Effect of cervical margin relocation on marginal adaptation and microleakage of indirect ceramic restorations

PURPOSE

This study evaluated the effect of cervical margin relocation (CMR) with two different materials and contamination with hemostatic agents on the margin adaptation and microleakage of ceramic restorations.

MATERIALS AND METHODS

Mesial-occlusal-distal cavities were prepared in 60 human first molars and distributed to 3 groups (n = 20) according to the margin relocation procedure. The groups were: group F; flowable composite applied in two 2 mm increments, group B; bulk-fill flowable composite applied as a bulk increment of 4 mm thickness and group C (control); no CMR was done. Each group was subdivided into two subgroups (subgroup N; no hemostatic agent applied and subgroup H; hemostatic agent was applied). In all groups, ceramic inlays were prepared and cemented. The samples were subjected to thermocycling (10,000 cycles). The adaptation of the cervical margin was evaluated with scanning electron microscopy (200×). Samples were then assessed for microleakage analysis with the dye penetration method. Marginal adaptation data were normally distributed and analyzed using two-way ANOVA followed by Tukey's post hoc test. Ordinal microleakage score data were analyzed using cumulative link models followed by the analysis of deviance using Wald chi-square tests.

RESULTS

Both CMR and contamination with a hemostatic agent had significant effects on the margin adaptation of the cervical margin. Group C showed the highest adaptation with no significant difference from group F. The lowest adaptation was revealed in group B with a significant difference from group C. Subgroup N (in all groups) showed a statistically higher adaptation than subgroup H. Regarding microleakage assessment, CMR had no significant effect but hemostatic agent application showed a significantly higher microleakage score for all groups.

CONCLUSIONS

Both the CMR procedure and contamination with AlCl3 hemostatic agent had a negative effect on marginal adaptation. For microleakage assessment, only contamination with hemostatic agent negatively affected the microleakage with no effect on the margin relocation procedure.

Build angle effect on 3D-printed dental crowns marginal fit using digital light-processing and stereo-lithography technology: an in vitro study

BACKGROUND

The effect of 3D printing technology and build angle on the marginal fit of printed crowns is unclear. The objective of this research was to use digital light processing (DLP) and stereo-lithography (SLA)-based 3D printing to construct single restorations with varied build angles and to analyze the crowns' marginal fit.

METHODS

A prepared resin first molar was scanned utilizing an optical scanner. Three build orientations were used to construct the specimens: 0, 45, and 90º. DLP and SLA technology were used to produce the casting patterns. A digital microscope was used to measure the marginal gaps. The effect of build orientation was statistically analyzed by using Two-way ANOVA followed by pair-wise Tukey test.

RESULTS

Two-way ANOVA revealed a significant effect of printer technology and build angle on the marginal discrepancy of 3D printed crowns (p < 0.001). One-way ANOVA revealed that SLA printers (55.6 [± 13.59]) showed significantly better mean [± SD] marginal discrepancy in µm than DLP printers (72 [± 13.67]) (p < 0.001). Regarding build angle, one-way ANOVA revealed significant differences between the different angles. Tukeys post-hoc test revealed that 0° (48.5 [± 9.04]) had the significantly smallest marginal discrepancy followed by 45° (62.5 [± 8.05]) then 90° (80.5 [± 8.99]) (p < 0.001).

CONCLUSION

The build orientation affects the marginal discrepancy of single crowns manufactured utilizing DLP and SLA.

Accuracy and repeatability of different intraoral instruments on shade determination compared to visual shade selection

OBJECTIVE

To evaluate the accuracy and repeatability of intraoral instruments used for shade determination compared to visual shade selection (VSS).

MATERIALS AND METHODS

A total of 20 subjects and 10 observers, balanced by gender, participated in the study. Observers performed VSS of the upper right central incisor from each subject. Instrumental shade determination of the same teeth was performed using a spectrophotometer (Easyshade V) and intraoral scanners (CEREC Omnicam, Primescan, Trios 3 and Trios 4). Vita Classical shade nomenclature was used to record the shade designation for all instruments and VSS. The accuracy of the instruments was determined by comparing the instrument readings with the most frequent visual shade selected. The percentage of accuracy was obtained by comparing the number of agreements with the number of comparisons. The percentage of repeatability was obtained by comparing the number of repeated shades with the number of shade measurements in each group. Accuracy was compared using Cochran Q test followed by pairwise comparisons using multiple McNemar's tests with Bonferroni correction. Repeatability of the instruments was evaluated using Cronbach's alpha.

RESULTS

Omnicam showed a significant lower accuracy than the other instruments (p < 0.05). No statistical difference on repeatability was found among the different instruments (p > 0.05). It was not found any statistical differences for VSS accuracy among the observers (p = 0.437) and between genders (p = 0.867).

CONCLUSION

Instrumental repeatability (≥75%) and similar accuracy between the best performed instruments (69%-77.5%) and the observers performance (65%-90%) supports the use of high-performance instruments for dental shade determination.

CLINICAL SIGNIFICANCE

Most instruments (Easyshade V, Primescan, Trios 3, and Trios 4) showed similar accuracy performance to observers in the VSS.

Evaluation of Autophagy Process in Differentiation of Human Induced Pluripotent Stem Cells toward Insulin Producing Cells

Background

Autophagy is an intracellular self-degradative homeostasis process which eliminates undesirable and harmful macromolecules and organelles. Autophagy is also involved in self-renewal and differentiation of induced pluripotent stem cell (iPSCs).

Objective

In this study, we investigated the expression profile of autophagy marker genes in human iPSCs during their differentiation induction toward insulin producing β-like cells.

Methods

Human iPSC line, R1-hiPSC1, was used for differentiation induction toward β-like cells. The mRNA expression of Nanog, OCT4 (pluripotency markers), SOX17, FOXA2 (endodermic markers), PTF1A, NKX6.1 (exocrine/endocrine determinants), and PDX1 were measured during differentiation stages. Autophagy was monitored by genes expression study of four autophagy markers, MAP1LC3B, BECN1, SQSTM1/P62 and ATG5, along with protein expression profile of LC3b-II during differentiation stages.

Results

The mRNA expression measurement of pluripotency, endoderm and exocrine/endocrine marker genes confirmed that hiPSCs skipped pluripotency, differentiated into endoderm, passed through the pancreatic lineage commitment stage and successfully generated insulin producing β-like cells. Expression profile of autophagy genes during differentiation stages indicated the decreased expression levels at the early stages (EB and MEI) and then increased at the definitive endoderm stages (DEI 1, DEI 2 and DE) followed by a subtractive pattern toward the end of differentiation. The results of protein expression of LC3b-II were consistent with gene expression data.

Conclusion

This study demonstrated the high contribution of key autophagy genes/proteins during the differentiation of hiPSC toward β-like cells. The enhanced autophagy levels were a prominent feature of early stages of differentiation and DE rather than the later stages.

Influence of different combinations of CAD-CAM crown and customized abutment materials on the force absorption capacity in implant supported restorations - In vitro study

OBJECTIVES

To evaluate the force absorption capacity of implant supported restorations utilizing different CAD-CAM materials for the fabrication of crowns and customized abutments.

METHODS

80 titanium inserts were scanned to design customized abutments and crowns. The specimens were divided into four groups (n = 20/material): (Z): zirconia, (P): PEEK, (V): VITA Enamic, and (E): IPS e.max. Each group was subdivided into two subgroups according to customized abutment material: (Z) zirconia, and (P) for PEEK. For the assessment of force absorption, all specimens were loaded in a universal testing machine, applied loads curves were collected from the machine's software, and resulting loads curves were collected from forcemeter below the assembly. The slopes of all curves were analyzed using Two-way multivariate analysis of variance with pairwise comparisons using Tukey Post Hoc test (p < 0.05).

RESULTS

The curve progression of the applied and resulting forces varied among the investigated materials for each specimen. For zirconia abutments, ZZ showed the highest slope values of the applied and resulting force curves, followed by EZ, VZ, and PZ demonstrating statistically significant differences (P < .001). As for PEEK abutments, ZP and EP showed the least slope values, followed by PP then VP demonstrating statistically significant differences (P < .001). For Zirconia and e.max crowns, using PEEK abutments significantly increased slope loss. As for PEEK and Vita Enamic crowns changing abutment material did not significantly affect slope loss.

SIGNIFICANCE

Combining rigid crown materials with less rigid abutments might enhance their force absorption capacity. However, with less rigid crown materials a stiff substructure might be mandatory to preserve their force absorption behavior.

Effect of Different Preparation Depths for an Inlay-Retained Fixed Partial Denture on the Accuracy of Different Intraoral Scanners: An In Vitro Study

PURPOSE

The aim was to evaluate the effect of different preparation depths for inlay-retained fixed partial dentures on the accuracy of intraoral scanners.

MATERIALS AND METHODS

Tooth preparations for two inlay-retained fixed partial dentures were done and divided according to depth of the preparation. Group A: 2mm pulpal floor depth, 3mm gingival floor depth and Group B: 3mm pulpal floor depth, 4mm gingival floor depth. The CEREC Omnicam4.4.4, Omnicam4.6.2. Trios3 and Medit i500 intraoral scanners were used in this study. Tooth preparations were scanned by each scanner 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision) using a 3D comparison software. Data were then statistically analyzed.

RESULTS

Regarding trueness, two-way ANOVA revealed significant differences between the different types of scanners (p<0.001) (Omnicam4.4.4: 65.09 ±2.87 Omnicam4.6.1: 52.73 ±3.31 Medit i500: 58.45 ±2.63 Trios 3: 41.79 ±4.42). Preparation depth had no significant influence on the trueness (p = 0.083). For precision two-way ANOVA revealed significant differences between the different types of scanners (p<0.001). Preparation depth had no significant influence on the precision (p = 0.111). Statistically significant interactions were found between the different variables.

CONCLUSIONS

The depth of preparation did not have an influence on the accuracy of different scanners. However, the type of scanner influenced the accuracy of digital impressions with Trios3 showing the highest accuracy. This article is protected by copyright. All rights reserved.

Focus on radioiodine-131 biokinetics: the influence of methylprednisolone on intratherapeutic effective half-life of 131I during radioiodine therapy of Graves' disease

AIM

Radioiodine therapy (RIT) may trigger the development of Graves' ophthalmopathy (GO) or exacerbate pre-existing subclinical GO. Therefore, glucocorticoid administration is recommended for patients with pre-existing GO. Aim of this study was to analyze the influence of glucocorticoid therapy with methylprednisolone on intratherapeutic effective half-life (EHL) of radioiodine-131 in patients with Graves' disease (GD) as recent studies showed an effect for prednisolone.

METHODS

In a retrospective study, 264 patients with GD who underwent RIT without any additional antithyroid medication were evaluated. Intrathyroidal EHL was determined pre- and intratherapeutically. Patients with co-existing GO (n = 43) received methylprednisolone according to a fixed scheme starting 1 day prior to RIT, patients without GO (n = 221) did not receive any protective glucocorticoid medication. The ratios of EHL during RIT and during radioiodine uptake test (RIUT) were compared.

RESULTS

Patients receiving methylprednisolone showed a slight decrease of the mean EHL from 5.63 d (RIUT) to 5.39 d (RIT) (p > 0.05). A comparable result was obtained in patients without glucocorticoids (5.71 d (RIUT) to 5.47 d (RIT); p > 0.05). The ratios of the EHL between RIT and RIUT failed to show a significant difference between the two groups. EHL is therefore not significantly influenced by an additional protective treatment with methylprednisolone.

CONCLUSIONS

In the present study a decreased intrathyroidal EHL under glucocorticoid medication with methylprednisolone could not be detected. Therefore, co-medication with methylprednisolone in patients with GO may be preferred to avoid an intratherapeutic decrease of EHL by accompanying protective glucocorticoides.

In vitro evaluation of material dependent force damping behavior of implant-supported restorations using different CAD-CAM materials and luting conditions

STATEMENT OF PROBLEM

Although force-damping behavior that matches natural teeth may be unobtainable, an optimal combination of crown material and luting agent might have a beneficial effect on the force absorption capacity of implant-supported restorations. However, the force-absorbing behavior of various restorative materials has not yet been satisfactorily investigated.

PURPOSE

The purpose of this in vitro study was to evaluate the material dependent force-damping behavior of implant-supported crowns fabricated from different computer-aided design and computer-aided manufacturing (CAD-CAM) materials luted to implant abutments under different conditions.

MATERIAL AND METHODS

Titanium inserts (N=84) were screwed to implant analogs, scanned to design zirconia abutments, and divided into 4 groups to receive CAD-CAM fabricated crowns in 4 materials: zirconia, polyetheretherketone (PEEK), polymer-infiltrated ceramics (VITA ENAMIC), and lithium disilicate (e.max). The crowns were subdivided as per the luting agent: none, interim cement, and adhesive resin cement. Measurements were performed by loading specimens in a universal testing machine with an increasing force and measuring the resulting force with a digital forcemeter, followed by image processing and data acquisition. Two-way multivariate analysis of variance (MANOVA) was used to assess all interactions with multiple pairwise comparisons (α=.05).

RESULTS

The curve progression of the applied and resulting forces varied significantly among the investigated materials, resulting in differently inclined slopes for each material (P<.001). With no cementation, the mean slope values of the resulting force curves ranged from 77.5 ±0.03 degrees for zirconia, followed by 71.8 ±0.03 degrees for lithium disilicate, 56.2 ±0.1 degrees for polymer-infiltrated ceramics, and 51.1 ±0.01 degrees for polyetheretherketone. With interim cementation, the mean slope values ranged from 75.4 ±0.01 degrees for zirconia, followed by 70.05 ±0.02 degrees for lithium disilicate, 56.1 ±0.02 degrees for polymer-infiltrated ceramics, and 52.2 ±0.1 degrees for polyetheretherketone. As with adhesive cementation, curve slopes ranged from 73.2 ±0.02 degrees for zirconia, followed by 70.5 ±0.2 degrees for lithium disilicate, 55.9 ±0.04 degrees for polymer-infiltrated ceramics, and 52.3 ±0.1 degrees for polyetheretherketone. Slope loss was significant after the cementation of zirconia and lithium disilicate crowns but less significant for polymer-infiltrated ceramics and polyetheretherketone.

CONCLUSIONS

Force damping is generally material dependent, yet implant-supported crowns fabricated from resilient materials such as polymer-infiltrated ceramics and PEEK show better force absorption than rigid materials such as zirconia and lithium disilicate ceramics. Furthermore, cementation of rigid materials significantly increased slope loss, indicating enhancement in their force-damping behavior, whereas less-rigid materials benefit less from cementation. Further studies are essential to investigate the effect of prosthetic materials on the stress distribution to the peri-implant bone in the crown-abutment-implant complex.

Accuracy and repeatability of different intraoral scanners on shade determination

OBJECTIVE

To evaluate the accuracy and repeatability of different intraoral scanners on shade determination.

MATERIALS AND METHODS

Ten different shades of Vita Mark II blocks were used. A disc-shape specimen (10 mm in diameter and 1 mm thick) per ceramic block was fabricated. Ten color measurements per specimen were performed by each instrument (Vita Easyshade V [control], 3shape Trios, Cerec Omnicam, Cerec Primescan) and recorded in Vita Classic color system. The number of correct shade match per instrument for each shade was recorded. Instrumental accuracy was compared using Cochran Q test and repeatability was analyzed using Cronbach's alpha.

RESULTS

There was a significant difference in the instrumental accuracy for shade determination (p < 0.001). There was no statistical difference between the Easyshade V (78%) and the 3Shape Trios (66%) (p > 0.05), with the latter being similar to the other scanners Primescan(63%) and Omnicam (57%) (p > 0.05). No significant difference was found (p > 0.05) when different shades were evaluated by the same instrument. Similar repeatability was found for the different devices, ranging from 44.3% for Easyshade to 51.9% for Omnicam.

CONCLUSION

The evaluated instruments showed less than expected repeatability and accuracy on measuring different dental shades. Therefore, caution should be exercised when using instrumental shade determination, which should be accompanied by experienced human visual assessment.

CLINICAL SIGNIFICANCE

The outcome of this study might help clinicians evaluate the performance of intraoral scanners as a shade matching tool.

Correction for hyperfunctioning radiation-induced stunning (CHRIS) in benign thyroid diseases

PURPOSE

Radioiodine-131 treatment has been a well-established therapy for benign thyroid diseases for more than 75 years. However, the physiological reasons of the so-called stunning phenomenon, defined as a reduced radioiodine uptake after previous diagnostic radioiodine administration, are still discussed controversially. In a recent study, a significant dependence of thyroid stunning on the pre-therapeutically administered radiation dose could be demonstrated in patients with goiter and multifocal autonomous nodules. A release of thyroid hormones to the blood due to radiation-induced destruction of thyroid follicles leading to a temporarily reduced cell metabolism was postulated as possible reason for this indication-specific stunning effect. Therefore, the aim of this study was to develop dose-dependent correction factors to account for stunning and thereby improve precision of radioiodine treatment in these indications.

METHODS

A retrospective analysis of 313 patients (135 with goiter and 178 with multifocal autonomous nodules), who underwent radioiodine uptake testing and radioiodine treatment, was performed. The previously determined indication-specific values for stunning of 8.2% per Gray in patients with multifocal autonomous nodules and 21% per Gray in patients with goiter were used to modify the Marinelli equation by the calculation of correction factors for hyperfunctioning radiation-induced stunning (CHRIS). Subsequently, the calculation of the required activity of radioiodine-131 to obtain an intra-therapeutic target dose of 150 Gy was re-evaluated in all patients. Furthermore, a calculation of the hypothetically received target dose by using the CHRIS-calculated values was performed and compared with the received target doses.

RESULTS

After integrating the previously obtained results for stunning, CHRIS-modified Marinelli equations could be developed for goiter and multifocal autonomous nodules. For patients with goiter, the mean value of administered doses calculated with CHRIS was 149 Gy and did not differ from the calculation with the conventional Marinelli equation of 152 Gy with statistical significance (p = 0.60). However, the statistical comparison revealed a highly significant improvement (p < 0.000001) of the fluctuation range of the results received with CHRIS. Similar results were obtained in the subgroup of patients with multifocal autonomous nodules. The mean value of the administered dose calculated with the conventional Marinelli equation was 131 Gy and therefore significantly below the CHRIS-calculated radiation dose of 150 Gy (p < 0.05). Again, the fluctuation range of the CHRIS-calculated radiation dose in the target volume was significantly improved compared with the conventional Marinelli equation (p < 0.000001).

CONCLUSIONS

With the presented CHRIS equation it is possible to calculate a required individual stunning-independent radioiodine activity for the first time by only using data from the radioiodine uptake testing. The results of this study deepen our understanding of thyroid stunning in benign thyroid diseases and improve precision of dosimetry in radioiodine-131 therapy of goiter and multifocal autonomous nodules.

Effect of photo-polymerization mode on the degree of conversion of resin cement under different ceramic materials

BACKGROUND

This study evaluated the effect of different polymerization modes and duration on the degree of conversion (DC) of resin cement under different types of ceramics.

METHODS

Ceramic materials were divided into 3 groups (N.=60): group 1, Cerasmart; group 2, Vita Enamic; and group 3, Vita Mark II. Each group was then divided into three subgroups (N.=20) according to the polymerization mode (A: low-intensity; B: high-intensity; and C: soft-start). Subgroups were then divided into two further groups according to the polymerization time (I: 10 s; and II: 20 s). DC of light-cured resin cement beneath different kinds of ceramics was tested using FTIR spectroscopy. Results were compared to a control group cured without overlying ceramic.

RESULTS

While the type of ceramic and mode of polymerization showed a significant effect on the DC of resin cement, polymerization duration did not. Vita Mark II group showed the highest DC of resin cement followed by Vita Enamic and Cerasmart. High- and low-intensity polymerization modes did not show significant difference, but both showed significantly lower DC when compared to soft start mode.

CONCLUSIONS

Type of ceramic and polymerization mode showed a direct effect on the DC of resin cement.

Influence of Preparation Type and Tooth Geometry on the Accuracy of Different Intraoral Scanners

PURPOSE

To evaluate the influence of preparation design and tooth geometry on the accuracy of scans obtained from three different intraoral scanners (IOS).

MATERIALS AND METHODS

Full coverage crown and inlay preparations with known axial wall tapers (6ᵒ and 12ᵒ) were performed on typodont teeth using a computer numerical control machine. Reference models were scanned with a highly accurate reference scanner (Ineos X5) and saved in standard tessellation language (STL) format then each IOS (Omnicam, Trios, and i500) scanned each model 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision). Data were statistically analyzed using three- way ANOVA and one- way ANOVA.

RESULTS

When comparing trueness values extracoronal preparations (32.30 ± 11.23 µm) was significantly better than intra-coronal preparation (59.61 ± 16.42 µm). As for opposing wall taper, one-way ANOVA revealed that the more the convergence or divergence between opposing walls the better is the trueness. Significant differences were observed between the scanners. 3 Shape Trios (35.70 ± 14.12 µm) and medit i500 (44.31 ± 11.41 µm) showed no statistically significant differences. However, both showed significantly better precision results when compared to Omnicam (57.83 ± 22.14 µm).

CONCLUSION

Extracoronal preparations show better trueness and precision in comparison to intracoronal preparations. Trios and i500 have better trueness and precision than Omnicam. Increasing the taper of the axial wall has a direct effect on trueness of scans obtained from the IOS.

Abstract P5-03-05: Model of acquired resistance to the tyrphostin NT157 in hormone receptor-positive breast cancer

As previously reported, the small-molecule tyrphostin NT157 binds to the type I insulin-like growth factor-1 receptor (IGF-1R) beta subunit (IGF-IRβ) resulting in degradation of the insulin receptor substrate (IRS) adaptor proteins and inhibits growth of tamoxifen sensitive and resistant ER+ breast cancer cells (Yang, Y. et al. Horm Canc, in press). To investigate effects related to long-term NT157 exposure on IGF signaling, we incubated T47D parental cells in increasing concentrations of NT157 for 20 months. This prolonged exposure resulted in resistant cells (T47D-NTR). Monolayer growth assays showed parental cells inhibited at 0.7 μM of NT157 whereas resistant cells were suppressed by 8 μM of NT157. In parental cells, NT157 caused G0-G1 arrest and an increase in the sub-G1 fraction. However, resistant cells did not show these cell cycle changes after exposure to NT157. Furthermore, the antiproliferative effect of prolonged exposure to 96 hours of NT157 was correlated with decreased activation of Akt/S6k signaling axis and reduction of cyclin D1 expression in T47D parental cells. 48 hours treatment with 5 μM of NT157 resulted in a decrease of IGF-IR and insulin receptor (InR) expression level at 33% and 39% respectively, along with the downregulation of the adaptor proteins IRS-1/2 in only the parental cell line. In resistant cells, the NT157 treatment induced minimal IGF-1R suppression and a 21% increase of IR expression. Additionally, the T47D-NTR cells-maintained IRS protein levels at 10 μM. This absence of IRS protein degradation observed in NT157-resistant cells correlated with the continued expression of estrogen receptor-alpha (ERα), suggesting functional changes within IGF and ERα complex. IGF ligands (IGF-1 or IGF-2) and estradiol (E2) stimulated growth in both cell lines. When NT157 was removed from T47D-NTR cells, they were not re-sensitized to NT157 nor were they affected by IGF dependent growth in the re-introduction of NT157. These findings suggest that resistance to NT157 is mediated by the maintained expression of the IRS adaptor proteins. The continued responsiveness to estradiol and IGF ligands could be due to either a decrease in the drug's half-life or possible changes in NT157 binding to the beta subunit of IGF-IR in resistant cells.

Citation Format: Ekyalongo RC, Abdelwahab R, Holtz A, Sabet A, Yee D. Model of acquired resistance to the tyrphostin NT157 in hormone receptor-positive breast cancer [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P5-03-05.

Assessment of marginal adaptation and fracture resistance of endocrown restorations utilizing different machinable blocks subjected to thermomechanical aging

OBJECTIVE

This in vitro study was conducted to assess the marginal adaptation and fracture resistance of computer aided design/computer aided manufacturer (CAD-CAM) fabricated endocrowns restoring endodontically treated molars using different machinable blocks with thermomechanical loading protocols.

MATERIALS AND METHODS

Devitalized mandibular molars were prepared in a standardized way and divided into 4 groups (n = 10) to receive CAD/CAM fabricated endocrowns using four materials (Lithium disilicate ceramics, polymer infiltrated ceramics, zirconia-reinforced lithium silicate ceramics and resin nanoceramics. Marginal gaps (µm) were measured using stereomicroscope before cementation and after cementation. After thermomechanical aging, marginal gap measurements were repeated, and then fracture resistance test was performed. Two-way analysis of variance (ANOVA) and Tukey HSD multiple comparisons were used to assess the effect of material on the marginal gap before, after cementation, and after thermomechanical aging. One Way ANOVA was used to assess the effect of material on the fracture resistance.

RESULTS

The difference between marginal gaps values of the tested materials was statistically insignificant but with significant increase after cementation and after thermomechanical aging. Cerasmart endocrowns showed the highest mean fracture load value (1508.5 ± 421.7N) with statistically significant difference than Vita Enamic endocrowns and Celtra Duo.

CONCLUSION

The tested materials showed marginal vertical gap readings within the limits of clinically acceptable standards. Resin nanoceramics and lithium disilicate showed the highest values of fracture resistance followed by polymer infiltrated ceramics favoring their use for endocrown restorations.

CLINICAL SIGNIFICANCE

The mechanical behavior of ceramic materials varies with the variation of their structure and mechanical properties. Accordingly, further investigation is always needed to explore the biomechanical behavior of recent materials when used as endocrowns before clinical trials.

Early prediction of tumour response to PRRT

[177Lu-DOTA0, Tyr3]-octreotate (177Lu-octreotate) in peptide receptor radionuclide therapy (PRRT) offers direct intra-therapeutic dosimetry. The aim of this study was to compare tumour and non-tumour parameters and assess intra-individual variations. Patients, methods: Retrospective analysis of 53 consecutive PRRT treatment cycles (mean activity of 7.53 ± 0.46 GBq 177Lu-octreotate, intended four cycles at intervals of 10–14 weeks, standard nephroprotection) in 27 GEP NET patients. Extended planar dosimetry with serial wholebody imaging on selected, non-superimposed tumour and non-tumour regions; liver (LM), bone (BM), and other (OM) metastases. The per-cycle variation was compared with posttreatment response (CT/MRI three months post-treatment, modified SWOG criteria). Results: Residence time in tumor lesions (133–147 h) exceeded that in kidneys (93 h). Tumour-to-kidney absorbed dose ratios ranged from 14 to 28 (LM, BM, OM). Intra-individual per-cycle dose variation was insignificant for kidneys, but significant for metastases (LM, BM, and OM; p < 0.05). The mean per-cycle decrease of tumour absorbed dose (_D/A0[%]) was linked to morphologic response after PRRT. A mean decrease of >20% was predictive of a partial or minor remission in all 11 evaluable patients, while absent significant dose reduction indicated stable or progressive disease in 4/5 patients. The dose decrease was unrelated to volume effects and also observed for BM. Conclusion: Besides confirmation of a favourable tumour-to-kidney parameter relation for 177Lu-octreotate, stepwise intra-lesional comparison seems to imply a prognostic impact of tumor dosimetry: The early per-cycle change _D/A0 between treatment cycles may predict the outcome after PRRT. Larger studies are needed to confirm this finding.

Osseous metastases of gastro- entero - pancreatic neuroendocrine tumours

Aim: Peptide receptor radionuclide therapy with 177Lu-octreotate is an effective treatment option for metastatic gastroenteropancreatic neuroendocrine tumors (GEP NET) and allows intratherapeutic imaging through a 177Lu-octreotate scan (LuS). The diagnostic value of this treatment scan is not yet established. This study aims to compare the sensitivity of LuS and bone scintigraphy (BS) regarding bone metastases and investigate potential implications of functional imaging results. Patients, methods: We retrospectively analyzed 29 consecutive GEP NET patients with bone metastases and baseline BS treated with 177Lu-octreotate. A semi-quantitative scoring system was used for the comparative evaluation. Treatment outcome (time-to-progression of bone metastases) was correlated with the intra-individual imaging discrepancy (Kaplan- Meyer curves, log-rank test, p < 0.05). Results: In 19 of 29 patients (65.5%) LuS was superior (LuS > BS), whereas in 10 patients (34.5%) both modalities were comparable. BS showed no additional (LuS-negative) metastatic bone lesions in our cohort. None of the investigated baseline characteristics was associated with Imaging discrepancy. On the other hand, functional imaging discrepancy had no impact on treatment response (p = 0.43) or time-to-progression (p = 0.92). Conclusions: Intra-therapeutic 177Lu-octreotate imaging is superior over bone scintigraphy for detection of bone metastases in GEP NET. BS may help to distinguish osseous from non-osseous localization. The presence of an osteoblastic correlate in BS seems to have no impact on therapeutic outcome

A survey of the incidence of dyslipidemia and its components in people over 20 years old in Ahvaz: A cohort study 2009-2014

INTRODUCTION

Dyslipidemia is one of the major risk factors for atherosclerosis and the main cause of death in the developing and developed countries. In this cohort study, the incidence of dyslipidemia and its components have been studied among individuals over 20 years old in Ahvaz, southwest of Iran.

MATERIALS AND METHODS

The Phase 1 of this study was conducted on the prevalence of Metabolic syndrome and its related factors by Diabetes Research Center in 2009. The target population included individuals over 20 years old who were selected using cluster sampling in Ahvaz health centers. In the second phase of the study, 5 years later in 2014, subjects were again recalled by health centers. Questionnaires, anthropometric indices and measurements were repeated similar to Phase 1. The blood sample was taken from everyone after 12h of fasting and then the factors (Chol, TG, HDL) were measured.

RESULTS

The cumulative incidence of dyslipidemia obtained 60.7% (males 56.7% and females 64.8%). lipid profile {HDL, Triglycerides and Cholesterol had changes in their means(a significant reduction in the mean about 10, 22.25 and 13 units respectively) between baseline and 5 years later. Waist circumference here associated with incidence of high LDL and high chol, also sex and High LDL 'educational level and daily consumption of vegetables were associated with incidence of low HDL and dyslipidemia respectively.

CONCLUSION

Age, educational level and daily intake of fruits and vegetables were effective variables on incidence of dyslipidemia. According to various studies, LDL and HDL levels in different regions of Iran, seems to be influenced by factors such as climate, nutrition and activity levels.

A Comparative Workflow for Different Hydraulic Fracturing Techniques in the Western Desert Oil Fields of Egypt

"When everything else fails, frac it" was the sentiment expressed by most engineers who were working on hydraulic fracturing during the late 1970s. This statement indicates how important the hydraulic fracturing technique is, not only in stimulating, and thus greatly increasing, the well's production, but also as a powerful tool to manage the field development. Hydraulic fracturing has become the most applicable and reliable reservoir stimulation technique in all reservoir rock types, even more than the matrix acidizing techniques. Starting from 1940s, when the first hydraulic fracture was performed, until now, the improvement in the hydraulic fracturing technology has never stopped. Currently, the state-of-the-art technology in hydraulic fracturing is the channel fracturing technology or, in other words, open channel fracturing. This is a unique technique of pumping a treatment that helps in forming channels within the proppant pack in the fracture, which improves the fracture conductivity and well productivity.

This study consists of two main parts. The first part is dedicated to the evaluation of the channel fracturing technique by comparing it to conventional fracturing. This comparison depends on three primary evaluation methods. First, well testing data obtained for conventionally fractured wells and wells in which the new technology was implemented were evaluated. Second, the actual production data for offset wells, which were fractured either by conventional technique or by the new channel fracturing one, were analyzed. Finally, an economic comparison of the techniques and an assessment of the gain that can be obtained from the new channel fracturing technique over the conventional one were performed.

After the evaluation and comparison, a statistical analysis was conducted based on a sample consisting of more than 50 wells that were fractured using the channel fracturing technique. This statistical analysis aims to attain the channel fracturing treatment parameters that lead to the best corresponding production results.

These two main parts represents a full evaluation and optimization process that gives a complete picture of the channel fracturing technique and an assessment of the new technique. The assessment considers how to achieve best performance based on a sound statistical analysis constructed by actual day-to-day data and well performance. The assessment proves the economic and production value of the new technique over the conventional fracturing technique, which failed to give the same values.

Introduction of a metabolic joint asymmetry score derived from conventional bone scintigraphy. A new tool to differentiate psoriatic from rheumatoid arthritis

AIM

Clinical differentiation of psoriatic arthritis (PsA) and rheumatoid arthritis (rA) based on the pattern of joint involvement can be difficult; the frequent form of PsA with polyarthritis of the peripheral joints may sometime resemble rA. We investigated a metabolic joint asymmetry score (MJAS), reflecting the overall asymmetric joint involvement on conventional bone scintigraphy, for differentiating PsA from rA in patients presenting with peripheral polyarthritis.

PATIENTS, METHODS

106 patients (n = 61, PsA; n = 45, rA) with peripheral polyarthritis (≥ 5 joints) as well as 26 control subjects with no history of chronic joint disorders were analyzed. The intensity of articular 99mTc-MDP uptake in 40 peripheral joint pairs was scored regarding the bilateral difference of each joint based on a scale of 0-2 (no significant, moderate, and marked asymmetry, respectively). The patient's MJAS was defined as the sum of uptake difference scores of all joint pairs. The association of MJAS with the underlying condition (Psoriasis criteria, Revised Criteria of the ACR) was examined.

RESULTS

5280 peripheral joint pairs were investigated. There was no significant difference in the total number of involved joints in PsA 15.0 ± 8.2 versus rA 17.5 ± 8.8 patients (p = 0.132), but significantly less involvement in the control group (6.7 ± 5.0, p < 0.001). MJAS was markedly higher in PsA (17.0 ± 9.6) than in rA (4.8 ± 3.9, p < 0.001), and correlated with the total number of involved joints in PsA (r = 0.516, p < 0.001), but not in rA (r = 0.078, p = 0.380). The MJAS disparity between PsA and rA persisted after exclusion of the DIP joints (14.4 ± 7.7 vs. 4.4 ± 3.3; p<0.001).

CONCLUSIONS

The new reproducible semi-quantification method for the asymmetry of metabolic joint involvement permits differentiation of psoriatic from rheumatoid peripheral arthritis with MJAS being markedly higher in patients with PsA as compared to rA patients. The score may offer an effective complementary tool for characterizing patients with peripheral polyarthritis.

Can peptide receptor radionuclide therapy be safely applied in florid bone metastases? A pilot analysis of late stage osseous involvement

AIM

Highly advanced metastatic bone disease with extensive osseous infiltration of neuroendocrine tumours (NET) may preclude patients from treatment with peptide receptor radionuclide therapy (PRRT) in concern about haematotoxicity. This study aims to assess the safety and efficacy of PRRT with 177Lu-octreotate in a patient cohort with this condition.

PATIENTS, METHODS

41 PRRT courses were performed in 11 patients with gastroenteropancreatic neuroendocrine tumours (GEP-NET) and florid bone metastases (severely advanced widespread metastatic bone disease). A mean activity of 6.95 GBq 177Lu-octreotate was administered per treatment cycle, aimed at four courses with standard intervals of 3 months. Haematological parameters were determined prior to each treatment course, in 2-4 weeks intervals between the courses, 8-12 weeks after the last course of PRRT and in 3 monthly intervals thereafter. Toxicity was recorded using Common Terminology Criteria for Adverse Events v3.0. Restaging was performed 3 months after termination of PRRT with CT/MRI and functional imaging (modified MDA criteria).

RESULTS

Significant (grade III-IV), reversible haematotoxicity occurred in 4 (35%) patients and after 10 (24%) administrations. It either resolved spontaneously (1 patient) or was controlled by supportive measures (3 patients), such as blood transfusions (3 patients) or deferral of the subsequent therapy cycle (1 patient). Patients returned to baseline blood values within up to 23 months after termination of PRRT. The observed treatment response of bone metastases consisted of a partial response in 2, a minor response in 1, stable disease in 7, and progressive disease in 1 patient. Of the 4 patients with metastatic bone pain, 1 experienced complete and 3 partial resolution of symptoms within 3-10 weeks after commencement of PRRT.

CONCLUSION

These preliminary data indicate that PRRT with 177Lu-octreotate can be safely applied even in florid bone metastases with extensive, severely advanced osseous replacement. The higher myelosuppression rate was not associated with serious complications and should not preclude patients from being treated and potentially experiencing remarkable treatment efficacy despite the very advanced stage.

Survival in patients with hepatocellular carcinoma treated with 90Y-microsphere radioembolization. Prediction by 18F-FDG PET

AIM

This retrospective study aims to evaluate the predictive value of FDG PET/CT in patients with unresectable hepatocellular carcinoma (HCC) undergoing radioembolization with yttrium-90 labeled microspheres (RE).

PATIENTS, METHODS

The study cohort comprised 33 patients who were treated with RE at our institution and underwent FDG PET/CT at baseline and four weeks after radioembolization. According to the baseline FDG metabolic status of the HCC lesions, patients were divided into two groups: FDG-negative (n = 12) and FDG-positive (n = 21) HCC. FDG-positive patients were further divided into early metabolic responders and non-responders according to the relative change in SUVmax of the treated lesions. Survival analyses were performed with the Kaplan-Meier method (log-rank test, p < 0.05). Multivariate analysis was performed to assess the influence of prognostic factors on overall survival (OS).

RESULTS

FDG-negative patients had a significantly longer OS (13 months, 95%CI 7-19) than FDG-positive patients (9 months, 95%CI 7-11; p = 0.010). Among FDG-positive patients, metabolic responders survived significantly longer than metabolic non-responders (10 months, 95%CI 8-12 vs. 5 months, 95%CI 4-6; p = 0.003). From the other baseline factors (including performance status, hepatic tumour burden, presence of extra-hepatic disease, administered activity) only the BCLC stage had a significant impact on OS (p = 0.028).

CONCLUSION

Pre- and post-therapeutic FDG PET independently predicts overall survival in patients with HCC undergoing radioembolization. Interestingly, early metabolic response seems to be assessable as early as four weeks post-treatment.

Residual activity after radioembolization of liver tumours with 90Y resin microspheres

The actual number of resin microspheres is approximately 30-60 times higher than glass microspheres per 3 GBq vial. Thus, radioembolization (RE) with resin microspheres exerts an embolization effect besides the radiation effect. This embolization effect can occasionally cause early back flow of the microspheres before application of the entire calculated dose. To avoid these adverse side effects, RE has to be terminated at an earlier time point. Measurement of the residual activity in the delivery box, which includes the v-vial, tube and catheter, to calculate the achieved target dose is often challenging. The aim of the current study was to establish a post-RE measurement method comparable to the glass microspheres method without unnecessary radiation exposure to the staff and risk of contamination. Methods: Two different measurements were performed. First, total radioactivity in the shipping vial was measured in an ion chamber and then it was put in the delivery box and the radiation was measured from a 30 cm distance from the centre of the box with a dosimeter. The required radioactivity was then transferred to the v-vial, and the shipping vial was measured again. After that, the v-vial was measured from the same distance from the centre of the box with dosimeter. Results: Altogether 62 times the shipping vial with different activities were measured with a significant positive correlation between the amount of the activity measured in the iron chamber and the radiation dose, measured with dosimeter (r2 = 0.98; p < 0.001). There was also a strong positive correlation between these measurements of the v-vial (r2 = 0.98; p < 0.001). Conclusion: With measurement of the residual activity in the delivery box using a dosimeter the percentage of the whole injected activity can be easily calculated. This facilitates the calculation of the actual, achieved target and non-target dose in those cases, where therapy had to be stopped because of eminent flow reversal or obstruction.

Magnetic Resonance Measurement of Transient Shear Wave Propagation in a Viscoelastic Gel Cylinder

A magnetic resonance measurement technique was developed to characterize the transient mechanical response of a gel cylinder subjected to angular acceleration. The technique employs tagged magnetic resonance imaging (MRI) synchronized to periodic impact excitation of a bulk specimen. The tagged MRI sequence provides, non-invasively, an array of distributed displacement and strain measurements with high spatial (here, 5 mm) and temporal (6 ms) resolution. The technique was validated on a cylindrical gelatin sample. Measured dynamic strain fields were compared to strain fields predicted using (1) a closed-form solution and (2) finite element simulation of shear waves in a three-parameter "standard" linear viscoelastic cylinder subjected to similar initial and boundary conditions. Material parameters used in the analyses were estimated from measurements made on the gelatin in a standard rheometer. The experimental results support the utility of tagged MRI for dynamic, non-invasive assays such as measurement of shear waves in brain tissue during angular acceleration of the skull. When applied in the inverse sense, the technique has potential for characterization of the mechanical behavior of gel biomaterials.

Skin biopsies demonstrate MPZ splicing abnormalities in Charcot-Marie-Tooth neuropathy 1B

OBJECTIVE

To demonstrate that intronic mutations in the myelin protein zero (MPZ) cause Charcot-Marie-Tooth neuropathy 1B (CMT1B) by disrupting MPZ splicing.

METHODS

We report a family with a T>G transversion at the invariant + 2 position in intron 4 of MPZ (c.614 + 2T>G) that abolishes 5' donor site recognition and is predicted to alter MPZ splicing. We obtained detailed clinical and neurophysiologic analysis of the family. We performed skin biopsies to investigate splicing abnormalities, MPZ protein levels, and localization in myelinated nerves.

RESULTS

Patients developed a late onset neuropathy with minimally slow nerve conduction velocities. Skin biopsies confirmed the predicted skipping of exon 4 and downstream frameshift of the mutant MPZ. Quantitative immuno-EM demonstrated normal nerve MPZ levels, suggesting that the mutant MPZ was transported to compact myelin.

CONCLUSIONS

Intronic mutations cause CMT1B by disrupting splicing and certain MPZ mutations may cause neuropathy by interacting with the wild type MPZ in the extracellular space of compact myelin.

Enhancing proper sitting position using a new sEMG protocol, the "minimax" procedure, with Boolean logic

The modification of posture in children using sEMG is a new area that offers much potential to aid disabled children regain function. This article describes a new protocol, the "minimax" procedure, to aid children regain motor function in sitting. The protocol uses selective reinforcement to encourage recruiting/relaxing target sites (gluteus medius/maximus) in a predetermined way so as to encourage good form in sitting. Children often are unaware how to make changes in posture, and when they do succeed the progress is so slow that sustaining motivation is a challenge. This paper describes a procedure that helps the child recognize when they have achieved the correct posture, immediately rewards them for doing so, and generates data using Boolean operations to numerically substantiate the clinically observed changes in posture.

Changes in adenylyl cyclase isoforms as a mechanism for thyroid hormone modulation of cardiac beta-adrenergic receptor responsiveness

Although thyroid hormones are known to modulate cardiac beta-adrenergic receptor expression, the physiologic implications of these changes in the cardiac manifestations of altered thyroid hormone metabolism have been disputed. This study examined whether thyroid hormone modulates signaling via the cyclic adenosine monophosphate (cAMP) pathway by regulating cardiac adenylyl cyclase (AC) isoform expression. Northern blot analyses and AC enzyme assays were performed on preparations from hypothyroid, euthyroid, and hyperthyroid rat ventricles. Steady-state levels of cardiac AC mRNA types V and VI in hypothyroid ventricles were 173% +/- 8% and 149% +/- 12%, respectively, of the values in euthyroid ventricles (P < .01). This increase in AC mRNA isoforms was accompanied by a 1.5-fold increase (P < .05) in the activation of catalytic AC by forskolin and Mn. In contrast, the relative abundance of transcripts for types V and VI AC was similar in hyperthyroid and euthyroid ventricles, but catalytic AC activation by forskolin and Mn was significantly reduced by 35% in membranes obtained from hyperthyroid ventricles. AC activation through beta-adrenergic receptor stimulation by isoproterenol was not altered by thyroid hormone status. Thus, the effect of thyroid hormone to repress AC catalytic activity would be anticipated to offset the increase in beta-adrenergic receptor expression in hyperthyroidism. These studies identify cardiac AC enzymes as important targets for thyroid hormone-dependent regulation of signaling via the cAMP pathway, and support the finding that cardiac adrenergic responsiveness is unaltered in thyroid disease states.

Regulation of rat cardiac Kv1.5 gene expression by thyroid hormone is rapid and chamber specific

Thyroid hormone affects the contractile and electrophysiological properties of the cardiac myocyte that result in part from changes in the expression of thyroid hormone-responsive cardiac genes, including those that regulate membrane ion currents. To determine the molecular mechanisms underlying this effect, expression of a voltage-gated K+ channel, Kv1.5, was measured in response to thyroid hormone. Using quantitative RT-PCR methodology, the content of Kv1.5 messenger RNA (mRNA) in left ventricles of euthyroid rats was 4.25+/-0.6x10(-20) mol/microg total RNA and was decreased by 70% in the hypothyroid rat ventricle to 1.27+/-0.80x10(-20) mol/microg RNA (P<0.01). Administration of T3 to hypothyroid animals restored ventricular Kv1.5 mRNA to control levels within 1 h of treatment, making this the most rapid T3-responsive cardiac gene reported to date. The half-life of Kv1.5 mRNA was 1.9 h and 2.0 h in euthyroid and hypothyroid ventricles, respectively, and T3 treatment of the rats did not alter its half-life. In atrial myocardium, expression of Kv1.5 mRNA (6.10+/-0.37x10(-20) mol/microg RNA) was unaltered by thyroid hormone status. The myocyte-specific and chamber-selective expression of Kv1.5 mRNA was confirmed in primary cultures of rat atrial and ventricular myocytes.

Neurometabolite markers of cerebral injury in the antiphospholipid antibody syndrome of systemic lupus erythematosus

BACKGROUND AND PURPOSE

To determine the neurometabolic patterns of brain injury in systemic lupus erythematosus with antiphospholipid antibody syndrome (SLE-aPLS).

METHODS

Forty-nine SLE patients (12 SLE-aPLS) and 23 control subjects were studied using magnetic resonance imaging and spectroscopy. N-Acetylaspartate/creatine (NAA/Cre) and choline/Cre (Cho/Cre) were measured in normal-appearing tissue. IgG and IgM antiphospholipid antibodies (aPL) were measured by enzyme-linked immunosorbent assay.

RESULTS

Stroke, epilepsy, and elevated IgG-aPL were more common in SLE-aPLS patients than in SLE patients (P<0.001). NAA/Cre was lower (P<0.05) and Cho/Cre higher (P<0.001) in SLE-aPLS patients than in SLE patients without aPLS. Regression models showed NAA/Cre was most related to injury seen by imaging (P<0.01), disease duration (P<0. 05), and prior neuropsychiatric SLE (NPSLE) (P=0.07). Reduced NAA/Cre was more closely related to IgG-aPL (P<0.01) than the presence of stroke or aPLS. When adjusted for all factors, Cho/Cre was most associated with the presence of aPLS (P=0.05).

CONCLUSIONS

SLE and SLE-aPLS are actually a clinical continuum describing brain injury in SLE, with SLE-aPLS being characterized by increased aPL, NPSLE, stroke, epilepsy, and disturbed neurochemistry. An elevated IgG-aPL level is a potent risk factor for brain injury as measured by NAA/Cre in SLE that is independent of stroke and aPLS. However, thrombotic phenomena and the presence of aPL (aPLS) are most closely associated with increased Cho/Cre in SLE. These results suggest that aPLs exacerbate SLE, resulting in increased thrombotic and nonthrombotic brain injuries. Spectroscopy detects brain injury in SLE and may permit better understanding of the neurological consequences of SLE and SLE-aPLS.

Neurochemistry of brain lesions determined by spectroscopic imaging in systemic lupus erythematosus

OBJECTIVE

The significance and etiology of focal brain lesions in systemic lupus erythematosus (SLE) are unknown. Our purpose was to determine whether the neurochemistry of focal lesions and normal appearing brain tissues in SLE were consistent with neuronal loss, demyelination, or ischemia.

METHODS

Patients with SLE (n = 14) and controls (n = 13) were studied using magnetic resonance imaging (MRI) and spectroscopic imaging (SI) at 1.5 Tesla.

RESULTS

MRI detected fixed focal brain lesions (n = 16) and SI measured brain metabolites, including N-acetylaspartate (NAA), creatine (Cre), choline (Cho), and lactate (Lac). NAA/Cre of normal appearing brain was decreased in patients with SLE compared to controls: grey matter (1.74 +/- 0.16 vs 1.92 +/- 0.18; p = 0.01), occipital white matter (1.98 +/- 0.22 vs 2.23 +/- 0.16; p = 0.004), and periventricular white matter (2.00 +/- 0.23 vs 2.33 +/- 0.23; p = 0.001). Lesions were characterized by markedly decreased NAA/Cre relative to normal appearing tissues in the same patient (1.67 +/- 0.22 vs 1.88 +/- 0.14; p = 0.0002). Elevated Cho/Cre was observed in 25% of focal lesions and 21% of normal appearing tissues. No elevation of lactate was observed in lesions or normal appearing tissues.

CONCLUSION

SI detects focal and generalized brain abnormalities in SLE characterized by decreased NAA, elevated choline, and normal lactate. These findings are consistent with widespread neuronal injury and demyelination, but are not consistent with anaerobic metabolism.