When thermoelectric generator (TEG) modules are attached to a rectangular chimney plate for venting hot flue gases, the power generated per unit surface area (power density) is strongly dependent on ...the TEG module spacing. The thermoelectric module consists of a hot plate, a spreader, a thermoelectric generator and a cold plate based on water cooling. In this study, the optimization of TEG module spacing and its spreader thickness as used in a waste heat recovery system is investigated and solved numerically using the finite difference method along with a simplified conjugate-gradient method. The power density for a thermoelectric module is the objective function to be maximized. A search for the optimum module spacing (S) and spreader thickness (Hsp), ranging from 40 mm < S < 300 mm and 1 mm < Hsp < 30 mm, respectively, is performed. The effects of different operating conditions, including the temperature difference between the waste gas and the cooling water (ΔT = 200–800 K), and effective waste gas heat transfer coefficients (hh = 20–80 W/m2 K) are discussed in detail. The predicted numerical data for the power vs. current (P–I) curve are in good agreement (within 8%) with the experimental data.
► We provided a 3D numerical model of a TEG module used in a waste heat recovery system. ► The effects of temperature difference and waste gas heat transfer coefficients were investigated. ► The power density for a TEG module is the objective function to be maximized. ► The numerical data are in good agreement (within 8%) with the experimental data. ► The optimum TEG module spacing and spreader thickness are strongly dependent on the waste gas heat transfer coefficient.
Subgingival microorganisms are potentially associated with periodontal diseases. However, the correlation between the variance in the periodontal microbiome and the prevalence and severity of ...periodontitis remains unclear. The aim of this study was to determine the subgingival microbiota in Taiwanese individuals with severe chronic periodontitis (SP).
The composition of the subgingival microbiota in healthy and diseased individuals was compared using a 16S rRNA metagenomic approach and quantitative polymerase chain reaction (qPCR). A total of 20 samples, including 10 from healthy individuals and 10 from SP patients, were analyzed.
We found high microbial diversity, with an average of 774 classified phylotypes per sample and a total of six bacterial phyla across all samples. Cluster analysis by principal component analysis and heat map showed that the bacterial communities were different in the two groups. Streptococcus dominated across all the healthy samples, whereas Prevotella, Porphyromonas, and Treponema were highly abundant across all diseased samples. At least 13 bacterial genera were conserved among all the samples. Only eight genera, including Lautropia, Parvimonas, Actinomyces, Capnocytophaga, Paludibacter, Streptococcus, Haemophilus, and Corynebacterium, were significantly enriched in the healthy group, and six genera, including Porphyromonas, Treponema, Tannerella, Aggregatibacter, Peptostreptococcus, and Filifactor, were significantly enriched in the diseased group. Furthermore, a trend of abundance of bacteria at the species level measured by qPCR in all samples was consistent with the 16S rRNA metagenomics results.
This study is the first in Taiwan to provide a picture of the microbiome in SP via 16S rRNA metagenomics.
The miRNA participates in a variety of biologic processes, and dysregulation of miRNA is associated with malignant transformation. In this study, we determined specific profile of miRNA associated ...with oral cancer by using miRNA array screening method. There were 23 miRNAs found with considerably differential expressions between six oral cancer cell lines and five lines of normal oral keratinocytes, in which, 10 miRNAs showed the highest significant difference after independent examination by reverse transcription quantitative PCR. Eight molecules were upregulated, miR-10b, miR-196a, miR-196b, miR-582-5p, miR-15b, miR-301, miR-148b, and miR-128a, and two molecules, miR-503 and miR-31, were downregulated. The most upregulated miR-10b was further examined, and its functions were characterized in two oral cancer cell lines. The miR-10b actively promotes cell migration (2.6- to 3.6-fold) and invasion (1.7- to 1.9-fold) but has minimal effect on cell growth or chemo-/radiosensitivity. Furthermore, miR-10b was considerably elevated in the plasma of xenografted tumor mice (20-fold). This upregulation of miR-10b in plasma was further shown in the patients with oral cancer P < 0.0001, area under curve (AUC) = 0.932 and precancer lesions (P < 0.0001, AUC = 0.967), suggesting that miR-10b possesses a high potential to discriminate the normal subjects. In conclusion, we have identified at least 10 miRNAs significantly associated with oral cancer, including the most elevated miR-10b. The miR-10b actively participates in cancer formation by promoting cell migration and invasion. Our study using clinical samples suggests that plasma miR-10b has high potential as an early detection marker for oral cancer.
The prognostic significance of the relapse interval in patients with resected oral cavity squamous cell carcinoma (OCSCC) is a matter of ongoing debate. In this large-scale, registry-based, ...nationwide study, we examined whether the time interval between surgery and the first disease relapse may affect survival outcomes in Taiwanese patients with OCSCC.
Data made available by the Taiwan Health Promotion Administration as of 2004 were obtained. The study cohort consisted of patients who were included in the registry between 2011 and 2017. Disease staging was performed according to the American Joint Committee on Cancer (AJCC) Staging Manual, Eight Edition. We retrospectively reviewed the clinical records of 13,789 patients with OCSCC who received surgical treatment. A total of 2327 (16.9%) patients experienced a first disease relapse. The optimal cutoff value for the relapse interval was 330 days when both 5-year disease-specific survival (DSS) and overall survival (OS) (≤ 330/>330 days, n = 1630/697) were taken into account. In addition, we undertook a propensity score (PS)-matched analysis of patients (n = 654 each) with early (≤ 330 days) versus late (> 330 days) relapse.
The median follow-up time in the entire study cohort was 702 days (433 and 2001 days in the early and late relapse groups, respectively). Compared with patients who experienced late relapse, those with early relapse showed a higher prevalence of the following adverse prognostic factors: pT4, pN3, pStage IV, poor differentiation, depth of invasion ≥ 10 mm, and extra-nodal extension. Multivariable analysis revealed that early relapse was an independent adverse prognostic factor for both 5-year DSS and OS (average hazard ratios AHRs: 3.24 and 3.91, respectively). In the PS-matched cohort, patients who experienced early relapse showed less favorable 5-year DSS: 58% versus 30%, p < 0.0001 (AHR: 3.10 2.69 - 3.57) and OS: 49% versus 22%, p < 0.0001 (AHR: 3.32 2.89 - 3.81).
After adjustment for potential confounders and PS matching, early relapse was an adverse prognostic factor for survival outcomes in patients with OCSCC. Our findings may have significant implications for risk stratification.
Background
Elective tracheotomy is commonly performed in resected oral squamous cell carcinoma (OCSCC) to maintain airway patency. However, the indications for this procedure vary among surgeons. ...This nationwide study evaluated the impact of tracheotomy on both the duration of in‐hospital stay and long‐term survival outcomes in patients with OCSCC.
Methods
A total of 18,416 patients with OCSCC were included in the analysis, comprising 7981 patients who underwent elective tracheotomy and 10,435 who did not. The primary outcomes assessed were 5‐year disease‐specific survival (DSS) and overall survival (OS). To minimize potential confounding factors, a propensity score (PS)‐matched analysis was performed on 4301 patients from each group. The duration of hospital stay was not included as a variable in the PS‐matched analysis.
Results
Prior to PS matching, patients with tracheotomy had significantly lower 5‐year DSS and OS rates compared to those without (71% vs. 82%, p < 0.0001; 62% vs. 75%, p < 0.0001, respectively). Multivariable analysis identified tracheotomy as an independent adverse prognostic factor for 5‐year DSS (hazard ratio = 1.10 1.03–1.18, p = 0.0063) and OS (hazard ratio = 1.10 1.04–1.17, p = 0.0015). In the PS‐matched cohort, the 5‐year DSS was 75% for patients with tracheotomy and 76% for those without (p = 0.1488). Five‐year OS rates were 66% and 67%, respectively (p = 0.0808). Prior to PS matching, patients with tracheotomy had a significantly longer mean hospital stay compared to those without (23.37 ± 10.56 days vs. 14.19 ± 8.34 days; p < 0.0001). Following PS matching, the difference in hospital stay duration between the two groups remained significant (22.34 ± 10.25 days vs. 17.59 ± 9.54 days; p < 0.0001).
Conclusions
While elective tracheotomy in resected OCSCC patients may not significantly affect survival, it could be associated with prolonged hospital stays.
Our study indicates that, following propensity score matching, patients with oral cavity squamous cell carcinoma (OCSCC) who underwent tracheotomy exhibit similar 5‐year disease‐specific and overall survival rates compared to those who did not. While elective tracheotomy in resected OCSCC patients may not significantly affect survival, it could be associated with prolonged hospital stays.
Background
In the treatment of oral cavity squamous cell carcinoma (OCSCC), surgical quality measures which are expected to affect outcomes, including the achievement of a clear margin, are ...surgeon-dependent but might not be invariably associated with hospital volume. Our objective was to explore surgical margin variations and survival differences of OCSCC between two highest-volume hospitals in Taiwan.
Materials and methods
A total of 2009 and 1019 patients with OCSCC who were treated at the two highest-volume Taiwanese hospitals (termed Hospital 1 and Hospital 2, respectively) were included. We examined how a pathological margin <5 mm impacted patient outcomes before and after propensity score (PS) matching.
Results
The prevalence of margins <5 mm was markedly lower in Hospital 1 than in Hospital 2 (34.5%/65.2%,
p
<0.0001). Compared with Hospital 2, tumor severity was higher in Hospital 1. On univariable analysis, being treated in Hospital 2 (versus Hospital 1; hazard ratio HR for 5-year disease-specific survival DSS = 1.34,
p
=0.0002; HR for 5-year overall survival OS = 1.17,
p
=0.0271) and margins <5 mm (versus ≥5 mm; HR for 5-year DSS = 1.63,
p
<0.0001; HR for 5-year OS = 1.48,
p
<0.0001) were identified as adverse factors. The associations of treatment in Hospital 2 and margins <5 mm with less favorable outcomes remained significant after adjustment for potential confounders in multivariable analyses, as well as in the PS-matched cohort. The 5-year survival differences between patients operated in Hospital 1 and Hospital 2 were even more pronounced in the PS-matched cohort (before PS matching: DSS, 79%/74%,
p
=0.0002; OS, 71%/68%,
p
=0.0269; after PS matching: DSS, 84%/72%,
p
<0.0001; OS, 75%/66%,
p
<0.0001). In the entire cohort, the rate of adjuvant therapy was found to be lower in patients with margins ≥5 mm than in those with margins <5 mm (42.7%
/
57.0%,
p
<0.0001).
Conclusions
Within the two highest-volume hospitals in Taiwan, patients with OCSCC with a clear margin status (≥5 mm) achieved more favorable outcomes. These results have clinical implications and show how initiatives aimed at improving the margin quality can translate in better outcomes. A clear margin status can reduce the need for adjuvant therapy, ultimately improving quality of life.
Background
To assess the prognostic significance of different nodal parameters i.e., number of pathologically positive nodes, log odds of positive lymph nodes, lymph node ratio (LNR), and extra-nodal ...extension (ENE) in Taiwanese patients with oral cavity squamous cell carcinoma (OCSCC), and to devise an optimized pN classification system for predicting survival in OCSCC.
Methods
A total of 4287 Taiwanese patients with first primary OCSCC and nodal metastases were enrolled. Cox proportional hazards regression analysis with the spline method was applied to identify the optimal cut-off values for LNR, log odds of positive lymph nodes, and number of pathologically positive nodes.
Results
On multivariable analysis, we identified a LNR ≥0.078/0.079, the presence of at least three pathologically positive nodes, and ENE as independent prognosticators for 5-year disease-specific survival (DSS) and overall survival (OS) rates. We therefore devised a four-point prognostic scoring system according to the presence or absence of each variable. The 5-year DSS and OS rates of patients with scores of 0−3 were 70%/62%/50%/36% (
p <
0.0001) and 61%/52%/40%25%, respectively (
p <
0.0001). On analyzing the AJCC 2017 pN classification, patients with pN3a displayed better survival rates than those with pN2 disease. The 5-year DSS and OS rates of patients with pN1/pN2/pN3a/pN3b disease were 72%/60%/67%/43% (
p <
0.0001) and 63%/51%/67%/33%, respectively (
p <
0.0001).
Conclusions
Three nodal parameters (i.e., a LNR ≥0.078/0.079, the presence of at least three pathologically positive nodes, and ENE) assessed in combination provided a better prognostic stratification than the traditional AJCC pN classification.
Methods
We sought to compare the prognostic impact of tumor differentiation with respect to adverse risk factors (RFs) identified by the National Comprehensive Cancer Network (NCCN) ...guidelines––including extranodal extension (ENE), positive/close margins, perineural invasion, lymphatic invasion, and vascular invasion––in patients with locally advanced oral cavity squamous cell carcinoma (OCSCC).
Results
Between 1996 and 2018, 1179 consecutive patients with first primary pT3–4 OCSCC were included. A three‐level grading system was adopted––in which the final classification was assigned according to the most prevalent tumor grade. We identified 382/669/128 patients with well/moderately/poorly differentiated tumors, respectively. Compared with well/moderately differentiated tumors, poorly differentiated OCSCC had a higher prevalence of the following variables: female sex (4%/6%/11%), ENE, (14%/36%/61%), positive margins (0.5%/2%/4%), close margins (10%/14%/22%), perineural invasion (22%/50%/63%), lymphatic invasion (2%/9%/17%), vascular invasion (1%/4%/10%), and adjuvant therapy (64%/80%/87%). The 5‐year rates of patients with well/moderately/poorly differentiated OCSCC were as follows: local control (LC, 85%/82%/84%, p = 0.439), neck control (NC, 91%/83%/70%, p < 0.001), distant metastases (DM, 6%/18%/40%, p < 0.001), disease‐free survival (DFS, 78%/63%/46%, p < 0.001), disease‐specific survival (DSS, 85%/71%/49%, p < 0.001), and overall survival (OS, 68%/55%/39%, p < 0.001). Multivariable analysis identified the following variables as independent prognosticators for 5‐year outcomes: ENE (LC/NC/DM/DFS/DSS/OS), poorly differentiated tumors (NC/DM/DFS/DSS/OS), positive margins (LC/DFS), lymphatic invasion (DFS/DSS/OS), perineural invasion (DM), and age ≥65 years (OS).
Conclusions
In addition to ENE, poor tumor differentiation was identified as the second most relevant adverse RF for patients with pT3–4 OCSCC. We suggest that the NCCN guidelines should include poor tumor differentiation as an adverse RF to refine and tailor clinical management.
Final tumor grading of oral cavity squamous cell carcinoma (OCSCC) is assigned according to the most prevalent grade. Relapses of poorly differentiated OCSCC tended to occur regionally and distantly. Poor tumor differentiation was the second most relevant adverse risk factor after extranodal extension. The NCCN guidelines should include poor differentiation as an adverse risk factor.
(1) Background: The optimal cutoff value that maximizes the prognostic value of surgical margins in patients with resected oral cavity squamous cell carcinoma has not yet been identified. (2) ...Methods: Data for this study were retrieved from the Taiwan Cancer Registry Database. A total of 13,768 Taiwanese patients with oral cavity squamous cell carcinoma were identified and stratified according to different margin statuses (0, 0.1-4 and > 4 mm). The five-year local control, disease-specific survival and overall survival rates were the main outcome measures. (3) Results: The 5-year local control, disease-specific survival and overall survival rates of patients with close margins (0 and 0.1-4 mm) were significantly lower than those observed in patients with clear margins (> 4 mm; all
values < 0.001). In multivariate analysis, margin status, depth of invasion and extra-nodal extension were identified as independent adverse prognostic factors for 5-year local control. (4) Conclusions: A thorough assessment of surgical margins can provide a reliable prognostic prediction in patients with OCSCC. This has potential implications for treatment approaches tailored to the individual level. The achievement of clear margins (>4 mm) should be considered a key surgical goal to improve outcomes in this patient group.
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