Characterization of Carbon-Contaminated B4C-Coated Optics after Chemically Selective Cleaning with Low-Pressure RF Plasma.

Boron carbide (B4C) is one of the few materials that is expected to be most resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at light source facilities, B4C-coated optics are subject to ubiquitous carbon contaminations. Carbon contaminations represent a serious issue for the operation of FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B4C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the low-pressure RF plasma cleaning of carbon contaminated B4C test samples via inductively coupled O2/Ar, H2/Ar, and pure O2 RF plasma produced following previous studies using the same ibss GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B4C optical coating before and after the plasma cleaning are reported. We conclude that among the above plasma processes only plasma based on pure O2 feedstock gas exhibits the required chemical selectivity for maintaining the integrity of the B4C optical coatings.

Low-lipid diet reduces frequency and severity of acute migraine attacks.

BACKGROUND AND AIM: There is uncertainty regarding the prevention of migraine crises by changing the lifestyle of patients. The aim of this randomized, crossover intervention trial was to evaluate the effects of a low lipid intake on the incidence and severity of migraine crises, in comparison to a diet with moderate lipid intake. METHODS AND RESULTS: After a 2-month run-in when patients received preventive medication but were left on their habitual diet, a low-lipid or a normal-lipid diet was randomly prescribed for 3 months and thereafter diets were crossed over for the following 3 months. Headache was diagnosed based on the International Classification of Headache Disorders (IHCD) III criteria. The number and severity of attacks were assessed using a self-reported calendar. Adherence to the diet was assessed by a food frequency questionnaire. An analysis was performed on the 83 episodic or chronic migraineurs (63 female and 20 male), in the age range of 18-57 years, who completed both intervention periods. Obese subjects had a significantly higher number of attacks than those overweight or with normal body weight (24.7 ± 8, 16.3 ± 12, and 15.6 ± 11, respectively, p < 0.03) with a significant relationship between the body mass index (BMI) and the number of monthly attacks (r = 0.238, p < 0.03). The number (2.9 ± 3.7 vs. 6.8 ± 7.5, p < 0.001) and severity (1.2 + 0.9 vs. 1.7 ± 0.9, p < 0.01) of attacks significantly decreased during both intervention periods, with a significant difference in favour of the low-lipid diet. CONCLUSIONS: In this group of patients, the low-lipid diet significantly affected the number and severity of migraine attacks in comparison to a normal-lipid diet. ClinicalTrials.gov Identifier: NCT 01917474.

How do biomaterials affect the biological activities and responses of cells? An in vitro study.

AIM: As part of regenerative bone surgery, according to the principles of tissue engineering and GBR, the use of biomaterials aims to restore bone deficiencies by restoring both functionality and original morphology of the bone tissue. Besides being biocompatible, biofunctional and reabsorbable, the ideal scaffolding should possess an osteoinductive geometry, which depends on many physical-chemical characteristics and, in particular, on a three-dimensional morphology and the placement of molecules, which would determine pore size and interconnection between them. The purpose of this study was, therefore, to carry out an analysis with a scanning electron microscope, in order to evaluate the effect of the diameter size of the scaffold pores on the bio-molecular interaction between osteoblast-like MG63 cells and four biomaterials with different pore sizes: polylactic-co-glycolic acid, deproteinized bovine bone, equine bone, demineralized bone matrix (DBM). METHODS: Through the observations made with SEM and X-ray microanalysis, it is possible to infer how the morphology, the proliferative ability, the modality of adhesion and the differentiation of MG63 cells are influenced in different ways by the porous structure of the various biomaterials used as a substrate for growth. RESULTS: From among all of the biomaterials examined, DBM represented the best substrate for growth; in fact, there would be a more intense and precocious adhesion of MG-63 cells. CONCLUSION: The strong osteoconductive effect observed in human DBM, seems to be related to the presence of the organic component, while the osteoinductive effect would be mainly attributed to the presence of BMPs.

Phlegmon of the face and neck: a case report.

Deep face and neck infections are potentially life threatening if they are not diagnosed in time and then treated quickly. This report describes a case of face and deep neck infection, associated with a semi-impacted and decayed wisdom tooth in a cardiopathic, immunosuppressed patient suffering from, diabetes, hypothyroidism, osteoporosis, breathlessness, chronic bronchitis, with oral, cutaneous and vaginal erythematous lichen, Cushing's Syndrome, penicillin allergy, subjected to past hypophysectomy. The swelling was, first of all, treated in urgency, with an intravenous antibiotic therapy and, immediately afterwards, the phlegmonous infiltration linked to the avulsion of the lower third molar was surgically drained. The patient was then treated with intravenous multiple antibiotics, with the aim of eradicating the predominating bacteria that was encountered in the microbiological culture test. A complete remission of the pathological picture was obtained .

Bone regeneration: in vitro evaluation of the behaviour of osteoblast-like MG63 cells placed in contact with polylactic-co-glycolic acid, deproteinized bovine bone and demineralized freeze-dried bone allograft.

Insufficient bone density of the alveolar crests, caused by loss of the dental elements, sometimes impedes the primary stability of an integrated bone implant. The techniques of bone regeneration allow to obtain a sufficient quantity of alveolar bone to permit the implant rehabilitation of the edentulous crests. Today several grafting materials are available and they have different characteristics, according to their structure, which influence the different behaviour of the grafting materials to the bone and the implant surface. The aim of this study is to evaluate the interaction between a human osteosarcoma MG63 cell line and three different biomaterials: polylactic-co-glycolic acid (PLAGA), deproteinized bovine bone and demineralised freeze-dried bone allograft (DFDBA). From this study a different behaviour emerges of the osteoblast-like MG63 cells in relation to the sublayer on which these cells were placed in culture. The results of the study, in fact, demonstrate that the most osteoconductive material of the three analysed is the DFDBA, followed by DPBB. On the contrary, the PLGA, because of its roughness, does not seem to represent a valid support for cell growth, and does not encourage any morphologic modification in tumor cells. Furthermore, deproteinized bovine bone shows a differentiating effect which could lead to hypothesise an osteoconductive capacity of this biomaterial. Further studies should be carried out with the aim of explaining the results obtained.

Mandibular osteomyelitis due to Pseudomonas aeruginosa. Case report.

Osteomyelitis is a relatively frequent bacterial infection of the jaw bones. This report describes a case of mandibular osteomyelitis in a surgical site after enucleation of a follicular cyst and extraction of the associated tooth. This case is unusual because maxillary osteomyelitis generally results from polymicrobial infection. In our patient, however, laboratory analysis identified Pseudomonas aeruginosa as the etiologic agent, an opportunistic pathogen normally found on moist surfaces and vegetation. Notorious for its antibiotic multiresistance, P. aeruginosa is increasingly recognized as a serious problem in hospitalized patients. Isolation of the responsible microbe permitted specific antibiotic treatment with a 10-day course of ciprofloxacin (250 mg/12 h), which fully cleared the infection.

Bone substitutes in oral surgery.

Osseous defects pose a clinical challenge the operator can meet with the aid of techniques that promote bone tissue regeneration. The current gold standard is autologous bone harvested from intra- and extraoral donor sites; however, autologous bone grafting requires two surgical sites (donor and recipient), resulting in greater morbidity and prolonged operating times, particularly for extraoral sites, with greater discomfort for the patient. Such disadvantages can be overcome with the use of bone substitute materials. There is a notable variety of so-called intelligent biomaterials that can modulate bone response in regeneration. Based on origin, bone substitute materials are classified as allogenic, heterologous and alloplastic materials. The first refer to bone from same-species donors, the second are obtained through processing of bone from different species, while alloplastic materials are synthetic composites. Besides different resorption rates, they possess different chemical and structural characteristics that influence the stimulation or support of bone regeneration. In daily clinical practice, before selecting from the wide variety of biomaterials, a wise step is to analyze and compare the clinical and histological results obtained with these materials. This article examines the clinical applications and osteoconductive and/or osteoinductive properties of some currently available biomaterials.

Effects of site-directed mutagenesis of protolytic residues in subunit I of Bacillus subtilis aa3-600 quinol oxidase. Role of lysine 304 in proton translocation.

Various protolytic residues in subunit I of aa3-600 quinol oxidase of the aerobic Gram-positive Bacillus subtilis were mutagenized to nonpolar residues. Two of the mutations, Y284F and K304L, impaired the bioenergetic function of the microorganism. The Y284F mutation suppressed the electron-transfer activity of quinol oxidase and altered its interaction with CO and H2O2, thus showing destruction of the binuclear domain as observed for the bo3 quinol oxidase of Escherichia coli. The K304L mutation did not alter significantly the redox activity of the oxidase and its interaction with CO and H2O2 but suppressed the proton pumping activity of the enzyme. These results show that the K304 residue, which is invariantly conserved (as K or R) in practically all the sequences of the heme-copper oxidases so far available (around 100), is essential for the proton pumping activity of the oxidase.

Cooperative coupling and role of heme a in the proton pump of heme-copper oxidases.

In the last few years, evidence has accumulated supporting the applicability of the cooperative model of proton pumps in cytochrome systems, vectorial Bohr mechanisms, to heme-copper oxidases. The vectorial Bohr mechanism is based on short- and long-range protonmotive cooperative effects linked to redox transitions of the metal centers. The crystal structure of oxidized and reduced bovine-heart cytochrome c oxidase reveals, upon reduction, the occurrence of long-range conformational changes in subunit I of the oxidase. Analysis of the crystal structure of cytochrome c oxidase shows the existence of hydrogen-bonded networks of amino acid residues which could undergo redox-linked pK shifts resulting in transmembrane proton translocation. Our group has identified four proteolytic groups undergoing reversible redox-linked pK shifts. Two groups result in being linked to redox transitions of heme a3. One group is apparently linked to CuB. The fourth group is linked to oxido-reduction of heme a. We have shown that the proton transfer resulting from the redox Bohr effects linked to heme a and CuB in the bovine oxidase displays membrane vectorial asymmetry, i.e., protons are taken up from the inner aqueous space (N), upon reduction, and released in the external space (P), upon oxidation of the metals. This direction of proton uptake and release is just what is expected from the vectorial Bohr mechanism. The group linked to heme a, which can transfer up to 0.9 H+/e- at pHs around neutrality, can provide the major contribution to the proton pump. It is proposed that translocation of pumped protons, linked to electron flow through heme a, utilizes a channel (channel D) which extends from a conserved aspartate at the N entrance to a conserved glutamate located between heme a and the binuclear center. The carboxylic group of this glutamic acid, after having delivered, upon electron flow through heme a, pumped protons towards the P phase, once reprotonated from the N phase, moves to deliver, subsequently, to the binuclear center chemical protons consumed in the conversion of the peroxy to ferryl and of the latter to the oxy intermediate in the redox cycle. Site-directed mutagenesis of protolytic residues in subunit I of the aa3-600 quinol oxidase of Bacillus subtilis to non-polar residues revealed that the conserved Lys 304 is critical for the proton pumping activity of the oxidase. Crystal structures of cytochrome c oxidase show that this lysine is at the N entrance of a channel which translocates the protons consumed for the production of the peroxy intermediate. Inhibition of this pathway, by replacement of the lysine, short-circuits protons from channel D to the binuclear center, where they are utilized in the chemistry of oxygen reduction.

Steady-state proton translocation in bovine heart mitochondrial bc1 complex reconstituted into liposomes.

The effect of different anions on the steady-state proton translocation in bovine bc1 complex reconstituted in liposomes was studied. The H+/e- ratio for vectorial proton translocation is at the steady state definitely lower than that measured at level flow, (0.3 vs. 1.0). The presence of azide or arachidonate at micro- and submicromolar concentrations, respectively, gave a substantial reactivation of the proton pumping activity at the steady state, without any appreciable effect on respiration-dependent transmembrane pH difference. Addition of azide to turning-over bc1 vesicles also caused a transition of b cytochromes toward oxidation. The results are discussed in terms of possible involvement of an acidic residue in the protonation of the semiquinone/quinol couple at the N side of the membrane.