Liver-on-chip model and application in predictive genotoxicity and mutagenicity of drugs.

Currently, there is no test system, whether in vitro or in vivo, capable of examining all endpoints required for genotoxicity evaluation used in pre-clinical drug safety assessment. The objective of this study was to develop a model which could assess all the required endpoints and possesses robust human metabolic activity, that could be used in a streamlined, animal-free manner. Liver-on-chip (LOC) models have intrinsic human metabolic activity that mimics the in vivo environment, making it a preferred test system. For our assay, the LOC was assembled using primary human hepatocytes or HepaRG cells, in a MPS-T12 plate, maintained under microfluidic flow conditions using the PhysioMimix® Microphysiological System (MPS), and co-cultured with human lymphoblastoid (TK6) cells in transwells. This system allows for interaction between two compartments and for the analysis of three different genotoxic endpoints, i.e. DNA strand breaks (comet assay) in hepatocytes, chromosome loss or damage (micronucleus assay) and mutation (Duplex Sequencing) in TK6 cells. Both compartments were treated at 0, 24 and 45 h with two direct genotoxicants: methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS), and two genotoxicants requiring metabolic activation: benzo[a]pyrene (B[a]P) and cyclophosphamide (CP). Assessment of cytochrome activity, RNA expression, albumin, urea and lactate dehydrogenase production, demonstrated functional metabolic capacities. Genotoxicity responses were observed for all endpoints with MMS and EMS. Increases in the micronucleus and mutations (MF) frequencies were also observed with CP, and %Tail DNA with B[a]P, indicating the metabolic competency of the test system. CP did not exhibit an increase in the %Tail DNA, which is in line with in vivo data. However, B[a]P did not exhibit an increase in the % micronucleus and MF, which might require an optimization of the test system. In conclusion, this proof-of-principle experiment suggests that LOC-MPS technology is a promising tool for in vitro hazard identification genotoxicants.

Fleaborne Typhus-Associated Deaths - Los Angeles County, California, 2022.

Fleaborne typhus (also known as murine typhus), a widely distributed vectorborne zoonosis caused by Rickettsia typhi, is a moderately severe, but infrequently fatal illness; among patients who receive doxycycline, the case-fatality rate is <1%. Fleaborne typhus is a mandated reportable condition in California. Reported fleaborne typhus cases in Los Angeles County have been increasing since 2010, with the highest number (171) reported during 2022. During June-October 2022, Los Angeles County Department of Public Health learned of three fleaborne typhus-associated deaths. This report describes the clinical presentation, illness course, and methods used to diagnose fleaborne typhus in these three cases. Severe fleaborne typhus manifestations among these cases included hemophagocytic lymphohistiocytosis, a rare immune hyperactivation syndrome that can occur in the infection setting; myocarditis; and septic shock with disseminated intravascular coagulation. Increased health care provider and public health awareness of the prevalence and severity of fleaborne typhus and of the importance of early doxycycline therapy is essential for prevention and treatment efforts.

Preterm birth among pregnant persons with severe acute respiratory syndrome Coronavirus 2 infection.

OBJECTIVE: We examined the relationship between trimester of SARS-CoV-2 infection, illness severity, and risk for preterm birth. STUDY DESIGN: We analyzed data for 6336 pregnant persons with SARS-CoV-2 infection in 2020 in the United States. Risk ratios for preterm birth were calculated for illness severity, trimester of infection, and illness severity stratified by trimester of infection adjusted for age, selected underlying medical conditions, and pregnancy complications. RESULT: Pregnant persons with critical COVID-19 or asymptomatic infection, compared to mild COVID-19, in the second or third trimester were at increased risk of preterm birth. Pregnant persons with moderate-to-severe COVID-19 did not show increased risk of preterm birth in any trimester. CONCLUSION: Critical COVID-19 in the second or third trimester was associated with increased risk of preterm birth. This finding can be used to guide prevention strategies, including vaccination, and inform clinical practices for pregnant persons.

Epidemiology of early esophageal adenocarcinoma.

BACKGROUND/AIMS: Endoscopic resection has become the preferred treatment approach for select early esophageal adenocarcinoma (EAC); however, the epidemiology of early stage disease has not been well defined. METHODS: Surveillance Epidemiology and End Results (SEER) data were analyzed to determine age-adjusted incidence rates among major epithelial carcinomas, including EAC, from 1973 to 2017. The percent change in incidence over time was compared according to tumor subtype. Early T-stage, node-negative EAC without metastasis was examined from 2004 to 2017 when precise T-stage data were available. RESULTS: The percent change in annual incidence from 1973 to 2017 was 767% for EAC. Joinpoint analysis showed that the average annual percent change in EAC from 1973 to 2017 was 5.11% (95% confidence interval, 4.66%-5.56%). The annual percent change appeared to plateau between 2004 and 2017; however, early EAC decreased from 2010 to 2017, with an annual percent change of -5.78%. CONCLUSION: There has been a 7-fold increase in the incidence of EAC, which was significantly greater than that of the other major epithelial malignancies examined. More recently, the incidence of early EAC has been decreasing. Approximately one in five patients has node negative, potentially resectable early stage disease.

Novel speed sintered zirconia by microwave technology.

OBJECTIVE: Continuous efforts have been made to hasten the zirconia densification process without compromising properties. This study evaluated the long-term structural durability of microwave speed-sintered zirconia (MWZ) relative to a conventionally sintered zirconia (CZ). METHODS: As-machined dental 3Y-TZP discs (Ø12 × 1.2 mm) were speed sintered at 1450 °C for 15 min using an industrial microwave oven, while conventional sintering was conducted in a standard dental furnace at 1530 °C for 2 h. Both were followed by natural cooling. The total sintering time was 105 min for MWZ and 600 min for CZ. Groups were compared regarding density, grain size, phase composition, and fracture resistance. Structural durability was investigated employing two fatigue protocols, step-stress and dynamic fatigue. RESULTS: Compared to CZ, MWZ exhibited a slightly lower density (MWZ = 5.98 g/cm3, CZ = 6.03 g/cm3), but significantly smaller grain sizes (MWZ = 0.53 ± 0.09 µm, CZ = 0.89 ± 0.10 µm), lower cubic-zirconia contents (MWZ = 15.3%, CZ = 22.7%), and poorer translucency properties (TP) (MWZ = 13 ± 1, CZ = 29 ± 0.8). However, the two materials showed similar flexural strength (MWZ = 978 ± 112 MPa, CZ = 1044 ± 161 MPa). Additionally, step-stress testing failed to capture the fatigue effect in 3Y-TZP, whereas dynamic fatigue revealed structural degradation due to moisture-assisted slow-crack-growth (SCG). Finally, MWZ possessed a slightly higher Weibull modulus (MWZ = 7.9, CZ = 6.7) but similar resistance to SCG (MWZ = 27.5, CZ = 24.1) relative to CZ. SIGNIFICANCE: Dental 3Y-TZP with similar structural durability can be fabricated six-times faster by microwave than conventional sintering.

The optimal timing and management of hepatitis B and C in patients with hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is the fourth most common cause of cancer related mortality worldwide, with the most common underlying etiologies being chronic hepatitis B and hepatitis C infections. Treatment of these viral hepatidities in the setting of HCC has been debated, and there is increasing study addressing this topic. Patients with advanced HCC of either etiology are unlikely to benefit from antiviral treatments, and futility should be considered prior to starting antiviral therapy. Hepatitis B treatment has demonstrated improved survival, decreased risk of hepatitis B reactivation, and decreased risk of late HCC recurrence. The mainstay treatment of chronic hepatitis B has been nucleos(t)ide analogues (NAs), and in the setting of HCC, entecavir and tenofovir are preferred given their higher potency and barriers to resistance. Those who were already on a NAs at the time of HCC diagnosis should be continued on them regardless of the HCC management planned. Patients who are suitable candidates to start NAs should start them at the time of HCC diagnosis. Direct-acting antivirals (DAAs) are the first line therapies for hepatitis C. Unlike with hepatitis B, those with HCV-associated HCC are recommended to start treatment 3-6 months after complete treatment of their HCC, given lower rates of sustained virologic response (SVR) with active HCC. There are also controversial concerns about DAAs contributing to a more aggressive HCC phenotype, but data are limited by retrospective studies, and more recent retrospective studies are more reassuring. In transplant candidates, starting DAAs may be deferred until after transplant depending on median regional wait times, availability of HCV positive organs, and the degree of the patient's liver dysfunction. Overall, in patients with HCC from hepatitis B or C, treatment of the underlying viral hepatitis should be considered unless advanced stage limits benefits and results in futility.

Diagnosis clinical criteria of sport related concussion: Toward an operational criteria definition in France.

OBJECTIVE: An expert working group was set up at the initiative of the French Ministry of Sports with the objective of harmonising the management of sport related concussion (SRC) in France, starting with its definition and diagnosis criteria. RESULTS: Definition: A clinical definition in 4 points have been established as follows: Concussion is a brain injury: 1) caused by a direct or indirect transmission of kinetic energy to the head; 2) resulting in an immediate and transient dysfunction of the brain characterised by at least one of the following disorders: a) Loss of consciousness, b) loss of memory, c) altered mental status, d) neurological signs; 3) possibly followed by one or more functional complaints (concussion syndrome); 4) the signs and symptoms are not explained by another cause. Diagnosis criteria: In the context of the direct or indirect transmission of kinetic energy to the head, the diagnosis of concussion may be asserted if at least one of the following signs or symptoms, observed or reported, is present within the first 24hours and not explained by another cause: 1) loss of consciousness; 2) convulsions, tonic posturing; 3) ataxia; 4) visual trouble; 5) neurological deficit; 6) confusion; 7) disorientation; 8) unusual behaviour; 9) amnesia; 10) headaches; 11) dizziness; 12) fatigue, low energy; 13) feeling slowed down, drowsiness; 14) nausea; 15) sensitivity to light/noise; 16) not feeling right, in a fog; 17) difficulty concentrating. CONCLUSION: Sharing the same definition and the same clinical diagnostic criteria for concussion is the prerequisite for common rules of management for all sports and should allow the pooling of results to improve our knowledge of this pathology.

Resistance of bonded premolars to four artificial ageing models post enamel conditioning with a novel calcium-phosphate paste.

BACKGROUND: This in vitro study compares a novel calcium-phosphate etchant paste to conventional 37% phosphoric acid gel for bonding metal and ceramic brackets by evaluating the shear bond strength, remnant adhesive and enamel damage following water storage, acid challenge and fatigue loading. MATERIAL AND METHODS: Metal and ceramic brackets were bonded to 240 extracted human premolars using two enamel conditioning protocols: conventional 37% phosphoric acid (PA) gel (control), and an acidic calcium-phosphate (CaP) paste. The CaP paste was prepared from ß-tricalcium phosphate and monocalcium phosphate monohydrate powders mixed with 37% phosphoric acid solution, and the resulting phase was confirmed using FTIR. The bonded premolars were exposed to four artificial ageing models to examine the shear bond strength (SBS), adhesive remnant index (ARI score), with stereomicroscopic evaluation of enamel damage. RESULTS: Metal and ceramic control subgroups yielded significantly higher (p < 0.05) SBS (17.1-31.8 MPa) than the CaP subgroups (11.4-23.8 MPa) post all artificial ageing protocols, coupled with higher ARI scores and evidence of enamel damage. In contrast, the CaP subgroups survived all artificial ageing tests by maintaining adequate SBS for clinical performance, with the advantages of leaving unblemished enamel surface and bracket failures at the enamel-adhesive interface. CONCLUSIONS: Enamel conditioning with acidic CaP pastes attained adequate bond strengths with no or minimal adhesive residue and enamel damage, suggesting a suitable alternative to the conventional PA gel for orthodontic bonding. Key words:Enamel etching, calcium phosphate, bracket bond strength, adhesive residue, enamel damage.

Nanoscale and Macroscale Effects of Mineral Deposition During Water Evaporation on Nanoporous Surfaces.

Recent studies have indicated that droplet evaporation heat transfer can be substantially enhanced by fabricating a thin nanoporous superhydrophilic layer on a metal substrate. Such surfaces have immense potential to improve spray cooling processes, however, little durability testing of the surface has been performed. In spray cooling applications, as water evaporates any impurities in the water will be deposited onto the surface. Primarily, this investigation serves to demonstrate how minerals in hard water deposit on the surface and interact with the ZnO nanopillars of the superhydrophilic surface. Quantifying the effects of mineral scale on droplet spreading and vaporization heat transfer on the surface is important in determining implementation requirements to advance the surface into industry applications. Micrographs of the surface demonstrate minerals deposit nonuniformly and quickly fill the nanostructure. Despite a reduction in the extent of droplet spreading due to the mineral deposition, scaled surfaces still demonstrated improved thermal performance compared to an uncoated, smooth copper surface. Scale tended to build up on previously deposited scale, leaving largely uncoated areas where droplets chose to preferentially spread and resulting in a continued low contact angle. Maintaining these uncoated areas and reducing the contaminants present in the water will extend the life and performance of the nanostructured surface.

Effect of indenter material on reliability of all-ceramic crowns.

OBJECTIVES: Controversy exists about whether the elastic modulus (E) mismatch between the loading indenter and ceramic materials influences fatigue testing results. The research hypotheses were that for porcelain veneered Y-TZP crowns 1) A low modulus Steatite indenter (SB) leads to higher fatigue reliability compared to a high modulus tungsten carbide indenter (WC); 2) Different surface damage patterns are expected between low and high modulus indenters after sliding contact fatigue testing. All ceramic crowns will exhibit similar step-stress accelerated life testing (SSALT) contact fatigue reliability (hypothesis 1) and failure characteristics (hypothesis 2) when using high stiffness tungsten carbide (WC, E = 600 GPa) vs. enamel like steatite (SB, E = 90 GPa) indenters. METHODS: Manufacturer (3M Oral Care) prepared Y-TZP-veneered all-ceramic molar crowns were bonded to aged resin composite reproductions of a standard tooth preparation and subjected to mouth-motion SSALT fatigue (n = 18 per indenter type). Failure was defined either as initial inner cone crack (IC), or final fracture (FF) when porcelain fractured (chipping). Selected IC specimens that did not progress to FF were embedded in epoxy resin and sectioned for fractographic analysis. RESULTS: The distribution of failures across the load and cycle profiles lead to similar calculated Weibull Use Level Probability Plots with overlap of the 2-sided 90% confidence bounds. The calculated reliability for IC and FF was equivalent at a mission of 300 N or 700 N load and 50,000 cycles, although the WC indenter had a trend for lower reliability for IC at 700 N. Both indenters produced similar patterns of wear and cracking on crown surfaces. Fractographic landmarks showed competing failure modes, but sliding contact partial inner cone cracks were the most dominant for both groups. SIGNIFICANCE: The more compliant Steatite indenter had similar veneered crown fatigue reliability and failure modes to those found with use of a high stiffness tungsten carbide indenter (hypotheses 1 and 2 rejected).

Results from the Survey of Antibiotic Resistance (SOAR) 2016-18 in Vietnam, Cambodia, Singapore and the Philippines: data based on CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints.

OBJECTIVES: To determine antibiotic susceptibility of Streptococcus pneumoniae and Haemophilus influenzae isolates collected from community-acquired respiratory tract infections (CA-RTIs) in 2016-18 in four Asian countries. METHODS: MICs were determined by CLSI broth microdilution and susceptibility was assessed using CLSI, EUCAST (dose-specific) and pharmacokinetic/pharmacodynamic (PK/PD) breakpoints. RESULTS: In total, 260 S. pneumoniae and 258 H. influenzae isolates were tested. Pneumococci from Vietnam (n = 161) were the least susceptible, with rates of susceptibility >90% for fluoroquinolones by CLSI breakpoints, ∼60% for amoxicillin, amoxicillin/clavulanic acid and ceftriaxone but <14% for most other agents. Pneumococcal isolates from Cambodia (n = 48) and Singapore (n = 34) showed susceptibilities ranging from ∼30% for trimethoprim/sulfamethoxazole and oral penicillin to 100% for fluoroquinolones. Among isolates of H. influenzae from Cambodia (n = 30), the Philippines (n = 59) and Singapore (n = 80), rates of susceptibility using CLSI breakpoints were >90% for amoxicillin/clavulanic acid, cephalosporins [except cefaclor in Singapore (77.5%)], macrolides and fluoroquinolones; for isolates from Vietnam (n = 89) the rates of susceptibility were >85% only for amoxicillin/clavulanic acid (95.5%), ceftriaxone (100%) and macrolides (87.6%-89.9%). Susceptibility to other antibiotics ranged from 7.9% (trimethoprim/sulfamethoxazole) to 57.3%-59.6% (fluoroquinolones) and 70.8% (cefixime). The application of different EUCAST breakpoints for low and higher doses for some of the antibiotics (amoxicillin, amoxicillin/clavulanic acid, ampicillin, penicillin, ceftriaxone, clarithromycin, erythromycin, levofloxacin and trimethoprim/sulfamethoxazole) allowed, for the first time in a SOAR study, the effect of raising the dosage on susceptibility to be quantified. A limitation of the study was the small sample sizes and only one or two sites participating per country; however, since susceptibility data are scarce in some of the participating countries any information concerning antibiotic susceptibility is of value. CONCLUSIONS: Antibiotic susceptibility varied across countries and species, with isolates from Vietnam demonstrating the lowest susceptibility. Knowledge of resistance patterns can be helpful for clinicians when choosing empirical therapy options for CA-RTIs.

Variational principles and nonequilibrium thermodynamics.

Variational principles play a fundamental role in deriving the evolution equations of physics. They work well in the case of non-dissipative evolution, but for dissipative systems, the variational principles are not unique and not constructive. With the methods of modern nonequilibrium thermodynamics, one can derive evolution equations for dissipative phenomena and, surprisingly, in several cases, one can also reproduce the Euler-Lagrange form and symplectic structure of the evolution equations for non-dissipative processes. In this work, we examine some demonstrative examples and compare thermodynamic and variational techniques. Then, we argue that, instead of searching for variational principles for dissipative systems, there is another viable programme: the second law alone can be an effective tool to construct evolution equations for both dissipative and non-dissipative processes. This article is part of the theme issue 'Fundamental aspects of nonequilibrium thermodynamics'.

Nonequilibrium thermodynamics: emergent and fundamental.

How can we derive the evolution equations of dissipative systems? What is the relation between the different approaches? How much do we understand the fundamental aspects of a second law based framework? Is there a hierarchy of dissipative and ideal theories at all? How far can we reach with the new methods of nonequilibrium thermodynamics? This article is part of the theme issue 'Fundamental aspects of nonequilibrium thermodynamics'.

Genetic characterization of the spike gene of porcine epidemic diarrhea viruses (PEDVs) circulating in Vietnam from 2015 to 2016.

BACKGROUND: Porcine epidemic diarrhea (PED) is a highly contagious swine disease caused by the PED virus (PEDV), which is a member of the family Coronaviridae. Since the first outbreaks in Belgium and the United Kingdom were reported in 1971, PED has spread throughout many countries around the world and causing significant economic loss. This study was conducted to investigate the recent distribution of PEDV strains in Vietnam during the 2015-2016 seasons. METHODS: A total of 30 PED-specific PCR-positive intestinal and faecal samples were collected from unvaccinated piglets in Vietnam during the 2015-2016 seasons. The full length of the spike (S) gene of these PEDV strains were analysed to determine their phylogeny and genetic relationship with other available PEDV strains globally. RESULTS: Phylogenetic analysis of the complete S gene sequences revealed that the 28 Vietnamese PEDV strains collected in the northern and central regions clustered in the G2 group (both G2a and G2b sub-groups), while the other 2 PEDV strains (HUA-PED176 and HUA-PED254) collected in the southern region were clustered in the G1/G1b group/sub-group. The nucleotide (nt) and deduced amino acid (aa) analyses based on the complete S gene sequences showed that the Vietnamese PEDV strains were closely related to each other, sharing nt and aa homology of 93.2%-99.9% and 92.6%-99.9%, respectively. The N-glycosylation patterns and mutations in the antigenic region were observed in Vietnamese PEDV strains. CONCLUSIONS: This study provides, for the first time, up-to-date information on viral circulation and genetic distribution, as well as evidence to assist in the development of effective PEDV vaccines in Vietnam.

In vitro bond strengths post thermal and fatigue load cycling of sapphire brackets bonded with self-etch primer and evaluation of enamel damage.

BACKGROUND: This in vitro study compares a self-etch primer (SEP) to an etch-and-rinse (EaR) for bonding sapphire brackets by evaluation of the enamel etch-pattern, shear bond strength, amount of remnant adhesive and enamel surface damage following thermal and fatigue cyclic loading. MATERIAL AND METHODS: Ceramic (sapphire) brackets were bonded to 80 extracted human premolars using two enamel etching protocols: conventional EaR using 37% phosphoric acid (PA) gel (control), and a SEP (Transbond Plus). Each group was subdivided into two subgroups (n=20 teeth) according to the time of bracket debonding: after 24 h water storage or following 5000 thermo-cycles plus 5000 cycles fatigue loading, to determine the shear bond strength (SBS), adhesive remnant index (ARI score), with scanning electron microscopy (SEM) evaluation of enamel condition. RESULTS: The control subgroups consistently exhibited significantly higher (p<0.05) SBS mean values (23.4-29.8 MPa) than the SEP subgroups (15.1-22.4 MPa) at both bracket debonding time points. However, the SEP subgroups yielded milder etch-patterns and attained SBS values above the minimum requirement range for clinical performance. In addition, the higher SBS of control subgroups was accompanied with higher ARI scores and enamel damage grades than SEP subgroups as confirmed by SEM. Thermocycling and fatigue significantly reduced the SBS of all subgroups, with a non-significant drop in the amount of adhesive residue or enamel damage. CONCLUSIONS: The use of SEP can be a suitable alternative to the conventional PA gel for sapphire bracket bonding as it maintains suitable bond strength and has the potential to produce both less remnant adhesive and enamel damage. Key words:Enamel etching, ceramic brackets, orthodontic bonding, adhesive remnants, enamel damage.

The tooth: An analogue for biomimetic materials design and processing.

OBJECTIVE: Overview the development of human tooth; enamel, dentoenamel junction and dentin in regard to hierarchical structure property relationships and how these component structures can serve as templates for the design of tough materials. METHODS: The dental, engineering and ceramic literature (PubMed, Science Direct, Google Scholar) covering the last 20years was over viewed regarding enamel and dentin characterization, structure-property studies, as well as, publications related to bioinspired materials with relationship to tooth structure. Relevant publications were selected for inclusion. RESULTS: Enamel has been studied and modelled at 3 hierarchical levels, prism structure, parallel prism interactions and enamel decussation effects. Missing is a 4th level where the previous three hierarchies are combined with the 3D arrangement of these levels in enamel areas. Aspects of the enamel prism infrastructure and prism decussation have been used in 3D printing of Bouligand ceramic structures. The dento-enamel junction serves to arrest cracks and reduce the stress in enamel as a graded elastic modulus layer, leading to development of dental ceramics with increased strength and fatigue resistance. Dentin is a compliant structure that supports enamel mechanically and may, through providing interstitial fluid at the DEJ, allow repair of microcracks in enamel. Adequate models of dentin properties remain to be developed as it remains highly variable in tubule lumen size and the degree of mineral density around and between tubules. SIGNIFICANCE: The structure of teeth, particularly the 4 hierarchical levels of enamel, creates a vital, hard, tough damage tolerant system for inspiring new materials.