Automated liver volumetry and hepatic steatosis quantification with magnetic resonance imaging proton density fat fraction.

BACKGROUND: Preoperative imaging evaluation of liver volume and hepatic steatosis for the donor affects transplantation outcomes. However, computed tomography (CT) for liver volumetry and magnetic resonance spectroscopy (MRS) for hepatic steatosis are time consuming. Therefore, we investigated the correlation of automated 3D-multi-echo-Dixon sequence magnetic resonance imaging (ME-Dixon MRI) and its derived proton density fat fraction (MRI-PDFF) with CT liver volumetry and MRS hepatic steatosis measurements in living liver donors. METHODS: This retrospective cross-sectional study was conducted from December 2017 to November 2022. We enrolled donors who received a dynamic CT scan and an MRI exam within 2 days. First, the CT volumetry was processed semiautomatically using commercial software, and ME-Dixon MRI volumetry was automatically measured using an embedded sequence. Next, the signal intensity of MRI-PDFF volumetric data was correlated with MRS as the gold standard. RESULTS: We included the 165 living donors. The total liver volume of ME-Dixon MRI was significantly correlated with CT (r = 0.913, p < 0.001). The fat percentage measured using MRI-PDFF revealed a strong correlation between automatic segmental volume and MRS (r = 0.705, p < 0.001). Furthermore, the hepatic steatosis group (MRS ≥5%) had a strong correlation than the non-hepatic steatosis group (MRS <5%) in both volumetric (r = 0.906 vs. r = 0.887) and fat fraction analysis (r = 0.779 vs. r = 0.338). CONCLUSION: Automated ME-Dixon MRI liver volumetry and MRI-PDFF were strongly correlated with CT liver volumetry and MRS hepatic steatosis measurements, especially in donors with hepatic steatosis.

Case report of an unusual hepatic abscess caused by Actinomyces odontolyticus in a patient with human immunodeficiency virus infection.

BACKGROUND: Actinomyces odontolyticus is not commonly recognized as a causative microbe of liver abscess. The detection and identification of A. odontolyticus in laboratories and its recognition as a pathogen in clinical settings can be challenging. However, in the past decades, knowledge on the clinical relevance of A. odontolyticus is gradually increasing. A. odontolyticus is the dominant oropharyngeal flora observed during infancy [Li et al. in Biomed Res Int 2018:3820215, 2018]. Herein we report a case of severe infection caused by A. odontolyticus in an immunocompromised patient with disruption of the gastrointestinal (GI) mucosa. CASE PRESENTATION: We present a unique case of a patient with human immunodeficiency virus infection who was admitted due to liver abscess and was subsequently diagnosed as having coinfection of A. odontolyticus, Streptococcus constellatus, and Candida albicans during the hospital course. The empirical antibiotics metronidazole and ceftriaxone were replaced with the intravenous administration of fluconazole and ampicillin. However, the patient's condition deteriorated, and he died 3 weeks later. CONCLUSION: This report is one of the first to highlight GI tract perforation and its clinical relevance with A. odontolyticus infection. A. odontolyticus infection should be diagnosed early in high-risk patients, and increased attention should be paid to commensal flora infection in immunocompromised individuals.

Src-dependent phosphorylation of ROCK participates in regulation of focal adhesion dynamics.

When a cell migrates, the RhoA-ROCK-mediated contractile signal is suppressed in the leading edge to allow dynamic adhesions for protrusion. However, several studies have reported that RhoA is indeed active in the leading edge of a migrating cell during serum stimulation. Here, we present evidence that regulation of ROCKII phosphorylation at the Y722 site in peripheral focal contacts is crucial for controlling the turnover of the focal adhesion (FA) complex uncoupled from RhoA activation during serum-stimulated migration. However, this phosphorylation control is dispensable for migration when RhoA is downregulated in cells treated with platelet-derived growth factor (PDGF). We further present evidence that ROCKII is phosphorylated by Src in FAs and this phosphorylation event decreases RhoA binding activity of ROCKII. Lack of this regulatory control leads to sustained myosin-mediated contractility and FA elongation during lysophosphatidic acid (LPA) stimulation. Altogether, our data suggest that Src-dependent ROCKII phosphorylation provides a means of tuning contractility required for FAs dynamics when RhoA is active.

Mineral Nanomedicine to Enhance the Efficacy of Adjuvant Radiotherapy for Treating Osteosarcoma.

It is vital to remove residual tumor cells after resection to avoid the recurrence and metastasis of osteosarcoma. In this study, a mineral nanomedicine, europium-doped calcium fluoride (CaF2:Eu) nanoparticles (NPs), is developed to enhance the efficacy of adjuvant radiotherapy (i.e., surgical resection followed by radiotherapy) for tumor cell growth and metastasis of osteosarcoma. In vitro studies show that CaF2:Eu NPs (200 µg/mL) exert osteosarcoma cell (143B)-selective toxicity and migration-inhibiting effects at a Eu dopant amount of 2.95 atomic weight percentage. These effects are further enhanced under X-ray irradiation (6 MeV, 4 Gy). Furthermore, in vivo tests show that intraosseous injection of CaF2:Eu NPs and X-ray irradiation have satisfactory therapeutic efficacy in controlling primary tumor size and inhibiting primary tumor metastasis. Overall, our results suggest that CaF2:Eu NPs with their osteosarcoma cell (143B)-selective toxicity and migration-inhibiting effects combined with radiotherapy might be nanomedicines for treating osteosarcoma after tumor resection.

RNA interference of argininosuccinate synthetase restores sensitivity to recombinant arginine deiminase (rADI) in resistant cancer cells.

BACKGROUND: Sensitivity of cancer cells to recombinant arginine deiminase (rADI) depends on expression of argininosuccinate synthetase (AS), a rate-limiting enzyme in synthesis of arginine from citrulline. To understand the efficiency of RNA interfering of AS in sensitizing the resistant cancer cells to rADI, the down regulation of AS transiently and permanently were performed in vitro, respectively. METHODS: We studied the use of down-regulation of this enzyme by RNA interference in three human cancer cell lines (A375, HeLa, and MCF-7) as a way to restore sensitivity to rADI in resistant cells. The expression of AS at levels of mRNA and protein was determined to understand the effect of RNA interference. Cell viability, cell cycle, and possible mechanism of the restore sensitivity of AS RNA interference in rADI treated cancer cells were evaluated. RESULTS: AS DNA was present in all cancer cell lines studied, however, the expression of this enzyme at the mRNA and protein level was different. In two rADI-resistant cell lines, one with endogenous AS expression (MCF-7 cells) and one with induced AS expression (HeLa cells), AS small interference RNA (siRNA) inhibited 37-46% of the expression of AS in MCF-7 cells. ASsiRNA did not affect cell viability in MCF-7 which may be due to the certain amount of residual AS protein. In contrast, ASsiRNA down-regulated almost all AS expression in HeLa cells and caused cell death after rADI treatment. Permanently down-regulated AS expression by short hairpin RNA (shRNA) made MCF-7 cells become sensitive to rADI via the inhibition of 4E-BP1-regulated mTOR signaling pathway. CONCLUSIONS: Our results demonstrate that rADI-resistance can be altered via AS RNA interference. Although transient enzyme down-regulation (siRNA) did not affect cell viability in MCF-7 cells, permanent down-regulation (shRNA) overcame the problem of rADI-resistance due to the more efficiency in AS silencing.

Comparison Between Transposed Brachiobasilic Fistula and Arteriovenous Graft for Upper Limb Arteriovenous Access in Patients on Hemodialysis.

BACKGROUND: Creating and maintaining a functioning arteriovenous access is essential for long-term hemodialysis patients. Transposed brachiobasilic fistula (BBF) or arteriovenous graft (AVG) becomes an option when radiocephalic or brachiocephalic fistula cannot be created or fails. This study compared the patency and complications between BBFs and AVGs among patients on hemodialysis. METHODS: A retrospective study was performed in Shuang Ho Hospital, Taiwan, from November 2015 to May 2020. All the operations were done by a single surgeon. Primary outcomes were primary patency, primary-assisted patency, and secondary patency of the BBF and AVG groups. Secondary outcomes were incidence of complications and reinterventions. RESULTS: Of the 144 consecutive patients, 20 and 124 patients underwent BBF and AVG creation, respectively. Median follow-up time was 19.2 months. Primary patency at 1 and 2 years were 67% and 19% in the BBF group and 44% and 16% in the AVG group (P = 0.126). Primary-assisted patency at 1 and 2 years were 82% and 54% in the BBF group and 54% and 30% in the AVG group (P = 0.012). Secondary patency at 1 and 2 years were 100% and 82% in the BBF group and 81% and 67% in the AVG group (P = 0.078). The incidence of complication was significantly higher in the AVG than in the BBF group (1.7 per patient-year vs 0.93, P < 0.001). CONCLUSION: Compared with the AVG group, BBF group showed better primary-assisted patency, less complication and intervention rates. Therefore, BBF is a reliable option for patients with exhausted cephalic veins if basilic vein is available for reconstruction.

Guanine nucleotide exchange factor-H1 regulates cell migration via localized activation of RhoA at the leading edge.

Cell migration involves the cooperative reorganization of the actin and microtubule cytoskeletons, as well as the turnover of cell-substrate adhesions, under the control of Rho family GTPases. RhoA is activated at the leading edge of motile cells by unknown mechanisms to control actin stress fiber assembly, contractility, and focal adhesion dynamics. The microtubule-associated guanine nucleotide exchange factor (GEF)-H1 activates RhoA when released from microtubules to initiate a RhoA/Rho kinase/myosin light chain signaling pathway that regulates cellular contractility. However, the contributions of activated GEF-H1 to coordination of cytoskeletal dynamics during cell migration are unknown. We show that small interfering RNA-induced GEF-H1 depletion leads to decreased HeLa cell directional migration due to the loss of the Rho exchange activity of GEF-H1. Analysis of RhoA activity by using a live cell biosensor revealed that GEF-H1 controls localized activation of RhoA at the leading edge. The loss of GEF-H1 is associated with altered leading edge actin dynamics, as well as increased focal adhesion lifetimes. Tyrosine phosphorylation of focal adhesion kinase and paxillin at residues critical for the regulation of focal adhesion dynamics was diminished in the absence of GEF-H1/RhoA signaling. This study establishes GEF-H1 as a critical organizer of key structural and signaling components of cell migration through the localized regulation of RhoA activity at the cell leading edge.

GEF-H1 couples nocodazole-induced microtubule disassembly to cell contractility via RhoA.

The RhoA GTPase plays a vital role in assembly of contractile actin-myosin filaments (stress fibers) and of associated focal adhesion complexes of adherent monolayer cells in culture. GEF-H1 is a microtubule-associated guanine nucleotide exchange factor that activates RhoA upon release from microtubules. The overexpression of GEF-H1 deficient in microtubule binding or treatment of HeLa cells with nocodazole to induce microtubule depolymerization results in Rho-dependent actin stress fiber formation and contractile cell morphology. However, whether GEF-H1 is required and sufficient to mediate nocodazole-induced contractility remains unclear. We establish here that siRNA-mediated depletion of GEF-H1 in HeLa cells prevents nocodazole-induced cell contraction. Furthermore, the nocodazole-induced activation of RhoA and Rho-associated kinase (ROCK) that mediates phosphorylation of myosin regulatory light chain (MLC) is impaired in GEF-H1-depleted cells. Conversely, RhoA activation and contractility are rescued by reintroduction of siRNA-resistant GEF-H1. Our studies reveal a critical role for a GEF-H1/RhoA/ROCK/MLC signaling pathway in mediating nocodazole-induced cell contractility.