The Effect of Cement and Screw on the Resistance of an Implant Crown Telescopically Engaged to a Hexagonal Shaped Abutment Under Compressive Dynamic Cyclic Fatigue Loading.

PURPOSE: To investigate the resistance of an implant crown telescopically engaged to a geometrically defined hexagonal abutment with and without cement under compressive dynamic cyclic fatigue loading. MATERIALS AND METHODS: 40 crowns, 9 mm in height, were cast from prefabricated plastic copings each telescopically engaged to a 3 mm high machined hexagonal abutment. 20 crowns were retained with zinc phosphate cement and 20 crowns were retained with a screw. A vertical load of 15 kg was applied to all samples under oscillation. A Periotest was used to measure the mobility of the implant crown in Periotest values (PTV). Test endpoints were defined by; fatigue cycles ≥ 20 million; crown PTV > 10; or if samples became visibly loose or component fracture. RESULTS: Cement-retained crowns failed on average at 2.60 x 106 cycles ± 2.27, while screw-retained crown samples failed at 2.17 x 106 cycles ± 1.27 with no significant difference (p > 0.05). Implant and abutment screw fractures were the most prevalent mode of failure in the cement-retained group, while in the screw-retained group failures were caused by the loosening of one or both screw joints. The rate of increase in PTV was higher in the screw-retained group than in the cement-retained group. CONCLUSIONS: Under the experimental conditions, an implant crown telescopically engaged vertically to a 3 mm tall hexagonal abutment, under compressive dynamic cyclic fatigue loading with or without cement demonstrated no differences in resistance or failure outcomes. A cement-retained implant crown with telescopic engagement to the abutment is more rigid, resulting in more implant and abutment screw fractures than loosening.

Investigating Risk Factors for Falls among Community-Dwelling Older Adults According to WHO's Risk Factor Model for Falls.

OBJECTIVES: The World Health Organization developed the Risk Factor Model for Falls to describe fall risks in a comprehensive manner. However, there was a lack of study adopting such framework in quantifying falls risk from different factors in a single model. Therefore, this study examined the risk factors from four domains in the Risk Factor Model for Falls among older adults. DESIGN: Secondary data analysis of 10-year assessment records of the Minimum Data Set-Home Care instrument. SETTING: Hong Kong. PARTICIPANTS: 89,100 community-dwelling adults aged 65 and over who first applied for publicly funded long-term care services from 2005 to 2014. MEASUREMENTS: The Minimum Data Set-Home Care instrument was used to ascertain older adults' care needs and match them with appropriate services. Additionally, meteorological records from the same period were extracted from the Hong Kong Observatory. The logistic regression model was used to examine risk factors and their associations with falls. RESULTS: In total 70 factors were included in the analysis, of which 37 were significantly associated with falls. Behavioral risk factors generally had greater odds ratios of falling, as compared with biological, socioeconomic, and environmental factors. Out of all significant factors, functional status, alcohol drinking, and locomotion outdoors had the largest odds ratios of falling. CONCLUSION: Behavioral risk factors for falls are of remarkable influence yet are modifiable among older adults. Hence, falls prevention programs may need to prioritize addressing these factors.

The Intersection between Oral Microbiota, Host Gene Methylation and Patient Outcomes in Head and Neck Squamous Cell Carcinoma.

The role of oral microbiota in head and neck squamous cell carcinoma (HNSCC) is poorly understood. Here we sought to evaluate the association of the bacterial microbiome with host gene methylation and patient outcomes, and to explore its potential as a biomarker for early detection or intervention. Here we performed 16S rRNA gene amplicon sequencing in sixty-eight HNSCC patients across both tissue and oral rinse samples to identify oral bacteria with differential abundance between HNSCC and controls. A subset of thirty-one pairs of HNSCC tumor tissues and the adjacent normal tissues were characterized for host gene methylation profile using bisulfite capture sequencing. We observed significant enrichments of Fusobacterium and Peptostreptococcus in HNSCC tumor tissues when compared to the adjacent normal tissues, and in HNSCC oral rinses when compared to healthy subjects, while ten other bacterial genera were largely depleted. These HNSCC-related bacteria were discriminative for HNSCC and controls with area under the receiver operating curves (AUCs) of 0.84 and 0.86 in tissue and oral rinse samples, respectively. Moreover, Fusobacterium nucleatum abundance in HNSCC cases was strongly associated with non-smokers, lower tumor stage, lower rate of recurrence, and improved disease-specific survival. An integrative analysis identified that enrichment of F. nucleatum was associated with host gene promoter methylation, including hypermethylation of tumor suppressor genes LXN and SMARCA2, for which gene expressions were downregulated in the HNSCC cohort from The Cancer Genome Atlas. In conclusion, we identified a taxonomically defined microbial consortium associated with HNSCC that may have clinical potential regarding biomarkers for early detection or intervention. Host-microbe interactions between F. nucleatum enrichment and clinical outcomes or host gene methylation imply a potential role of F. nucleatum as a pro-inflammatory driver in initiating HNSCC without traditional risk factors, which warrants further investigation for the underlying mechanisms.

Serological diagnosis of Mycobacterium avium complex lung diseases by enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen.

INTRODUCTION: There is an increasing trend worldwide in the incidence of Mycobacterium avium complex pulmonary diseases (MAC-PD) and the diagnosis is sometimes complicated. Recently, an enzyme immunoassay (EIA) kit that detects serum IgA antibody against MAC-specific glycopeptidolipid (GPL) core antigen had been developed and found to be useful in discriminating MAC-PD from other lung diseases. The antibody was subsequently also found to be elevated in patients suffering Mycobacterium abscessus pulmonary diseases (MAB-PD). This study is to evaluate this EIA kit in the serological diagnosis of MAC-PD in Hong Kong Chinese patients. METHODS: The study was conducted in Grantham Hospital, Hong Kong between July 2017 and July 2018. Assay of the IgA antibody level using the EIA kit was done on blood samples collected from patients suffering from MAC-PD, MAB-PD, pulmonary tuberculosis and other lung diseases. RESULTS: There were 100 subjects recruited into the study, among which 11 were excluded. By using the cut-off value 0.7 U/mL provided by the manufacturer, the sensitivity and specificity for diagnosis were 73.7% and 77.6% for MAC-PD; 50% and 77.6% for MAB-PD. By receiver operating characteristic curves analysis, new cut-off for MAC-PD and MAB-PD were calculated as 1.771 U/mL and 0.172 U/m, respectively. The sensitivity and specificity were 68.4% and 86.2% for MAC-PD, whereas 66.7% and 72.4% for MAB-PD. CONCLUSIONS: Our study showed that the enzyme immunoassay of IgA antibodies against MAC-specific glycopeptidolipid core antigen could help to distinguishing MAC and M. abscessus pulmonary diseases from pulmonary tuberculosis and other lung diseases among Hong Kong Chinese patients. Further larger scale studies in our local population for the usefulness of this antibody test in the diagnosis and monitoring of MAC and M. abscessus lung diseases might be warranted.

Universal scaling of weak localization in graphene due to bias-induced dispersion decoherence.

The differential conductance of graphene is shown to exhibit a zero-bias anomaly at low temperatures, arising from a suppression of the quantum corrections due to weak localization and electron interactions. A simple rescaling of these data, free of any adjustable parameters, shows that this anomaly exhibits a universal, temperature- (T) independent form. According to this, the differential conductance is approximately constant at small voltages (V < kBT/e), while at larger voltages it increases logarithmically with the applied bias. For theoretical insight into the origins of this behaviour, which is inconsistent with electron heating, we formulate a model for weak-localization in the presence of nonequilibrium transport. According to this model, the applied voltage causes unavoidable dispersion decoherence, which arises as diffusing electron partial waves, with a spread of energies defined by the value of the applied voltage, gradually decohere with one another as they diffuse through the system. The decoherence yields a universal scaling of the conductance as a function of eV/kBT, with a logarithmic variation for eV/kBT > 1, variations in accordance with the results of experiment. Our theoretical description of nonequilibrium transport in the presence of this source of decoherence exhibits strong similarities with the results of experiment, including the aforementioned rescaling of the conductance and its logarithmic variation as a function of the applied voltage.

Cachexia and Cognitive Function in the Community-Dwelling Older Adults: Mediation Effects of Oral Health.

BACKGROUND: Cognitive impairment and poor oral health are common problems in older adults and are associated with malnutrition. However, it is unclear how they are related to cachexia in community-dwelling older adults. The aim of this study was to examine the relationships among cachexia, cognitive function, and oral health in community-dwelling older adults. METHODS: This study is a secondary analysis of a data-set. Data were collected in the community setting on older adults who applied for government-funded long-term care services in Hong Kong in 2017. Subjects were community-dwelling and aged ≥60 years. The outcome variable was cachexia. The predictors were cognitive function and oral health. The covariates included demographics and comorbidities associated with cachexia or malnutrition. Path analysis was employed to examine the associations among cachexia, cognitive function, and oral health using the software SAS/STAT and Mplus. RESULTS: This analysis included 12,940 subjects. The prevalence of cachexia was 1.3%. Cognitive function was also found to have a direct effect on the oral health indicators of chewing problems (OR=1.073, p<0.001), brushing teeth problems (OR=1.349, p<0.001), and swallowing problems (coeff.=0.177, p<0.001). Oral health indicators with a direct effect on cachexia included dry mouth (OR=1.250, p<0.001), brushing teeth problems (OR = 1.185, p<0.01), and swallowing problems (OR=1.231, p<0.001). Cognitive function had no significant direct effect, but had a significant indirect effect on cachexia (OR=1.100, p<0.001) which is mediated by brushing teeth problems (OR=1.052, p<0.001) and swallowing problems (OR=1.038, p<0.001). CONCLUSION: Cognitive impairment causes cachexia indirectly through poor oral health. This study recommends adding cognitive function when screening community-dwelling older adults for cachexia. Health policymakers should stress regular oral health screening and interventions, and encourage increased utilization of oral health services by community-dwelling older adults with cognitive problems.

Treatment of cutaneous angiosarcoma of the scalp and face in Chinese patients: local experience at a regional hospital in Hong Kong.

INTRODUCTION: Angiosarcoma is a rare aggressive sarcoma that occurs mostly in the skin of the head and neck in the elderly population. The optimal management is dubious and most studies are from Caucasian populations. We aimed to examine the treatment and outcome of this disease in Chinese patients. METHODS: Data of patients with histopathologically verified cutaneous angiosarcoma of the head and neck during December 1997 to September 2016 were retrieved from our hospital cancer registry. The demographic data, clinicopathological information, modality of treatment, and outcomes were reviewed. RESULTS: During the study period, 17 Chinese patients were treated. Their median age was 81 years. The tumours were present in the scalp only (n=11), face only (n=4), or both scalp and face (n=2). Only two patients had distant metastases. The modalities of treatment were surgery (n=6), surgery and adjuvant radiotherapy (n=1), palliative radiotherapy (n=5), or palliative chemotherapy (n=3). The remaining two patients refused any treatment initially. Of the seven patients treated surgically, there were four local and two regional recurrences. The median time to relapse was 7.5 months. Overall, 16 patients had died; causes of death were disease-related in 12 whereas four other patients died of inter-current illnesses. One patient was still living with the disease. The median overall survival was 11.1 months and the longest overall survival was 42 months. CONCLUSION: The outcome of angiosarcoma in our series is poor. A high index of suspicion is mandatory for prompt diagnosis. Adjuvant radiotherapy is recommended following surgery. The benefit and role of systemic treatment in various combinations with surgery or radiotherapy require further study.

Evaluating the Sources of Graphene's Resistivity Using Differential Conductance.

We explore the contributions to the electrical resistance of monolayer and bilayer graphene, revealing transitions between different regimes of charge carrier scattering. In monolayer graphene at low densities, a nonmonotonic variation of the resistance is observed as a function of temperature. Such behaviour is consistent with the influence of scattering from screened Coulomb impurities. At higher densities, the resistance instead varies in a manner consistent with the influence of scattering from acoustic and optical phonons. The crossover from phonon-, to charged-impurity, limited conduction occurs once the concentration of gate-induced carriers is reduced below that of the residual carriers. In bilayer graphene, the resistance exhibits a monotonic decrease with increasing temperature for all densities, with the importance of short-range impurity scattering resulting in a "universal" density-independent (scaled) conductivity at high densities. At lower densities, the conductivity deviates from this universal curve, pointing to the importance of thermal activation of carriers out of charge puddles. These various assignments, in both systems, are made possible by an approach of "differential-conductance mapping", which allows us to suppress quantum corrections to reveal the underlying mechanisms governing the resistivity.

Negative Differential Conductance & Hot-Carrier Avalanching in Monolayer WS2 FETs.

The high field phenomena of inter-valley transfer and avalanching breakdown have long been exploited in devices based on conventional semiconductors. In this Article, we demonstrate the manifestation of these effects in atomically-thin WS2 field-effect transistors. The negative differential conductance exhibits all of the features familiar from discussions of this phenomenon in bulk semiconductors, including hysteresis in the transistor characteristics and increased noise that is indicative of travelling high-field domains. It is also found to be sensitive to thermal annealing, a result that we attribute to the influence of strain on the energy separation of the different valleys involved in hot-electron transfer. This idea is supported by the results of ensemble Monte Carlo simulations, which highlight the sensitivity of the negative differential conductance to the equilibrium populations of the different valleys. At high drain currents (>10 µA/µm) avalanching breakdown is also observed, and is attributed to trap-assisted inverse Auger scattering. This mechanism is not normally relevant in conventional semiconductors, but is possible in WS2 due to the narrow width of its energy bands. The various results presented here suggest that WS2 exhibits strong potential for use in hot-electron devices, including compact high-frequency sources and photonic detectors.

Thermally Assisted Nonvolatile Memory in Monolayer MoS2 Transistors.

We demonstrate a novel form of thermally-assisted hysteresis in the transfer curves of monolayer MoS2 FETs, characterized by the appearance of a large gate-voltage window and distinct current levels that differ by a factor of ∼102. The hysteresis emerges for temperatures in excess of 400 K and, from studies in which the gate-voltage sweep parameters are varied, appears to be related to charge injection into the SiO2 gate dielectric. The thermally-assisted memory is strongly suppressed in equivalent measurements performed on bilayer transistors, suggesting that weak screening in the monolayer system plays a vital role in generating its strongly sensitive response to the charge-injection process. By exploiting the full features of the hysteretic transfer curves, programmable memory operation is demonstrated. The essential principles demonstrated here point the way to a new class of thermally assisted memories based on atomically thin two-dimensional semiconductors.

"Freeing" Graphene from Its Substrate: Observing Intrinsic Velocity Saturation with Rapid Electrical Pulsing.

Rapid (nanosecond-scale) electrical pulsing is used to study drift-velocity saturation in graphene field-effect devices. In these experiments, high-field pulses are utilized to drive graphene's carriers on time scales much faster than that on which energy loss to the underlying substrate can occur, thereby allowing the observation of the highest saturation velocities reported to date. In a dramatic departure from the behavior exhibited by conventional metals and semiconductors, as the electron or hole density is reduced toward the charge-neutrality point, the drift velocity is found to reach values comparable to the Fermi velocity itself. Corresponding current densities are as large as 10(9) A/cm(2), similar to the values reported for carbon nanotubes and for graphene-on-diamond transistors. In essence, our approach of rapid pulsing allows us to "free" graphene from the deleterious influence of its substrate, revealing a pathway to achieve the superior electrical performance promised by this material. The usefulness of this approach is not merely limited to graphene but should extend also to a broad variety of two-dimensional semiconductors.

Residents with Alzheimer's disease in long-term care facilities in Hong Kong: patterns of hospitalization and emergency room use.

OBJECTIVES: This study examined the frequency and predictors of hospitalization and emergency room (ER) use among residents with Alzheimer's disease at admission and after 1 year in a long-term care facility. METHOD: This secondary analysis used data collected with the Chinese version of the Residential Assessment Instrument Minimum Data Set 2.0 during the Hong Kong Longitudinal Study on Long-Term Care Facility Residents. RESULTS: A sample of 169 residents with Alzheimer's disease who were newly admitted between 2005 and 2010 was included in the analysis. Mixed-effects modeling was adopted to assess the associations between risk factors and the frequency of hospitalization and ER use. At admission, 27 (15.98%) respondents had been hospitalized and 19 (11.24%) required ER services during the previous 90 days. At admission, polypharmacy (ß = .081, p < .01) and use of psychotropic drugs (ß = ­.506, p < .05) were significantly associated with frequency of hospitalization. At 1-year follow-up, cognitive impairment (ß = .088, p < .05) and polypharmacy (ß = .058, p < .001) had significant positive associations with frequency of hospitalization, as well as use of ER services (ß = .084, p < .01; ß = .077, p < .001, respectively). Use of psychotropic drugs had a negative association with frequency of ER use at both time points. CONCLUSION: Practitioners should periodically observe cognitive ability, polypharmacy, and use of psychotropic drugs among long-term care residents with Alzheimer's disease.

Apocynum venetum leaf extract, an antihypertensive herb, inhibits rat aortic contraction induced by angiotensin II: a nitric oxide and superoxide connection.

ETHNOPHARMACOLOGICAL RELEVANCE: The leaves extract of Apocynum venetum (AVLE), also known as "luobuma", have long been used in traditional Chinese medicine to treat hypertension and depression in parts of China and it has been shown to possess anti-oxidant and anti-lipid peroxidation effects. AVLE (10 µg/ml) has been reported to have a long-lasting endothelium-dependent relaxant effect and this effect has been proposed to be due to its nitric oxide(NO)-releasing and superoxide anion(SOA)-scavenging properties. AIM OF THE STUDY: The present study seeks to evaluate the differential actions of AVLE extract between Ang II- and PE-induced vasoconstriction and the involvement of superoxide anions. MATERIALS AND METHODS: Single dose of Ang II (100 nM and 1 nM)- or PE (0.1 µM)-induced contraction were assessed in both endothelium-intact and -denuded aortic rings after pre-incubation of AVLE (10 µg/ml) for 15 min. The experiment was repeated in either the presence of NO synthase inhibitor, L-NAME (300 µM) or selective AT(1) receptor inhibitor, losartan (0.1 nM), or superoxide scavenger, tiron (1 mM) or a combination of L-NAME and AVLE. Superoxide production was measured by using enhanced-chemiluminescence assay. RESULTS: We have demonstrated that AVLE (10 µg/ml) effectively suppressed the Ang II-induced contraction (100 nM and 1 nM) of both endothelium-intact and -denuded rat aortic rings. In endothelium-intact rings, L-NAME, reversed AVLE-induced inhibition of Ang II-contraction. PE-induced contraction was significantly inhibited by AVLE in endothelium-intact rings, but not in endothelium-denuded rings. The inhibition by AVLE of PE-induced contraction was totally abolished in the presence of L-NAME. Ang II-induced SOA production concentration dependently with the optimal effect seen at 100 nM of Ang II, and AVLE (0.3, 1, 10 µg/ml) reduced this effect. SOA production in Ang II-stimulated rings was significantly higher than unstimulated control rings, while PE did not stimulate SOA production at all. SOA formation in the presence of Ang II was also inhibited in the presence of SOD (superoxide scavenger), DPI (NADPH inhibitor) and losartan (specific AT(1) receptor antagonist). CONCLUSION: These results collectively suggest that the ability of AVLE in inhibiting Ang II-induced contraction via its SOA scavenging properties and nitric oxide releasing effect may account for its usage as an antihypertensive treatment in traditional folk medicine.

Effects of intra-articular sodium pentosan polysulfate and glucosamine on the cytology, total protein concentration and viscosity of synovial fluid in horses.

OBJECTIVE: Evaluate synovial fluid cytology, total protein concentration and viscosity after intra-articular administration of combined pentosan polysulfate and glucosamine in horses. DESIGN: Ten adult Standardbred horses had each carpal joint (n = 20) randomly assigned to one of two treatments: control (5 mL saline) or treated (pentosan polysulfate and glucosamine). All horses received an intra-articular injection every 7 days for 3 weeks and synovial fluid samples were collected on days 1 (baseline), 2, 3, 7, 8, 9, 14, 15, 16 and 21. Synovial fluid variables measured included total protein concentration, total nucleated cell count, red blood cell count, the neutrophil, lymphocyte, mononuclear cell and eosinophil percentages, and viscosity. RESULTS: Following injection, the total nucleated cell count increased in the synovial fluid samples from both groups. Values were significantly higher in treated joints on days 2, 3, 15 and 16. Red blood cell counts were low and no differences were seen between treated and control joints. Total protein concentrations and neutrophil percentages increased in both groups after injection, but decreased towards normal ranges within 7 days. Total protein concentration was significantly higher in treated joints on days 1, 3, 8, 9 and 15. Percentages of neutrophils were higher in treated joints on day 2, but significantly lower on days 8 and 15. Viscosity was significantly higher in treated joints on day 2 only. CONCLUSIONS: Intra-articular administration of combined pentosan polysulfate and glucosamine causes a mild inflammatory synovitis that is not substantially different to that elicited by injection of a similar volume of saline and so we conclude that these drugs are safe to use in the horse.

Service learning in medical and nursing training: a randomized controlled trial.

The purpose of this study was to explore the long term effect of a service learning project on medical and nursing students' knowledge in aging and their attitudes toward older adults. A total of 124 students were recruited and then randomized to intervention group (IG) and control group (CG). A pre-and-post-intervention design measured students' knowledge in aging (using modified Palmore's Fact on Aging Quiz) and attitudes toward older adults (using Kogan's Old People Scale). A total of 103 students completed all the activities and questionnaires. After the intervention, there were significant differences between the IG and CG on Palmore's mental health (MH) (P = .04), Palmore's total score (P = .02) and Kogan's negative attitudes toward older adults (P = .001). All students increased their positive attitude toward older adults after the intervention. However, both the IG and CG showed a decrease in positive attitudes 1 month after the interventon, and such decrease varied, depending on the programme which students attended. The current study showed that the 10-week service learning activities significantly increased medical and nursing students' overall knowledge of aging and their understanding of mental health needs in old age, and reduced their negative attitudes toward older adults. However, the effect is not long-lasting. On the other hand, its effect on positive attitudes toward older adults cannot be concluded. Periodic contacts with older adults via service learning activities may be needed to sustain attitude change toward older adults.

Langerhans Cell Histiocytosis of Maxillary sinus.

Langerhan cell histiocytosis is a rare disease and usually occurs in paediatric age group. This disease may involve single or multiple organs system and has an unpredictable course of disease. The involvement of head and neck region are almost 90% of cases, however maxillary sinus involvement is very rare. We report a case of 2 year old boy presented with multi organ LCH (orbit, skull, sinus and liver). The mainstay treatment for this high risk multi organ LCH group is chemotherapy. Unfortunately, although with the advancement of treatment, their mortality rate is still high.