Radiomics models based on multisequence MRI for predicting PD-1/PD-L1 expression in hepatocellular carcinoma

The purpose of this study was to explore the effectiveness of radiomics based on multisequence MRI in predicting the expression of PD-1/PD-L1 in hepatocellular carcinoma (HCC). One hundred and eight patients with HCC who underwent contrast-enhanced MRI 2 weeks before surgical resection were enrolled in this retrospective study. Corresponding paraffin sections were collected for immunohistochemistry to detect the expression of PD-1 and PD-L1. All patients were randomly divided into a training cohort and a validation cohort at a ratio of 7:3. Univariate and multivariate analyses were used to select potential clinical characteristics related to PD-1 and PD-L1 expression. Radiomics features were extracted from the axial fat-suppression T2-weighted imaging (FS-T2WI) images and the arterial phase and portal venous phase images from the axial dynamic contrast-enhanced MRI, and the corresponding feature sets were generated. The least absolute shrinkage and selection operator (LASSO) was used to select the optimal radiomics features for analysis. Logistic regression analysis was performed to construct single-sequence and multisequence radiomics and radiomic-clinical models. The predictive performance was judged by the area under the receiver operating characteristic curve (AUC) in the training and validation cohorts. In the whole cohort, PD-1 expression was positive in 43 patients, and PD-L1 expression was positive in 34 patients. The presence of satellite nodules served as an independent predictor of PD-L1 expression. The AUC values of the FS-T2WI, arterial phase, portal venous phase and multisequence models in predicting the expression of PD-1 were 0.696, 0.843, 0.863, and 0.946 in the training group and 0.669, 0.792, 0.800 and 0.815 in the validation group, respectively. The AUC values of the FS-T2WI, arterial phase, portal venous phase, multisequence and radiomic-clinical models in predicting PD-L1 expression were 0.731, 0.800, 0.800, 0.831 and 0.898 in the training group and 0.621, 0.743, 0.771, 0.810 and 0.779 in the validation group, respectively. The combined models showed better predictive performance. The results of this study suggest that a radiomics model based on multisequence MRI has the potential to predict the preoperative expression of PD-1 and PD-L1 in HCC, which could become an imaging biomarker for immune checkpoint inhibitor (ICI)-based treatment.

A correlative study between IVIM-DWI parameters and VEGF and MMPs expression in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the fourth most common cause of cancer-related death worldwide. Angiogenic factors may be valuable indices of tumor recurrence and treatment and potentially useful markers for predicting the response to antiangiogenesis therapy. Vascular endothelial growth factor (VEGF) and matrix metalloproteinases (MMPs) are major drivers of tumor angiogenesis. Preoperatively predicting the expression of VEGF and MMPs is crucial for treating HCC. Intravoxel incoherent motion (IVIM) diffusion-weighted imaging (DWI) has been successfully used in the differential diagnosis of HCC, pathological grading, and treatment response evaluation. However, the correlations between IVIM-DWI parameters and VEGF and MMP expression have not been reported. This study provides a preliminary analysis of the correlation between IVIM-DWI parameters and the expression of VEGF, MMP-2, and MMP-9 to investigate the value of IVIM-DWI in the noninvasive evaluation of angiogenesis in HCC.

Methods

IVIM-DWI was performed in 61 patients with HCC 1 week before they underwent surgical resection. VEGF, MMP-2, and MMP-9 expression was detected using immunohistochemistry staining. Spearman correlation analysis was used to analyze the correlations between the IVIM-DWI parameters and VEGF, MMP-2, and MMP-9 expression in HCC.

Results

The fast apparent diffusion coefficient fraction (f) value was positively correlated with the expression of VEGF (P<0.001), MMP-2 (P=0.002), and MMP-9 (P<0.001). The fast apparent diffusion coefficient (D*) was positively correlated with VEGF (P<0.001) and MMP-9 (P<0.001) expression but was not correlated with MMP-2 (P=0.659) expression. The apparent diffusion coefficient (ADC) and slow apparent diffusion coefficient (D) values were not significantly correlated with the expression of VEGF (P=0.103 and P=0.543, respectively), MMP-2 (P=0.596 and P=0.338, respectively), or MMP-9 (P=0.102 and P=0.660, respectively).

Conclusions

IVIM-DWI can be used to noninvasively evaluate angiogenesis in HCC.

Radiomic Analysis Based on Magnetic Resonance Imaging for Predicting PD-L2 Expression in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is the sixth most common malignant tumour and the third leading cause of cancer death in the world. The emerging field of radiomics involves extracting many clinical image features that cannot be recognized by the human eye to provide information for precise treatment decision making. Radiomics has shown its importance in HCC identification, histological grading, microvascular invasion (MVI) status, treatment response, and prognosis, but there is no report on the preoperative prediction of programmed death ligand-2 (PD-L2) expression in HCC. The purpose of this study was to investigate the value of MRI radiomic features for the non-invasive prediction of immunotherapy target PD-L2 expression in hepatocellular carcinoma (HCC). A total of 108 patients with HCC confirmed by pathology were retrospectively analysed. Immunohistochemical analysis was used to evaluate the expression level of PD-L2. 3D-Slicer software was used to manually delineate volumes of interest (VOIs) and extract radiomic features on preoperative T2-weighted, arterial-phase, and portal venous-phase MR images. Least absolute shrinkage and selection operator (LASSO) was performed to find the best radiomic features. Multivariable logistic regression models were constructed and validated using fivefold cross-validation. The area under the receiver characteristic curve (AUC) was used to evaluate the predictive performance of each model. The results show that among the 108 cases of HCC, 50 cases had high PD-L2 expression, and 58 cases had low PD-L2 expression. Radiomic features correlated with PD-L2 expression. The T2-weighted, arterial-phase, and portal venous-phase and combined MRI radiomics models showed AUCs of 0.789 (95% CI: 0.702-0.875), 0.727 (95% CI: 0.632-0.823), 0.770 (95% CI: 0.682-0.875), and 0.871 (95% CI: 0.803-0.939), respectively. The combined model showed the best performance. The results of this study suggest that prediction based on the radiomic characteristics of MRI could noninvasively predict the expression of PD-L2 in HCC before surgery and provide a reference for the selection of immune checkpoint blockade therapy.

Cervical aortic arch with aneurysm formation and an anomalous right subclavian artery and left vertebral artery: A case report

BACKGROUND

A cervical aortic arch (CAA) refers to a high-riding aortic arch (AA) that often extends above the level of the clavicle. This condition is very rare, with an incidence of less than 1/10000.

CASE SUMMARY

A 29-year-old woman was admitted to the otolaryngology department of our hospital for repeated bilateral purulent nasal discharge for the prior 3 mo. The patient was diagnosed with chronic sinusitis and chronic rhinitis at admission. A preoperative noncontrast chest computed tomography scan showed a high-riding, tortuous AA extending to the mid-upper level of the first thoracic vertebra with local cystic dilatation. A further computed tomography angiography examination showed that the brachiocephalic trunk, left common carotid artery, left vertebral artery (LVA) (slender), and left subclavian artery sequentially branched off of the aorta from the proximal end to the distal end of the AA. The proximal end of the right subclavian artery (RSCA) was tortuous and dilated. The AA showed tumor-like local expansion, with a maximum diameter of approximately 4 cm. After consultation with the department of cardiac macrovascular surgery, the patient was diagnosed with left CAA with aneurysm formation and an anomalous RSCA and LVA and was transferred to that department. The patient underwent AA aneurysm resection and artificial blood vessel replacement under general anesthesia and cardiopulmonary bypass. No abnormality was found during the 2-mo follow-up after discharge.

CONCLUSION

A CAA is a rare congenital anomaly of vascular development. The present unique case of CAA with aneurysm formation and an anomalous RSCA and LVA enriches existing CAA data.

Progress of MRI Radiomics in Hepatocellular Carcinoma

Background

Hepatocellular carcinoma (HCC) is the sixth most common cancer in the world and the third leading cause of cancer-related death. Although the diagnostic scheme of HCC is currently undergoing refinement, the prognosis of HCC is still not satisfactory. In addition to certain factors, such as tumor size and number and vascular invasion displayed on traditional imaging, some histopathological features and gene expression parameters are also important for the prognosis of HCC patients. However, most parameters are based on postoperative pathological examinations, which cannot help with preoperative decision-making. As a new field, radiomics extracts high-throughput imaging data from different types of images to build models and predict clinical outcomes noninvasively before surgery, rendering it a powerful aid for making personalized treatment decisions preoperatively.

Objective

This study reviewed the workflow of radiomics and the research progress on magnetic resonance imaging (MRI) radiomics in the diagnosis and treatment of HCC.

Methods

A literature review was conducted by searching PubMed for search of relevant peer-reviewed articles published from May 2017 to June 2021.The search keywords included HCC, MRI, radiomics, deep learning, artificial intelligence, machine learning, neural network, texture analysis, diagnosis, histopathology, microvascular invasion, surgical resection, radiofrequency, recurrence, relapse, transarterial chemoembolization, targeted therapy, immunotherapy, therapeutic response, and prognosis.

Results

Radiomics features on MRI can be used as biomarkers to determine the differential diagnosis, histological grade, microvascular invasion status, gene expression status, local and systemic therapeutic responses, and prognosis of HCC patients.

Conclusion

Radiomics is a promising new imaging method. MRI radiomics has high application value in the diagnosis and treatment of HCC.

A study of the correlations between IVIM-DWI parameters and the histologic differentiation of hepatocellular carcinoma

The present study aimed to investigate the value of intravoxel incoherent motion diffusion weighted imaging (IVIM-DWI) in the preoperative prediction of the histologic differentiation of hepatocellular carcinoma (HCC). Seventy HCC patients were scanned with a 3.0 T magnetic resonance scanner. The values of apparent diffusion coefficient (ADC), slow apparent diffusion coefficient (D), fast apparent diffusion coefficient (D*), and the fraction of the fast apparent diffusion coefficient (f) were measured. Analysis of variance was used to compare the differences in parameters between groups with different degrees of histologic differentiation. p < 0.05 was considered statistically significant. Receiver operating characteristic (ROC) curves were used to analyse the efficacy of IVIM-DWI parameters for predicting the histologic differentiation of HCC. The ADC and D values for well, moderately and poorly differentiated HCC were 1.35 ± 0.17 × 10⁻³ mm²/s, 1.16 ± 0.17 × 10⁻³ mm²/s, 0.98 ± 0.21 × 10⁻³ mm²/s, and 1.06 ± 0.15 × 10⁻³ mm²/s, 0.88 ± 0.16 × 10⁻³ mm²/s, 0.76 ± 0.18 × 10⁻³ mm²/s, respectively, and all differences were significant. The D* and f values of the three groups were 32.87 ± 14.70 × 10⁻³ mm²/s, 41.68 ± 17.90 × 10⁻³ mm²/s, 34.54 ± 18.60 × 10⁻³ mm²/s and 0.22 ± 0.07, 0.23 ± 0.08, 0.18 ± 0.07, respectively, with no significant difference. When the cut-off values of ADC and D were 1.25 × 10⁻³ mm²/s and 0.97 × 10⁻³ mm²/s, respectively, their diagnostic sensitivities and specificities for distinguishing well differentiated HCC from moderately differentiated and poorly differentiated HCC were 73.3%, 85.5%, 86.7%, and 78.2%, and their areas under the ROC curve were 0.821 and 0.841, respectively. ADC and D values can be used preoperatively to predict the degree of histologic differentiation in HCC, and the D value has better diagnostic value.

Application of Diffusion Weighted Imaging in Prostate Cancer Bone Metastasis: Detection and Therapy Evaluation

BACKGROUND

Bone metastasis is one of the most common complications of Prostate Cancer (PCa). The detection of distal bone metastasis at the time of initial PCa diagnosis is valuable for the determination of therapeutic methods and for the prognosis of PCa. Many current therapeutic methods target PCa bone metastasis, but no uniform evaluation standard for therapeutic efficacy has been established; in addition, traditional therapeutic evaluation standards that rely on changes in the measured tumor volume are quite controversial. In clinical practice, the volumes of some tumors often change nonsignificantly at the early stage of therapy (especially targeted therapy), while the volumes of other tumors, such as metastatic bone lesions, are difficult to measure. Diffusion-Weighted Imaging (DWI) not only reflects the diffusion characteristics of tissues but can also allow the analysis of microstructural and functional changes in tissues. Therefore, DWI is suitable for evaluations of early responses to tumor therapy.

OBJECTIVE

This study mainly reviews the principle of DWI and its progress in the detection and therapy evaluation of PCa bone metastasis.

METHODS

PubMed was searched to identify eligible articles up to December 26, 2020. The keywords of the analysis included DWI, PCa, bone metastasis, therapeutic response, targeted therapy, Bone Scintigraphy (BS), Positron Emission Tomography/Computed Tomography (PET/CT) and metastatic Castration-Resistant Prostate Cancer (mCRPC).

RESULTS

This review based on collected articles achieved an imaging biomarker for detection and therapy evaluation of PCa bone metastasis.

CONCLUSION

DWI is a promising imaging method for the detection and therapeutic evaluation of PCa bone metastases.

The Application of rs-fMRI in Vascular Cognitive Impairment

The incidence of vascular cognitive impairment (VCI) has been increasing for years and has become a major disabling factor in middle-aged and elderly populations. The pathogenesis of VCI is unclear, and there are no standard diagnostic criteria. Resting-state functional magnetic resonance imaging (rs-fMRI) can be used to detect spontaneous brain functional activity in a resting state, which facilitates in-depth investigation of the pathogenesis of VCI and provides an objective reference for early diagnosis, differential diagnosis, and prognostic evaluation. This article mainly reviews the principle and analysis of rs-fMRI data, as well as the progress of its application for VCI diagnosis.

Progress of intravoxel incoherent motion diffusion-weighted imaging in liver diseases

Traditional magnetic resonance (MR) diffusion-weighted imaging (DWI) uses a single exponential model to obtain the apparent diffusion coefficient to quantitatively reflect the diffusion motion of water molecules in living tissues, but it is affected by blood perfusion. Intravoxel incoherent motion (IVIM)-DWI utilizes a double-exponential model to obtain information on pure water molecule diffusion and microcirculatory perfusion-related diffusion, which compensates for the insufficiency of traditional DWI. In recent years, research on the application of IVIM-DWI in the diagnosis and treatment of hepatic diseases has gradually increased and has achieved considerable progress. This study mainly reviews the basic principles of IVIM-DWI and related research progress in the diagnosis and treatment of hepatic diseases.

Intravoxel incoherent motion diffusion-weighted imaging to differentiate hepatocellular carcinoma from intrahepatic cholangiocarcinoma

The present study aimed to explore the value of intravoxel incoherent motion diffusion-weighted imaging (IVIM-DWI) in differentiating hepatocellular carcinoma (HCC) from intrahepatic cholangiocarcinoma (ICC). This study included 65 patients with malignant hepatic nodules (55 with HCC, 10 with ICC), and 17 control patients with normal livers. All patients underwent IVIM-DWI scans on a 3.0 T magnetic resonance imaging (MRI) scanner. The standard apparent diffusion coefficient (ADC), pure diffusion coefficient (Dslow), pseudo-diffusion coefficient (Dfast), and perfusion fraction (f) were obtained. Differences in the parameters among the groups were analysed using one-way ANOVA, with p < 0.05 indicating statistical significance. Receiver operating characteristic (ROC) curve analysis was used to compare the efficacy of each parameter in differentiating HCC from ICC. ADC, Dslow, Dfast, f significantly differed among the three groups. ADC and Dslow were significantly lower in the HCC group than in the ICC group, while Dfast was significantly higher in the HCC group than in the ICC group; f did not significantly differ between the HCC and ICC groups. When the cut-off values of ADC, Dslow, and Dfast were 1.27 × 10−3 mm2/s, 0.81 × 10−3 mm2/s, and 26.04 × 10−3 mm2/s, respectively, their diagnostic sensitivities for differentiating HCC from ICC were 98.18%, 58.18%, and 94.55%, their diagnostic specificities were 50.00%, 80.00%, and 80.00%, and their areas under the ROC curve (AUCs) were 0.687, 0.721, and 0.896, respectively. Dfast displayed the largest AUC value. IVIM-DWI can be used to differentiate HCC from ICC.

Trifluoromethyl-phenyl-triazolyl derivative of beta-bisabolol induces cell death in ME-180 cervical cancer cells through induction of apoptosis and ROS generation

<p class="Abstract">The aim of the current investigation was to design, synthesize and demonstrate the anticancer and apoptotic activity of trifluoromethyl-phenyl-triazolyl derivative of beta-bisabolol (TTB) in ME-180 human cervical cancer cells.  MTT and clonogenic assays were used to evaluate the cell viability and colony formation tendencies of the cells respectively. Phase contrast and fluorescence microscopic investigations were used to evaluate the effect of TTB on cellular morphology and apoptosis. Flow cytometric analysis using fluorescent CM-DCFH2-DA were used to study the effect of TTB on reactive oxygen species (ROS) formation. The results revealed that TTB significantly inhibited the proliferation of ME-180 human cervical cancer cells in a time-dependent as well as dose-dependent manner. TTB has the capacity to inhibit both anchorage dependent as well as anchorage independent growth of ME-180 cervical cancer cells. TTB-treated cells revealed chromatin condensation, fragmented nuclei and nuclear shrinkage. A 3-fold increase of ROS production was seen after 72 μM TTB treatment.</p><p><strong><br /></strong></p><p><strong>VIDEO CLIPS</strong></p><p><a href="https://www.youtube.com/v/9yrPL3uy6Ls">Phase contrast microscopic study:</a>  2 min</p><p> </p>

Size selectivity between gap junction channels composed of different connexins

Gap junction channels are traditionally viewed as large, nonspecific pores connecting cells. Recently the diversity in the connexin family has drawn more attention to their permeability characteristics. Several studies have shown that both size and charge contribute to the permeability of gap junctional channels. We have used a graded series of neutral polyethylene glycol probes (PEGs), which eliminate charge contribution completely, to specifically assess the physical exclusion limits of gap junction channels formed by different connexins. Cx 26, 32 and 37 were expressed in paired Xenopus oocytes to form homotypic gap junctional channels. PEG probes were perfused intracellularly into one side of the oocyte pair. A reversible drop in conductance of the gap juctional channels indicated that the probe was small enough to enter the pore and hinder ion flux. Our data suggest that Cx32 channels have a size cut-off between PEG 400 (11.2 A) and PEG 300 (9.6 A) despite their relatively small single channel conductance (approximately 55 pS). Cx26 channels (approximately 130 pS single channel conductance) have a size exclusion limit around PEG 200 (8.0 A), while Cx37 channels show the most restricted size cut-off between PEG 200 (8.0 A) and TriEG (6.8 A), despite having the largest unitary conductance (approximately 300 pS).

Epidermal growth factor receptor vIII enhances tumorigenicity in human breast cancer

Epidermal growth factor receptor vIII (EGFRvIII) is a tumor-specific, ligand-independent, constitutively active variant of the EGFR. Its expression has been detected in gliomas and various other human malignancies. To more fully characterize the function and potential biological role of EGFRvIII in regulating cell proliferation and in tumorigenesis, we transfected EGFRvIII cDNA into a nontumorigenic, interleukin 3 (IL-3)-dependent murine hematopoietic cell line (32D cells). We observed 32D cells expressing high levels of EGFRvIII (32D/EGFRvIII P5) to be capable of abrogating the IL-3-dependent pathway in the absence of ligands. In contrast, the parental cells, 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells, all depended on IL-3 or EGF-like ligands for growth. 32D/EGFRvIII P5 cells subjected to long-term culture conditions in the absence of IL-3 revealed further elevation of EGFRvIII expression levels. These results suggested that the IL-3-independent phenotype is mediated by EGFRvIII. The level of expression is a critical driving force for the IL-3-independent phenotype. Dose-response analysis revealed 32D/EGFRvIII cells to require 500-fold higher concentrations (50 ng/ml) of EGF to further stimulate the EGF-mediated proliferation than in the 32D/EGFR cells (100 pg/ml). Similar effects were also observed in beta-cellulin-mediated proliferation. Moreover, 32D cells expressing high levels of EGFRvIII formed large tumors in nude mice, even when no exogenous EGF ligand was administered. In contrast, no tumors grew in mice injected with 32D/EGFR, 32D/ErbB-4, and 32D/ErbB-2+ErbB-3 cells or low-expressing clone 32D/EGFRvIII C2 cells or the parental 32D cells. The changes of the ligand specificity support the notion for an altered conformation of EGFRvIII to reveal an activated ligand-independent oncoprotein with tumorigenic activity analogous to v-erbB. These studies clearly demonstrate that EGFRvIII is capable of transforming a nontumorigenic, IL-3-dependent murine hematopoietic cell line (32D cells) into an IL-3-independent and ligand-independent malignant phenotype in vitro and in vivo. To delineate the biological significance of EGFRvIII in human breast cancer, we expressed EGFRvIII in the MCF-7 human breast cancer cell line. Expression of EGFRvIII in MCF-7 cells produced a constitutively activated EGFRvIII receptor. Expression of EGFRvIII in MCF-7 cells also elevated ErbB-2 phosphorylation, presumably through heterodimerization and cross-talk. These MCF-7/EGFRvIII transfectants exhibited an approximately 3-fold increase in colony formation in 1% serum with no significant effect observed at higher percentages of serum. A similar result was also seen in anchorage-dependent assays. Furthermore, EGFRvIII expression significantly enhanced tumorigenicity of MCF-7 cells in athymic nude mice with P < 0.001. Collectively, these results provide the first evidence that EGFRvIII could play a pivotal role in human breast cancer progression.

The role of microvascular permeability in the mechanism for stunned myocardium in rats

The microvascular permeability of stunned myocardium in rats in vivo was studied with FITC-labeled albumin (FITC-BSA). It was found that 15 and 20 min of myocardial ischemia followed by 1 hr of reperfusion resulted in myocardial stunning. The concentrations of FITC-BSA in myocardial tissue were 240.6 +/- 7.8 (IS15) and 267.4 +/- 7.9 (IS20) micrograms/g myocardium in ischemic groups, respectively, which were significantly higher than those in the control group (166.0 +/- 7.9 micrograms/g myocardium; P < 0.01). In stunned groups, the concentrations were 224.8 +/- 11.8 (MS15) and 241.7 +/- 6.0 (MS20) micrograms/g myocardium, decreased from those in ischemic groups but still higher than those in control group by 35.4 and 45.6%, respectively. The more significant the concentration of FITC-BSA, the more serious the myocardial stunning. Electron microscopy revealed no significant vascular injury. The results suggest that the increase in microvascular permeability resulting from transient ischemia is functional and is involved in the pathogenesis of stunned myocardium.

Effect of glucocorticoid receptor (GR) blockade on endotoxemia in rats

To study the clinical significance of the decrease of glucocorticoid receptor (GR) in stress and shock, GR was blocked about 80% by mifepristone (RU38486), and the effects of the blockade on the pathological changes of endotoxemia were studied in rats. The results revealed that GR blockade may exacerbate the pathological and pathophysiological changes of endotoxemia: (1) the more rapid drop in arterial blood pressure, (2) the more severe pathological changes involving multiple organs, especially the lung and small intestine, (3) the increase of leukocyte adherence in venules and more pronounced rheological changes in the mesenteric microcirculation, and (4) the striking elevation of serum acid phosphatase (ACP), phospholipase A2 (PLA2) activity, and lipoperoxide (LPO). The changes of serum ACP, PLA2, and LPO in the rats with 80% GR blockade were more marked than in those with 50% GR blockade. Based on these findings, we propose that the decrease in GR during stress and shock might be a contributing factor in the pathogenesis of shock and multiple organ failure (MOF). The possible mechanisms of the above noted findings are discussed.

Effects of platelet-activating factor on rat mesenteric microcirculation

The actions of platelet-activating factor (PAF) on rat mesenteric microcirculation were studied by laser Doppler microscopy in vivo. PAF 0.2 -0.6 micrograms/kg iv produced a dose-related decrease in the blood flow velocity and an increase in the diameters of the mesenteric arterioles and venules. These responses were completely reversed by pretreatment with PAF receptor antagonist SRI 63441. The results suggest that PAF may be a mediator of microcirculatory disturbances in the disease conditions associated with excessive PAF release.

Triazine monomers and their adhesion to dentin

A series of 4,6-dichloro-1,3,5-triazines [e.g., 2-allylamino-(ADT), diallylamino-(DADT), 2-N-p-allyloxyphenylamino-, 2-N-allyl-N-phenylamino-, and 2-N-allyl-N-p-tolylamino-4,6-dichloro-1,3,5-triazine] was synthesized and characterized by IR, NMR, and mass spectrometry. These monomers have chlorine atoms that can react with NH2 or OH groups and double bonds capable of copolymerization. Aniline reacted readily with ADT and DADT, ethanol reacted with ADT, but acetone, H2O, and DMF did not react with either triazine. It appears that ADT or DADT will react with dentinal collagen through NH2 or OH groups in the peptide side-chains. An aprotic solvent should be used for ADT or DADT, but absolute dryness in clinical usage is not essential because of the slow hydrolysis of ADT and DADT. Stability of the N-di-substituted amino derivative (DADT) is greater than that of the mono-substituted compound (ADT), which may isomerize. ADT and methyl methacrylate were copolymerized at 37 degrees C with amine-peroxide. ADT solutions enhanced the adhesive strength of restorative resin to dentin. Thus, monomers such as ADT and DADT appear to be promising dentin-bonding agents.