Structural, radiation shielding, thermal and dynamic mechanical analysis for waste rubber/EPDM rubber composite loaded with Fe2O3 for green environment.

Increasing waste rubber recycling produces a specious range of products for many valuable applications. Waste Rubber/EPDM composite with different concentrations was prepared. Infrared spectroscopy (FTIR) is used to identify the chemical composition. A water absorption test, Dynamic mechanical analysis (DMA), and Thermal Gravimetric Analysis (TGA) were performed. The (75/25) WR/EPDM rubber composite exhibited the best behavior with the highest mechanical performance. Fe2O3 was added to (75/25) WR/EPDM rubber composite. Water absorption, FTIR, TGA, and DMA were investigated. The composite performance was improved with increasing Fe2O3 content. The linear attenuation coefficients (µ) were also measured as a function of the concentrations of Fe2O3 for γ-ray energy 662 keV by using 137Cs point source; the radiation shielding can be denoted by numbers of parameters like mass attenuation coefficient (µm), half value layer (HVL), Tenth value layer TVL and radiation protection efficiency (RPE%), radiation protection efficiency increased as Fe2O3 increased.

The protective effect of xanthenone against LPS-induced COVID-19 acute respiratory distress syndrome (ARDS) by modulating the ACE2/Ang-1-7 signaling pathway.

OBJECTIVE: Acute respiratory distress syndrome (ARDS) is an inflammatory lung disease that has a high rate of morbidity and mortality. It's an acute diffusive lung injury caused by the release of pro-inflammatory cytokines into the lungs. Specific microRNAs have been identified to play a crucial role in the renin-angiotensin system signaling pathways the main pathophysiological pathway responsible for ARDS. Since the ARDS life-threatening complication associated with COVID-19 is an ongoing challenge, this current study aimed to investigate the potential efficacy of xanthenone in the treatment of ARDS induced with LPS in mice through ACE2 activation and modulation of miR-200 and ACE2/Ang 1-7 pathways. MATERIALS AND METHODS: Mice were categorized into three groups randomly. The first set of mice served as the normal control group. The ARDS group was injected with LPS (15 mg/kg; i.p.). The last group was treated with xanthenone (2 mg/kg/day; p.o.) for one week before the LPS injection. RESULTS: Xanthenone treatment resulted in a significant down-regulation of miRNA-200 expression, leading to the activation of ACE2 accompanied with marked inhibition of Angiotensin II as well as increases the levels of Ang 1-7 and SP-A. CONCLUSIONS: Xanthenone has the potential to be a promising therapeutic drug for the treatment of ARDS COVID-19 complication through activation of ACE2/Ang 1-7 pathways.https://www.europeanreview.org/wp/wp-content/uploads/Graphical_abstract.tif.

The effect of ultrasonics on sealer distribution and sealing of root canals.

The purpose of this study was to compare the ultrasonic and hand methods of sealer placement using three types of sealers: Sultan "Grossman's formula," AH-26, and CRCS. The effect of these methods on radiographic density, sealer distribution, and on the apical seal of the different sealers was evaluated. The in vitro experiment was carried out using human extracted mandibular incisors and mesio-buccal roots of maxillary first and second molars. Following standardized canal instrumentation, 120 single canal mandibular incisors were randomly assigned to six groups, depending on the type of sealer and method of sealer placement (hand versus ultrasonic). An additional ten teeth were used as controls. In the molar groups 40 canals were randomly assigned to two groups, with the method of sealer placement as the variable. Eight canals were used as controls. Postsealer analyses using radiographic density scores transformed to mm of sealer indicated that ultrasonics was superior to manual placement only for CRCS. Taken together, our investigation suggests that ultrasonics may enhance the placement of some sealers (i.e. CRCS) but not of others (i.e. AH-26 or Sultan). Method of sealer placement had no effect on apical leakage and therefore apparently on apical seal.

Restorative and endodontic management of an anomalous mandibular molar.

Morphologic variations of dental hard tissue should be recognized and considered during restorative procedures. Overlooking anomalies increases the potential for clinical complications. Amalgam was used erroneously in a patient when the presence of a paramolar structure was overlooked. The clinical complications that resulted from overlooking the anomaly led to restorative, endodontic, and periodontal failures. The present report describes the use of conservative endodontics and a cast restoration, taking into account the presence of the paramolar structure, to correct the case.

Long-term follow-up of the use of nonporous hydroxyapatite for augmentation of the alveolar ridge.

Particulate hydroxyapatite (HA) was used in the augmentation of 18 mandibular and four maxillary ridges in 21 patients whose cases were followed postoperatively for 5 to 7 years. Patients were evaluated clinically, radiographically, and through questionnaires. Prosthodontic assessment of retention and stability of dentures showed improvement 5 years postoperatively. Patients receiving HA rated their dentures favorably using parameters of the Cornell Medical Index. The results of this study show that particulate HA alone can be used as a satisfactory material for augmentation of the alveolar ridge.

Extracranial and mandibular augmentation with hydroxyapatite-collagen in induced diabetic and nondiabetic rats.

This study evaluated three hydroxyapatite (HA) preparations placed subperiosteally in rats given streptozotocin (70 mg/kg) to induce diabetes (ID) (n = 24) and in nondiabetic (ND) rats (n = 24) used as controls. Implants of 1) nonporous HA granules (HAG), 2) HA granules hand-mixed with bovine collagen (HACM), and 3) HA granules and purified fibrillar collagen in a preprocessed block (PFC-HA) were randomly placed in subperiosteal pockets created on the cranium and adjacent to the left/right mandibles of each rat. Six rats from each group were killed at 3, 6, 12, and 24 weeks postimplantation. Animals killed after 3 weeks showed sporadic bone proliferation and bone resorption, whereas those killed after 6, 12, and 24 weeks showed formation of new bone at the implant/bone interface. Contact of the implant with bone was a requirement for osteogenesis, but bone formed only into the basilar layers of the implants. The ID group showed the greatest inflammatory response as well as the greatest degree of osteogenesis at all intervals of time. The addition of collagen to HA appeared to reduce the inflammatory response. Specimens implanted with HACM showed the least inflammation of the three implanted materials in both ID and ND groups.

Effects of interdental osteotomies on the periodontal and osseous supporting tissues.

The effects of 40 interdental osteotomies on surrounding osseous and periodontal structures were evaluated clinically and radiographically. No statistically significant changes were noted in any of the clinical parameters except gingival height, which decreased slightly in the maxilla and increased in the mandible. These changes were found to be statistically significant, but not clinically significant, and are most likely explained by the direction of movement of the bony segment. Radiographic evaluations revealed no statistically significant changes other than an increase in interdental width in both the maxillary and mandibular sites. These measurements were made at the root level, and, although the crowns were moved closer, the roots may actually have flared apart because the anterior segment was tipped to upright the incisors. The lack of change in the other radiographic parameters indicated that there was no loss of alveolar bone support.

Tyrosine radicals in photosystem II and related model compounds. Characterization by isotopic labeling and EPR spectroscopy.

Deuteration at selected positions on the phenol ring and at the beta-methylene carbon for the YD.tyrosine radical in Photosystem II in the cyanobacterium Synechocystis 6803 was achieved by growing the organism under conditions in which it is a functional aromatic amino acid auxotroph (Barry, B. A., and Babcock, G. T. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 7099-7103). A series of model tyrosine radicals, also deuterated at specific sites on the aromatic ring and the methylene group, was generated by UV irradiation of frozen solutions. The EPR spectra of the specifically deuterated in vivo radicals confirm that YD.is a tyrosine; nevertheless its spectra differ from those of the tyrosine models. By comparing the EPR spectra of the specifically deuterated radicals with those of the fully protonated, the hyperfine couplings of the various protons of both YD.and the model compound radicals were determined. For both species, the unpaired electron spin density distribution is essentially identical and follows an odd-alternant pattern with high rho values at the carbons ortho and para to the tyrosine phenol oxygen; the meta positions have low spin densities. The differences in EPR spectral characteristics for the two radicals are rationalized as arising from variations in the conformation of the beta-methylene group with respect to the phenol head group. Considering these EPR results and those reported for other model and naturally occurring tyrosine radicals, we conclude that this situation is general; there is little deviation in this class of compounds from the odd-alternant spin density distribution; variations in EPR lineshapes arise primarily from variations in beta-methylene orientation. The conformation of the -CH2- group in biologically active tyrosine radicals deviates from that observed in the models and may be functionally significant. Because the EPR spectrum of YZ., the second redox active tyrosine radical in Photosystem II, is identical to that of YD., we conclude that the two radicals are in similar protein environments, a conclusion that is supported by the protein sequences in the vicinity of the two radicals.

Facial augmentation with Proplast and nonporous hydroxylapatite in rhesus monkeys.

Using an extra-oral approach, subperiosteal pockets were created bilaterally over zygomatic and mandibular areas in six Rhesus monkeys. One side of each anatomic site received a Proplast I implant and the contralateral a nonporous hydroxylapatite (NPHA) block. Two animals were killed postoperatively at 3, 6, and 12 months, and the implants retrieved en bloc for histologic evaluation. Clinical evaluation showed the Proplast implants more stable than NPHA implants. Histologic evaluation for Proplast implants demonstrated complete encapsulation, fibrous tissue infiltration, fragmentation of implants, and some giant cell reaction. The NPHA implants were completely encapsulated with fibrous tissues, and no giant cell response, fragmentation, biodegradation, or bone formation was observed. We concluded that the Proplast was more stable than NPHA implants, but the NPHA produced less inflammatory cell and giant cell reaction.

Tissue response to hydroxylapatite in induced diabetic and nondiabetic rats: histologic evaluation.

This study evaluated the tissue response to the subcutaneous implantation of nonporous hydroxylapatite (HA) in 24 induced-diabetic (ID) and 24 nondiabetic (ND) rats. One cubic centimeter of HA was implanted subcutaneously in each rat's chest. Subgroups of 6 rats from the ID and ND groups were killed at 3, 6, 12, and 24 weeks postimplantation. The implants were removed with the surrounding soft tissues and processed for histologic evaluation. This revealed that soft tissue inflammation was mild at each time interval. There was a decreased response at 6 months in ND rats and a persistent inflammatory reaction in ID rats. Collagen maturity and fibroplasia increased within ND rats, whereas the ID rats showed a marked delay in collagen maturity and density. No osteogenesis was observed in any specimen. Dystrophic calcification was observed at the HA-tissue interface in 37% of ND and 59% of ID specimens. It was concluded that HA elicited a greater inflammatory response in ID than in ND rats when implated subcutaneously.

Subcutaneous implantation of hydroxylapatite/collagen in induced diabetic and non-diabetic rats.

To evaluate tissue reaction to hydroxylapatite (HA) and HA/collagen mixtures in rats with uncontrolled induced diabetes, 48 males were divided: 24 with induced diabetes (ID) from Streptozotocin (70 mg/kg) and 24 non-diabetic (ND) controls. Three subcutaneous sites in each chest were randomly implanted with non-porous HA, or non-porous HA and bovine collagen, or non-porous HA and purified fibrillar collagen. Subgroups of 6 ID and 6 ND rats were killed at 4, 6, 12, and 24 weeks post-implantation. Histologic specimens showed that all materials elicited greater inflammatory response in ID than in ND at all intervals. Each specimen had HA particles encapsulated by host fibrous tissue. Compared to ND, ID specimens had markedly reduced ingrowth and maturity of collagen at each time interval. There was no osteogenesis, but there was dystrophic mineralization within the implant sites in both ID and ND. Mixed HA/collagen exceeded HA alone in maintaining implant contour. In soft tissue, no materials were osteoinductive. Adding collagen did not increase or decrease inflammatory reaction nor improve density and maturity of tissue synthesized around implants.

Bilateral mammary artery surgery or percutaneous transluminal coronary angioplasty for multivessel coronary artery disease? An analysis of effects and costs.

Seventy-two patients with stable or unstable angina treated since 1983 by multivessel-PTCA(MVP) were retrospectively compared with 44 similar patients that were suitable for MVP, but who had undergone bilateral mammary artery (BIMA) surgery (and additional vein grafts in 60.5% of the patients) since 1986. Both groups were comparable (P = not significant [NS]) for gender, age, most risk factors, objective ischaemia and left ventricular function; however, in the BIMA group there were more previous infarctions (P = 0.02), hypertension (P = 0.03), three-vessel disease (P = 0.0001), and less severe angina (P = 0.007). In the BIMA group, a mean of 3.1 (range 2-5) vessels were treated and in the MVP group 2.0 (range 2-3) vessels (P = 0.0001). Both groups were almost completely revascularized (NS). In 39.5% of the BIMA group, no veins were used and in 20.9% the BIMAs were used as sequential grafts. In-hospital mortality was comparable: 2.3% for BIMA and 1.4% for MVP, so were periprocedural infarctions (13.6% vs 8.3%), rethoracotomies (9.1% vs 0%), emergency procedures (0% vs 5.7%), low cardiac output (2.3% vs 5.6%) and other complications (18.2% vs 9.2%). The mean stay (days) on the ICU/CCU for BIMA was 2.3 and for MVP 1.6 (P = 0.005) and the mean hospital stay for BIMA 12.3 and for MVP 6.6 (P = 0.0001). The maximum and mean follow-up (months) of 43 BIMA and 71 MVP hospital survivors was 35 vs 72 and 9.5 vs 22.3 (P = 0.0001) with a late mortality of 0% and 4.2% (NS). MVP patients, including 12 with re-procedures, had more recurrent angina (17.7% vs 4.7%, P less than 0.05) and more often used anti-anginal medications (62.0% vs 18.6%, P less than 0.0001). Late complications (excluding re-procedures) were comparable for MVP and BIMA (20% vs 9.3%, 4.4% vs 0%, 9.2% vs 14%). MVP patients had more re-hospitalizations (34 vs 5, P less than 0.0001), re-catheterizations (33% vs 2.3%, P less than 0.0001) and cardiac re-procedures (16 vs 0, P = 0.0006) than BIMA patients. Recurrent-angina-free survival at 1 year was 96% after BIMA and 64% after MVP (P less than 0.01). Event-free survival at 1 year was 86% after BIMA and 58% after MVP (P less than 0.05).(ABSTRACT TRUNCATED AT 400 WORDS)

Tissue response to facial contour augmentation with dense and porous hydroxylapatite in rhesus monkeys.

Using extraoral incisions, subperiosteal pockets were created bilaterally over the zygomatic and mandibular areas in six rhesus monkeys. One side of each anatomic site received a dense block of hydroxylapatite (HA) implant, and the contralateral side received an equivalent-sized block of porous HA implant. Monkeys were killed at 3, 6, and 12 months, and the implants were manually tested for mobility. The implants were then retrieved in block specimens. Half of each specimen was decalcified, embedded in paraffin, and stained. The other half was embedded in plastic, and sections were stained or carbon coated for scanning electron microscope histometry. The dense HA implants showed complete fibrous encapsulation and they popped out when cut in half. The porous HA implants were attached to the underlying cortex by bone ingrowth. The porous implant volume sampled within 2.5 mm of underlying cortex contained 33.0% HA matrix and 35.7% bone. The surface area of the porous HA matrix (4.8 mm2/mm3) was 54.3% covered by bone ingrowth. It is hypothesized that micromotion may have accounted for the lack of osseointegration of the dense HA specimens. In contrast, the early ingrowth of fibrous tissue into the porous HA block might be responsible for reducing micromotion to levels acceptable for ingrowth of bone. The contrasting biologic response of implant sites to two variants of the same implant material supports the value of comparative studies to permit informed surgical selection decisions.

Correction of the deficient alveolar ridge.

The success of a denture is dependent on a good foundation; therefore, construction of the prosthesis begins with extraction of the teeth. The teeth should be maintained as long as possible if they can be restored. When the teeth are extracted, bone resorption usually starts, owing to systemic and local factors. Good communication between the prosthodontist and the oral and maxillofacial surgeon must exist during the diagnostic procedure, must be maintained through the various stages of treatment, and must prevail through the follow-up care of the patient. Each clinician must be aware of both the objectives and the possible limitations of the treatment the other will provide, to ensure optimal care for the edentulous patient. The development of the osteointegrated titanium implant system opens an exciting new avenue with respect to total rehabilitation of the edentulous patient. This is the future, and in our opinion, the preferred technique for mandibular reconstruction.

Complications of orthognathic surgery.

The following are the most important factors in decreasing postoperative complications related to orthognathic surgery: 1. A good medical history, 2. Thorough clinical evaluation, analysis of surgical model, and cephalometric analysis, 3. Proper diagnosis and treatment planning, 4. Thorough knowledge of anatomy and tissue physiology, 5. Proper surgical technique, 6. Delicate handling of soft tissues, 7. Careful cutting of bone, 8. Good communication among surgeon, orthodontist, and patient. In spite of all the precautions the surgeon may take, complications may still occur. The surgeon should be familiar with possible complications and how to manage them.

Nonporous hydroxylapatite in the repair of alveolar clefts in a primate model: clinical and histologic findings.

Twelve adult Rhesus monkeys with surgically created alveolar clefts (ACs) underwent repair that used nonporous hydroxylapatite (NPHA) granules on one side and autogenous particulate bone in the contralateral defect. Clinical and radiographic evaluations at 1, 2, 3, 6, and 12 months postoperatively disclosed some displacement of granules initially, but this stabilized by 2 months. Three of 12 sites repaired with NPHA and four of 12 sites repaired with bone dehisced; however, all of these healed by 2 months. No untoward inflammatory or resorptive changes were observed beyond 3 months. The repaired alveolar processes were similar in bulk and contour in sites grafted with NPHA and with bone. Histologically, giant cells were noted at 3 months, but the number decreased at 6 months and remained at that level up to 12 months. The NPHA granules were embedded in mature fibrous connective tissue with osseous ingrowth evident in eight of the 12 defects. It was concluded that NPHA granules are an acceptable implant material for repair of residual alveolar clefts in which erupting teeth and orthodontic movements are not factors.

Standardized panoramic radiography in assessment of mandibular augmentation with hydroxylapatite material: preliminary report.

This study evaluates the usefulness of a head-positioner/cephalostat in producing standardized panoramic radiographs by assessing the reproducibility of the radiographs and comparing the standardized panoramic radiographic findings with those obtained from 45 degrees right and left lateral cephalograms. Comparison of measurements indicated that this cephalostat produced reproducible panoramic radiographs. Measurements on each panoramic radiograph showed standard deviations ranging from 0.0 to 0.24 mm (pooled SD = 0.12), whereas the SDs for the 45 degrees lateral cephalograms ranged from 0.0 to 0.45 (pooled SD = 0.14). This indicates that the panoramic radiographs obtained with this head-positioner/cephalostat were comparable to those obtained by 45 degrees lateral cephalograms.

Zygomatic and mandibular augmentation with proplast and porous hydroxyapatite in rhesus monkeys.

Using an extraoral approach, subperiosteal pockets were created bilaterally over the zygomatic and mandibular regions in six Rhesus monkeys. One side of each animal received a Proplast I (Vitek Inc, Houston) implant and the contralateral side received an equivalent sized block of porous hydroxyapatite (HA). The animals were followed clinically and radiographically. Two animals were killed postoperatively at 3, 6, and 12 months, respectively. The implants were retrieved en bloc and halved. Half of each specimen was decalcified, embedded in paraffin, and stained. The other half was embedded in plastic, and sections were stained or carbon-coated for histometry scanning under electron microscopy. Clinical evaluation revealed that porous HA implants were more stable than Proplast implants. The Proplast implants showed complete encapsulation by infiltration with fibrovascular connective tissue, and progressive fragmentation with giant cell reactions. The porous HA implants were united to the underlying cortex by bony ingrowth. The volume of implants sampled within 2.5 mm of the underlying cortex contained 42.5% HA matrix and 23.8% bony ingrowth, and the surface area of the HA matrix (9.7 mm2/mm3) was 47.8% covered by bony ingrowth. No giant cell response, fragmentation, or biodegradation was observed or measured in the porous HA implants. The data from this primate model further substantiate previous canine studies and permit more reliable estimation of clinical performance. These results provide comparative data that can contribute to the decision-making process in selecting clinical implants.

Canines erupted through grafted alveolar cleft defects in patients with alveolar clefts: a pulp testing evaluation study.

An electric pulp tester (EPT) was used to evaluate the pulpal response of erupted canines in 75 patients: 16 patients with unilateral cleft palate who received autogenous bone grafts to correct their alveolar cleft defects before canine eruption; 35 patients without cleft palate whose canines erupted spontaneously, but who required orthodontic treatment for alignment; and 24 patients without clefts whose canines required surgical uncovering and orthodontic assistance for eruption. Thirty-one percent of the erupted canines in the patients with grafted unilateral clefts did not respond to EPT, whereas all canines in the contralateral noncleft side responded to EPT. There was no clinical or radiographic evidence of pulpal pathosis of the canines that had erupted through the grafted alveolar clefts. However, these teeth had a high incidence of nonresponsiveness to pulp stimulation, therefore necessitating close follow-up in case they show eventual signs of pulpal degeneration that may require endodontic intervention.