New Monomer Capable of Dual Chemical Binding with Dentin to Improve Bonding Durability.

The water-rich nature of the dentin bonding microenvironment, coupled with the stresses on the bonding interface, contributes to the hydrolytic degradation of the hybrid layer, resulting in a decline in bonding durability and, ultimately, restoration failure. Currently, the 3-step etch-and-rinse technique remains the gold standard for dentin bonding, and the bonding mechanism mainly involves a physical interaction with little chemical bonding. In this study, we have developed a siloxane-modified polyurethane monomer (SPU) with acrylate and siloxane modifications that chemically binds to both collagen and hydroxyapatite in dentin. Formulated as a bisphenol A-glycidyl methacrylate alternative, the SPU monomer-based adhesive was designed to improve dentin bonding quality and durability. Attenuated total reflection Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscope, and hydroxyproline release assays were performed on SPU-treated collagen, hydroxyapatite, and acid-etched dentin slices to dentin. The physicochemical properties of the configured SPU adhesives were profiled for polymerization behavior, water contact angle, and tensile strain and strength. The bonding effectiveness was assessed through micro-tensile strength, nano-leakage tests conducted on the bonded samples before and after thermal cycle aging. Finally, we further conducted in vivo and in vitro experiments to assess the biocompatibility of adhesives. The results showed that the siloxane groups of SPU monomer could covalently bind to dentin collagen and hydroxyapatite. The incorporation of SPU in the adhesive led to a significant increase in adhesive polymerization (P < 0.05) and tensile strain at break up to 134.11%. Furthermore, the SPU adhesive significantly improved dentin bond strength (P < 0.05), reduced interfacial nano-leakage (P < 0.05), and displayed good biocompatibility. In conclusion, the application of SPU, which achieves dual chemical bonding with dentin, can improve the quality of the hybrid layer, buffer the interfacial stresses, enhance the interfacial resistance to hydrolysis, and provide a feasible strategy to extend the service life of adhesive restorations.

Effect of Collagen-Reactive Functional Monomer on Etch-and-Rinse Adhesives.

In this study, we evaluated a novel functional monomer (4-formylphenyl acrylate [FA]) that can specifically and covalently bind to the dentin collagen matrix as a potential alternative hydrophobic diluent-like monomer for improving the durability of dentin bonding. Experimental adhesives with different FA contents (0%, 10%, 20%, and 30%) were evaluated as partial substituents for the hydrophilic monomer 2-hydroxyethyl methacrylate, with the commercial adhesive One-Step (Bisco, Inc.) employed as the positive control. Their degree of conversion, viscosity, hydrophobicity, mechanical properties, and water absorption/solubility were measured as the comprehensive characterization. In situ zymographic assays were performed to determine the extent to which FA inhibits the endogenous hydrolytic activity of dentin. Finally, the bonding performances of the novel adhesives were evaluated with microtensile strength tests and scanning electron microscopy. The results showed that the incorporation of FA significantly improved the mobility of experimental adhesives attributable to the dilution property of FA. In contrast to the possible compromised rate of polymerization by hydroxyethyl methacrylate, FA exhibited typical characteristics of favorable copolymerization with polymerizable monomers in adhesives and improved the degree of conversion of experimental adhesives. The rigidity and hydrophobic properties of the phenyl framework of the FA molecule conferred superior mechanical properties and hydrolysis resistance to the novel experimental adhesives. An inhibitory effect on gelatinolytic activities within the hybrid layer was also observed in the in situ zymographic assays, even at a low FA concentration (10%). In conjunction with the significantly improved infiltration found via scanning electron microscopy, the experimental adhesives containing FA possessed significantly better-maintained microtensile strength, even after aging. Thus, the incorporation of this novel monomer endowed the experimental adhesives with multiple enhanced functionalities. These remarkable advantages highlight the suitability of the monomer for further applications in clinical practice.

[Respiratory drive in acute respiratory distress syndrome: evaluation and control].

Acute respiratory distress syndrome (ARDS) is a common critical disease, which often leads to poor prognosis in critically ill patients. The excessive respiratory drive in ARDS is related to lung injury. Control of excessive respiratory drive is helpful to reduce lung injury and mortality of ARDS. The mechanisms of abnormal increase in respiratory drive in ARDS include hypoxemia, hypercapnia, stretch reflex caused by alveolar collapse and inflammatory stimulation. Respiratory drive should be evaluated by clinical manifestations, physiological parameters and respiratory mechanics indexes. It is particularly important to make individual therapy strategies according to the evaluation of respiratory drive. Analgesia and sedation combined with muscle relaxation, high positive end-expiratory pressure (PEEP) and prone position can be used to control excess respiratory drive. This article reviews the evaluation and management of excess respiratory drive in ARDS patients.

A Novel Chemical Binding Primer to Improve Dentin Bonding Durability.

The dentin collagen matrix that is not completely enveloped by resin adhesive is vulnerable to degradation by intrinsic collagenases during the etch-and-rinse process, which contributes to the deterioration of the bonding interface. Current commercial adhesives have no functional components that can form covalent bonds to the dentin collagen matrix. In this study, a photocurable aldehyde, 4-formylphenyl acrylate (FA), was synthesized and for the first time applied as a primer in adhesive dentistry to covalently bind to collagen. Experimental groups with different concentrations of FA (1%, 3%, 5%, 7%, 9%) were prepared as primers. The cytotoxicity was evaluated by live/dead-cell staining and thiazolyl blue tetrazolium bromide assay. The interaction of FA with collagen was examined by attenuated total reflection Fourier transform infrared spectroscopy, hydroxyproline release under the degradation of type I collagenase, and thermogravimetric analysis. An optimal group was selected based on the degree of conversion of 2 universal adhesives and further divided depending on the treatment time (20 s, 30 s, 1 min, 2 min). The bonding performances were evaluated by microtensile strength before and after aging. Finally, the bonding interface was observed under confocal laser scanning microscopy and scanning electron microscope. The results indicated that FA demonstrated good biocompatibility, dentin modification capability, and infiltration. It not only effectively cross-linked dentin collagen to improve its stability against enzymatic hydrolysis and modify the adhesive interface but also potentially acted as a diluting monomer to induce deep penetration of adhesive resin monomers into the dentin. The bonding strength after aging was improved without jeopardizing the degree of conversion of 2 commercial adhesives. Such prominent advantages of using FA to improve the bonding performance promotes its further application in adhesive dentistry.

Middle cranial fossa sphenoidal region dural arteriovenous fistulas: anatomic and treatment considerations.

BACKGROUND AND PURPOSE: DAVFs rarely involve the sphenoid wings and middle cranial fossa. We characterize the angiographic findings, treatment, and outcome of DAVFs within the sphenoid wings. MATERIALS AND METHODS: We reviewed the clinical and radiologic data of 11 patients with DAVFs within the sphenoid wing that were treated with an endovascular or with a combined endovascular and surgical approach. RESULTS: Nine patients presented with ocular symptoms and 1 patient had a temporal parenchymal hematoma. Angiograms showed that 5 DAVFs were located on the lesser wing of sphenoid bone, whereas the other 6 were on the greater wing of the sphenoid bone. Multiple branches of the ICA and ECA supplied the lesions in 7 patients. Four patients had cortical venous reflux and 7 patients had varices. Eight patients were treated with transarterial embolization using liquid embolic agents, while 3 patients were treated with transvenous embolization with coils or in combination with Onyx. Surgical disconnection of the cortical veins was performed in 2 patients with incompletely occluded DAVFs. Anatomic cure was achieved in all patients. Eight patients had angiographic and clinical follow-up and none had recurrence of their lesions. CONCLUSIONS: DAVFs may occur within the dura of the sphenoid wings and may often have a presentation similar to cavernous sinus DAVFs, but because of potential associations with the cerebral venous system, may pose a risk for intracranial hemorrhage. Curative embolization through a transarterial or transvenous approach is the primary therapeutic strategy for these lesions. In incompletely embolized patients, exclusion of any refluxing cortical veins is necessary.

Remodeling of synapses in the CA1 area of the hippocampus after transient global ischemia.

Synapses are essential to neuronal functions. Synaptic changes occur under physiological and pathological conditions. Here we report the remodeling of synapses in the CA1 area of the hippocampus after transient global ischemia using electron microscopy. Much electron-dense material appeared in the cytoplasm of dendrites at 24h after ischemia. Many dark axons or terminals were found in the CA1 neuropil; some of which were phagocytized by dendrites. Interestingly autophagosomes appeared in many axons or dendrites at 48 h after ischemia. In addition, postsynaptic density (PSD) - like structures or synaptic - like structures were found inside spines and dendrites. Statistical analysis demonstrated that the thickness of PSDs in the CA1 neuropil increased from 12 to 48 h after ischemia. The frequency of autophagosomes appeared to escalate from 12 to 48 h after ischemia. The frequency of asymmetric synapses was significantly increased at 12h and 24h after ischemia in stratum oriens, proximal and distal stratum radiatum. Among asymmetric synapses, the number of perforated synapses consistently increased and reached a peak (approximately 10-fold increase) at 48 h after ischemia. On the other hand, the number of multiple synaptic boutons decreased after ischemia reaching a two to fourfold decrease at 48 h after ischemia. These results have shown that ischemia induces an increase of asymmetric synapses as well as synaptic autophagy, which may contribute to the neuronal death in the CA1 area after transient global ischemia.

Partial recanalization of concomitant internal carotid-middle cerebral arterial occlusions promotes distal recanalization of residual thrombus within 24 h.

OBJECTIVES: Acute, simultaneous, concomitant internal carotid artery (ICA) and middle cerebral arteries (MCA) occlusions almost invariably lead to significant neurological disability if left untreated. Endovascular therapy is frequently the method of treatment in such situations but there remains a chance of incomplete recanalization. Successful recanalization of the proximal aspect of the occlusion may allow for endogenous thrombolysis and facilitate further endogenous recanalization of any residual MCA occlusion. METHODS: Consecutive patients with acute ischemic stroke undergoing endovascular therapy for tandem extracranial ICA-MCA or contiguous intracranial ICA-MCA occlusions were retrospectively analyzed. Rates of facilitated endogenous recanalization at 24 h (FER(24)) were compared by imaging within the immediate post-intervention 5-24 h period in those with proximal recanalization and in those without. RESULTS: 17 patients were included in the analysis. 12 patients had good initial proximal recanalization but a residual partial or total occlusion of the MCA while five patients failed any recanalization. Seven patients (58.3%) in the first group and none in the second had FER(24) on interval imaging after intervention (p=0.04). The probability of death and disability at discharge was less in patients with FER(24) than those without (p=0.05). CONCLUSIONS: More than half of all patients who present with both ICA and MCA occlusions who are only partially recanalized will undergo facilitated endogenous recanalization within the subsequent 24 h following intervention.

The risk of acute radiocontrast-mediated kidney injury following endovascular therapy for acute ischemic stroke is low.

BACKGROUND AND PURPOSE: Endovascular therapy is an alternative for the treatment of AIS resulting from large intracranial arterial occlusions that depends on the use of iodinated RCM. The risk of RCM-mediated AKI following endovascular therapy for AIS may be different from that following coronary interventions because patients may not have identical risk factors. MATERIALS AND METHODS: All consecutive patients with large-vessel AIS undergoing endovascular therapy were prospectively recorded. We recorded the baseline kidney function, and RCM-AKI was assessed according to the AKIN criteria at 48 hours after RCM administration. We compared the rate of RCM-AKI 48 hours after the procedure and sought to determine whether any preexisting factors increased the risk of RCM-AKI. RESULTS: We identified 99 patients meeting inclusion criteria. The average volume of contrast was 189 ± 71 mL, and the average creatinine change was -4.6% at 48 hours postangiography. There were 3 patients with RCM-AKI. Although all 3 patients died as a result of their strokes, return to baseline creatinine levels occurred before death. There was a trend toward higher rates of premorbid diabetes mellitus, chronic renal insufficiency, preadmission statin and NSAID use, and a higher serum creatinine level on admission for the RCM-AKI group. The volume of procedural contrast was similar between groups (those with and those without RCM-AKI) (P = .5). CONCLUSIONS: In this small study, the rate of RCM-AKI following endovascular intervention for AIS was very low. A much larger study is required to determine its true incidence.

Higher rates of mortality but not morbidity follow intracranial mechanical thrombectomy in the elderly.

BACKGROUND AND PURPOSE: Mechanical thrombectomy is a promising means of recanalizing acute cerebrovascular occlusions in certain situations. We sought to determine if increasing age adversely affects prognosis. MATERIALS AND METHODS: We reviewed all Merci thrombectomy cases and compared patients younger than 80 years of age with older individuals. We compared these 2 age groups with respect to recanalization rates, hospital LOS, hemorrhagic transformation, and death and disability on discharge. RESULTS: Elderly patients were more likely to die from their stroke than those younger than 80 years of age, regardless of recanalization success (48% versus 15%; OR, 5.5; 95% CI, 2.1-14.1). Among survivors, there was no difference in the probability of having a good functional outcome (mRS,

Recanalization rates decrease with increasing thrombectomy attempts.

BACKGROUND AND PURPOSE: Use of the Merci retriever is increasing as a means to reopen large intracranial arterial occlusions. We sought to determine whether there is an optimum number of retrieval attempts that yields the highest recanalization rates and after which the probability of success decreases. MATERIALS AND METHODS: All consecutive patients undergoing Merci retrieval for large cerebral artery occlusions were prospectively tracked at a comprehensive stroke center. We analyzed ICA, M1 segment of the MCA, and vertebrobasilar occlusions. We compared the revascularization of the primary AOL with the number of documented retrieval attempts used to achieve that AOL score. For tandem lesions, each target lesion was compared separately on the basis of where the device was deployed. RESULTS: We identified a total of 97 patients with 115 arterial occlusions. The median number of attempts per target vessel was 3, while the median final AOL score was 2. Up to 3 retrieval attempts correlated with good revascularization (AOL 2 or 3). When >or=4 attempts were performed, the end result was more often failed revascularization (AOL 0 or 1) and procedural complications (P = .006). CONCLUSIONS: In our experience, 3 may be the optimum number of Merci retrieval attempts per target vessel occlusion. Four or more attempts may not improve the chances of recanalization, while increasing the risk of complications.

Vulnerable plaque in a Swine model of carotid atherosclerosis.

BACKGROUND AND PURPOSE: Distal embolism and acute thrombosis due to rupture of a vulnerable atherosclerotic plaque are the common mechanisms of stroke in patients with carotid disease. The purpose of this study was to develop the first animal model of vulnerable carotid atherosclerotic plaque. MATERIALS AND METHODS: Carotid atherosclerotic models were created in 12 Yucatan minipigs by using a combination of partial ligation and high cholesterol diet. Retia mirabilia from these animals were examined histopathologically to identify distal embolism. The association of distal embolism with advanced atherosclerosis and a thin fibrous cap was analyzed by using the Fisher exact test. RESULTS: Typical features of vulnerable plaques, including a thin fibrous cap, necrotic core, and intraplaque hemorrhage, were observed in this swine model of carotid atherosclerosis. Distal embolism was detected in retia mirabilia supplied by 7 of 10 carotid arteries with advanced atherosclerotic plaques, compared with 3 of 14 carotid arteries without advanced plaque (P < .05). CONCLUSIONS: This swine model of carotid atherosclerosis contains the salient features of vulnerable plaques, including plaque rupture and distal embolism.

Suppressive effects of sairei-to on monoclonal antibody 1-22-3-induced glomerulonephritis: analysis of effective components.

The effects of traditional Chinese medicine (Sairei-to) on experimental glomerulonephritis induced in rats by monoclonal antibody (mAb) 1-22-3 injection was examined. The level of proteinuria in the Sairei-to-treated group was significantly lower than that in the PBS treated group. This suppressive effect was caused by the major component of Sairei-to, Syo-saiko-to but not by another component, Gorel-san. The suppressive effect of Syo-saiko-to was identified in its components (Bupleuri radix, Pinelliae tuber and Zingiberis rhizoma), but not in the other combined components (Ginseng radix and Zizyphi fructus). Further study revealed that the suppressive effects of the combined components were mainly derived from Bupleuri radix. It was demonstrated that the actual active ingredient is probably Saikosaponin-d. Light microscopy revealed that Sairei-to and its effective components suppressed the proliferation of mesangial cells and mesangial matrix expansion. Semiquantitative morphological studies of glomerular lesions on the eighth day showed that Syo-saiko-to and its combined components (Bupleuri radix, Zingiberis rhizoma and Pinelliae tuber) suppressed mesangial matrix expansion significantly compared with phosphate-buffered saline control groups (matrix score: 28.0 +/- 19.1 vs 102.3 +/- 14.1; 30.9 +/- 30.1 vs 102.3 +/- 14.1, P < 0.005, respectively). It was concluded that Saikosaponin-d, as well as Bupleuri radix, Syo-saiko-to and Sairei-to can suppress proteinuria and morphological changes in the rat glomerulonephritis model induced by mAb 1-22-3.