In vitro characterization of peptide-modified p(AAm-co-EG/AAc) IPN-coated titanium implants.

Interpenetrating polymer networks (IPNs) of poly(acrylamide-co-ethylene glycol/acrylic acid) [p(AAm-co-EG/AAc)] functionalized with an -Arg-Gly-Asp- containing peptide derived from rat bone sialoprotein [bsp-RGD(15)] were grafted to titanium implants in an effort to modulate osteoblast behavior in vitro. Surface characterization data were consistent with the presence of an IPN, and ligand density measurements established that the range of peptide density on the modified implants spanned three orders of magnitude (0.01-20 pmol/cm2). In vitro biological characterization of the modified implants employing the primary rat calvarial osteoblast (RCO) model resulted in the identification of a critical ligand density (0.01相似文献   

Quantitative analysis of binary adsorbed protein films by time of flight secondary ion mass spectrometry

Time of flight secondary ion mass spectrometry (ToF-SIMS) is an ideal technique for the analysis of adsorbed protein films because of its surface sensitivity and chemical specificity. In this study, we examined ToF-SIMS with the multivariate calibration method partial least squares regression (PLSR) for the determination of the relative abundance of the components in binary protein films adsorbed onto mica, PTFE, and heptyl amine plasma polymer substrates. These results have been compared with independently measured 125I-radiolabeled protein adsorption experiments. By applying PLSR to the ToF-SIMS data, the relative abundance of the components in the binary adsorbed protein films was quantified, and the agreement between the ToF-SIMS and 125I-radiolabeling data was measured by the root mean square prediction error (RMSPE). Differences in protein quantification by PLSR and 125I-radiolabeling ranged from 5 to 25 mass % RMSPE and were highly dependent on the structure of the adsorbed protein film, the substrate surface chemistry and morphology, and the number of latent variables retained in the PLSR model. The limit of detection for the minor component in the adsorbed protein film was found to be approximately 10 mass %. This study demonstrates that the combination of ToF-SIMS and multivariate calibration provide complementary information to 125I-radiolabeling about the composition and structure of binary adsorbed protein films.     

Correction to: How to support dental students in reading radiographs: effects of a gaze‑based compare‑and‑contrast intervention

Advances in Health Sciences Education -     

Validation of fitness tracker for sleep measures in women with asthma

Objective: Nighttime wakening with asthma symptoms is a key to assessment and therapy decisions, with no gold standard objective measure. The study aims were to (1) determine the feasibility, (2) explore equivalence, and (3) test concordance of a consumer-based accelerometer with standard actigraphy for measurement of sleep patterns in women with asthma as an adjunct to self-report. Methods: Panel study design of women with poorly controlled asthma from a university-affiliated primary care clinic system was used. We assessed sensitivity and specificity, equivalence and concordance of sleep time, sleep efficiency, and wake counts between the consumer-based accelerometer Fitbit Charge? and Actigraph wGT3X+. We linked data between devices for comparison both automatically by 24-hour period and manually by sleep segment. Results: Analysis included 424 938?minutes, 738 nights, and 833 unique sleep segments from 47 women. The fitness tracker demonstrated 97% sensitivity and 40% specificity to identify sleep. Between device equivalence for total sleep time (15 and 42-minute threshold) was demonstrated by sleep segment. Concordance improved for wake counts and sleep efficiency when adjusting for a linear trend. Conclusions: There were important differences in total sleep time, efficiency, and wake count measures when comparing individual sleep segments versus 24-hour measures of sleep. Fitbit overestimates sleep efficiency and underestimates wake counts in this population compared to actigraphy. Low levels of systematic bias indicate the potential for raw measurements from the devices to achieve equivalence and concordance with additional processing, algorithm modification, and modeling. Fitness trackers offer an accessible and inexpensive method to quantify sleep patterns in the home environment as an adjunct to subjective reports, and require further informatics development.     

Amphetamine sensitization alters dendritic morphology in prefrontal cortical pyramidal neurons in the non-human primate.

Amphetamine (AMPH) sensitization in the nonhuman primate induces persistent aberrant behaviors reminiscent of the hallmark symptoms of schizophrenia, including hallucinatory-like behaviors, psychomotor depression, and profound cognitive impairment. The present study examined whether AMPH sensitization induces similarly long-lasting morphologic alterations in prefrontal cortical pyramidal neurons. Three to 3(1/2) years postsensitization, sensitized, and AMPH-na?ve control monkeys were killed. Blocks of prefrontal cortex were Golgi-impregnated for elucidation of pyramidal dendritic morphology in layers II/superficial III (II/IIIs), deep III, and V/VI. In AMPH-sensitized animals as compared to AMPH-na?ve controls, pyramidal dendrites in layer II/IIIs exhibited reduced overall dendritic branching and reduced peak spine density (22%) on the apical trunk. Across all layers, the distance from soma to peak spine density along the apical trunk was decreased (126.38+/-7.65 mum in AMPH-sensitized compared to 162.98+/-7.26 microm in AMPH-na?ve controls), and basilar dendritic length was reduced (32%). These findings indicate that chronic dopamine dysregulation, consequent to AMPH sensitization, results in enduring, atrophic changes in prefrontal pyramidal dendrites that resemble the pathologic alterations described in patients with schizophrenia and may contribute to the persistence of schizophrenia-like behavioral changes and cognitive dysfunction associated with sensitization. These findings may also provide key insights into the etiologic origin of the pronounced behavioral disturbances and cognitive dysfunction associated with schizophrenia.     

The Ross procedure: long-term clinical and echocardiographic follow-up

Background

Progressive dilatation of the pulmonary autograft is the principal cause for reoperation following the Ross procedure when the root replacement technique is used. We examined the relation between enlargement of the pulmonary autograft and the development and progression of neo-aortic valve regurgitation, and the long-term clinical follow-up, including the need for reoperation, in patients followed for up to 13 years postoperatively.

Methods

A Ross procedure was performed on 119 older children and young adults (mean age: 31 years old), using the root replacement technique, between June 1989 and January 2002. Serial echocardiography studies were obtained in 108 patients and analyzed blinded to clinical data. The following variables were measured: diameter of annulus, sinuses of Valsalva, and supravalvular ridge; presence and severity of aortic regurgitation; and valve thickening.

Results

The 30 day and late mortality rates were 1.7% and 1.7% (2 patients each). Forty-one patients were followed for more than 5 years, 19 for more than 7 years, and 9 for more than 10 years. There was one thrombotic and no endocarditis events. The 10-year actuarial survival was 96%. Reoperation on the pulmonary autograft or the pulmonary allograft was required in 12 patients. The principal indication for operation on the pulmonary autograft in 11 patients was neo-aortic valve regurgitation (7), aneurysm formation (3), and false aneurysm (1). At 10 years, actuarial freedom from reoperation on the pulmonary autograft was 75%. At last follow-up, 8 of 97 patients without reoperation on the autograft had moderate and none had severe regurgitation of the neo-aortic valve. Independent predictors of progression of neo-aortic valve regurgitation were time from operation, dilatation of the supravalvular ridge, and neo-aortic valve thickening (all p < 0.0002). Freedom from reoperation in the pulmonary allograft at 10 years was 86%.

Conclusions

Long-term follow-up of patients with the Ross procedure using the root replacement technique indicates excellent survival and low thromboembolic and endocarditis risk. The main limitation is the need for reoperation. The prevalence of severe neo-aortic valve regurgitation is low, however there is a progressive increase in regurgitation and in aortic root diameters. Periodic follow-up with echocardiography is recommended because of the continuing risk of progressive regurgitation of the neo-aortic valve and aneurysm formation.     

Characterizing multicomponent adsorbed protein films using electron spectroscopy for chemical analysis,time-of-flight secondary ion mass spectrometry,and radiolabeling: capabilities and limitations

Characterization of complex adsorbed protein films is a critical aspect of biomaterials science, particularly in understanding the in vivo response to biomaterials. The surface analysis techniques electron spectroscopy for chemical analysis (ESCA) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) are particularly suited to the analysis of complex adsorbed protein films due to their wide applicability to a variety of materials. We have investigated the applicability of ESCA for studying the structure of adsorbed serum and plasma protein layers. ESCA was able to monitor the thickness of the adsorbed protein film. Due to its chemical specificity, ToF-SIMS was used to estimate the composition of the plasma and serum protein layers by comparison of their spectra with the spectra of single protein films. The limit of detection of ToF-SIMS for the plasma protein fibrinogen was determined by comparison with independent radiolabeled fibrinogen adsorption measurements. While ToF-SIMS was able to determine some qualitative trends in the composition of the plasma protein films as a function of adsorption time, the detection limit of the minor components in multicomponent adsorbed protein films ultimately limits the ability of ToF-SIMS to quantify the composition of these films. However, both ESCA and ToF-SIMS can provide useful information on adsorbed plasma protein films without further sample treatment. This study outlines the strengths and weaknesses of ESCA and ToF-SIMS for studying multicomponent adsorbed plasma protein films.     

Preserving the structure of adsorbed protein films for time-of-flight secondary ion mass spectrometry analysis

The characterization of adsorbed protein films with ultrahigh vacuum (UHV) surface analysis techniques requires dehydration of the samples, which can cause significant alterations in protein structure. It is desirable to preserve the structure of adsorbed protein films during drying, so UHV analysis could be done in a state that is more representative of proteins' actual structure in the aqueous environment. In this study, two methods, trehalose protection and glutaraldehyde fixation, were explored for their feasibility in preserving adsorbed protein structure for a powerful UHV surface analysis technique, time-of-flight secondary ion mass spectrometry (ToF-SIMS). Trehalose protection had shown some promise for ToF-SIMS analysis in our previous study and was further examined with the model protein fibrinogen in this study. Using the combination of principal component analysis (PCA) and static ToF-SIMS analysis, we found that trehalose protection could reduce the conformation change of fibrinogen upon drying, and prevent it from unfolding and exposing hydrophobic domains. Moreover, when the adsorbed protein film became more densely packed, the drying-induced changes in protein structure were reduced. Thus, the protection afforded by trehalose coating was more significant at lower protein surface concentrations. The other method, glutaraldehyde fixation, was used in ToF-SIMS analysis for the first time. The epsilon-amino group of lysine was identified as the major reactive group in the protein structure toward glutaraldehyde fixation. Structural differences observed between fibrinogen films that were glutaraldehyde fixed before drying and after drying were similar to those observed between trehalose-protected and-unprotected dried fibrinogen films. Glutaraldehyde fixation was found to be a viable, alternative stabilizing method to trehalose protection for ToF-SIMS analysis.     

PEO-like plasma polymerized tetraglyme surface interactions with leukocytes and proteins: in vitro and in vivo studies

Polyethylene oxide (PEO) surfaces reduce non-specific protein and cell interactions with implanted biomaterials and may improve their biocompatibility. PEO-like polymerized tetraglyme surfaces were made by glow discharge plasma deposition onto fluorinated ethylene propylene copolymer (FEP) substrates and were shown to adsorb less than 10 ng/cm2 of fibrinogen in vitro. The ability of the polymerized tetraglyme surfaces to resist leukocyte adhesion was studied in vitro and in vivo. Polymerized tetraglyme and FEP were implanted subcutaneously in mice and removed after 1 day or 4 weeks. Histological analysis showed a similar degree of fibrous encapsulation around all of the 4-week implants. Darkly stained wells were present in the fibrous tissues at the tissue-material interface of both FEP and tetraglyme. Scanning electron micrographs showed that in vivo macrophage adhesion to polymerized tetraglyme was much higher than to FEP. After 2-hour contact with heparinized whole blood, polymorphonuclear leukocyte (PMN) adhesion to polymerized tetraglyme was much higher than to FEP, while platelet adhesion to polymerized tetraglyme was lower than to FEP. When PMNs isolated from blood were suspended in 10% autologous plasma, cell adhesion to polymerized tetraglyme was higher than to FEP; however when the cells were suspended in heat inactivated serum, cell adhesion to FEP was higher than to polymerized tetraglyme. The surface chemistry of polymerized tetraglyme did not change after 2-hour blood contact, but displayed nitrogen functional groups after 1-day implantation and became slightly degraded after 4-week implantation. The surface chemistry of FEP did not change significantly after blood contact or implantation. Loosely bound proteins such as fibrinogen on polymerized tetraglyme may contribute to the adhesion of PMNs and macrophages and ultimately to fibrous encapsulation (the foreign body response) around the implants.