New fluorescent probes for the measurement of cell membrane viscosity

BACKGROUND

Molecular rotors are fluorescent molecules that exhibit viscosity-dependent fluorescence quantum yield, potentially allowing direct measurements of cell membrane viscosity in cultured cells. Commercially available rotors, however, stain not only the cell membrane, but also bind to tubulin and migrate into the cytoplasm. We synthesized molecules related to 9-(dicyanovinyl)-julolidine (DCVJ), which featured hydrocarbon chains of different length to increase membrane compatibility.

RESULTS

Longer hydrocarbon chains attached to the fluorescent rotor reduce the migration of the dye into the cytoplasm and internal compartments of the cell. The amplitude of the fluorescence response to fluid shear stress, known to decrease membrane viscosity, is significantly higher than the response obtained from DCVJ. Notably a farnesyl chain showed a more than 20-fold amplitude over DCVJ and allowed detection of membrane viscosity changes at markedly lower shear stresses.

CONCLUSIONS

The modification of molecular rotors towards increased cell membrane association provides a new research tool for membrane viscosity measurements. The use of these rotors complements established methods such as fluorescence recovery after photobleaching with its limited spatial and temporal resolution and fluorescence anisotropy, which has low sensitivity and may be subject to other effects such as deformation.

Human MDR 1 protein overexpression delays the apoptotic cascade in Chinese hamster ovary fibroblasts

Several laboratories have reported that overexpression of the multidrug resistance (MDR) protein is associated with intracellular alkalinization, and several investigators have reported that cells induced to undergo programmed cell death (apoptosis) acidify quite significantly. Because it is difficult to fully explain the resistance to apoptosis-inducing chemotherapeutic drugs that is exhibited by MDR tumor cells solely via altered drug transport alone [Hoffman et al. (1996) J. Gen. Physiol. 108, 295-313], we have investigated whether overexpression of the hu MDR 1 protein alters progression of the apoptotic cascade. LR73 fibroblasts induced to undergo apoptosis either via treatment with the chemotherapeutic drug colchicine or by serum withdrawal exhibit cellular volume changes, intracellular acidification, nuclear condensation, and chromosomal digestion ("ladder formation"), characteristic of apoptosis, in a temporally well-defined pattern. However, multidrug resistant LR73/20E or LR73/27 hu MDR 1 transfectants recently created in our laboratory without selection on chemotherapeutic drug are significantly delayed in the onset of apoptosis as defined by the above criteria, regardless of whether apoptosis is induced by colchicine treatment or by serum withdrawal. Thus, the delay cannot simply be due to the well-known ability of MDR protein overexpression to lower chemotherapeutic drug accumulation in MDR cells. LR73/27V500 "selectants", exhibiting similar levels of MDR protein overexpression but higher multidrug resistance due to selection with the chemotherapeutic drug vincristine, exhibit a slightly longer delay in the progression of apoptosis. Normal apoptotic cascade kinetics are partially restored by pre-treatment of the MDR cells with the MDR protein inhibitor verapamil. Untransfected LR73 cells not expressing MDR protein but elevated in pHi via manipulation of CO2/HCO3- as described [Hoffman et al. (1996) J. Gen. Physiol. 108, 295-313] are inhibited in DNA ladder formation, similar to LR73/hu MDR 1 transfectants. These results uncover an additional mechanism whereby MDR protein overexpression may promote the survival of tumor cells and further support the notion that in some systems intracellular acidification may be either causal or permissive for proper progression of the apoptotic cascade.

Depth of interaction decoding of a continuous crystal detector module

We present a clustering method to extract the depth of interaction (DOI) information from an 8 mm thick crystal version of our continuous miniature crystal element (cMiCE) small animal PET detector. This clustering method, based on the maximum-likelihood (ML) method, can effectively build look-up tables (LUT) for different DOI regions. Combined with our statistics-based positioning (SBP) method, which uses a LUT searching algorithm based on the ML method and two-dimensional mean-variance LUTs of light responses from each photomultiplier channel with respect to different gamma ray interaction positions, the position of interaction and DOI can be estimated simultaneously. Data simulated using DETECT2000 were used to help validate our approach. An experiment using our cMiCE detector was designed to evaluate the performance. Two and four DOI region clustering were applied to the simulated data. Two DOI regions were used for the experimental data. The misclassification rate for simulated data is about 3.5% for two DOI regions and 10.2% for four DOI regions. For the experimental data, the rate is estimated to be approximately 25%. By using multi-DOI LUTs, we also observed improvement of the detector spatial resolution, especially for the corner region of the crystal. These results show that our ML clustering method is a consistent and reliable way to characterize DOI in a continuous crystal detector without requiring any modifications to the crystal or detector front end electronics. The ability to characterize the depth-dependent light response function from measured data is a major step forward in developing practical detectors with DOI positioning capability.

Clinical pharmacokinetics of ganciclovir in patients with normal and impaired renal function

The pharmacokinetics of ganciclovir was evaluated in 21 patients with life- or sight-threatening cytomegalovirus infections. Thirteen patients had normal renal function and eight patients had various degrees of renal insufficiency. Most patients received 5 mg of ganciclovir/kg as a 1-hour intravenous infusion twice daily for periods of up to 2 weeks. Quantification of ganciclovir was assessed by high-performance liquid chromatography and radioimmunoassay. In patients with normal renal function, a biexponential decay of ganciclovir from plasma was observed, with an initial distribution half-life (t1/2) of 0.76 +/- 0.67 hour and a terminal elimination t1/2 of 3.60 +/- 1.40 hours. A large fraction of the administered dose was excreted in urine, and total clearance of ganciclovir correlated well with creatinine clearance. In patients with renal insufficiency who were receiving 5 mg of ganciclovir/kg, the terminal elimination t1/2 of ganciclovir was markedly increased (11.50 +/- 3.90 hours), as compared with values obtained in patients with normal renal function. Hemodialysis efficiently reduced levels of ganciclovir in plasma by approximately 53.0% +/- 11.5%, a finding that indicates this drug should be administered after dialysis.

Calicheamicin-DNA complexes: warhead alignment and saccharide recognition of the minor groove

The solution structures of calicheamicin gamma 1I, its cycloaromatized analog (calicheamicin epsilon), and its aryl tetrasaccharide complexed to a common DNA hairpin duplex have been determined by NMR and distance-refined molecular dynamics computations. Sequence specificity is associated with carbohydrate-DNA recognition that places the aryl tetrasaccharide component of all three ligands in similar orientations in the minor groove at the d(T-C-C-T).d(A-G-G-A) segment. The complementary fit of the ligands and the DNA minor groove binding site creates numerous van der Waals contacts as well as hydrogen bonding interactions. Notable are the iodine and sulfur atoms of calicheamicin that hydrogen bond with the exposed amino proton of the 5'- and 3'-guanines, respectively, of the d(A-G-G-A) segment. The sequence-specific carbohydrate binding orients the enediyne aglycone of calicheamicin gamma 1I such that its C3 and C6 proradical centers are adjacent to the cleavage sites. While the enediyne aglycone of calicheamicin gamma 1I is tilted relative to the helix axis and spans the minor groove, the cycloaromatized aglycone is aligned approximately parallel to the helix axis in the respective complexes. Specific localized conformational perturbations in the DNA have been identified from imino proton complexation shifts and changes in specific sugar pucker patterns on complex formation. The helical parameters for the carbohydrate binding site are comparable with corresponding values in B-DNA fibers while a widening of the groove is observed at the adjacent aglycone binding site.

Outbreaks of infection with methicillin-resistant Staphylococcus aureus on neonatal and burns units of a new hospital

Multiple introductions of methicillin-resistant Staphylococcus aureus (MRSA) strains occurred to a new hospital in Hong Kong. Two years of clinical microbiological surveillance of the resulting outbreaks was combined with laboratory investigation by phage and antibiogram typing, and plasmid profiling. The outbreaks on the special care baby (SCBU) and burns (BU) units were studied in detail, and colonization of staff and contamination of the environment were investigated. MRSA were spread by the hands of staff on the SCBU, where long-term colonization of dermatitis was important, but were probably transmitted on the BU by a combination of the airborne, transient hand-borne and environmental routes. Simple control measures to restrict hand-borne spread on the SCBU were highly effective, but control was not successful on the BU.

Enantioselective synthesis of the antiinflammatory agent (-)-acanthoic acid

An enantioselective synthesis of the potent antiinflammatory agent (-)-acanthoic acid (1) is described. The successful strategy departs from (-)-Wieland-Miescher ketone (10), which is readily available in both enantiomeric forms and constitutes the starting point toward a fully functionalized AB ring system of 1. Conditions were developed for a regioselective double alkylation at the C4 center of the A ring, which produced compound 32 as a single stereoisomer. Construction of the C ring of 1 was accomplished via a Diels-Alder reaction between sulfur-containing diene 43 and methacrolein (36), which after desulfurization and further functionalization yielded synthetic acanthoic acid. The described synthesis confirms the proposed stereochemistry of the natural product and represents a fully stereocontrolled entry into an underexplored class of biologically active diterpenes.

Enantioselective Total Synthesis of Avarol and Avarone

Formation of the C11-C1' bond through application of Barton's radical decarboxylation and quinone addition is the cornerstone of a new convergent and concise synthesis of the marine metabolites avarol (1) and avarone (2; see scheme), for which antimitotic, antileukemic, and antiviral effects have been reported.

Parametric positioning of a continuous crystal PET detector with depth of interaction decoding

Here we demonstrate a parametric positioning method on a continuous crystal detector. Three different models for the light distribution were tested. Diagnosis of the residues showed that the parametric model fits the experimental data better than Gaussian and Cauchy models in our particular experimental setup. Based on the correlation between the spread and the peak value of the light distribution model with the depth of interaction (DOI), we were able to estimate the three-dimensional position of a scintillation event. On our continuous miniature crystal element (cMiCE) detector module with 8 mm thick LYSO crystal, the intrinsic spatial resolution is 1.06 mm at the center and 1.27 mm at the corner using a maximum-likelihood estimation (MLE) method and the parametric model. The DOI resolution (full width at half maximum) is estimated to be approximately 3.24 mm. The positioning method using the parametric model outperformed the Gaussian and Cauchy models, in both MLE and weighted least-squares (WLS) fitting methods. The key feature of this technique is that it requires very little calibration of the detector, but still retains high resolution and high sensitivity.

Low nanomolar concentrations of Cucurbitacin-I induces G2/M phase arrest and apoptosis by perturbing redox homeostasis in gastric cancer cells in vitro and in vivo

Cucurbitacin-I (Cu-I, also known as Elatericin B or JSI-124) is developed to inhibit constitutive and abnormal activation of STAT3 in many cancers, demonstrating a potent anticancer activity by targeting disruption of STAT3 function. Here, we for the first time systematically studied the underlying molecular mechanisms of Cu-I-induced gastric cancer cell death both in vitro and in vivo. In our study, we show that Cu-I markedly inhibits gastric cancer cell growth by inducing G2/M phase cell cycle arrest and apoptosis at low nanomolar concentrations via a STAT3-independent mechanism. Notably, Cu-I significantly decreases intracellular GSH/GSSG ratio by inhibiting NRF2 pathway to break cellular redox homeostasis, and subsequently induces the expression of GADD45α in a p53-independent manner, and activates JNK/p38 MAPK signaling. Interestingly, Cu-I-induced GADD45α and JNK/p38 MAPK signaling form a positive feedback loop and can be reciprocally regulated by each other. Therefore, the present study provides new insights into the mechanisms of antitumor effects of Cu-I, supporting Cu-I as an attractive therapeutic drug in gastric cancer by modulating the redox balance.

Method of evaluating ultrasonic pachometers

Although many ultrasonic pachometers are commercially available, little has been reported about their performance. We outline a technique for evaluating the accuracy of ultrasonic pachometers by simulating corneal thickness measurements using hydrogel contact lenses. On-eye contact lens thickness is determined using ultrasonic and optical pachometry. Absolute lens thickness is determined using a thickness gauge. Comparisons are made between measurements from the ultrasonic pachometer and measurements from the thickness gauge and optical pachometer. We used this technique to evaluate the performance of the Vida-55 ultrasonic pachometer. This technique was also used to determine the ultrasonic velocity for cat corneal tissue and two hydrogel lens materials. We determined the velocity of ultrasound in cat corneal tissue to be 1590 m/s at 33 degrees C. The velocity of ultrasound in hydroxyethyl methacrylate (HEMA) was 1740 +/- 24 m/s and 1700 +/- 40 m/s in Snoflex 50. We found the Vida-55 pachometer measured corneal thickness accurately when the appropriate ultrasound velocity was used (SEM = 6 microns).

Moving beyond individual choice in policies to reduce health inequalities: the integration of dynamic with individual explanations

Background

A strong focus on individual choice and behaviour informs interventions designed to reduce health inequalities in the UK. We review evidence for wider mechanisms from a range of disciplines, demonstrate that they are not yet impacting on programmes, and argue for their systematic inclusion in policy and research.

Methods

We identified potential mechanisms relevant to health inequalities and their amelioration from different disciplines and analysed six policy documents published between 1976 and 2010 using Bacchi's 'What's the problem represented to be?' framework for policy analysis.

Results

We found substantial evidence of supra-individualistic and relational mechanisms relevant to health inequalities from sociology, history, biology, neuroscience, philosophy and psychology. Policy documents sometimes expressed these mechanisms in policy rhetoric but rarely in policy recommendations, which continue to focus on individual behaviour.

Discussion

Current evidence points to the potential of systematically applying broader thinking about causal mechanisms, beyond individual choice and responsibility, to the design, implementation and evaluation of policies to reduce health inequalities. We provide a set of questions designed to enable critique of policy discussions and programmes to ensure that these wider mechanisms are considered.

Stereoselective synthesis of (-)-acanthoic acid

[reaction: see text] The first stereoselective synthesis of (-)-acanthoic acid (1) has been designed and accomplished. Our synthetic plan departs from (-) Wieland-Miesher ketone (7) and calls upon a Diels-Alder cycloaddition reaction for the construction of the C ring of 1. The described synthesis confirms the proposed stereochemistry of 1 and represents an efficient entry into an unexplored class of biologically active diterpenes.

Long-term outcomes of peroral endoscopic myotomy for patients with achalasia: a retrospective single-center study

Peroral endoscopic myotomy (POEM) has been widely applied to the treatment of achalasia. The aim of this study is to retrospectively investigate the long-term outcome of POEM in patients with achalasia. Patients undergoing POEM at our center with a minimum follow-up of 3 years were enrolled in this study. Relief of patients' symptom was defined as the primary outcome. Secondary outcomes included lower esophageal sphincter pressure, esophageal emptying, symptoms relapse, and clinical reflux adverse events. The Chi-square test was performed to determine the potential predictors of surgical failure. Sixty-seven patients (aged 40.7 ± 15.3 years) were recruited in the study, with a mean follow-up period of 40.1 ± 2.8 months. At the final follow-up, the median Eckardt score reduced from 7.6 ± 2.3 preoperatively to 1.9 ± 1.7 (P < 0.001), the lower esophageal sphincter pressure was reduced from 35.4 ± 13.7 mmHg preoperatively to 8.9 ± 4.1 mmHg (P < 0.001), and the height of the barium column at 5 min after barium swallowed was reduced from 9.7 ± 1.6 cm preoperatively to 2.9 ± 2.1 cm (P < 0.001). Eight patients had symptoms relapse and nine patients developed reflux esophagitis. Type III achalasia was found to be indicative of surgical failure. POEM was a promising treatment for patients with achalasia, which can yield a long-term relief of the symptom and a low rate of clinical reflux adverse events.

Percutaneous absorption of nicardipine and ketorolac in rhesus monkeys

Vehicle effects on the percutaneous absorption of nicardipine base, nicardipine hydrochloride, ketorolac acid, and ketorolac tromethamine were determined using the rhesus monkey as an in vivo model for human skin penetration. Vehicles investigated included blends of propylene glycol, trimethylene glycol, ethanol, Azone, Tween 20, water, and long-chain fatty acids. Formulations were prepared such that the compound dose, application area, and percentage saturation of the compound in the vehicle were held constant. Variations in absorption of the compounds were therefore attributable to vehicle effects. Each formulation was applied to three monkeys for a period of 24 hr using 10 Hill Top Chambers. Plasma samples were taken at appropriate intervals for 36 to 48 hr. The results indicated that trimethylene glycol and Tween 20 did not enhance absorption of the test compounds despite claims by other investigators. Azone and ethanol provided moderate enhancement of both the rate and the extent of absorption, while long-chain fatty acids in combination with propylene glycol significantly enhanced penetration. In general, higher fluxes were observed with the more lipophilic compounds nicardipine base and ketorolac acid as compared to the hydrochloride and tromethamine salts.

Susceptibility of Hong Kong isolates of methicillin-resistant Staphylococcus aureus to antimicrobial agents

Two hundred and sixty-six non-replicate Hong Kong isolates of methicillin-resistant Staphylococcus aureus were tested for their susceptibility to various anti-staphylococcal agents. Multiple resistance was common. More than 95% of patient isolates were resistant to both gentamicin and tetracycline, 68% to erythromycin, 37% to chloramphenicol, 10% to trimethoprim, 5% to rifampicin and 2% to fusidic acid. No isolate was resistant to all these agents, but nineteen different patterns of resistance were identified. Selected gentamicin-resistant isolates were tested against other aminoglycosides, and were sensitive to amikacin and netilmicin. The pattern of aminoglycoside resistance indicated that all isolates produced the aminoglycoside-modifying enzymes APH-(2") and AAC-(6')-I. All isolates were sensitive to vancomycin and teicoplanin. A single strain was resistant to three of the five quinolones tested, but resistance to all the quinolones could be induced easily in vitro by exposure to increasing subinhibitory concentrations of norfloxacin in broth.

Enantioselective synthesis of the [6,6] spiroketal core of reveromycin A

[structure: see text] Reveromycin A (1) belongs to a family of microbial polyketides with unusual structural features and biological activities. The structure of 1 is composed of a [6,6] spiroketal core decorated with highly unsaturated side chains. As a prelude to the synthesis of 1, we present herein a short, efficient, and enantioselective synthesis of the C9-C21 fragment 5 (spiroketal core) of reveromycin A.

Osmotically induced central and peripheral corneal swelling in the cat

A number of factors have been suggested to account for the reduced swelling response of the peripheral cornea. The osmotic swelling was determined in 25 adult cats by dripping deionized water onto the cornea for 30 min. The central cornea swelled 62 +/- 19 microns compared to 32 +/- 21 microns for the peripheral cornea. Before treatment, the cat was found to have a very uniform thickness profile, measuring 592 +/- 42 microns centrally, and 585 +/- 46 microns peripherally. The difference in central and peripheral swelling was therefore not due to topographical differences in baseline thickness. Endothelial cell density (ECD) determined with specular microscopy was 2920 cells/mm2 centrally, compared to 3,185 cells/mm2 peripherally. Differences in cell density between the center and periphery are not responsible for the reduced swelling response of the corneal periphery inasmuch as swelling response was not correlated with cell density either in the center of the cornea or in the periphery (r = 0.179 and r = 0.221, respectively). By selecting an animal with a uniform thickness profile and by using an osmotic stimulus, this study has shown that the most likely cause for the reduced swelling response near the limbus is a difference in structural and/or hydration characteristics of the cornea at the limbus.

Plasma levels and pharmacokinetics of norethindrone and ethinylestradiol administered in solution and as tablets to women

Twenty-four normal adult female volunteers were dosed orally with a solution and tablet formulation containing the contraceptive combination of norethindrone (NET, 1.0 mg) and ethinylestradiol (EE2, 0.12 mg) in a crossover bioequivalence study. Blood was sampled sequentially following single oral doses and the plasma separated for analysis of NET and EE2 by specific radioimmunoassays. Comparisons of both drugs following a dose in solution and tablets were made with respect to the following parameters: (a) plasma concentrations at each sample time; (b) maximum plasma concentration (Cpmax); (c) time to maximum plasma concentration (Tmax); (d) total area under the plasma concentration vs. time curve (AUC), and (e) plasma half-life (t1/2). It was found that the tablet and solution doses were bioequivalent with respect to EE2 absorption. However, absorption of NET from solution and tablet doses exhibited significant differences with respect to plasma levels at certain time points as well as AUC (which were higher following the tablet dose), but Cpmax, Tmax and t1/2 were not significantly different. Pharmacokinetic analysis of both drugs following the tablet dose was carried out using a two-compartment open model. The absorption rate constant (ka) and peripheral to central compartment transfer rate constant (k21) were similar for NET and EE2, but statistically significant differences were observed with respect to the distribution rate constant (alpha), the central to peripheral transfer rate constant (k12), the overall elimination rate constant (ke1), and volume of distribution (V1/F). The elimination rate constant (beta) for both drugs showed a difference of borderline statistical significance.

Mechanisms of Light-Induced Deformations in Photoreceptors

Biological cells deform on a nanometer scale when their transmembrane voltage changes, an effect that has been visualized during the action potential using quantitative phase imaging. Similar changes in the optical path length have been observed in photoreceptor outer segments after a flash stimulus via phase-resolved optical coherence tomography. These optoretinograms reveal a fast, millisecond-scale contraction of the outer segments by tens of nanometers, followed by a slow (hundreds of milliseconds) elongation reaching hundreds of nanometers. Ultrafast measurements of the contractile response using line-field phase-resolved optical coherence tomography show a logarithmic increase in amplitude and a decreasing time to peak with increasing stimulus intensity. We present a model that relates the early receptor potential to these deformations based on the voltage-dependent membrane tension-the mechanism observed earlier in neurons and other electrogenic cells. The early receptor potential is caused by conformational changes in opsins after photoisomerization, resulting in the fractional shift of the charge across the disk membrane. Lateral repulsion of the ions on both sides of the membrane affects its surface tension and leads to its lateral expansion. Because the volume of the disks does not change on a millisecond timescale, their lateral expansion leads to an axial contraction of the outer segment. With increasing stimulus intensity and the resulting tension, the area expansion coefficient of the disk membrane also increases as thermally induced fluctuations are pulled flat, resisting further expansion. This leads to the logarithmic saturation observed in measurements as well as the peak shift in time. This imaging technique therefore relates the structural changes in the photoreceptor to the underlying neurological function of transducing light into electrical signals. Such label-free optical monitoring of neural activity using fast interferometry may be applicable not only to optoretinography but also to neuroscience in general.

High-level expression of porcine fructose-1,6-bisphosphatase in Escherichia coli: purification and characterization of the enzyme

A cDNA encoding porcine fructose-1,6-bisphosphatase was isolated from total pig liver RNA. The enzyme's coding sequence was fused to the bacteriophage T7 gene 10 promoter and transcription terminator sequence and expressed in E. coli under control of the T7 RNA polymerase. Induced cells contain elevated levels of fructose-1,6-bisphosphatase enzymatic activity and an abundant 37,000 dalton protein. The enzyme was purified to apparent homogeneity and judged identical to wild-type porcine fructose-1,6-bisphosphatase. The kinetic parameters are similar to those reported for the pig kidney enzyme. The N-terminal amino acid sequence is identical to the predicted sequence and the kinetic parameters are consistent with freedom from proteolysis. As estimated from enzymatic activity and visual inspection of coomassie blue-stained SDS-PAGE gels, porcine fructose-1,6-bisphosphatase constitutes as much as 20% of the soluble protein from the over-expressing E. coli strain.

Smoking behavior among adolescents in the city, suburbs, and rural areas of Shanghai

PURPOSE

The study was designed to investigate differences in predisposing factors, enabling factors, reinforcing factors, and smoking behavior among middle school students living in the city, suburbs, and rural areas of Shanghai.

DESIGN

A one-time cross-sectional survey design was applied in this study.

SETTING

The study was conducted in 11 schools in three areas.

SUBJECTS

A total number of 1116 students from these three areas participated in this study. The response rates were 92, 88, and 84% for city, suburbs, and rural areas, respectively.

MEASURE

A PRECEDE instrument including predisposing, enabling, and reinforcing factors was employed to collect data. A Multivariate Analysis of Variance (MANOVA) and Multiple Regression Analysis were used to analyze the data.

RESULTS

Smoking was reported by 39.8% of boys and 5.14% of girls. Students in the city of Shanghai had the best (against smoking) predisposing factors, but students in rural areas had the best (against smoking) enabling and reinforcing factors and consumed the fewest cigarettes.

CONCLUSION

Results indicated that smoking behavior in students was affected strongly by enabling factors and reinforcing factors that were related to socioeconomic, cultural, and environmental influences in China.

Guided bone regeneration using acellular bovine pericardium in a rabbit mandibular model: in-vitro and in-vivo studies

BACKGROUND AND OBJECTIVE

To investigate the feasibility of acellular bovine pericardium (BP) for guided bone regeneration (GBR) in vitro and in vivo. The success of GBR relies on the fact that various cellular components possess different migration rates into the defect site and that a barrier membrane plays a significant role in these processes.

MATERIAL AND METHODS

BP membrane was isolated and decellularized using an enzymatic method. The microarchitecture, mechanical properties, cytotoxicity and cell chemotaxis properties of the acellular BP were evaluated in vitro, and the in-vivo efficacy of the acellular BP was also investigated in a rabbit mandibular model.

RESULTS

The acellular BP membrane possessed an interconnected fibrous structure. Glutaraldehyde (GA) treatment was efficient for enhancement of the mechanical properties of the acellular BP bur and resulted in negligible cytotoxicity. After 16 wk, standardized osseous defects created in the rabbit mandible, and covered with acellular BP, were associated with an enhanced deposition of mineralized tissue when compared with defects left to spontaneous healing.

CONCLUSION

GA-treated acellular BP is promising as a barrier membrane for GBR for further in-vivo and clinical studies.