Anatomic resection improved the long-term outcome of hepatocellular carcinoma patients with microvascular invasion: A prospective cohort study.

BACKGROUND: The long-term effect of anatomic resection (AR) is better than that of non-anatomic resection (NAR). At present, there is no study on microvascular invasion (MVI) and liver resection types. AIM: To explore whether AR improves long-term survival in patients with hepatocellular carcinoma (HCC) by removing the peritumoral MVI. METHODS: A total of 217 patients diagnosed with HCC were enrolled in the study. The surgical margin was routinely measured. According to the stratification of different tumor diameters, patients were divided into the following groups: ≤ 2 cm group, 2-5 cm group, and > 5 cm group. RESULTS: In the 2-5 cm diameter group, the overall survival (OS) of MVI positive patients was significantly better than that of MVI negative patients (P = 0.031). For the MVI positive patients, there was a statistically significant difference between AR and NAR (P = 0.027). AR leads to a wider surgical margin than NAR (2.0 ± 2.3 cm vs 0.7 ± 0.5 cm, P < 0.001). In the groups with tumor diameters < 2 cm, both AR and NAR can obtain a wide surgical margin, and the surgical margins of AR are wider than that of NAR (3.5 ± 5.8 cm vs 1.6 ± 0.5 cm, P = 0.048). In the groups with tumor diameters > 5 cm, both AR and NAR fail to obtain wide surgical margin (0.6 ± 1.0 cm vs 0.7 ± 0.4 cm, P = 0.491). CONCLUSION: For patients with a tumor diameter of 2-5 cm, AR can achieve the removal of peritumoral MVI by obtaining a wide incision margin, reduce postoperative recurrence, and improve prognosis.

Folding Thermodynamics and Mechanism of Five Trp-Cage Variants from Replica-Exchange MD Simulations with RSFF2 Force Field.

To test whether our recently developed residue-specific force field RSFF2 can reproduce the mutational effect on the thermal stability of Trp-cage mini-protein and decipher its detailed folding mechanism, we carried out long-time replica-exchange molecular dynamics (REMD) simulations on five Trp-cage variants, including TC5b and TC10b. Initiated from their unfolded structures, the simulations not only well-reproduce their experimental structures but also their melting temperatures and folding enthalpies reasonably well. For each Trp-cage variant, the overall folding free energy landscape is apparently two-state, but some intermediate states can be observed when projected on more detailed coordinates. We also found different variants have the same major folding pathway, including the well formed PII-helix in the unfolded state, the formation of W6-P12/P18/P19 contacts and the α-helix before the transition state, the following formation of most native contacts, and the final native loop formation. The folding mechanism derived here is consistent with many previous simulations and experiments.

Residue-specific force field based on protein coil library. RSFF2: modification of AMBER ff99SB.

Recently, we developed a residue-specific force field (RSFF1) based on conformational free-energy distributions of the 20 amino acid residues from a protein coil library. Most parameters in RSFF1 were adopted from the OPLS-AA/L force field, but some van der Waals and torsional parameters that effectively affect local conformational preferences were introduced specifically for individual residues to fit the coil library distributions. Here a similar strategy has been applied to modify the Amber ff99SB force field, and a new force field named RSFF2 is developed. It can successfully fold α-helical structures such as polyalanine peptides, Trp-cage miniprotein, and villin headpiece subdomain and ß-sheet structures such as Trpzip-2, GB1 ß-hairpins, and the WW domain, simultaneously. The properties of various popular force fields in balancing between α-helix and ß-sheet are analyzed based on their descriptions of local conformational features of various residues, and the analysis reveals the importance of accurate local free-energy distributions. Unlike the RSFF1, which overestimates the stability of both α-helix and ß-sheet, RSFF2 gives melting curves of α-helical peptides and Trp-cage in good agreement with experimental data. Fitting to the two-state model, RSFF2 gives folding enthalpies and entropies in reasonably good agreement with available experimental results.

Residue-specific force field based on the protein coil library. RSFF1: modification of OPLS-AA/L.

Traditional protein force fields use one set of parameters for most of the 20 amino acids (AAs), allowing transferability of the parameters. However, a significant shortcoming is the difficulty to fit the Ramachandran plots of all AA residues simultaneously, affecting the accuracy of the force field. In this Feature Article, we report a new strategy for protein force field parametrization. Backbone and side-chain conformational distributions of all 20 AA residues obtained from protein coil library were used as the target data. The dihedral angle (torsion) potentials and some local nonbonded (1-4/1-5/1-6) interactions in OPLS-AA/L force field were modified such that the target data can be excellently reproduced by molecular dynamics simulations of dipeptides (blocked AAs) in explicit water, resulting in a new force field with AA-specific parameters, RSFF1. An efficient free energy decomposition approach was developed to separate the corrections on ϕ and ψ from the two-dimensional Ramachandran plots. RSFF1 is shown to reproduce the experimental NMR (3)J-coupling constants of AA dipeptides better than other force fields. It has a good balance between α-helical and ß-sheet secondary structures. It can successfully fold a set of α-helix proteins (Trp-cage and Homeodomain) and ß-hairpins (Trpzip-2, GB1 hairpin), which cannot be consistently stabilized by other state-of-the-art force fields. Interestingly, the RSFF1 force field systematically overestimates the melting temperature (and the stability of native state) of these peptides/proteins. It has a potential application in the simulation of protein folding and protein structure refinement.

[Unrelated umbilical cord blood transplantation with TBI/Ara-c/CY non-ATG conditioning regimen for adults with hematologic malignancies].

OBJECTIVE: To retrospectively analyze the curative efficacy of umbilical cord blood transplantation (UCBT) with improved myeloablative conditioning regimen (total body irradiation (TBI)/cytosine arabinoside (Ara-c)/cyclophosphamide (CY) without antithymocyte globulin (ATG)) in adult patients with hematological malignancies. METHODS: Forty consecutive adult patients with hematological malignancies received improved myeloablative unrelated CBT at a single center from September 2006 to May 2011. Their average age was (23 ± 6) years and the average weight (58 ± 9) kg. Thirty-five (87.5%) patients were high-risk and 15 (37.5%) at the advanced disease status at pre-transplantation. They received 1 (n = 23) or 2 (n = 17) cord blood units. Seventy-five percent of them were transplanted with 1/2-human leukocyte antigen mismatched unit. The conditioning regimen consisted of 12 Gy TBI, granulocyte colony-stimulating factor (G-CSF) plus Ara-c and CY without ATG. All patients received a combination of cyclosporine (CsA) and mycophenolate mofetil (MMF) for the prophylaxis of graft-versus-host disease (GVHD). RESULTS: For the entire group of patients, the average cell doses infused were (4.1 ± 1.1)×107 total nucleated cells/kg and (2.4 ± 1.0)×105 CD34(+) cells/kg. All patients acquired engraftment with an implantation rate of 100%. The average time of absolute neutrophil count (ANC) ≥ 0.5×109/L was (20 ± 5) days and the average time of platelet ≥ 20×109/L was(38 ± 12) days. Acute GVHD occurred in 23 patients (57.5%) and 4 (10.0%) were of grade III-IV. Chronic GVHD occurred in 22.9% (8/35) evaluable patients. Relapse occurred in 12.5% (5/40) patients. During a median follow-up period of 19.8 (range 4.6 - 55.0) months, the transplantation-related mortality was 15.0% (6/40) within 100 days and 35.0% (14/40) within 1 year. The main causes of mortality were pneumonia and severe acute GVHD. Two-year overall survival (OS) or disease-free survival was 58.8% and 58.8%, respectively. Two-year OS for patients with advanced or complete remission disease was 48.6% and 63.8%, respectively. CONCLUSIONS: The TBI/Ara-c/CY myeloablative conditioning regimen is well-tolerated and capable of establishing sustained donor cell engraftment and decreasing the risks of transplant-related death in adults with hematologic malignancies. For the high-risk and advanced patients, it may reduce the occurrences of relapse and chronic GVHD.