Absorbable collagen membranes for periodontal regeneration: a systematic review

Guided tissue regeneration (GTR) with bioabsorbable collagen membranes (CM) is commonly used for the treatment of periodontal defects. The objective of this systematic review of randomized clinical trials was to assess the clinical efficacy of GTR procedures with CM, with or without bone substitutes, in periodontal infrabony defects compared with that of open flap debridement (OFD) alone. Primary outcomes were tooth loss and gain in clinical attachment level (CAL). Screening of records, data extraction, and risk-of-bias assessments were performed by two reviewers. Weighted mean differences were estimated by random effects meta-analysis. We included 21 reports on 17 trials. Risk of bias was generally high. No data were available for the primary outcome tooth loss. The summary treatment effect for change in CAL for GTR with CM compared with OFD was 1.58 mm (95% CI, 1.27 to 1.88). Despite large between-trial heterogeneity (I2 = 75%, p < .001), all trials favored GTR over OFD. No differences in treatment effects were detected between trials of GTR with CM alone and trials of GTR with CM in combination with bone substitutes (p for interaction, .31). GTR with CM, with or without substitutes, may result in improved clinical outcomes compared with those achieved with OFD alone. Our findings support GTR with CM for the treatment of infrabony periodontal defects.

Characterization of Optically Stimulated Luminescent Detectors in Photon & Proton Beams for Use in Anthropomorphic Phantoms

This study investigated characteristics of optically stimulated luminescent detectors (OSLDs) in protons, allowing comparison to thermoluminescent detectors, and to be implemented into the Radiological Physics Center’s (RPC) remote audit quality assurance program for protons, and for remote anthropomorphic phantom irradiations. The OSLDs used were aluminum oxide (Al2O3:C) nanoDots from Landauer, Inc. (Glenwood, Ill.) measuring 10x10x2 mm3. A square, 20(L)x20(W)x0.5(H) cm3 piece of solid water was fabricated with pockets to allow OSLDs and TLDs to be irradiated simultaneously and perpendicular to the beam. Irradiations were performed at 5cm depth in photons, and in the center of a 10 cm SOBP in a 200MeV proton beam. Additionally, the Radiological Physics Center’s anthropomorphic pelvic phantom was used to test the angular dependence of OSLDs in photons and protons. A cylindrical insert in the phantom allows the dosimeters to be rotated to any angle with a fixed gantry angle. OSLDs were irradiated at 12 angles between 0 and 360 degrees. The OSLDs were read out with a MicroStar reader from Landauer, Inc. Dose response indicates that at angles where the dosimeter is near parallel with the radiation beam response is reduced slightly. Measurements in proton beams do not show significant angular dependence. Post-irradiation fading of OSLDs was studied in proton beams to determine if the fading was different than that of photons. The fading results showed no significant difference from results in photon beams. OSLDs and TLDs are comparable within 3% in photon beams and a correction factor can be posited for proton beams. With angular dependence characteristics defined, OSLDs can be implemented into multiple-field treatment plans in photons and protons and used in the RPC’s quality assurance program.

The nonsteroidal anti-inflammatory drug indomethacin induces heterogeneity in lipid membranes: potential implication for its diverse biological action.

BACKGROUND: The nonsteroidal anti-inflammatory drug (NSAID), indomethacin (Indo), has a large number of divergent biological effects, the molecular mechanism(s) for which have yet to be fully elucidated. Interestingly, Indo is highly amphiphilic and associates strongly with lipid membranes, which influence localization, structure and function of membrane-associating proteins and actively regulate cell signaling events. Thus, it is possible that Indo regulates diverse cell functions by altering micro-environments within the membrane. Here we explored the effect of Indo on the nature of the segregated domains in a mixed model membrane composed of dipalmitoyl phosphatidyl-choline (di16:0 PC, or DPPC) and dioleoyl phosphatidyl-choline (di18:1 PC or DOPC) and cholesterol that mimics biomembranes. METHODOLOGY/PRINCIPAL FINDINGS: Using a series of fluorescent probes in a fluorescence resonance energy transfer (FRET) study, we found that Indo induced separation between gel domains and fluid domains in the mixed model membrane, possibly by enhancing the formation of gel-phase domains. This effect originated from the ability of Indo to specifically target the ordered domains in the mixed membrane. These findings were further confirmed by measuring the ability of Indo to affect the fluidity-dependent fluorescence quenching and the level of detergent resistance of membranes. CONCLUSION/SIGNIFICANCE: Because the tested lipids are the main lipid constituents in cell membranes, the observed formation of gel phase domains induced by Indo potentially occurs in biomembranes. This marked Indo-induced change in phase behavior potentially alters membrane protein functions, which contribute to the wide variety of biological activities of Indo and other NSAIDs.

Immunostaining of a heterodimeric dermatan sulphate proteoglycan is correlated with smooth muscles and some basement membranes.

A heterodimeric 760-kDa dermatan sulphate proteoglycan tentatively named PG-760 was characterized as a product of keratinocytes, endothelial cells, and fibroblasts. The two core proteins of 460 kDa and 300 kDa are linked by disulphide bridges, and both carry one or only very few dermatan sulphate chains. Different antisera against PG-760 were used in the present study to investigate the distribution in selected murine tissues by light and electron microscopy. PG-760 immunostaining was observed in cornea (epithelium including basement membrane, stroma, and Descemet's membrane), skin, mucosa of the small intestine, Engelbreth-Holm-Swarm (EHS)-tumour (matrix and cells), and the smooth muscle layers of uterus, small intestine, and blood vessels. No staining was observed in capillaries, striated muscles, and liver parenchyma including the central vein. The expression of PG-760 in EHS-tumour was also demonstrated after extraction with 4 M guanidine and partial purification by diethylaminoethyl (DEAE)-chromatography. We conclude that this novel proteoglycan exhibits a unique tissue distribution being a constituent of some but not all basement membranes, of some other extracellular matrices, and additionally, of all investigated smooth muscle layers.

Molecular architecture of basement membranes

Basement membranes are specialized extracellular matrices with support, sieving, and cell regulatory functions. The molecular architectures of these matrices are created through specific binding interactions between unique glycoprotein and proteoglycan protomers. Type IV collagen chains, using NH2-terminal, COOH-terminal, and lateral association, form a covalently stabilized polygonal framework. Laminin, a four-armed glycoprotein, self-assembles through terminal-domain interactions to form a second polymer network, Entactin/nidogen, a dumbbell-shaped sulfated glycoprotein, binds laminin near its center and interacts with type IV collagen, bridging the two. A large heparan sulfate proteoglycan, important for charge-dependent molecular sieving, is firmly anchored in the basement membrane and can bind itself through a core-protein interaction to form dimers and oligomers and bind laminin and type IV collagen through its glycosaminoglycan chains. Heterogeneity of structure and function occur in different tissues, in development, and in response to different physiological needs. The molecular architecture of these matrices may be regulated during or after primary assembly through variations in compositions, isoform substitutions, and the modifying influence of exogenous macromolecules such as heparin and heparan sulfate.

Development of light-responsive porous polycarbonate membranes for controlled caffeine delivery

For controlled caffeine release, light-responsive membranes were developed. It was possible to produce membranes that reduced their caffeine permeability resistance by about 97% when irradiated with UV-light compared to measurements at daylight. This was achieved by grafting polymers possessing photochromic units onto track-edged polycarbonate membranes. Covalently linked coatings on porous polycarbonate membranes were obtained by plasma activation of the membrane surface followed by plasma-induced graft polymerization. Copolymerization of spiro-compounds during the coating process as well as postmodification of preformed coatings with spiropyran resulted in photochromic membranes. For the copolymerization process, the synthesis of five photochromic methacrylic and acrylic spiropyrans and spirooxazines was successfully performed. Additionally, a spiropyran with carboxylic acid functionality was synthesized for the postmodification process. This enabled us to postmodify polymeric materials containing alcohol or amine groups to obtain photochromic materials. UV-irradiation of these light-responsive membranes resulted in a strong colouration of the membrane, in a reduction of surface tension, which resulted in a decreased caffeine permeability resistance. The membranes were characterized using XPS for the elemental composition of the coating, contact angle measurements for the surface tension, solid-state UV/VIS measurements for the determination of the kinetic and stability properties, and two-photon microscopy for the localisation of the photochromic substance in the porous membrane.

Dynamics of red blood cells in microporous membranes

We have performed microfluidic experiments with erythrocytes passing through a network of microchannels of 20–25 μm width and 5 μm of height. Red blood cells (RBCs) were flowing in countercurrent directions through microchannels connected by μm pores. Thereby, we have observed interesting flow dynamics. All pores were blocked by erythrocytes. Some erythrocytes have passed through pores, depending on the channel size and cell elasticity. Many RBCs split into two or more smaller parts. Two types of splits were observed. In one type, the lipid bilayer and spectrin network were cut at the same time. In the second type, the lipid bilayer reconnected, but the part of spectrin network stayed outside the cell forming a rope like structure, which could eventually break. The microporous membrane results in multiple breakups of the cells, which can have various clinical implications, e.g., glomerulus hematuria and anemia of patients undergoing dialysis. The cell breakup procedure is similar to the one observed in the droplet breakage of viscoelastic liquids in confinement.

SNARE-fusion mediated insertion of membrane proteins into native and artificial membranes

Membrane proteins carry out functions such as nutrient uptake, ATP synthesis or transmembrane signal transduction. An increasing number of reports indicate that cellular processes are underpinned by regulated interactions between these proteins. Consequently, functional studies of these networks at a molecular level require co-reconstitution of the interacting components. Here, we report a SNARE protein-based method for incorporation of multiple membrane proteins into artificial membrane vesicles of well-defined composition, and for delivery of large water-soluble substrates into these vesicles. The approach is used for in vitro reconstruction of a fully functional bacterial respiratory chain from purified components. Furthermore, the method is used for functional incorporation of the entire F1F0 ATP synthase complex into native bacterial membranes from which this component had been genetically removed. The novel methodology offers a tool to investigate complex interaction networks between membrane-bound proteins at a molecular level, which is expected to generate functional insights into key cellular functions.

SNARE-fusion mediated inserton of membrane proteins into native and artificial membranes

Membrane proteins carry out functions such as nutrient uptake, ATP synthesis or transmembrane signal transduction. An increasing number of reports indicate that cellular processes are underpinned by regulated interactions between these proteins. Consequently, functional studies of these networks at a molecular level require co-reconstitution of the interacting components. Here, we report a SNARE-protein based method for incorporation of multiple membrane proteins into membranes, and for delivery of large water-soluble substrates into closed membrane vesicles. The approach is used for in vitro reconstruction of a fully functional bacterial respiratory chain from purified components. Furthermore, the method is used for functional incorporation of the entire F1F0-ATP synthase complex into native bacterial membranes from which this component had been genetically removed. The novel methodology offers a tool to investigate complex interaction networks between membrane-bound proteins at a molecular level, which is expected to generate functional insights into key cellular functions.

Increased periodontal inflammation in women with preterm premature rupture of membranes

OBJECTIVES To evaluate possible differences in periodontal inflammatory, microbiological and clinical parameters between women with preterm premature rupture of membranes (PPROM) and controls with uncomplicated pregnancies. MATERIALS AND METHODS Fifty-six women (32 test (PPROM) and 24 controls (uncomplicated pregnancies)) were examined at three time-points (T1: gestational weeks 20-35, T2: within 48 h after parturition, T3: 4-6 weeks after parturition). The examinations included assessment of the Periodontal Screening Index, collection of gingival crevicular fluid (GCF) and subgingival as well as vaginal bacterial sampling. RESULTS Periodontal inflammation was found to be higher in the test compared with the control group (p < 0.05) and decreased over time in both groups (p < 0.05). Microbiological outcomes showed no intergroup differences (p > 0.05) in prevalence of bacteria, but a decrease in subgingival periodontopathogens from T1 to T2 in the test group (p < 0.05) was observed. Interleukin (IL)-1β levels in GCF at T2 were not different between groups (p > 0.05). In women with PPROM, GCF levels of IL-8 (p < 0.05) and C-reactive protein (p < 0.05) were lower and IL-10 levels higher (p < 0.05) compared with controls. CONCLUSIONS Periodontal inflammation is elevated during pregnancy and seems to be more pronounced in women with PPROM. CLINICAL RELEVANCE The findings of the present study revealed an association between periodontal inflammation and PPROM, thus emphasizing the importance of optimizing self-performed oral hygiene in pregnant women.

Treatment of Retained Fetal Membranes: Comparison of the Postpartum Period after Routine Treatment or Routine Treatment Including an Additional Phytotherapeutic Substance in Dairy Cattle in Switzerland

Background: The therapy of retained fetal membranes (RFM) is a controversial subject. In Switzerland, intrauterine antibiotics are routinely administered although their effect on fertility parameters is questionable. The objective of this study was to compare the post-partal period after a routine treatment of RFM in 2 groups: one group received a placebo additionally (A), whereas the other group received a phytotherapeutic substance (lime bark) (B) additionally. The routine treatment of RFM included an attempt to manually remove the fetal membranes (for a maximum of 5 min), intramuscular administration of oxytetracycline and intrauterine treatment with tetracycline. In case of an elevated rectal temperature (>39.0°C), an additional non-steroidal inflam-matory drug was allowed. Methods: Cows undergoing caesarean section, suffering from prolapse of the uterus, deep cervical or vaginal injuries, hypocalcaemia, and illnesses during the last 14 days before calving were excluded. Cows had to be more than 265 days pregnant. Only cows that were artificially inseminated after RFM were included. Group stratification was done according to the last number on the ear tag (even/uneven) with (n = 50) cows in group A and (n = 55) cows in group B. Results: The number of treatments after the initial treatment of RFM was not significantly different between groups. The median interval from calving to the first insemination was 77 days in group A compared to 82 days in group B (p = 0.72). The number of AI’s until conception was not significantly different between groups. The median number of days open was 89 days in group A compared to 96 days in group B (p = 0.57). The culling rate was not significantly different between groups. Conclusion: There was neither a difference between the groups concerning therapies within the first 50 days after RFM nor concerning the subsequent fertility variables.

Efficient luminescent solar concentrators based on self-absorption free, Tm2+ doped halides

The optical and luminescence properties of CaI2 and NaCl doped with divalent thulium are reported for solar energy applications. These halides strongly absorb solar light from the UV up to 900 nm due to the intense Tm2+ 4f13→4f125d1 electronic transitions. Absorption is followed by emission of 1140 nm light due to the 2F5/2→2F7/2 transition of the 4f13 configuration that can be efficiently converted to electric power by thin film CuInSe2 (CIS) solar cells. Because of a negligible spectral overlap between absorption and emission spectra, a luminescent solar concentrator (LSC) based on these black luminescent materials would not suffer from self-absorption losses. The Tm2+ doped halides may therefore lead to efficient semi-transparent power generating windows that absorb solar light over the whole visible spectrum. It will be shown that the power efficiency of the Tm2+ based LSCs can be up to four times higher compared to LSCs based on organic dyes or quantum dots.