A Systematic Review of Whether the Use of N95 Respirator Masks Decreases the Incidence of Cardiovascular Disease in the General Population.

The usage of masks such as the N95 has increased exponentially worldwide. With the ever-increasing global rates of cardiovascular disease, it is vital that preventative measures are adopted to help tackle this crisis. N95 masks have been promoted as health prevention odysseys in the battle against viruses such as COVID-19. A systematic review was conducted on whether the N95 masks could help improve our cardiovascular health. Our data sources included PubMed, Medline and Scopus. Eleven studies met the eligibility criteria to be included in the review. N95 mask usage led to increased reports of dyspnoea, however, no significant effect was seen on blood pressure. N95 masks also showed improvement in aortic parameters. While encouraging results were yielded, further focussed studies on the use of N95 masks and the effect on various cardiovascular parameters would help strengthen the association.

Graphene oxide-based experimental silane primers enhance shear bond strength between resin composite and zirconia.

Despite various mechanical and chemical surface-pretreatment methods, long-term bonding of resin composite to dental zirconia (ZrO2 ) remains a major concern. In this study, graphene oxide (GO) sheets were infused into two commercially available primers and the enclosed mould shear bond strength (EM-SBS) of resin composite to ZrO2 was evaluated. Twelve fully sintered ZrO2 blanks were pretreated and randomly allocated to four groups according to the primers used: RelyX (RX); GO blended RelyX (RXGO); Monobond-S (MB); and GO blended Monobond-S (MBGO). The resin composite stubs were bonded onto the pretreated ZrO2 surfaces and analysed at baseline and after storage in distilled water for 2 and 4 months. The experimental primers blended with GO sheets influenced the surface morphology, visualized as increased surface roughness, and slightly increased the water contact angle measurements. Moreover, the infusion of primers with GO increased the mass fraction (wt%) of carbon and oxygen. The highest EM-SBS values were found for RXGO, with mean (SD) EM-SBS values of 26.4 (3.7) MPa and 21.5 (5.1) MPa after 2 and 4 months of storage, respectively. Infusion of silane primers with nanometre- to micrometre-size GO sheets enhanced the SBS between resin composite and ZrO2 .

Influence of Monomer Systems on the Bond Strength Between Resin Composites and Polymerized Fiber-Reinforced Composite upon Aging.

PURPOSE: This study examined the influence of different monomer systems on the tensile bond strength between a resin composite and a polymerized fiber-reinforced composite (FRC). The influence of the age (shelf-life) of the FRC prepreg (reinforcing fiber pre-impregnated with a resin system) before preparing the FRC substrate for the bonding test was also assessed. MATERIALS AND METHODS: Semi-interpenetrating polymer network (semi-IPN)-based glass FRC prepregs were aged for various durations (1, 1.5, and 3 years) at 4°C before being used to prepare FRC substrates via light polymerization. Four groups of aged prepregs were prepared through different treatments with: 1. no primer; 2. a dimethacrylate-based adhesive primer; 3. a universal primer; and 4. a specific composite primer. Subsequently, a resin composite luting cement was applied on the treated FRC substrates and cured with light. The water sorption of the FRC-composite specimens was determined. Then, the differences in the tensile bond strength were evaluated using ANOVA (p ≤ 0.05). RESULTS: There were significant differences in the tensile bond strength between the composite cement and the FRC according to the primer used (p < 0.001), aging time (p < 0.001), and their interactive effect (p < 0.001). CONCLUSION: The monomers of the universal primer demonstrated the best ability to diffuse into the semi-IPN structure of the polymer matrix of FRC. This improved the interfacial bond strength between the composite cement and the FRC substrate.

Influence of primers on the properties of the adhesive interface between resin composite luting cement and fiber-reinforced composite.

OBJECTIVES: The purpose of this study was to characterize the adhesive interface formed due to the dissolving capability of 4 primer systems into pre-polymerized semi-interpenetrating polymer network (semi-IPN)-based fiber-reinforced composite (FRC) and luting cement. MATERIALS AND METHODS: Semi-IPN FRC (everStick C&B, StickTech) prepregs stored for various durations (at 4 °C; 1, 1.5, and 3 years) were used to fabricate the specimens. FRC specimens (n = 10) were light-cured and treated with primers before adhering a luting cement onto them. Each age group was divided into four subgroups according to the primer used: no priming, a dimethacrylate adhesive primer, universal primer, and primer intended for composite surfaces. The degree of monomer conversion (DC%) of the luting cement; nanohardness, elastic modulus and structural information of the luting cement-FRC adhesive interface were measured. RESULTS: According to analysis of variance (P ≤ 0.05), no statistical difference was observed in the DC% among the tested groups. However, both universal and composite primers showed increased nanohardness in 1- and 1.5-year-aged groups. The highest nanohardness (0.55 ±â€¯0.21 GPa) and elastic modulus (14.27 ±â€¯5.19 GPa) were observed in specimens of 1-year-aged FRC primed with the application of universal primer. Raman spectroscopy and scanning electron microscopy examination confirmed the presence of poly(methyl methacrylate) at the interface when the FRC prepregs were aged for 3 years before use. CONCLUSION: Both primers improved diffusion of monomers of composite luting cement into the polymerized semi-IPN polymer structure and possible covalent binding with pendant methacrylate groups in the polymer matrix of FRC. The diffusing capability of universal and composite primers might increase the opportunity to form solid adhesive interface bonding between the FRC and composite luting cement.

Polymer matrix of fiber-reinforced composites: Changes in the semi-interpenetrating polymer network during the shelf life.

This laboratory study was aimed to characterize semi-interpenetrating polymer network (semi-IPN) of fiber-reinforced composite (FRC) prepregs that had been stored for up to two years before curing. Resin impregnated prepregs of everStick C&B (StickTech-GC, Turku, Finland) glass FRC were stored at 4°C for various lengths of time, i.e., two-weeks, 6-months and 2-years. Five samples from each time group were prepared with a light initiated free radical polymerization method, which were embedded to its long axis in self-curing acrylic. The nanoindentation readings on the top surface toward the core of the sample were made for five test groups, which were named as "stage 1-5". To evaluate the nanohardness and modulus of elasticity of the polymer matrix, a total of 4 slices (100µm each) were cut from stage 1 to stage 5. Differences in nanohardness values were evaluated with analysis of variance (ANOVA), and regression model was used to develop contributing effect of the material's different stages to the total variability in the nanomechanical properties. Additional chemical and thermal characterization of the polymer matrix structure of FRC was carried out. It was hypothesized that time of storage may have an influence on the semi-IPN polymer structure of the cured FRC. The two-way ANOVA test revealed that the storage time had no significant effect on the nanohardness of FRC (p = 0.374). However, a highly significant difference in nanohardness values was observed between the different stages of FRC (P<0.001). The regression coefficient suggests nanohardness increased on average by 0.039GPa for every storage group. The increased nanohardness values in the core region of 6-months and 2-years stored prepregs might be due to phase-segregation of components of semi-IPN structure of FRC prepregs before their use. This may have an influence to the surface bonding properties of the cured FRC.

A highly efficient ligation-independent cloning system for CRISPR/Cas9 based genome editing in plants.

BACKGROUND: Most current methods for constructing guide RNAs (gRNA) for the CRISPR/Cas9 genome editing system, depend on traditional cloning using specific type IIS restriction enzymes and DNA ligation. These methods consist of multiple steps of cloning, and are time consuming, resource intensive and not flexible. These issues are particularly exacerbated when multiple guide RNAs need to be assembled in one plasmid such as for multiplexing or for the paired nickases approach. Furthermore, identification of functional gRNA clones usually requires expensive in vitro screening. Addressing these issues will greatly facilitate usage and accessibility of CRISPR/Cas9 genome editing system to resource-limited laboratories. RESULTS: To improve efficiency of cloning multiple guide RNAs for the CRISPR/Cas9 system, we developed a restriction enzyme- and ligation-independent strategy for cloning gRNAs directly in plant expression vectors in one step. Our method relies on a negative selection marker and seamless cloning for combining multiple gRNAs directly in a plant expression vector in one reaction. In addition, using the Agrobacterium-mediated transient assays, this method provides a simple in planta procedure for assaying the effectiveness of multiple gRNAs very rapidly. CONCLUSIONS: For a fraction of resources used in the type IIS restriction enzyme-based cloning method and in vitro screening assays, the system reported here allows efficient construction and testing several ready-to-transfect gRNA constructs in < 3 days. In addition, this system is highly versatile and flexible, and by designing only two additional target-specific primers, multiple gRNAs can be easily assembled in any plasmid in a single reaction.

The Neutrophil-to-Lymphocyte Ratio as a Marker of Lymph Node Status in Patients with Rectal Cancer.

AIM: The aim of the study was to investigate the role of the neutrophil-to-lymphocyte ratio (NLR) as a prognostic marker of rectal cancers. METHODS: We undertook a retrospective review of patients with rectal cancer. Pre-treatment NLR was assessed for association and predictive values against clinicopathological staging and post-treatment outcomes. RESULTS: A total of 140/180 cases were included in the final analysis [male:female 2:1; mean age 68 years (interquartile range 58-75)]. The pre-operative mean NLR was 5.4 ± 6.8. There was a strong positive correlation between NLR and C-reactive protein (Spearman's rho 64.3%, p < 0.001). A high NLR was associated with a positive nodal status on MRI (5.2 vs. 3.8, p = 0.03) and histopathological (4.8 vs. 3.8, p = 0.02) assessment. The NLR showed an average value for predicting MRI and pathological nodal status on receiver operating characteristic analysis [area under the curve = 0.72 (95% CI = 0.54-0.91), p = 0.031 and area under the curve = 0.64 (95% CI = 0.52-0.077), p = 0.021, respectively]. On multivariate analysis, the total lymph node retrieved at operation was the best predictor of pathological nodal involvement; NLR did not show any predictive value. Patients with an NLR >4 showed reduced recurrence-free (60 vs. 86 months, p = 0.52) and overall survival (57 vs. 84 months, p = 0.40) without statistical significance. CONCLUSION: Raised pre-treatment NLR may indicate nodal involvement in patients with rectal cancer.

Omental Torsion: An Unusual Cause of Right Iliac Fossa Pain and Role of Laparoscopic Management.

Omental torsion is a rare cause of acute abdomen. It usually presents with acute onset right-sided abdominal pain. Adult male between 40 and 50 years of age and obesity are the most common risk factor amongst others. Clinical diagnosis is challenging and difficult to differentiate from more common clinical pathologies such as acute appendicitis and/or acute cholecystitis. Transabdominal imagings such as ultrasonography and/or computed tomography are useful showing typical whirl pattern. Advocated management is surgical excision of torted omentum. Herein, we report a case of primary omental torsion in an adult and a review of current literature. The diagnosis was incidental when patient was undertaken for laparoscopic appendectomy. Only the distal edge of right omentum was torted making a fatty mass of 4 × 3 cm lying on the ascending colon that could have been easily missed if open appendectomy was opted. This case not only highlights the importance of considering torted omentum in differential diagnosis of right-sided abdominal pains but also backs the changing practice to laparoscopic approach for management of right iliac fossa pain.

Identification of a third osmoprotectant transport system, the osmU system, in Salmonella enterica.

The growth of Salmonella enterica serovar Typhimurium mutants lacking the ProP and ProU osmoprotectant transport systems is stimulated by glycine betaine in high-osmolarity media, suggesting that this organism has an additional osmoprotectant transport system. Bioinformatic analysis revealed that the genome of this organism contains a hitherto-unidentified operon, designated osmU, consisting of four genes whose products show high similarity to ABC-type transport systems for osmoprotectants in other bacteria. The osmU operon was inactivated by a site-directed deletion, which abolished the ability of glycine betaine to alleviate the inhibitory effect of high osmolarity and eliminated the accumulation of [(14)C]glycine betaine and [(14)C]choline-O-sulfate in high-osmolarity media in a strain lacking the ProP and ProU systems. Although the OsmU system can take up glycine betaine and choline-O-sulfate, these two osmoprotectants are recognized at low affinity by this transporter, suggesting that there might be more efficient substrates that are yet to be discovered. The transcription of osmU is induced 23-fold by osmotic stress (0.3 M NaCl). The osmU operon is present in the genomes of a number of Enterobacteriaceae, and orthologs of the OsmU system can be recognized in a wide variety of Bacteria and Archaea. The structure of the periplasmic binding protein component of this transporter, OsmX, was modeled on the crystallographic structure of the glycine betaine-binding protein ProX of Archaeoglobus fulgidus; the resultant model indicated that the amino acids that constitute substrate-binding site, including an "aromatic cage" made up of four tyrosines, are conserved between these two proteins.

Stereotactic radiosurgery for the treatment of symptomatic brainstem cavernous malformations.

OBJECT: The authors performed a retrospective review of prospectively collected data to evaluate the safety and efficacy of stereotactic radiosurgery (SRS) for the treatment of patients harboring symptomatic solitary cavernous malformations (CMs) of the brainstem that bleed repeatedly and are high risk for resection. METHODS: Between 1988 and 2005, 68 patients (34 males and 34 females) with solitary, symptomatic CMs of the brainstem underwent Gamma Knife surgery. The mean patient age was 41.2 years, and all patients had suffered at least 2 symptomatic hemorrhages (range 2-12 events) before radiosurgery. Prior to SRS, 15 patients (22.1%) had undergone attempted resection. The mean volume of the malformation treated was 1.19 ml, and the mean prescribed marginal radiation dose was 16 Gy. RESULTS: The mean follow-up period was 5.2 years (range 0.6-12.4 years). The pre-SRS annual hemorrhage rate was 32.38%, or 125 hemorrhages, excluding the first hemorrhage, over a total of 386 patient-years. Following SRS, 11 hemorrhages were observed within the first 2 years of follow-up (8.22% annual hemorrhage rate) and 3 hemorrhages were observed in the period after the first 2 years of follow-up (1.37% annual hemorrhage rate). A significant reduction (p < 0.0001) in the risk of brainstem CM hemorrhages was observed following radiosurgical treatment, as well as in latency period of 2 years after SRS (p < 0.0447). Eight patients (11.8%) experienced new neurological deficits as a result of adverse radiation effects following SRS. CONCLUSIONS: The results of this study support a role for the use of SRS for symptomatic CMs of the brainstem, as it is relatively safe and appears to reduce rebleeding rates in this high-surgical-risk location.

Gamma knife radiosurgery for benign tumors with symptoms from brainstem compression.

PURPOSE: This study evaluated the role of radiosurgery in the management of symptomatic patients with brainstem compression from benign basal tumors. METHODS AND MATERIALS: Over a 17-year, period 246 patients (202 vestibular schwannomas and 44 meningiomas) with brainstem compression from benign skull-base tumors were managed with Gamma Knife radiosurgery. Median tumor volumes were 3.9 cm(3) (range, 0.8-39.0 mL) and 6.6 mL (range, 1.6-25.1 mL) for vestibular schwannomas and meningiomas, respectively. For both tumors, a median marginal dose of 13 Gy was prescribed. Median follow-up of patients was 65 months for vestibular schwannomas and 60 months for meningiomas. Patients were categorized into four groups on the basis of the tumor-brainstem relationship on neuroimaging. RESULTS: Preservation of function was stratified according to grade of brainstem compression. We analyzed the effect of radiosurgery on symptoms of brainstem compression. The tumor control rate was 100 % for meningioma and 97% for vestibular schwannomas (although 5% required an additional procedure such as a ventriculoperitoneal shunt). In patients with vestibular schwannoma, serviceable hearing was preserved in 72.0%. Balance improved in 31.9%, remained unchanged in 56.5%, and deteriorated in 11.6% of patients who had imbalance at presentation. Balance improved significantly in patients who had less tumor compression (p = 0.0357) after radiosurgery. Symptoms improved in 43.2% of patients with meningioma. CONCLUSION: Radiosurgery is a minimally invasive option for patients with benign basal tumors that indent or distort the brainstem. A high tumor growth control rate and satisfactory rate of neurological preservation and symptom control can be obtained with radiosurgery.

Stereotactic radiosurgery for symptomatic solitary cerebral cavernous malformations considered high risk for resection.

OBJECT: A retrospective study was conducted to reassess the benefit and safety of stereotactic radiosurgery (SRS) in patients with solitary cerebral cavernous malformations (CCMs) that bleed repeatedly and are poor candidates for surgical removal. METHODS: Between 1988 and 2005 at the University of Pittsburgh, the authors performed SRS in 103 evaluable patients (57 males and 46 females) with solitary symptomatic CCMs. The mean patient age was 39.3 years. Ninety-eight percent of these patients had experienced 2 or more hemorrhages associated with new neurological deficits. Seventeen patients (16.5%) had undergone attempted resection before radiosurgery. Ninety-three CCMs were located in deep brain structures and 10 were in subcortical lobar areas of functional brain importance. The median malformation volume was 1.31 ml, and the median tumor margin dose was 16 Gy. RESULTS: The follow-up ranged from 2 to 20 years. The annual hemorrhage rate--that is, a new neurological deficit associated with imaging evidence of a new hemorrhage--before SRS was 32.5%. After SRS 22 hemorrhages were observed within 2 years (10.8% annual hemorrhage rate) and 4 hemorrhages were observed after 2 years (1.06% annual hemorrhage rate). The risk of hemorrhage from a CCM was significantly reduced after radiosurgery (p < 0.0001). Overall, new neurological deficits due to adverse radiation effects following SRS developed in 14 patients (13.5%), with most occurring early in our experience. Modifications in technique (treatment volume within the T2-weighted MR imaging-defined margin, use of MR imaging, and dose reduction for CCM in critical brainstem locations) further reduced risks after SRS. CONCLUSIONS: Data in this study provide further evidence that SRS is a relatively safe procedure that reduces the rebleeding rate for CCMs located in high-surgical-risk areas of the brain.

Stereotactic radiosurgery for cavernous sinus or orbital hemangiomas.

OBJECTIVE: Hemangiomas are rare but highly vascular tumors that may develop in the cavernous sinus or orbit. These tumors pose diagnostic as well as therapeutic challenges to neurosurgeons during attempted removal. We analyzed our increasing experience using stereotactic radiosurgery (SRS). METHODS: Eight symptomatic patients with hemangiomas underwent SRS between 1988 and 2007. The presenting symptoms included headache, orbital pain, diplopia, ptosis, proptosis and impaired visual acuity. The hemangiomas were located in either the cavernous sinus (7 patients) or the orbit (1 patient). Four patients underwent SRS as primary treatment modality based on clinical and imaging criteria. Four patients had previous microsurgical partial excision or biopsy. The median target volume was 6.8 mL (range, 2.5-18 mL). The median prescription dose delivered to the margin was 14.5 Gy (range, 12.5-19 Gy). The dose to the optic nerve in all patients was less than 9 Gy (range, 4.5-9 Gy). RESULTS: The median follow-up period after SRS was 80 months (range, 40-127 months). Six patients had symptomatic improvement; 2 patients reported persistent diplopia. Follow-up imaging revealed tumor regression in 7 patients and no change in tumor volume in 1 patient. All the patients improved after SRS. CONCLUSION: Our extended experience confirms that SRS is an effective management strategy for symptomatic intracavernous and intraorbital hemangiomas. Our study is the first long-term report on the safety and efficacy of SRS.

Establishing a benchmark for complications using frame-based stereotactic surgery.

We sought to establish a benchmark for complications using frame-based stereotactic surgery for both deep and lobar brain surgery. During a 28-year interval, we performed frame-based stereotactic surgery in 2,651 patients. Our database was retrospectively used to assess the risks of complications after frame-based stereotactic surgery. Routine immediate intraoperative imaging detected new blood products after diagnostic biopsy in 43 cases (2.6%); only 6 patients (0.36%) required craniotomy for hematoma evacuation. Perioperative seizures occurred in 6 patients (0.36%), and 2 patients developed burr hole site infections. One patient (1%) developed an intra-abscess hemorrhage after biopsy and catheter drainage. Two deaths (0.08%) related to surgery occurred. Some centers are currently migrating to frameless, even pinless, neuronavigation-guided needle procedures for both lobar and deep brain targets. Although experimental accuracy under optimal conditions is reported to be similar to that of frame-based systems, the complication rates from a significant number of cases have yet to be reported. This report establishes the safety profile of frame-based stereotactic surgery based on a 28-year period. These results may serve as a benchmark against which free-hand or guided neuronavigation approaches may be measured, as both the advantages and risks of such procedures are assessed.

Constrictive pericarditis after left extrapleural pneumonectomy and radiotherapy for malignant mesothelioma.

We report the devastating complication of constrictive pericarditis after multimodality therapy including left extrapleural pneumonectomy for malignant pleural mesothelioma. The patient presented with progressive dyspnea, ascites, and peripheral edema 6 months after receiving adjuvant radiotherapy. A diagnosis of constrictive pericarditis was made late in the clinical course after exhaustive investigation to exclude primary disease recurrence. Pericardial decortication was subsequently undertaken 12 months after the initial surgery, but the patient died of multi-organ failure. Our experience, combined with a review of the available literature, leads us to advise a low level of suspicion and early operation to relieve cardiac constriction. Furthermore, these complications emphasize the importance of trials such as the Mesothelioma and Radical Surgery (MARS) study.

Prolonged survival in a patient with recurrent pulmonary metastases secondary to mucinous cystadenocarcinoma of the appendix with pseudomyxomatous peritonei.

We report a 65-year-old man presenting with recurrent pulmonary metastases 20 years after an appendectomy for mucinous cystadenocarcinoma with pseudomyxomatous peritonei. He underwent bilateral staged metastatectomies for metastases 7 years after the diagnosis and further metastasectomy after a recent recurrence. This is a rare case of recurrent pulmonary metastatic mucinous cystadenocarcinoma, and despite poor prognosis and nondefinitive initial treatment, this patient remains alive and well 20 years later.