The predictive value of the thyroid nodule benign and malignant based on the ultrasound nodule-to-muscle gray-scale ratio.

OBJECTIVE: To investigate the efficacy of the ultrasonic nodule to muscle gray scale ratio as a predictive tool for distinguishing between benign and malignant thyroid nodules. METHODS: A retrospective study was undertaken at the First People's Hospital of Hangzhou, affiliated with the Zhejiang University School of Medicine, analyzing ultrasound and pathological data of patients with thyroid nodules between May 2020 and December 2022. The study extracted ultrasound features of nodules and employed univariate and multivariate logistic regression analyses to identify independent risk factors for malignant tumors in the nodules. Subsequently, a predictive model for distinguishing benign and malignant thyroid nodules was developed. RESULTS: A total of 466 patients were included in this retrospective study, of which 275 cases were malignant tumors. Univariate and multivariate logistic regression analyses showed that the nodular-muscle gray-scale ratio, nodule diameter, margin status, aspect ratio, and calcification were closely related to thyroid malignant tumors. The area under the curve (AUC) of training group was 0.832, with a sensitivity, specificity, and accuracy of 85.5%, 67.4%, and 76.6%, respectively. The AUC of the external validation group was 0.819, with a sensitivity, specificity, and accuracy of 76.4%, 74.5%, and 75.7%, respectively. The calibration and decision curves showed that the model had good diagnostic value. CONCLUSION: The research findings indicate that ratio is significantly associated with the malignant nature of thyroid nodules. The application of a line chart model based on these parameters exhibits a high level of predictive performance.

Nomogram model based on preoperative clinical characteristics of unilateral papillary thyroid carcinoma to predict contralateral medium-volume central lymph node metastasis.

Objectives: To explore the preoperative high-risk clinical factors for contralateral medium-volume central lymph node metastasis (conMVCLNM) in unilateral papillary thyroid carcinoma (uPTC) and the indications for dissection of contralateral central lymph nodes (conCLN). Methods: Clinical and pathological data of 204 uPTC patients who underwent thyroid surgery at the Hangzhou First People's Hospital from September 2010 to October 2022 were collected. Univariate and multivariate logistic regression analyses were conducted to determine the independent risk factors for contralateral central lymph node metastasis (conCLNM) and conMVCLNM in uPTC patients based on the preoperative clinical data. Predictive models for conCLNM and conMVCLNM were constructed using logistic regression analyses and validated using receiver operating characteristic (ROC) curves, concordance index (C-index), calibration curves, and decision curve analysis (DCA). Results: Univariate and multivariate logistic regression analyses showed that gender (P < 0.001), age (P < 0.001), tumor diameter (P < 0.001), and multifocality (P = 0.008) were independent risk factors for conCLNM in uPTC patients. Gender(P= 0.026), age (P = 0.010), platelet-to-lymphocyte ratio (PLR) (P =0.003), and tumor diameter (P = 0.036) were independent risk factors for conMVCLNM in uPTC patients. A predictive model was established to assess the risk of conCLNM and conMVCLNM, with ROC curve areas of 0.836 and 0.845, respectively. The C-index, the calibration curve, and DCA demonstrated that the model had good diagnostic value. Conclusion: Gender, age, tumor diameter, and multifocality are high-risk factors for conCLNM in uPTC patients. Gender, age, tumor diameter, and PLR are high-risk factors for conMVCLNM in uPTC patients, and preventive conCLN dissection should be performed.

Effects of Anesthetic Technique on Postoperative Pulmonary Metastasis in Patients Undergoing Laryngectomy.

BACKGROUND: Whether laryngeal cancer is directly implanted into the lungs during orotracheal intubation is still unclear. Therefore, this study aimed to find whether orotracheal intubation is an independent risk factor for postoperative pulmonary metastasis in patients undergoing laryngectomy. PATIENTS AND METHODS: Medical records from January 1, 2006, to December 31, 2016, were reviewed. According to similar propensity scores, patients who received orotracheal intubation (tracheal intubation group, n = 515) were matched 1:1 with those who received tracheotomy (tracheotomy group, n = 326) in the induction of general anesthesia. The primary outcome was postoperative pulmonary metastasis. Secondary outcomes included local recurrence, lymphatic metastasis, tracheostomal recurrence and overall survival. RESULTS: Between the two groups, there was no significant difference in postoperative pulmonary metastasis (P = 0.688), local recurrence (P = 0.215), lymphatic metastasis (P = 0.480), tracheostomal recurrence (P = 0.246) or all-cause death (P = 0.299). The primary site of cancer was an independent risk factor for pulmonary metastasis [HR 0.29, 95% CI 0.13-0.68; P = 0.013] and local recurrence (HR 2.69, 95% CI 1.39-5.21; P = 0.003). Type of surgery (HR 3.13, 95% CI 2.03-4.84; P < 0.001) and N classification of TNM (HR 0.27, 95% CI 0.10-0.75; P = 0.012) were risk factors for local recurrence. Postoperative chemotherapy was an independent risk factor for lung metastasis (HR 7.58, 95% CI 3.11-18.47; P < 0.001) and lymphatic metastasis (HR 5.18, 95% CI 2.57-11.91; P < 0.001), and 5-year overall survival was associated with age (P = 0.028), clinical stage (P < 0.001) and postoperative chemotherapy (P = 0.003) but not with anesthetic technique (P = 0.473). CONCLUSION: This retrospective study suggests that orotracheal intubation in laryngectomy is not a risk factor for postoperative pulmonary metastasis, local recurrence, lymphatic metastasis or overall survival.

Oxaliplatin Regulates Chemotherapy Induced Peripheral Neuropathic Pain in the Dorsal Horn and Dorsal Root Ganglion via the Calcineurin/NFAT Pathway.

OBJECTIVE: The aim of this study was to investigate the mechanism of oxaliplatin in the induction of neuropathic pain as a symptom of Chemotherapy-Induced Peripheral Neuropathy (CIPN). METHODS: The CIPN rat model was induced with a one-time injection of oxaliplatin, and the paw withdrawal response was determined using von Frey filaments. The Paw Withdrawal Threshold (PWT) value was recorded and the Dorsal Horn (DH) and Dorsal Root Ganglion (DRG) tissues were collected. The mRNA and protein levels of Calcineurin (CaN), Nuclear Factor of Activated T cells (NFAT), and other relevant cytokines were determined. CaN and NFAT inhibition reagents, FK506 and 11R-VIVIT, were applied in order to investigate the functions of the CaN/NFAT pathway in the neuropathic pain processes. The levels of the downstream inflammatory cytokines, TNF-α and IL-1ß, were assessed by ELISA. RESULTS: The application of oxaliplatin reduced the value of PWT by 4 times on days 7（4±1.33）and 14（5.13±3.07）compared with the control group(14±0.91; 13.67±0.76). After treatment, the CaN mRNA level decreased and that of NFAT increased in DH and DRG tissues (P<0.05). However, treatment with FK506 and 11R-VIVIT decreased the value of PWT that had increased after oxaliplatin treatment. The expression of downstream cytokines related to the CaN/NFAT pathway increased, including CCR2, COX2, p-ERK, and p-P38 (all p<0.05). In addition, when the CaN/NFAT pathway was activated, the concentration of TNFα increased to 40pg/mg in DH tissues and 60pg/mg in DRG tissues compared with the control group, while the concentration of IL-1ß increased to over 60pg/mg in DH and DRG tissues. CONCLUSION: It was the first time to prove that oxaliplatin-induced neuropathic pain was correlated to the activation of the CaN/NFAT pathway in our rat model. This finding can provide a new direction to explore the mechanism of oxaliplatin-induced neuropathic pain.

Fingers-closing and other rapid conformational changes in DNA polymerase I (Klenow fragment) and their role in nucleotide selectivity.

We have developed a FRET-based assay for the fingers-closing conformational transition that occurs when a binary complex of DNA polymerase I (Klenow fragment) with a primer-template binds a complementary dNTP and have used this and other fluorescence assays to place the fingers-closing step within the reaction pathway. Because the rate of fingers-closing was substantially faster than the rate of nucleotide incorporation measured in chemical quench experiments, fingers-closing cannot be the rate-limiting prechemistry step defined by earlier kinetic studies. Experiments using Ca (2+) instead of Mg (2+) as the metal cofactor suggest instead that the prechemistry step may involve a change in metal ion occupancy at the polymerase active site. The use of ribonucleotide substrates shows there is a base discriminating step that precedes fingers-closing. This earlier step, detected by 2-AP fluorescence, is promoted by complementary nucleotides (ribo- as well as deoxyribo-) but is blocked by mismatches. The complementary rNTP blocks the subsequent fingers-closing step. Thus, discrimination against rNTPs occurs during the transition from open to closed conformations, whereas selection against mismatched bases is initiated earlier in the pathway, in the open complex. Mismatched dNTPs accelerate DNA release from the polymerase, suggesting the existence of an early intermediate in which DNA binding is destabilized relative to the binary complex; this could correspond to a conformation that allows an incoming dNTP to preview the template base. The early kinetic checkpoints identified by this study provide an efficient mechanism for the rejection of mismatched bases and ribose sugars and thus enhance polymerase throughput.

Methylation of cytosine at C5 in a CpG sequence context causes a conformational switch of a benzo[a]pyrene diol epoxide-N2-guanine adduct in DNA from a minor groove alignment to intercalation with base displacement.

It is well known that CpG dinucleotide steps in DNA, which are highly methylated at the 5-position of cytosine (meC) in human tissues, exhibit a disproportionate number of mutations within certain codons of the p53 gene. There is ample published evidence indicating that the reactivity of guanine with anti-B[a]PDE (a metabolite of the environmental carcinogen benzo[a]pyrene) at CpG mutation hot spots is enhanced by the methylation of the cytosine residue flanking the target guanine residue on the 5'-side. In this work we demonstrate that such a methylation can also dramatically affect the conformational characteristics of an adduct derived from the reaction of one of the two enantiomers of anti-B[a]PDE with the exocyclic amino group of guanine ([BP]G adduct). A detailed NMR study indicates that the 10R (-)-trans-anti-[BP]G adduct undergoes a transition from a minor groove-binding alignment of the aromatic BP ring system in the unmethylated C-[BP]G sequence context, to an intercalative BP alignment with a concomitant displacement of the modified guanine residue into the minor groove in the methylated meC-[BP]G sequence context. By contrast, a minor groove-binding alignment was observed for the stereoisomeric 10S (+)-trans-anti-[BP]G adduct in both the C-[BP]G and meC-[BP]G sequence contexts. This remarkable conformational switch resulting from the presence of a single methyl group at the 5-position of the cytosine residue flanking the lesion on the 5'-side, is attributed to the hydrophobic effect of the methyl group that can stabilize intercalated adduct conformations in an adduct stereochemistry-dependent manner. Such conformational differences in methylated and unmethylated CpG sequences may be significant because of potential alterations in the cellular processing of the [BP]G adducts by DNA transcription, replication, and repair enzymes.

Structure of a high fidelity DNA polymerase bound to a benzo[a]pyrene adduct that blocks replication.

Of the carcinogens to which humans are most frequently exposed, the polycyclic aromatic hydrocarbon benzo[a]pyrene (BP) is one of the most ubiquitous. BP is a byproduct of grilled foods and tobacco and fuel combustion and has long been linked to various human cancers, particularly lung and skin. BP is metabolized to diol epoxides that covalently modify DNA bases to form bulky adducts that block DNA synthesis by replicative or high fidelity DNA polymerases. Here we present the structure of a high fidelity polymerase from a thermostable strain of Bacillus stearothermophilus (Bacillus fragment) bound to the most common BP-derived N2-guanine adduct base-paired with cytosine. The BP adduct adopts a conformation that places the polycyclic BP moiety in the nascent DNA minor groove and is the first structure of a minor groove adduct bound to a polymerase. Orientation of the BP moiety into the nascent DNA minor groove results in extensive disruption to the interactions between the adducted DNA duplex and the polymerase. The disruptions revealed by the structure of Bacillus fragment bound to a BP adduct provide a molecular basis for rationalizing the potent blocking effect on replication exerted by BP adducts.

Effects of base sequence context on translesion synthesis past a bulky (+)-trans-anti-B[a]P-N2-dG lesion catalyzed by the Y-family polymerase pol kappa.

The effects of bases flanking single bulky lesions derived from the binding of a benzo[a]pyrene 7,8-diol 9,10-epoxide derivative ((+)-7R,8S,9S,10R stereoisomer) to N(2)-guanine (G*) on translesion bypass catalyzed by the Y-family polymerase pol kappa (hDinB1) were examined in vitro. The lesions were positioned near the middle of six different 43-mer 5'-...XG*Y... sequences (X, Y = C, T, or G, with all other bases remaining fixed). The complementary dCTP is preferentially inserted opposite G* in all of the sequences; however, the proportions of other dNTPs inserted varies as a function of X and Y. The dCTP insertion efficiencies, f(ins) = (V(max)/K(m))(ins), are smaller in the XG*Y than in XGY sequences by factors of approximately 50-90 (GG*T and GG*C) or 5000-25000 (TG*G and CG*G). Remarkably, in XG*Y sequences, f(ins) varies by as much as 3 orders of magnitude, being smallest with G flanking the lesions on the 3'-side and highest with G flanking the adducts on the 5'-side. One-step primer extension efficiencies just beyond the lesions (f(ext)) are generally smaller than f(ins) and also depend on base sequence. However, reasonably efficient translesion bypass of the (+)-trans-[BP]-N(2)-dG adducts is observed in all sequences in running-start experiments with full, or nearly full, primer extension being observed under conditions of [dNTP] > K(m). The key features here are the relatively robust values of the kinetic parameters V(max) that are either diminished to a moderate extent or even enhanced in the presence of the (+)-trans-[BP]-N(2)-dG adducts. In contrast to the small effects of the lesions on V(max), the apparent K(m) values are orders of magnitude greater in XG*Y than in the unmodified XGY sequences. Thus the bypass of (+)-trans-[BP]-N(2)-dG adducts under conditions when [dNTP] < K(m) is quite inefficient. These considerations may be of importance in vivo where [dNTP]

Conformational changes of a benzo[a]pyrene diol epoxide-N(2)-dG adduct induced by a 5'-flanking 5-methyl-substituted cytosine in a (Me)CG double-stranded oligonucleotide sequence context.

Mutations in p53 genes are one of the most common genetic alterations in human cancers. A disproportionate number of mutations are found in certain codons of the p53 gene, mostly at CpG dinucleotide sequences, which are highly methylated in human tissues. The reactivities of the mutagenic metabolite of benzo[a]pyrene, the bay region diol epoxide r7,t8-dihydroxy-t9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE), to yield adducts with guanine at the exocyclic amino group (e.g., trans-anti-BPDE-N(2)-dG, or G*), are enhanced when the cytosine in CpG sequences in DNA is methylated at its 5-position ((Me)CpG). However, methylation may also affect the characteristics of these adducts, and we have therefore investigated whether adduct conformations are different in double-stranded DNA in methylated (Me)CpG* and in unmethylated CpG* sequence contexts in the oligonucleotide model system duplex 5'-d(CCAT[(5X)C]GCTACC).d(GGTAGCGATGG) with X = H or -CH(3). The (-)-trans-adduct exhibits a striking conformational change from a minor groove structure external to the DNA duplex in the unmethylated CpG* sequence, to an intercalative conformation in the (Me)CG* sequence context. In contrast, the conformation of the stereoisomeric (+)-trans-adduct is predominantly of the minor groove type in both the methylated and unmethylated sequences. These results indicate that methylation of CpG sequences may affect not only chemical reactivities of chemically reactive intermediates with DNA, but also the conformational properties of the DNA adducts formed. Thus, both factors must be considered in evaluating the effects of cytosine methylation in CpG sequences on the biological consequences of the DNA adducts formed.