Automatic control of water content in a polyurethane foam packed bed used in biotrickling filters for polluted air treatment

Biotrickling filters (BTF) have been applied to treat waste air. Controlling the water content (WC) of BTFs is fundamental to ensure an adequate interfacial mass transfer and the support of the biofilm activity. A sensor system based on electrical conductance measurement was developed for the online assessment of the WC in a bench scale polyurethane foam (PUF) packed bed. ON/OFF and rule-based control algorithms were applied to keep the water content in a biofilm-free PUF-packed bed within the optimal range of 70-90% through the activation of a hydraulic pump. The applied control algorithms activated the pump at various times, which yielded different energy and water savings even under similar WC conditions suitable for biotrickling filtration of waste air. It was estimated that using the ON/OFF and rule-based system control schemes reduced the electrical power consumption by 98% and 99.8%, respectively, compared to systems under continuous water irrigation.

The unrestricted global effort to complete the COOL trial

BACKGROUND

Severe complicated intra-abdominal sepsis (SCIAS) has an increasing incidence with mortality rates over 80% in some settings. Mortality typically results from disruption of the gastrointestinal tract, progressive and self-perpetuating bio-mediator generation, systemic inflammation, and multiple organ failure. A further therapeutic option may be open abdomen (OA) management with negative peritoneal pressure therapy (NPPT) to remove inflammatory ascites and attenuate the systemic damage from SCIAS, although there are definite risks of leaving the abdomen open whenever it might possibly be closed. This potential therapeutic paradigm is the rationale being assessed in the Closed Or Open after Laparotomy (COOL trial) ( https://clinicaltrials.gov/ct2/show/NCT03163095 ). Initially, the COOL trial received Industry sponsorship; however, this funding mandated the use of a specific trademarked and expensive NPPT device in half of the patients allocated to the intervention (open) arm. In August 2022, the 3 M/Acelity Corporation without consultation but within the terms of the contract canceled the financial support of the trial. Although creating financial difficulty, there is now no restriction on specific NPPT devices and removing a cost-prohibitive intervention creates an opportunity to expand the COOL trial to a truly global basis. This document describes the evolution of the COOL trial, with a focus on future opportunities for global growth of the study.

METHODS

The COOL trial is the largest prospective randomized controlled trial examining the random allocation of SCIAS patients intra-operatively to either formal closure of the fascia or the use of the OA with an application of an NPPT dressing. Patients are eligible if they have free uncontained intraperitoneal contamination and physiologic derangements exemplified by septic shock OR severely adverse predicted clinical outcomes. The primary outcome is intended to definitively inform global practice by conclusively evaluating 90-day survival. Initial recruitment has been lower than hoped but satisfactory, and the COOL steering committee and trial investigators intend with increased global support to continue enrollment until recruitment ensures a definitive answer.

DISCUSSION

OA is mandated in many cases of SCIAS such as the risk of abdominal compartment syndrome associated with closure, or a planned second look as for example part of "damage control"; however, improved source control (locally and systemically) is the most uncertain indication for an OA. The COOL trial seeks to expand potential sites and proceed with the evaluation of NPPT agnostic to device, to properly examine the hypothesis that this treatment attenuates systemic damage and improves survival. This approach will not affect internal validity and should improve the external validity of any observed results of the intervention.

TRIAL REGISTRATION

National Institutes of Health ( https://clinicaltrials.gov/ct2/show/NCT03163095 ).

True impact of the indication of cirrhosis and the MELD on the results of liver transplantation

Our Aim was to determine the impact of cirrhosis and the preoperative MELD score on the immediate postoperative mortality and hospital stay as well as survival at 1, 5, and 8 years in liver transplantation.

MATERIALS AND METHODS

Transplanted cirrhotic patients were selected who did not display some of the main known risk factors affecting recipient. Donor and surgical technique were included in this analysis. These exclusion criteria for recipient factors were emergency transplants and retransplants; for donor factors, age over 60 years, ischemia time over 10 hours, and moderate or severe steatosis on back-bench biopsy; and for surgery, prior complex upper abdominal surgery (mainly derivative and gastroduodenal surgery). Among 340 total liver transplants including 16 retransplants performed from March 1997 to December 2005, 197 patients met the selection criteria. The mean age of the recipients was 52 years (17-67) and the donors, 39 years (11-60). The transplant indication was cirrhosis in all cases: HCV in 69 cases (35%); alcohol in 55 (28%); hepatocarcinoma in 38 (19%); HBV in 19 (10%); PBC in 8 (4%), and other etiologies in 8 cases (4%). The MELD scores were divided as group 1, <10 points (33 cases = 17%); group 2, 10 to 18 points (136 cases = 69%); and group 3, >18 points (28 cases = 14%). The statistical analysis was performed with SPSS 11.0.

RESULTS

Postoperative mortality (up to 3 months) was 16 cases (8%). The median ICU and hospital stays were 3 and 13.5 days, respectively. Overall survivals at 1, 5, and 8 years were 89%, 80%, and 77%, respectively. The survival for the same periods according to MELD group was 97%, 97%, and 97% for group 1; 87%, 76%, and 72% for group 2; and 85%, 81%, and 81% for group 3 (P = NS). The survival according to the three main indications at 1, 5, and 8 years was: HCV, 91%, 80%, and 80%; alcohol, 87%, 80%, and 71%; and hepatocarcinoma, 84%, 80%, and 80% (P = NS). No significant differences were observed among early deaths between MELD groups or transplant indications.

CONCLUSIONS

In a favorable liver transplant setting including acceptable donors, absence of prior complex abdominal surgery in the recipient, and nonemergency transplants, neither the cause of the cirrhosis nor its severity, as measured preoperatively by the MELD, were predictive of early postoperative death or long-term survival.

Liver Transplant Results for Hepatocellular Carcinoma Applying Strict Preoperative Selection Criteria

INTRODUCTION

Liver transplantation is currently the best therapeutic option for small hepatocellular carcinoma (HC) in selected cirrhotic patients. The main aim of this study was to analyze the results of a recent series of liver transplant cirrhotic patients with small HC applying strict preoperative selection criteria.

PATIENTS AND METHODS

During a period of 6 years we performed 53 liver transplants with a final diagnosis of HC on cirrhosis. The selection criteria for liver transplantation (LT) by modern imaging techniques were the Milan criteria (TNM I and II of the modified classification).

RESULTS

Of the 53 patients, 44 (83%) were transplanted with preoperatively known HC, and 9 (17%) with incidental HC. The mean time on the waiting list was 74 +/- 62 days. Despite using strict selection criteria, 23 patients (43%) exceeded the Milan criteria in the specimen and 17 (32%) even exceeded the extended criteria of the UCSF. With a mean follow-up of 2 years, only two patients have developed recurrences. The overall survival at 1, 3, and 5 years was 80%, 70%, and 70%, respectively. The survival of patients that exceeded the Milan or USF criteria at 1, 3, and 5 years was 72% and 76%; 67% and 69%; 67% and 69%, respectively.

CONCLUSIONS

The results of liver transplantation for HC are excellent when applying strict preoperative selection criteria. The current imaging methods lead to a considerable infrastaging percentage (30% to 40%), extending the indications for liver transplant due to HC beyond the scope that clinical reports would justify.

Staging of commitment and differentiation of avian cardiac myocytes

The present study establishes the earliest time point for commitment of cardiac myocyte progenitors at gastrulation and determines the effects of bromodeoxyuridine (BrdU) on postgastrulated committed cardiac progenitor cells at a molecular level. Using immunochemical and reverse transcription/polymerase chain reaction assays for cardiac muscle-specific gene expression, we found that while both pre- and postgastrulated embryonic cells were capable of cardiogenic differentiation at high cell density, only postgastrulated cells exhibited the ability to differentiate at clonal density. These data indicate that while cardiac myocyte differentiation of pregastrulated cells can occur in vitro, cell-cell interactions are necessary for this to happen. Only gastrulated cardiac progenitor cells are able to differentiate in the absence of cell-cell interactions and are therefore both specified and committed. Next, by exposing postgastrulated committed cardiac progenitor cells from embryos at various stages to BrdU, we demonstrated that these cells from the lateral-plate mesoderm vary in their ability to differentiate into cardiac myocytes in vitro. Differentiation of cardiac myocyte progenitor cells from stages 4 and 5 was completely blocked by BrdU, whereas it was not blocked in cells from stages 7 and 8 and cells from stage 6 were varied in their reaction. Analysis of cardiac myogenesis in vivo revealed that cardiac progenitors acquire BrdU resistance as they migrate, postgastrulation, anteriorly along a rostrocaudal axis. The results from these two experiments suggest that while pregastrulated cells exhibit a limited ability to undergo cardiac myocyte differentiation, only postgastrulated anterior lateral-plate mesoderm contains committed cardiac myocyte progenitors and that these committed progenitors are not equivalent in their ability to differentiate.

In vitro analysis of cardiac progenitor cell differentiation

Cardiac myoblast commitment and differentiation were studied in the developing avian embryo. Single cell analysis of isolated cardiogenic cells grown in vitro established that stage 4 (newly gastrulated) mesodermal cells are capable of myocyte differentiation in the absence of intercellular contact or short range cellular interactions. While cardiac myocytes derived from single isolated progenitors expressed muscle-specific myosin heavy chains (MHC), atrial and ventricular MHCs characteristic of in vivo development were not detected. When the same progenitors were grown at high density or in organ cultures, cell-specific, expression of atrial and ventricular MHCs was observed, suggesting a role of cell density-dependent processes for differential MHC expression. Cardiogenic mesoderm (stages 4-8) was treated with the cocarcinogen 12-O-tetradecanoylphorbol-13-acetate (TPA), maintained as organ cultures, and assayed for muscle differentiation in an attempt to identify possible stage-specific variations in cardiac progenitors. TPA irreversibly blocked the differentiation of early (stages 4-7) progenitors. When exposed to TPA, stages 4-7 cardiogenic cells failed to synthesize several muscle-specific proteins as determined by immunochemical analysis of myosin synthesis and two-dimensional gel electrophoresis of 35S-labeled proteins isolated from cardiogenic cultures. In addition, stages 4-7, TPA-treated cells did not differentiate after the withdrawal of TPA. In contrast, TPA had no effect on the expression of several muscle-specific proteins in late (stage 8) cells including the cell-specific expression of atrial and ventricular MHCs.