Clinical strategies for securing negative proximal margin in early gastric cancer.

Securing an appropriate proximal resection margin (PRM) is crucial for oncological safety in treating gastric cancer. This study investigated the clinicopathological characteristics of patients with incomplete PRM length of <2 cm in early gastric cancer. Clinicopathological data of 1,493 patients who underwent subtotal gastrectomy for early gastric cancer in 2012 to 2021 were retrospectively reviewed. Patients were divided into the PRM length of <2 cm and ≥2 cm groups based on pathological results. Univariate and multivariate analyses evaluated factors for incomplete PRM length. Factors related to patients with a relative PRM positive were also analyzed. The proportion of patients with a PRM length of <2 cm was 17.9% (267/1,493). Multivariate regression analysis revealed that age <50, preoperative endoscopic size of ≥3 cm, size discrepancy of ≥2 cm, and midbody tumor with a lesser curvature significantly contributed to the PRM length of <2 cm. Twenty-four patients had a relative PRM positive (24/1493, 1.6%). An incomplete PRM was the only risk factor for a positive relative PRM. Surgical treatment for early gastric cancer requires an accurate preoperative endoscopic tumor size and location evaluation. A more aggressive resection is recommended for patients with age <50, preoperative endoscopic size of ≥3 cm, size discrepancy of ≥2 cm, and midbody tumor with a lesser curvature.

A retrospective study of factors affecting contralateral central-neck lymph node metastasis in unilateral papillary thyroid carcinoma.

BACKGROUND: In 30-40% of papillary thyroid cancer patients, central neck lymph node metastasis occurs. As a result, prophylactic central neck lymph node dissection is performed. The extent of lymph node dissection and prophylactic central neck lymph node dissection is still debatable. The incidence of central neck lymph node metastasis and related factors were investigated in this study, and also the necessity of both central neck lymph node dissections. METHODS: Between December 2017 and December 2019, 482 patients had thyroidectomy at Pusan National University Yangsan Hospital. A retrospective study of 186 patients who had a thyroidectomy with bilateral central neck lymph node dissection for unilateral thyroid carcinoma was done. RESULTS: Ipsilateral and contralateral central neck lymph node metastasis were identified in 40.9% (76/186) and 19.3% (36/186), respectively. Male (p < 0.001), tumor size >1 cm (p = 0.047), extrathyroidal extension (p = 0.002), central neck lymph node metastases >5 (p < 0.001), lateral neck lymph node metastasis (p = 0.012), and ipsilateral central neck lymph node metastasis (p < 0.001) were associated with the contralateral central neck lymph node metastasis in univariate analysis. In a multivariate analysis, extrathyroidal extension (OR, 3.664), more than 5 central neck lymph node metastases (OR, 29.667), ipsilateral central neck lymph node metastasis (OR, 3.911), and male (OR, 5.890) were related to contralateral central neck lymph node metastasis. CONCLUSION: Male, extrathyroidal extension, and ipsilateral central neck lymph node metastasis may be considered for contralateral prophylactic central neck lymph node dissection. In the future, it is thought that more research on the recurrence rate will be required.

A 3-year follow-up study of uncut Roux-en-Y reconstruction: clinical results and outcomes.

BACKGROUND: The goal of this study was to identify the clinical outcomes of uncut Roux-en-Y reconstruction in patients who underwent totally laparoscopic distal gastrectomy (TLDG) over 3-year follow-up. METHODS: From January 2016 to December 2017, 269 patients who underwent TLDG were enrolled in the study and analyzed retrospectively. They were classified into two groups according to the reconstruction method: uncut Roux-en-Y reconstruction (uncut RY) (n = 154) and Billroth II with Braun anastomosis (B-II/Braun) (n = 115). Postoperative endoscopic findings (residual food, bile reflux, gastritis, and esophagitis) and nutritional status (body weight, serum hemoglobin, total protein, and albumin levels) were assessed every 6 months for 3 years. RESULTS: Residual food was less frequent in the uncut RY group in the 6th month after TLDG (p = 0.022), but there were no differences between the two groups for the rest of the study period. The incidence of bile reflux and gastritis was low in the uncut RY group during all postoperative periods (all p < 0.001). In the B-II/Braun group, the frequency of reflux esophagitis was high in the 30th and 36th months after TLDG (both p < 0.001), and there were no differences between the two groups during the preceding periods. No significant differences were found with respect to nutritional status, such as body weight, serum hemoglobin, total protein, and albumin levels during all postoperative periods. CONCLUSIONS: Three-year follow-up outcomes showed that uncut RY can effectively reduce the incidence of bile reflux and gastritis in the remnant stomach compared to B-II/Braun after TLDG.

Utility of sentinel lymph node biopsy in papillary thyroid microcarcinoma.

Purpose: There are many studies on sentinel lymph node (SLN) biopsy in thyroid carcinoma but SLN biopsy (SLNB) in papillary thyroid carcinoma (PTC) remains open to debate. Therefore in this retrospective study, the usefulness of SLNB in thyroid carcinoma patients who had micro-PTC without cervical lymphadenopathy was assessed. Methods: SLNB was performed in 114 patients who were diagnosed with micro-PTC in a single lobe without palpable or ultrasound-detected lymph node at the tertiary center between January 2012 and December 2013. After SLNB, all patients underwent total thyroidectomy and central neck dissection or thyroid lobectomy and central neck dissection of the single side. Results: SLNs were identified in 112 of 114 patients with 41 positive SLNs and 71 negative SLNs on intraoperative frozen sections. However, eight negative patients were found to be positive in the final pathology. Sentinel node identification rate and false negative value of SLNB were 98.2% and 11.3%, respectively. In the univariate analysis, higher lymph node metastasis was detected in men than in women. Higher detection number of SLN showed higher probability of lymph node metastasis. Conclusion: SLNB may be helpful in papillary thyroid cancer, especially in male patients. Also, it is useful for the staging of nodal status and clearance of persistent disease.

Structure of the catalytic phosphatase domain of MTMR8: implications for dimerization, membrane association and reversible oxidation.

Myotubularin-related proteins are a large family of phosphoinositide phosphatases; their activity, stability and subcellular localization are regulated by dimeric interactions with other members of the family. Here, the crystal structure of the phosphatase domain of MTMR8 is reported. Conformational deviation of the two loops that mediate interaction with the PH-GRAM domain suggests that the PH-GRAM domain interacts differently with the phosphatase domain of each MTMR member. The protein exists as a dimer with twofold symmetry, providing insight into a novel mode of dimerization mediated by the phosphatase domain. Structural comparison and mutation studies suggest that Lys255 of MTMR8 interacts with the substrate diacylglycerol moiety, similar to Lys333 of MTMR2, although the positions of these residues are different. The catalytic activity of the MTMR8 phosphatase domain is inhibited by oxidation and is reversibly reactivated by reduction, suggesting the presence of an oxidation-protective intermediate other than a disulfide bond owing to the absence of a cysteine within a disulfide-bond distance from Cys338.

Expression, purification, crystallization and preliminary crystallographic analysis of human myotubularin-related protein 3.

Myotubularin-related proteins are a large family of phosphatases that have the catalytic activity of dephosphorylating the phospholipid molecules phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate. Each of the 14 family members contains a phosphatase catalytic domain, which is inactive in six family members owing to amino-acid changes in a key motif for the activity. All of the members also bear PH-GRAM domains, which have low homologies between them and have roles that are not yet clear. Here, the cloning, expression, purification and crystallization of human myotubularin-related protein 3 encompassing the PH-GRAM and the phosphatase catalytic domain are reported. Preliminary X-ray crystallographic analysis shows that the crystals diffracted to 3.30 Šresolution at a synchrotron X-ray source. The crystals belonged to space group C2, with unit-cell parameters a = 323.3, b = 263.3, c = 149.4 Å, ß = 109.7°.

Crystallization and preliminary X-ray crystallographic analysis of the PH-GRAM domain of human MTMR4.

Phosphoinositide lipid molecules play critical roles in intracellular signalling pathways and are regulated by phospholipases, lipid kinases and phosphatases. In particular, phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate are related to endosomal trafficking events through the recruitment of effector proteins and are involved in the degradation step of autophagy. Myotubularin-related proteins (MTMRs) are a large family of phosphatases that catalyze the dephosphorylation of phosphatidylinositol 3-phosphate and phosphatidylinositol 3,5-bisphosphate at the D3 position, thereby regulating cellular phosphoinositide levels. In this study, the PH-GRAM domain of human MTMR4 was cloned, overexpressed in Escherichia coli, purified and crystallized by the vapour-diffusion method. The crystals diffracted to 3.20 Šresolution at a synchrotron beamline and belonged to either space group P61 or P65, with unit-cell parameters a = b = 109.10, c = 238.97 Å.

Purification, crystallization and preliminary X-ray diffraction analysis of enoyl-acyl carrier protein reductase (FabK) from Streptococcus mutans strain UA159.

A triclosan-resistant flavoprotein termed FabK is the sole enoyl-acyl carrier protein reductase in Streptococcus pneumoniae and Streptococcus mutans. In this study, FabK from S. mutans strain UA159 was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 2.40 Å resolution using a synchrotron-radiation source. The crystal belonged to space group P6(2), with unit-cell parameters a = b = 105.79, c = 44.15 Å. The asymmetric unit contained one molecule, with a corresponding V(M) of 2.05 Å(3) Da(-1) and a solvent content of 39.9%.

Overexpression, crystallization and preliminary X-ray crystallographic analysis of the RNA polymerase domain of primase from Streptococcus mutans strain UA159.

Primase is the enzyme that synthesizes RNA primers on single-stranded DNA during normal DNA replication. In this study, the catalytic core domain of primase from Streptococcus mutans UA159 was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 1.60 Å resolution using a synchrotron-radiation source. The crystal belonged to space group P4(1) or P4(3), with unit-cell parameters a = b = 52.63, c = 110.31 Å. The asymmetric unit is likely to contain one molecule, with a corresponding V(M) of 1.77 Å(3) Da(-1) and a solvent content of 30.7%.

Overexpression, purification, crystallization and preliminary X-ray crystallographic analysis of the C-terminal domain of the GyrA subunit of DNA gyrase from Staphylococcus aureus strain Mu50.

DNA gyrase is a type II topoisomerase that is essential for chromosome segregation and cell division owing to its ability to modify the topological form of bacterial DNA. In this study, the C-terminal domain of the GyrA subunit of DNA gyrase from Staphylococcus aureus Mu50 strain was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 2.80 Šresolution using a synchrotron-radiation source. The crystal belonged to space group P2(1), with unit-cell parameters a = 37.28, b = 80.19, c = 50.22 Å, ß = 110.64°. The asymmetric unit contained one molecule, with a corresponding V(M) of 2.02 Å(3) Da(-1) and a solvent content of 39.2%.

Cloning, purification, crystallization and preliminary X-ray crystallographic analysis of the N-terminal domain of DEAD-box RNA helicase from Staphylococcus aureus strain Mu50.

DEAD-box helicases are enzymes with an ATP-dependent RNA-unwinding function that are involved in a variety of cellular processes including RNA splicing, ribosome biogenesis and RNA degradation. In this study, the N-terminal domain of DEAD-box RNA helicase from Staphylococcus aureus strain Mu50 was overexpressed in Escherichia coli, purified and crystallized. Diffraction data were collected to 2.60 Šresolution using a synchrotron-radiation source. The crystal belonged to space group P1, with unit-cell parameters a=70.81, b=80.23, c=86.25 Å, α=69.54, ß=66.54, γ=87.32°. The unit cell contained six molecules, with a corresponding VM of 2.91 Å3 Da(-1) and a solvent content of 56.1%.