EIgG rosettes or phagocytosis. These data suggested that both EAC43b and EAC43bi binding to macrophages were mediated via CR3. Because a drastic decrease of EAC43bi rosettes was observed in the case of EAC43bi cells prepared with smaller amounts of C3, a small contamination of C3bi molecules on EAC43b, itself, cannot explain the efficient attachment of EAC43b. We propose that EAC43b on the macrophage surface can be quickly converted to EAC43bi, forming EAC43bi rosettes, and that those erythrocytes are vigorously ingested by lymphokine-activated macrophages. In accordance with this hypothesis, we demonstrated that EAC43b was converted to EAC43bi in the medium in which macrophages had been incubated.     

Na+-H+ exchange is not important for pancreatic HCO-3 secretion in the pig

Veel , T., Villanger , O., Holthe , M.R., Cragoe jr ., E.J. & Reder , M.G. 1992. Na⁺-H exchange is not important for pancreatic HCO^-₃ secretion in the pig. Acta Physiol Scand 144 , 239–246. Received 13 September 1991, accepted 14 November 1991. ISSN 0001–6772. University of Oslo, Institute for Experimental Medical Research and Surgical Department, Ullevaal Hospital, Oslo, Norway. Pancreatic inter- and intralobular duct cells extrude H⁺-ions to interstitial fluid when they secrete HCO^-₃ to pancreatic juice. This study assesses the potential importance of Na⁺-H⁺-ion exchange for H⁺-ion extrusion and secretion of HCO^-₃ using the Na⁺-H⁺ exchange blockers amiloride and hexamethylene-amiloride. Intracellular pH (pH,) in inter- and intralobular pancreatic duct epithelium was measured using BCECF fluorescence. H⁺-ion efflux was measured using a NH₄Cl prepulse, acid-loading technique. In HCO^-₃-free media, pH₁ recovery following acid loading was blocked by amiloride (10^-4 m) and hexamethylene-amiloride (10^-6 m) , demonstrating amiloride-and hexamethylene-amiloride-sensitive Na⁺-H⁺ exchange. However, 5 × 10^-6 M hexamethylene-amiloride did not reduce secretin-dependent pancreatic HCO, secretion in vivo. Maximal H⁺-efflux through Na⁺-H⁺ exchange was 1.5 ± 0.2μmol min^-1 ml cell volume^-l, i.e. less than 1 % of estimated net H⁺-ion efflux during HCO^-₃ secretion. Conclusion: amiloride- and hexamethylene amiloride sensitive Na⁺-H⁺ exchange is not important for secretin-dependent pancreatic HCO^-₃ secretion in the pig. Other mechanisms for H⁺ extrusion dominate.     

Eosinophilic sialodochitis: redefinition of ‘allergic parotitis’ and ‘sialodochitis fibrinosa’

Sialodochitis fibrinosa and allergic parotitis have described rare patients with recurrent salivary gland swelling and mucus plugs, often with atopy. We have evaluated three patients with atopic disease, recurrent salivary gland swelling, and an eosinophilic sialodochitis. Two had eosinophil‐rich mucus plugs. Fifty‐six additional cases were identified in a medical literature database search, each defined by recurrent salivary gland swelling associated with eosinophil‐rich mucus plugs or sialodochitis with periductal eosinophilic infiltration. The majority (78%) were reported from Japan. Females were predominantly affected (F:M = 2.3) with a median age of 47 years at evaluation. The parotid and submandibular glands were involved, respectively, in 71% and 46%. Allergic symptoms were present in 66%, atopic disease in 63% of those with reported allergy testing, and blood eosinophilia in 71%. Contrast sialography and other imaging modalities documented ductal dilatation in 82%. Treatments included anti‐allergic medications (58%), systemic glucocorticoids (25%), duct cannulation with irrigation, steroid injection, and/or duct dilatation (36%), and glandular resection (19%). We recommend the diagnosis ‘eosinophilic sialodochitis’ be applied to patients who meet this case definition. The disease is a unique cause of chronic recurrent salivary gland swelling. Its likely allergic etiology may be amenable to current or future biologic therapies.     

The Management of Breech Presentation

The combination of prematurity and breech presentation subjects the fetus to great danger of death or birth trauma. Fetal mortality associated with breech presentation is 10 times higher when prematurity is added. Liberalization of indications for cesarean section is recommended as one way of improving fetal survival and lowering fetal morbidity associated with this abnormal fetal position.     

Facial Nerve Palsy

It is agreed that some cases of facial nerve palsy are surgical emergencies. Other cases are controversial. The best available electrodiagnostic test is 48 to 72 hours late in noting changes. An early test for axonotmesis is unavailable. Immediate consultation with a specialist qualified to deal with the problem is urged.