Thymic adenocarcinoma presenting as an incidental mediastinal mass.

BACKGROUND: Primary thymic adenocarcinoma represents an exceptionally rare malignancy, for which the cornerstone of therapy is margin-negative resection, with radiation and systemic therapy reserved for invasive and advanced disease. Thymic adenocarcinoma has not been previously reported in the setting of a concomitant malignancy, as reported herein. CASE PRESENTATION: We present a case of a 55-year-old previously healthy male diagnosed with acute myeloid leukemia, also found to have a mediastinal mass. Evaluation of the mediastinal mass with tumor markers, biopsies, and next-generation sequencing proved non-diagnostic, while he was simultaneously treated with induction chemotherapy to prevent leukemia-related blast crisis. After completing and recovering from induction chemotherapy, he underwent successful thymectomy during a chemotherapy holiday, with a margin-negative resection of thymic adenocarcinoma. He has subsequently recovered and undergone successful allogeneic hematopoietic stem cell transplant. CONCLUSIONS: We present a case of synchronous adult acute myeloid leukemia and primary thymic adenocarcinoma requiring a tailored approach for management of simultaneous malignancies.

Meeting the New Commission on Cancer Operative Standards: Where Do We Stand Now?

INTRODUCTION: The 2020 Commission on Cancer accreditation standards 5.7 and 5.8 address total mesorectal excision for rectal cancer and lymph node sampling for lung cancer. The purpose of this review was to assess our institution's compliance with these operative standards, which will be required in 2022 and 2023, and provide recommendations to other military training facilities seeking to comply with these standards. MATERIALS AND METHODS: A 2018-2020 single institution chart review was performed of operative and pathology reports. Identified deficits were addressed in meetings with colorectal and thoracic surgery leadership, and cases were followed to reassess compliance. RESULTS: A total of 12 rectal and 48 lung cancer cases met the inclusion criteria and were examined. Pre-intervention compliance for standards 5.7 and 5.8 was 58% and 35%, respectively, because of inadequate synoptic reporting and lymph node sampling. After intervention, compliance was 100%. CONCLUSIONS: Our institution requires changes to comply with new standards, including in areas of documentation and systematic pulmonary lymph node sampling. We provide lessons learned from our own institutional experience, including practical tips and recommendations to achieve compliance. All military training facilities performing lung and rectal oncologic resections should conduct an internal review of applicable cases in preparation for upcoming American College of Surgeons Commission on Cancer site visits.

The use of lobectomy for management of clinically significant pulmonary vein stenosis and occlusion refractory to percutaneous intervention.

Pulmonary vein stenosis (PVS) is a serious complication of radiofrequency ablation (RFA) for the treatment of atrial fibrillation. The prevalence of this complication was reported to be as high as 42% in 1999 when RFA was first implemented [1]. However, with improvements in operator technique including wide area circumferential ablation, antral isolation, and the use of intracardiac ultrasound, the incidence of symptomatic severe PVS following RFA ranges from 0% to 2.1% while the incidence of symptomatic pulmonary vein occlusion (PVO) following RFA was found to be 0.67% [2-8]. Despite a decrease in the incidence of clinically significant PVS following RFA, there have been increased reports of complications associated with PVS to include hemoptysis, scarring, lung infarction, and intraparenchymal hemorrhage [9]. Studies have shown that PVS is often misdiagnosed as pneumonia, pulmonary embolism, and lung cancer and as a result, patients are often subjected to unnecessary diagnostic procedures [2,10]. The current first line treatment for this condition is percutaneous balloon angioplasty with stenting; however, there are studies that have shown that there is a relatively high rate of restenosis despite optimal medical therapy [2-3,10,11]. Three case reports have described the use of lobectomy to treat patients with persistent respiratory symptoms in the setting of severe PVO with good outcomes [12-14]. We present a case of iatrogenic PVO and ipsilateral severe PVS following RFA who underwent attempted lobectomy for persistent exertional dyspnea and persistent hypoperfusion of the left upper lung lobe despite percutaneous intervention and six months of optimal medical therapy. The lobectomy was aborted due to the presence of a significant fibrothorax, and the patient continues to have significant exercise limitation despite participation in pulmonary rehabilitation.

Necrotizing soft tissue infection following a peripheral bypass.

BACKGROUND: Necrotizing soft tissue infection (NSTI), formerly referred to as necrotizing fasciitis, is a rare but serious postoperative complication. NSTI following arterial bypass is seen only once in the literature (for a coronary artery bypass) and is not mentioned following peripheral bypass. Although surgical site infections have been studied extensively, there are limited published data on postoperative NSTI and no data for NSTI following peripheral arterial bypass. CASE PRESENTATION: Here we present the first, to our knowledge, reported instance of an NSTI following a lower extremity peripheral bypass. Despite the continued function of the bypass, the patient became rapidly systemically ill with a focus at the surgical site. Because of prompt surgical debridement, the patient survived this severe infection, though did require an above the knee amputation to control the rapid spread of the disease. The patient, a native of American Samoa, was infected with organisms infrequently associated with NSTI, Morganella morganii and Aeromonas hydrophila. This article discusses the diagnosis and treatment of this rare postoperative complication, along with a brief review of the microbiology of the disease. CONCLUSIONS: NSTI is a rare but lethal postoperative complication. To our knowledge, this is the first reported case of an NSTI following an arterial peripheral bypass. This patient survived because of prompt and aggressive intervention.

Spinal epidural abscess due to tropical pyomyositis in immunocompetent adolescents.

Pyomyositis, a suppurative infection of skeletal muscle, is a disease not frequently encountered by neurosurgical providers. While previously considered an infection localized to tropical and semitropical locations, clinical reports of pyomyositis in temperate climates have increased over the past decade. Paraspinal involvement is uncommon in pyomyositis; however, the potential exists for spread into the epidural space resulting in a spinal epidural abscess (SEA). Early diagnosis of an SEA is frequently hampered by the absence of specific signs, unfamiliarity with the disease, atypical manifestations, and a broad differential diagnosis that includes more common causes of back pain. To date, 1 such case of paraspinal pyomyositis associated with an SEA has been reported in the neurosurgical literature. The authors present 2 cases of pyomyositis with an SEA and review the epidemiology, pathophysiology, diagnostic workup, and management of this disorder.

Raloxifene and selective cell cycle specific agents: a case for the inclusion of raloxifene in current breast cancer treatment therapies.

BACKGROUND: Breast cancer patients are at increased risk of osteoporosis. Contributing factors include age and/or chemotherapy. The selective estrogen modulator, raloxifene (RAL), effective in the prevention of breast cancer and approved for the treatment and prevention of osteoporosis, may prove beneficial in current breast cancer treatment modules. The purpose of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU) and trimetrexate (TMX) to determine the most effective sequence in which to administer these cell cycle specific agents while taking into consideration the cellular mechanism of action. The goal was to maintain cytotoxicity to breast cancer cells and capitalize on the selective estrogen receptor modulatory effects of RAL. MATERIALS AND METHODS: MCF-7 cells were exposed to (i) TMX, 5-FU or RAL alone, or (ii) RAL 24 h prior to 5-FU followed 2 h later by TMX, or (iii) 5-FU 2 h prior to TMX followed 24 h later by RAL. The cell viability was determined using the Quick Cell Proliferation Assay. RESULTS: The growth rate of MCF- 7 cells exposed to early RAL was 68.25 +/- 4.11% that of the control, however, late RAL exposure produced a growth of 34.75 +/- 4.79% that of the control. Late RAL maintained the cytotoxicity of the regimen. The findings were further supported by cell flow cytometry and Western blot analysis data. CONCLUSION: RAL given prior to 5-FU/TMX significantly compromised cytotoxicity to breast cancer cells.

Ligand binding and circular permutation modify residue interaction network in DHFR.

Residue interaction networks and loop motions are important for catalysis in dihydrofolate reductase (DHFR). Here, we investigate the effects of ligand binding and chain connectivity on network communication in DHFR. We carry out systematic network analysis and molecular dynamics simulations of the native DHFR and 19 of its circularly permuted variants by breaking the chain connections in ten folding element regions and in nine nonfolding element regions as observed by experiment. Our studies suggest that chain cleavage in folding element areas may deactivate DHFR due to large perturbations in the network properties near the active site. The protein active site is near or coincides with residues through which the shortest paths in the residue interaction network tend to go. Further, our network analysis reveals that ligand binding has "network-bridging effects" on the DHFR structure. Our results suggest that ligand binding leads to a modification, with most of the interaction networks now passing through the cofactor, shortening the average shortest path. Ligand binding at the active site has profound effects on the network centrality, especially the closeness.

Sequence-dependent administration of raloxifene and 5-fluorouracil/pemetrexed protects against pemetrexed cytotoxicity in human bone marrow.

BACKGROUND: Pemetrexed (Alimta) is a new-generation multitargeted antifolate that inhibits several key enzymes in the de novo pathways of pyrimidine and purine biosynthesis, including thymidylate synthase (TS), dihydrofolate reductase (DHFR) and glycinamide ribonucleotide formyltransferase (GARFT). Alimta has demonstrated antitumor activity in a broad array of human malignancies, e.g. breast, non-small cell lung cancer, malignant pleural mesothelioma and pancreatic, colorectal, gastric, bladder, head and neck cancer, and is currently in phase III clinical trials. It has been reported that a dose of 600 mg/m2 of pemetrexed showed toxicity to bone marrow and the gastrointestinal system. The aim of this investigation was to evaluate raloxifene (RAL) in combination with 5-fluorouracil (5-FU)/pemetrered multitargeted antifolate (MTA) to determine the most effective regimens and cellular mechanism of action to mitigate pemetrexed cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: In order to determine the sequence-dependent interaction between MTA, 5-FU and RAL on proliferation, cell viability was carried out using the Quick Cell Proliferation Assay by exposing the HS-5 and MCF-7 cells to (i) MTA, 5-FU and RAL alone, or (ii) RAL 24 h prior to 5-FU followed 2 h later by MTA, or (iii) 5-FU 2 h prior to MTA followed 24 h later by RAL. RESULTS: The growth rate in MCF-7 in early RAL was 69 +/- 8.65% and late RAL was 36 +/- 4.6% of the control whereas in bone marrow early RAL was 78 +/- 8.65% and late RAL was 52 +/- 5.49% of the control. The late RAL exhibits significant protection against MTA cytotoxicity in bone marrow. The findings were further supported by cell flow cytometry, apoptosis and Western blot analysis data. CONCLUSION: This study suggests that sequence-dependent administration of RAL (5FU/MTA/RAL), in combination with 5-FU/MTA, protects against MTA toxicity in human bone marrow while maintaining the maximum inhibitory effect of pemetrexed in breast cancer.

Sequence-dependent administration of 5-fluorouracil maintains methotrexate antineoplastic activity in human estrogen-negative breast cancer and protects against methotrexate cytotoxicity in human bone marrow.

BACKGROUND: Breast cancer is a leading cause of morbidity and mortality in women in developed countries and in increasingly developing countries. In general, estrogen receptor (ER)-positive breast cancers have a better prognosis and are often more responsive to anti-estrogen therapy. Unfortunately, ER-negative breast cancers are more aggressive and unresponsive to anti-estrogens. The aim of this investigation was to evaluate the 5-fluorouracil (5-FU) and methotrexate (MTX) combination to determine the most effective regimen considering the mechanism of action in treating ER-negative human breast cancer cells and at the same time mitigating methotrexate cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: In order to determine the sequence-dependent interaction between MTX and 5-FU on proliferation, cell viability was carried out using the Quick Cell Proliferation Assay by exposing the human estrogen negative (MDA-MB-436 and Hs-578T) and bone marrow (HS-5) cells to: (i) MTX and 5-FU alon; (ii) MTX 2 h prior to 5-FU (MTX/5-FU; (iii) 5-FU 2 h prior to MTX (5-FU/MTX). RESULTS: The growth rate in MDA-MB-436 was 23.5 +/- 3.98%, in Hs-578T 30 +/- 5.9% and HS-5 32 +/- 3.1% of the control for MTX/5-FU. Whereas the growth rate in MDA-MB-436 was 28.5 +/- 4.1%, in Hs-578T 34.7 +/- 3.5% and HS-5 68.6 +/- 6.3% of the control for 5-FU/MTX combinations. The later combination exhibits significant protection against MTX cytotoxicity in bone marrow and at same time maintained maximum cytotoxicity in estrogen negative breast cancer cell lines. The findings were further supported by cell flow cytometry, apoptosis and Western blot analysis data. CONCLUSION: The combination of 5-FU/MTX effectively maintains the maximum inhibitory effect of MTX in ER-negative breast cancer and protects against MTX cytotoxicity in human bone marrow.

Raloxifene attenuation of 5-FU/methotrexate cytotoxicity in human breast cancer cells: the importance of sequence in combination chemotherapy.

BACKGROUND: The selective estrogen receptor modulator raloxifene (RAL), used to treat and prevent osteoporosis, is under investigation for its use in the treatment and prevention of breast cancer. RAL in combination with the antimetabolites methotrexate (MTX) and 5-fluorouracil (5-FU) has not been extensively studied. Because RAL and the antimetabolites target different phases of the cell cycle and exhibit different mechanisms of action and clinical toxicity, the effects of sequence of administration on the growth inhibition of MCF-7 human breast cancer cells were investigated. MATERIALS AND METHODS: MCF-7 human breast cancer cells were exposed to vehicle alone, 10 microM MTX, 1 microM 5-FU, 10 microM RAL, 10 microM RAL 24 hours prior to 1 microM 5-FU followed 2 hours later by 10 microM MTX, and 1 microM 5-FU 2 hours prior to 10 microM MTX followed 24 hours later by 10 microM RAL. The cells were evaluated for viability and proliferation. The retinoblastoma (Rb) protein, a cell cycle regulator which when phosphorylated allows the progression of cells from G1- to S-phase, was used as a marker to determine the effects of early RAL and late RAL on cellular progression at the molecular level. RESULTS: Early RAL administration exhibited a cell viability of 66.83 +/- 6.17% of the control. However, late RAL administration exhibited cell viability 39.40 +/- 17.03% of the control. Late RAL was a more cytotoxic combination than RAL alone or early RAL. These findings from manual cell counting were also supported by cell flow cytometric analysis and Western blot data. CONCLUSION: Late RAL in combination with 5-FU and MTX, due to greater cytotoxicity, is a more desirable combination to treat breast cancer than RAL alone.

Raloxifene attenuation of methotrexate cytotoxicity in human bone marrow by sequence-dependent administration of raloxifene, 5-FU/methotrexate.

BACKGROUND: Increasing evidence suggests that adjuvant systemic chemotherapy is necessary for the survival of breast cancer patients. Antitumor agents are more effective when used in combination with drugs exhibiting different mechanisms of action than when used alone. Previous studies from this laboratory have shown that raloxifene (RAL) attenuation of 5-fluorouracil/methotrexate (5-FU/MTX) cytotoxicity to breast cancer cells was sequence-dependent. The aim was to evaluate the same combination of RAL, 5-FU and MTX to determine the most effective regimes and cellular mechanisms of action to mitigate MTX cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: The sequence-dependent interaction among MTX, 5-FU and RAL on the proliferation and viability of human bone marrow HS-5 cells was determined by the MTT assay and the Trypan blue dye exclusion assay by exposing the cells to MTX, 5-FU and RAL alone, RAL 24 h prior to 5-FU followed 2 h later by MTX, and 5-FU 2 h prior to MTX followed 24 h later by RAL. The control cells were untreated. RESULTS: The growth rate in MCF-7 in early RAL was 68 +/- 3.07% and late RAL 37 +/- 2.05% of the control rate, whereas in bone marrow the same drug combinations exhibit a significant protection against MTX cytotoxity, with the early RAL combination yielding 81 +/- 3.77% and late 54 +/- 2.74% of the control. The finding was further supported by cell flow cytometry and Western blot analysis. CONCLUSION: Sequence-dependent administration of RAL in combination with 5-FU/MTX may have maximum antineoplastic activity in breast cancer while at the same time provide protection to human bone marrow.

Barnase thermal titration via molecular dynamics simulations: detection of early denaturation sites.

The thermal stability of barnase has been studied using constant pressure and temperature (CPT) molecular dynamics at different temperatures. Barnase X-ray coordinates were obtained from the Research Collaboratory for Structural Bioinformatics (RCSB) Protein Data Bank (PDB code:1rnb). Simulations were performed at 285, 295, 300, 335, 345, and 395 K in explicit water under periodic boundary conditions for 280 ps. For each simulation, conformations were saved every 0.2 ps. Root mean square deviation (RMSD) values were calculated relative to the starting structure at 300 K and at time t = 0. Root mean square fluctuation (RMSF) values were calculated relative to the average structure obtained from the 300K simulation. Both root mean square deviation and fluctuation analysis indicated the presence of discrete regions of hyper-sensitivity along the barnase polypeptide chain. These regions exhibited spikes in flexibility prior to any global structural changes. The specific changes in barnase backbone flexibility are accompanied by increased phi/psi angle fluctuations. These results suggest the presence of early denaturation sites or denaturation nuclei whose local structure is disrupted prior to global structure disruption. Identification of denaturation nuclei suggests that appropriate amino acid replacements at these sites may lead to the design and development of more stable barnase mutants. This strategy of identifying denaturation nuclei in protein structures may represent a first step in the design of more stable protein structures.

The protection against trimetrexate cytotoxicity in human bone marrow by sequence-dependent administration of raloxifene, 5-fluorouracil/trimetrexate.

BACKGROUND: Currently, one of the most effective strategies for the treatment and prevention of breast cancer is the use of drugs that block estrogen action in the breast. The success of the first clinically relevant selective estrogen receptor modulator (SERM), tamoxifen, provided the foundation for further testing of this drug to reduce breast cancer incidence in high-risk women. However, the negative effects associated with the long-term use of tanrhoxifen have initiated the search for compounds that are more effective but less toxic. The discovery of raloxifene (RAL), which functions as a potent antiestrogen in the breast but an estrogen receptor (ER) agonist in the bone and cardiovascular system with very little uterotropic activity, provided an alternative strategy to the targeted use of tamoxifen. The aim of this study was to evaluate RAL in combination with 5-fluorouracil (5-FU)/trimetrexate (TMX) to determine the most effective regimes and cellular mechanism of action to mitigate trimetrexate cytotoxicity in human bone marrow cells. MATERIALS AND METHODS: The cell viability was performed using the Quick Cell Proliferation Assay by exposing the cells to TMX, 5-FU and RAL alone; RAL 24 h prior to 5-FU followed 2 h by TMX, and 5-FU 2 h prior to TMX followed 24 h by RAL determined the sequence-dependent interaction between TMX, 5-FU and RAL on the proliferation. RESULTS: The growth rate in MCF-7 in late RAL was 34.75 +/- 4.79% of the control, whereas in bone marrow the same drug combination exhibits a significant protection against TMX cytotoxicity with late RAL yielding 51.25 +/- 4.43% of the control. The findings were also supported by Cell flow cytometry and Western blot analysis. CONCLUSION: Sequence-dependent administration of RAL in combination with 5-FU/TMX can act against TMX toxicity in human bone marrow, while not affecting the maximum inhibitory effect of TMX in breast cancer.

Sequence- and time-dependent antagonism between raloxifene and methotrexate in human breast cancer cells.

The selective estrogen receptor modulator (SERM) and an agent for the prevention of osteoporosis in postmenopausal women, raloxifene (Ral), decreased high-dose methotrexate (MTX) cytotoxicity in MCF-7 breast cancer cells. When Ral is given at least 24 hours prior to MTX, the resultant interaction is antagonistic. However, when breast cancer cells are exposed to Ral 24 hours after MTX, the interaction between Ral and MTX is not antagonistic. The proliferation of cells exposed to 10 microM Ral and 10 microM MTX alone or in combination with Ral 24 hours prior to MTX was in had the following order: MTX > Ral 24 hours prior to MTX > Ral. MTX administration 24 hours prior to Ral had the following inhibitory effects on the growth of cells: MTX 24 hours prior to Ral > or = MTX > Ral 24 hours prior to MTX > Ral > control (no drug exposure). To determine if the antagonistic interaction between Ral and MTX was a function of sequence and time, cells were exposed to Ral 24 hours and 36 hours prior to MTX exposure. The percentages of control rates were 43.48 +/- 3.90% and 54.43 +/- 2.93%, respectively, from a 24 hours and 36 hours exposure of Ral prior to MTX. The growth rates after 24 h and 36 h exposures to MTX alone were 30.30 +/- 0.61% and 33.11 +/- 2.27% of control rates, respectively. These studies suggest that: (a) the interactions between Ral and MTX are sequence-dependent; (b) Ral antagonizes the effect of MTX when Ral administration precedes MTX; and (c) Ral antagonism to MTX is a function of time.