Radiation therapy prior to a pancreaticoduodenectomy for adenocarcinoma is associated with longer operative times and higher blood loss.

BACKGROUND: Pancreatic adenocarcinoma is currently the fourth leading cause of cancer-related deaths in the United States. In patients with "borderline resectable" disease, current National Comprehensive Cancer Center guidelines recommend the use of neoadjuvant chemoradiation prior to a pancreaticoduodenectomy. Although neoadjuvant radiotherapy may improve negative margin resection rate, it is theorized that its administration increases operative times and complexity. AIM: To investigate the association between neoadjuvant radiotherapy and 30-d morbidity and mortality outcomes among patients receiving a pancreaticoduodenectomy for pancreatic adenocarcinoma. METHODS: Patients listed in the 2015-2019 National Surgery Quality Improvement Program data set, who received a pancreaticoduodenectomy for pancreatic adenocarcinoma, were divided into two groups based off neoadjuvant radiotherapy status. Multivariable regression was used to determine if there is a significant correlation between neoadjuvant radiotherapy, perioperative blood transfusion status, total operative time, and other perioperative outcomes. RESULTS: Of the 11458 patients included in the study, 1470 (12.8%) underwent neoadjuvant radiotherapy. Patients who received neoadjuvant radiotherapy were significantly more likely to require a perioperative blood transfusion [adjusted odds ratio (aOR) = 1.58, 95% confidence interval (CI): 1.37-1.82; P < 0.001] and have longer surgeries (insulin receptor-related receptor = 1.14, 95%CI: 1.11-1.16; P < 0.001), while simultaneously having lower rates of organ space infections (aOR = 0.80, 95%CI: 0.66-0.97; P = 0.02) and pancreatic fistula formation (aOR = 0.50, 95%CI: 0.40-0.63; P < 0.001) compared to those who underwent surgery alone. CONCLUSION: Neoadjuvant radiotherapy, while not associated with increased mortality, will impact the complexity of surgical resection in patients with pancreatic adenocarcinoma.

Enhanced continuous biohydrogen production using dynamic membrane with conductive biofilm supporter.

The present study investigated the effect of a conductive biofilm supporter on continuous production of biohydrogen in a dynamic membrane bioreactor (DMBR). Two lab-scale DMBRs were operated: one with a nonconductive polyester mesh (DMBR I) and the other with a conductive stainless-steel mesh (DMBR II). The highest average hydrogen productivity and the yield were 16.8% greater in DMBR II than in DMBR I, with values of 51.64 ± 0.66 L/L-d and 2.01 ± 0.03 mol H2/mol hexoseconsumed, respectively. The improved hydrogen production was concurrent with a higher NADH/NAD+ ratio and a lower ORP (Oxidation-reduction potential). Metabolic flux analysis implied that the conductive supporter promoted H2-producing acetogenesis and repressed competitive NADH-consuming pathways, such as homoacetogenesis and lactate production. Microbial community analysis revealed that electroactive Clostridium sp. were the dominant H2 producers in DMBR II. Conclusively, conductive meshes may be useful as biofilm supporters of dynamic membranes during H2 production for selectively enhancing H2-producing pathways.

Effect of bioaugmentation using Clostridium butyricum on the start-up and the performance of continuous biohydrogen production.

This study aimed to mitigate the instability in the start-up and continuous performance of dark fermentative biohydrogen production using heat-treated sludge by the addition of an exogenous H2-producing strain. Continuous fermentation augmented with Clostridium butyricum showed the highest average biohydrogen production rate (HPR) as 50.35 ± 2.56 and 58.57 ± 5.03 L/L-d with H2-producing butyric and acetic acid pathways, whereas the fermenters without bioaugmentation showed the termination of biohydrogen production in 3 days of continuous operation with non H2-producing lactic acid pathway and H2-consuming propionic acid pathway. The bioaugmentation blocked the growth of the competitors for hexose such as Streptococcus, Lactobacillus and Megasphaera, and provided H2-producer dominated microbiome with not only Clostridium butyricum, but also Clostridium puniceum and Clostridium neuense originated from heat-treated sludge. Bioaugmentation of a H2-producing strain would be a reliable dissemination strategy for dark fermentative biohydrogen production by minimizing the influence of seed sludge population.

Biohydrogen and biomethane production from food waste using a two-stage dynamic membrane bioreactor (DMBR) system.

This study examined a two-stage dynamic membrane bioreactor (DMBR) system for biohydrogen and biomethane production from food waste (FW) in mesophilic condition. The two-stage DMBR system enabled high-rate H2 and CH4 production from particulate feedstock by enhanced microorganism retention. Chemical energy in FW was recovered up to 79% as renewable energy. The highest average hydrogen production rate of 7.09 ± 0.42 L/L-d was observed at a hydraulic retention time (HRT) of 8 h in the H2-DMBR, while the highest CH4 average production rate of 0.99 ± 0.02 L/L-d was observed at an HRT of 6 d in the CH4-DMBR. The high specific methanogenic activity of 71.7 mL CH4/g VSS-d was maintained at the short HRT, which also contributed to the high MPR. The genus Clostridium was dominant in the H2-DMBR, while bacterial and archaeal populations in the CH4-DMBR were dominated by the class Clostridia and genera Methanobacterium and Methanosaeta, respectively.

High-rate biohydrogen production from xylose using a dynamic membrane bioreactor.

This study aimed a high-rate dark fermentative H2 production from xylose using a dynamic membrane module bioreactor (DMBR) with a 444-µm pore polyester mesh. 20 g xylose/L was fed continuously to the DMBR at different hydraulic retention times (HRTs) from 12 to 3 h at 37 °C. The maximum average H2 yield (HY) and H2 production rate (HPR) at 3 h HRT were found to be 1.40 ± 0.07 mol H2/mol xyloseconsumed and 30.26 ± 1.19 L H2/L-d, respectively. The short HRT resulted in the maximum suspended biomass concentration (8.92 ± 0.40 g VSS/L) along with significant attached biomass retention (7.88 ± 0.22 g VSS/L). H2 was produced by both butyric and acetic acid pathways. Low HY was concurrent with lactic acid production. The bacterial population shifted from non-H2 producers, such as Lactobacillus and Sporolactobacillus spp., to Clostridium sp., when HY increased. Thus, xylose from lignocellulose is a feasible substrate for dark fermentative H2 production using DMBR.

Effect of genus Clostridium abundance on mixed-culture fermentation converting food waste into biohydrogen.

This study examined the effect of various inocula on mixed-culture dark fermentative H2 production from food waste. Heat-treated and frozen H2-producing granular sludge (HPG) grown with monomeric sugars showed a higher H2 yield, production rate, and acidogenic efficiency along with a shorter lag phase than heat-treated methanogenic sludge. Among three different methods of methanogenic sludge inoculation, inoculation after centrifugation showed better H2 production performance. Propionic acid production and homoacetogenesis were regarded as major H2-consuming pathways when methanogenic sludge was used, whereas only homoacetogenesis was found in HPG-inoculated fermentation. During fermentation, the abundance of Clostridium increased greater than 48-fold for methanogenic sludge and greater than 108-fold for HPG, respectively. The initial abundance of Clostridium showed a linear relationship with the H2 production rate and lag-phase time. The use of inoculum with a high abundance of Clostridium is essential for H2 production from food waste.

Dynamic membrane bioreactor for high rate continuous biohydrogen production from algal biomass.

This study aimed to achieve continuous biohydrogen production from red algal biomass using a dynamic membrane bioreactor (DMBR). The DMBR was continuously fed with pretreated Echeuma spinosum containing 20 g/L hexose. The highest average hydrogen production rate (HPR) of 21.58 ± 1.59 L/L-d was observed at HRT 3 h, which was higher than previous reports for continuous H2 production from biomass feedstock. Metabolic flux analysis revealed that butyric acid and propionic acid were the major by-products of the H2-producing and H2-consuming pathways, respectively, of the algal biomass fermentation. Hydrogen consumption by propionic acid pathway could not be prevented completely by heat treatment. PICRUSt2 analysis predicted that Clostridium sp., Anaerostipes sp., and Caproiciproducens sp. might significantly contribute to the expression of both ferredoxin hydrogenase and propionate CoA-transferase. This study would provide the design and operational information on high-rate bioreactor for continuous hydrogen production using biomass.

High-rate mesophilic hydrogen production from food waste using hybrid immobilized microbiome.

This study examined the feasibility of dark fermentative biohydrogen production from food waste using hybrid immobilization in mesophilic condition. Among four different organic loading rates (OLRs), the highest average hydrogen production rate (HPR) of 9.82 ± 0.30 L/L-d was found at an OLR of 74.7 g hexose/L-d, which was higher than reported values from particulate feedstock in mesophilic condition. The average hydrogen yield (HY) at the condition was 1.25 ± 0.04 mol H2/mol hexoseconsumed. Whereas the average HPR and HY at an OLR 80 g hexose/L-d were 5.82 ± 0.12 L/L-d and 0.64 ± 0.02 mol H2/mol hexoseconsumed, respectively. Metabolic flux analysis showed the low HY was concurrent with the highest propionic acid and homoacetogenis. Bacterial population was shift from Clostridium sp. to non-hydrogen producers including Bifidobacterium, Bacteriodes, Olsenella, Dysgonomonas, and Dialister sp.

Effect of shear velocity on dark fermentation for biohydrogen production using dynamic membrane.

This study examined the effect of shear velocity on biohydrogen producing dynamic membrane bioreactor (DMBR) containing 50 µm polyester mesh as supporting material. Increase of shear velocity up to 6.75 m/h enhanced hydrogen production performance as well as biomass retention in both suspended and attached forms, while wash-out was found at a shear velocity of 11.69 m/h. The highest average HPR, HY, suspended biomass, and attached biomass were 26.56 ± 1.49 L/L-d, 1.78 ± 0.10 mol H2/mol glucoseadded, 9.99 ± 0.11 g VSS/L, and 8.82 g VSS/L, respectively, at a shear velocity of 6.75 m/h. Flux balance analysis showed homoacetogenic pathway decreased at the shear velocity of 4.70 m/h with the increase of hydrogen yield based on consumed substrate. The highest copy numbers of Clostridium butyricum was found at the optimum shear velocity. Shear velocity would be a critical operational criteria for continuous biohydrogen production using DMBR.

Formation of a dynamic membrane altered the microbial community and metabolic flux in fermentative hydrogen production.

This study aimed to investigate the relationship among dynamic membrane (DM) formation, metabolic flux, and microbial community population in dark fermentative hydrogen production. A continuously stirred tank reactor was equipped with an external submerged polyester screen mesh and inoculated with heat-treated anaerobic sludge without immobilization. DM was successfully developed on the polyester mesh and provided high-rate hydrogen production at 60.5 L H2/L.d and 2.39 mol H2/mol glucoseadded. DM formation was along with tightly bound extracellular polymeric substances. Flux balance analysis revealed that formation of DM altered the metabolic pathways for acetic acid production from homoacetogenesis to hydrogenesis. Bacterial community analysis suggested that Sporolactobacillaceae would contributed to this metabolic pathway shift. Nevertheless, lactic acid was not accumulated and assumed to be consumed by hydrogen producers including Clostridia.

Kinetic modeling and microbial community analysis for high-rate biohydrogen production using a dynamic membrane.

This study investigated the kinetic parameters of high-rate continuous performance and biofilm layer formation in a H2-producing dynamic membrane bioreactor, composed of a continuously stirred tank reactor along with an external module containing polyester mesh with a pore size of 100 µm. A maximum H2 production rate of 48.9 L/L-day and hydrogen yield of 2.8 mol/mol glucoseadded were attained at a hydraulic retention time of 3 h. The maximum specific growth rate and Monod constant were estimated as 14.92 d-1 and 1.02 g COD/L, respectively. During the entire operation without backwashing, the transmembrane pressure remained below 1.7 kPa, while tightly bound extracellular polymeric substances increased as the dynamic membrane was developed. Fluorescent in situ hybridization and quantitative polymerase chain reaction assays revealed that Clostridium butyricum was dominant in all samples; however, the biofilm had a higher proportion of Prevotella spp. than the fermentation liquor.