Arsenate-dependent growth is independent of an ArrA mechanism of arsenate respiration in the termite hindgut isolate Citrobacter sp. strain TSA-1.

Citrobacter sp. strain TSA-1 is an enteric bacterium isolated from the hindgut of the termite. Strain TSA-1 displays anaerobic growth with selenite, fumarate, tetrathionate, nitrate, or arsenate serving as electron acceptors, and it also grows aerobically. In regards to arsenate, genome sequencing revealed that strain TSA-1 lacks a homolog for respiratory arsenate reductase, arrAB, and we were unable to obtain amplicons of arrA. This raises the question as to how strain TSA-1 achieves As(V)-dependent growth. We show that growth of strain TSA-1 on glycerol, which it cannot ferment, is linked to the electron acceptor arsenate. A series of transcriptomic experiments were conducted to discern which genes were upregulated during growth on arsenate, as opposed to those on fumarate or oxygen. For As(V), upregulation was noted for 1 of the 2 annotated arsC genes, while there was no clear upregulation for tetrathionate reductase (ttr), suggesting that this enzyme is not an alternative to arrAB as occurs in certain hyperthermophilic archaea. A gene-deletion mutant strain of TSA-1 deficient in arsC could not achieve anaerobic respiratory growth on As(V). Our results suggest that Citrobacter sp. strain TSA-1 has an unusual and as yet undefined means of achieving arsenate respiration, perhaps involving its ArsC as a respiratory reductase as well as a detoxifying agent.

Single-Center Comparison of Overall Survival and Toxicities in Patients with Infiltrative Hepatocellular Carcinoma Treated with Yttrium-90 Radioembolization or Drug-Eluting Embolic Transarterial Chemoembolization.

PURPOSE: To compare overall survival and toxicities after yttrium-90 (90Y) radioembolization and chemoembolization with drug-eluting embolics (DEE) in patients with infiltrative hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Retrospective review of 50 patients with infiltrative HCC without main portal vein invasion who were treated with 90Y radioembolization (n = 26) or DEE chemoembolization (n = 24) between March 2007 and August 2012 was completed. Infiltrative tumors were defined by cross-sectional imaging as masses that lacked well-demarcated boundaries, and treatment allocations were made by a multidisciplinary tumor board. Median age was 63 years; median tumor diameter was 9.0 cm; and there were no significant differences between groups in performance status, severity of liver disease, or HCC stage. Toxicities were graded by Common Terminology Criteria for Adverse Events v4.03. Overall survival from treatment was assessed by Kaplan-Meier analysis, with analysis of potential predictors of survival with log-rank test. RESULTS: There was no difference in the average number of procedures performed in each treatment group (DEE, 1.5 ± 1.1; 90Y, 1.6 ± 0.5; P = .97), and technical success was achieved in all cases. Abdominal pain (73% vs 33%; P = .004) and fever (38% vs 8%; P = .01) were more frequent after DEE chemoembolization. There was no significant difference in median overall survival between treatment groups after treatment (DEE, 9.9 months; 90Y, 8.1 months; P = .11). CONCLUSIONS: 90Y radioembolization and DEE chemoembolization provided similar overall survival in the treatment of infiltrative HCC without main portal vein invasion. Abdominal pain and fever were more frequent after DEE chemoembolization.

Detection of Diazotrophy in the Acetylene-Fermenting Anaerobe Pelobacter sp. Strain SFB93.

Acetylene (C2H2) is a trace constituent of the present Earth's oxidizing atmosphere, reflecting a mixture of terrestrial and marine emissions from anthropogenic, biomass-burning, and unidentified biogenic sources. Fermentation of acetylene was serendipitously discovered during C2H2 block assays of N2O reductase, and Pelobacter acetylenicus was shown to grow on C2H2 via acetylene hydratase (AH). AH is a W-containing, catabolic, low-redox-potential enzyme that, unlike nitrogenase (N2ase), is specific for acetylene. Acetylene fermentation is a rare metabolic process that is well characterized only in P. acetylenicus DSM3246 and DSM3247 and Pelobacter sp. strain SFB93. To better understand the genetic controls for AH activity, we sequenced the genomes of the three acetylene-fermenting Pelobacter strains. Genome assembly and annotation produced three novel genomes containing gene sequences for AH, with two copies being present in SFB93. In addition, gene sequences for all five compulsory genes for iron-molybdenum N2ase were also present in the three genomes, indicating the cooccurrence of two acetylene transformation pathways. Nitrogen fixation growth assays showed that DSM3426 could ferment acetylene in the absence of ammonium, but no ethylene was produced. However, SFB93 degraded acetylene and, in the absence of ammonium, produced ethylene, indicating an active N2ase. Diazotrophic growth was observed under N2 but not in experimental controls incubated under argon. SFB93 exhibits acetylene fermentation and nitrogen fixation, the only known biochemical mechanisms for acetylene transformation. Our results indicate complex interactions between N2ase and AH and suggest novel evolutionary pathways for these relic enzymes from early Earth to modern days.IMPORTANCE Here we show that a single Pelobacter strain can grow via acetylene fermentation and carry out nitrogen fixation, using the only two enzymes known to transform acetylene. These findings provide new insights into acetylene transformations and adaptations for nutrient (C and N) and energy acquisition by microorganisms. Enhanced understanding of acetylene transformations (i.e., extent, occurrence, and rates) in modern environments is important for the use of acetylene as a potential biomarker for extraterrestrial life and for degradation of anthropogenic contaminants.

Patency and Complications of Translumbar Dialysis Catheters.

Translumbar tunneled dialysis catheter (TLDC) is a temporary dialysis access for patients exhausted traditional access for dialysis. While few small studies reported successes with TLDC, additional studies are warranted to understand the short- and long-term patency and safety of TLDC. We conducted a retrospective analysis of adult patients who received TLDC for hemodialysis access from June 2006 to June 2013. Patient demographics, comorbid conditions, dialysis details, catheter insertion procedures and associated complications, catheter patency, and patient survival data were collected. Catheter patency was studied using Kaplan-Meier curve; catheter functionality was assessed with catheter intervals and catheter-related complications were used to estimate catheter safety. There were 84 TLDCs inserted in 28 patients with 28 primary insertions and 56 exchanges. All TLDC insertions were technically successful with good blood flow during dialysis (>300 ml/minute) and no immediate complications (major bleeding or clotting) were noted. The median number of days in place for initial catheter, secondary catheter, and total catheter were 65, 84, and 244 respectively. The catheter patency rate at 3, 6, and 12 months were 43%, 25%, and 7% respectively. The main complications were poor blood flow (40%) and catheter-related infection (36%), which led to 30.8% and 35.9% catheter removal, respectively. After translumbar catheter, 42.8% of the patients were successfully converted to another vascular access or peritoneal dialysis. This study data suggest that TLDC might serve as a safe, alternate access for dialysis patients in short-term who have exhausted conventional vascular access.

Variability of apoptosis and response in N1-S1 rodent hepatomas to benzamide riboside and correlation to early changes in water apparent diffusion coefficient and sodium MR imaging.

PURPOSE: This pilot trial assesses variability of apoptosis and response 1 day after hepatic intraarterial (IA) benzamide riboside (BR) in rodent hepatomas and its correlation to water apparent diffusion coefficient (ADC) and single-quantum (SQ) and triple-quantum-filtered (TQF) sodium-23 ((23)Na) magnetic resonance (MR) imaging. MATERIALS AND METHODS: Sprague-Dawley rats (n = 8) were inoculated with 10(6) N1-S1 cells. IA BR (20 mg/kg) was infused after 14 days. Animals were killed 1 day (n = 4) or 21 days (n = 4) after therapy. Imaging was performed 1 day before and after treatment. Volume was assessed over 2 weeks. Percentage apoptosis was counted from terminal deoxynucleotidyl transferase dUTP nick-end labeling-stained slides at 400×magnification. Kruskal-Wallis tests were used to compare apoptosis, and Wilcoxon signed-rank tests were used to compare MR signal intensity (SI). RESULTS: Apoptosis was marginally greater in tumor than in nontumor (6.7% vs 1.3%; P = .08), varying from 2% to 10%. Before treatment, MR SI was greater in tumor than in nontumor (ADC, 1.18 vs 0.76 [P = .0078]; SQ, 1.20 vs 1.04 [P = .03]; TQF, 0.55 vs 0.34 [P = .03]). After treatment, tumors increased in volume (0.62 vs 0.33; P = .016) variably over 2 weeks. MR SI remained greater in tumor than in nontumor (ADC, 1.20 vs 0.77 [P = .0078]; SQ, 1.76 vs 1.15 [P = .016]; TQF, 0.84 vs 0.49 [P = .03]). SQ and TQF SI increased by 47% (P = .016) and 53% (P = .016) in tumors, whereas ADC did not change. CONCLUSIONS: Apoptosis was marginal and varied from 2% to 10%. Water ADC, SQ, and TQF MR imaging distinguished tumor from nontumor. Changes in water ADC and sodium MR imaging correlated to apoptosis and volume in select cases, but additional animals are needed to validate this trend against tumor growth.

Tumor response and apoptosis of N1-S1 rodent hepatomas in response to intra-arterial and intravenous benzamide riboside.

PURPOSE: Benzamide riboside (BR) induces tumor apoptosis in multiple cell lines and animals. This pilot study compares apoptosis and tumor response in rat hepatomas treated with hepatic arterial BR (IA) or intravenous (IV) BR. METHODS: A total of 10(6) N1-S1 cells were placed in the left hepatic lobes of 15 Sprague-Dawley rats. After 2 weeks, BR (20 mg/kg) was infused IA (n=5) or IV (n=5). One animal in each group was excluded for technical factors, which prevented a full dose administration (1 IA and 1 IV). Five rats received saline (3 IA and 2 IV). Animals were killed after 3 weeks. Tumor volumes after IA and IV treatments were analyzed by Wilcoxon rank sum test. The percentage of tumor and normal liver apoptosis was counted by using 10 fields of TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling)-stained slides at 40× magnification. The percentage of apoptosis was compared between IV and IA administrations and with saline sham-treated rats by the Wilcoxon rank sum test. RESULTS: Tumors were smaller after IA treatment, but this did not reach statistical significance (0.14 IA vs. 0.57 IV; P=0.138). There was much variability in percentage of apoptosis and no significant difference between IA and IV BR (44.49 vs. 1.52%; P=0.18); IA BR and saline (44.49 vs. 33.83%; P=0.66); or IV BR and saline (1.52 vs. 193%; P=0.18). CONCLUSIONS: Although differences in tumor volumes did not reach statistical significance, there was a trend toward smaller tumors after IA BR than IV BR in this small pilot study. Comparisons of these treatment methods will require a larger sample size and repeat experimentation.

Effect of implantation site and growth of hepatocellular carcinoma on apparent diffusion coefficient of water and sodium MRI.

Hepatocellular carcinoma (HCC) and liver metastases are an increasing problem worldwide. Non-invasive methods for the early detection of HCC and understanding of the tumor growth mechanisms are highly desirable. Both the diffusion-weighted (1)H (DWI) and (23)Na MRI reflect alterations in tissue compartment volumes in tumors, as well as physiological and metabolic transformation in cells. Effects of untreated growth on apparent diffusion coefficient of water (ADC), single quantum (SQ) and triple quantum-filtered (TQF) (23)Na MRI were compared in intrahepatically and subcutaneously implanted HCCs in rats. Animals were examined weekly for 4 weeks after injection of N1S1 cells. ADC of intrahepatic HCC was 1.5-times higher compared to the nearby liver tissue, and with growth, the ADC did not increase. ADC of subcutaneous HCC was lower compared to intrahepatic HCC and it increased with growth. Untreated growth of both intrahepatic and subcutaneous HCCs was associated with an increase in SQ and TQF (23)Na signal intensity suggesting an increase in tissue Na(+) and intracellular Na(+) (Na(+)(i)), respectively, most likely due to an increase in relative extracellular space and Na(+)(i) concentration as a result of changes in tissue structure and cellular metabolism. Thus, SQ and TQF (23)Na MRI may be complementary to diffusion imaging in areas susceptible to motion for characterizing hepatic tumors and for other applications, such as, predicting and monitoring therapy response.

Predicting response to benzamide riboside chemotherapy in hepatocellular carcinoma using apparent diffusion coefficient of water.

AIM: To monitor the effects of the apoptotic agent benzamide riboside (BR) on tumor volume and water apparent diffusion coefficient (ADC) in rat hepatocellular carcinoma (HCC). MATERIALS AND METHODS: Water ADC of the tumors and nearby liver tissue was measured using diffusion-weighted 1H MRI (DWI). The two groups of BR-treated animals, which differed in their sensitivity to the treatment, were identified as responsive (RBR) and non-responsive (NRBR). RESULTS: Tumor growth in the RBR group was arrested and the mean tumor volume in this group was 1/6th and 1/16th compared to that of the NRBR group on days 7 and 14 after treatment, respectively. Water ADC of HCC was higher than in nearby normal liver tissue. Before BR treatment, the mean water ADC was significantly higher in the RBR group compared to the NRBR group. BR therapy did not change the water ADC value regardless of tumor sensitivity. CONCLUSION: Although the water ADC did not change after chemotherapy by BR, DWI has great potential for detecting and predicting response to chemotherapy in HCC.

Technical aspects of imaging and transfemoral arterial treatment of N1-S1 tumors in rats: an appropriate model to test the biology and therapeutic response to transarterial treatments of liver cancers.

The present study was undertaken to assess the technical feasibility of transfemoral hepatic artery catheterization in rats and to describe the imaging techniques that can be used on tumors in rats. A total of 106 N1-S1 cells were inoculated into the left lobes of 74 rats. In 17, transfemoral angiography was attempted. Tumor volumes for 2 weeks before angiography were measured with magnetic resonance imaging in 40 animals. Tumors grew in 63 animals. Angiography was successful in 16 rats. Mean tumor volumes were 0.13 mL and 0.9 mL after 1 and 2 weeks, respectively. In conclusion, transfemoral hepatic artery catheterization is feasible in this animal model.

Expression of the unconventional myosin Myo1c alters sodium transport in M1 collecting duct cells.

Epithelial cells rely on proper targeting of cellular components to perform their physiological function. This dynamic process utilizes the cytoskeleton and involves movement of vesicles to and from the plasma membrane, thus traversing the actin cortical cytoskeleton. Studies support both direct interaction of actin with channels and an indirect mechanism whereby actin may serve as a track in the final delivery of the channel to the plasma membrane. Actin-dependent processes are often mediated via a member of the myosin family of proteins. Myosin I family members have been implicated in multiple cellular events occurring at the plasma membrane. In these studies, we investigated the function of the unconventional myosin I Myo1c in the M1 mouse collecting duct cell line. Myo1c was observed to be concentrated at or near the plasma membrane, often in discrete membrane domains. To address the possible role of Myo1c in channel regulation, we expressed a truncated Myo1c, lacking ATP and actin domains, in M1 cells and compared electrophysiological responses to control M1 cells, M1 cells expressing the empty vector, and M1 cells expressing the full-length Myo1c construct. Interestingly, cells expressing the Myo1c constructs had modulated antidiuretic hormone (ADH)-stimulated short-circuit current and showed little inhibition of short-circuit current with amiloride addition. Evaluation of enhanced green fluorescent protein-Myo1c constructs supports the importance of the IQ region in targeting the Myo1c to its respective cellular domain. These data are consistent with Myo1c participating in the regulation of the Na+ channel after ADH stimulation.

Differences in host susceptibility to disease progression in the human challenge model of Haemophilus ducreyi infection.

With human volunteers inoculated at two sites with Haemophilus ducreyi, outcomes for a subject were not independent. In a reinfection trial, 2 of 11 previous pustule formers and 6 of 10 previous resolvers resolved all sites of infection. There was no correlation between serum bactericidal or phagocytic activity and outcome in the trial. These data indicate that different hosts are differentially susceptible to disease progression versus resolution in the model.