Timing of radiotherapy (RT) after radical prostatectomy (RP): long-term outcomes in the RADICALS-RT trial (NCT00541047)

BACKGROUND

The optimal timing of radiotherapy (RT) after radical prostatectomy for prostate cancer has been uncertain. RADICALS-RT compared efficacy and safety of adjuvant RT versus an observation policy with salvage RT for prostate-specific antigen (PSA) failure.

PATIENTS AND METHODS

RADICALS-RT was a randomised controlled trial enrolling patients with ≥1 risk factor (pT3/4, Gleason 7-10, positive margins, preoperative PSA≥10 ng/ml) for recurrence after radical prostatectomy. Patients were randomised 1:1 to adjuvant RT ('Adjuvant-RT') or an observation policy with salvage RT for PSA failure ('Salvage-RT') defined as PSA≥0.1 ng/ml or three consecutive rises. Stratification factors were Gleason score, margin status, planned RT schedule (52.5 Gy/20 fractions or 66 Gy/33 fractions) and treatment centre. The primary outcome measure was freedom-from-distant-metastasis (FFDM), designed with 80% power to detect an improvement from 90% with Salvage-RT (control) to 95% at 10 years with Adjuvant-RT. Secondary outcome measures were biochemical progression-free survival, freedom from non-protocol hormone therapy, safety and patient-reported outcomes. Standard survival analysis methods were used; hazard ratio (HR)<1 favours Adjuvant-RT.

RESULTS

Between October 2007 and December 2016, 1396 participants from UK, Denmark, Canada and Ireland were randomised: 699 Salvage-RT, 697 Adjuvant-RT. Allocated groups were balanced with a median age of 65 years. Ninety-three percent (649/697) Adjuvant-RT reported RT within 6 months after randomisation; 39% (270/699) Salvage-RT reported RT during follow-up. Median follow-up was 7.8 years. With 80 distant metastasis events, 10-year FFDM was 93% for Adjuvant-RT and 90% for Salvage-RT: HR=0.68 [95% confidence interval (CI) 0.43-1.07, P=0.095]. Of 109 deaths, 17 were due to prostate cancer. Overall survival was not improved (HR=0.980, 95% CI 0.667-1.440, P=0.917). Adjuvant-RT reported worse urinary and faecal incontinence 1 year after randomisation (P=0.001); faecal incontinence remained significant after 10 years (P=0.017).

CONCLUSION

Long-term results from RADICALS-RT confirm adjuvant RT after radical prostatectomy increases the risk of urinary and bowel morbidity, but does not meaningfully improve disease control. An observation policy with salvage RT for PSA failure should be the current standard after radical prostatectomy.

TRIAL IDENTIFICATION

RADICALS, RADICALS-RT, ISRCTN40814031, NCT00541047.

Local governments and community-based rehabilitation for developmental disabilities: leaving no one behind

SETTING

The BUDS (not an acronym) institutions comprise a community-based rehabilitation initiative for children and families affected by developmental disabilities in Kerala, India.

OBJECTIVE

To explore the role of local governments in the establishment and functioning of BUDS institutions.

DESIGN

We used qualitative approaches comprising document review and in-depth interviews with trainers, parents of children with developmental disabilities and elected representatives.

RESULTS

BUDS was created by Kudumbasree, a decentralised women empowerment and poverty alleviation initiative. Our findings illustrate the role of local governments in facilitating expansion through the establishment of infrastructure, therapy equipment, transportation and financial allocation for these, as well as through the development of human resources, assistance with enrolment for financial assistance and insurance programmes, and coordination with education and health sectors. Programme implementation varied considerably regarding available infrastructure, staffing and services among the institutions studied. The institutions were physically closed during the COVID-19 pandemic but continued to function in alternative ways.

CONCLUSION

Despite variable implementation, local governments have supported the expansion of BUDS institutions, thereby creating more spaces for inclusive and integrated education and rehabilitation of persons with disabilities in Kerala. The expansion over the past two decades and measures during the COVID-19 pandemic suggest resilience and sustainability of the model.

An Update to the Malthus Model for Radiotherapy Utilisation in England

AIMS

The Malthus Programme predicts national and local radiotherapy demand by combining cancer incidence data with decision trees detailing the indications, and appropriate dose fractionation, for radiotherapy. Since the last model update in 2017, technological advancements and the COVID-19 pandemic have led to increasing hypofractionation of radiotherapy schedules. Indications for radiotherapy have also evolved, particularly in the context of oligometastatic disease. Here we present a brief update on the model for 2021. We have updated the decision trees for breast, prostate, lung and head and neck cancers, and incorporated recent cancer incidence data into our model, generating a current estimate of fraction demand for these four cancer sites across England.

MATERIALS AND METHODS

The decision tree update was based on evidence from practice-changing randomised controlled trials, published guidelines, audit data and expert opinion. Site- and stage-specific incidence data were taken from the National Disease Registration Service. We used the updated model to estimate the proportion of patients who would receive radiotherapy (appropriate rate of radiotherapy) and the fraction demand per million population at a national and Clinical Commissioning Group level in 2021.

RESULTS

The total predicted fraction demand has decreased by 11.4% across all four cancer sites in our new model, compared with the 2017 version. This reduction can be explained primarily by greater use of hypofractionated treatments (including stereotactic ablative radiotherapy) and a shift towards earlier stage presentation. The only large change in appropriate rate of radiotherapy was an absolute decrease of 3% for lung cancer.

CONCLUSIONS

Compared with our previous model, the current version predicts a reduction in fraction demand across England. This is driven principally by hypofractionation of radiotherapy regimens, using technology that requires increasingly complex planning. Treatment complexity and local service factors need to be taken into account when translating fraction burden into linear accelerator demand or throughput.

Paroxysmal atrial fibrillation ablation with a novel flexible tip radiofrequency catheter incorporating contact force sensing: acute results of the TactiFlex AF IDE trial

Background

Catheter ablation is an established therapy for paroxysmal atrial fibrillation (PAF). The TactiFlex™ Ablation Catheter, Sensor-Enabled™ (TactiFlex SE) is a next-generation radiofrequency ablation catheter incorporating highly accurate fiber optics-based contact force sensing technology with a flexible, laser-cut tip.

Purpose

To demonstrate that ablation with TactiFlex SE is safe and effective for the treatment of drug refractory, symptomatic PAF.

Methods

The TactiFlex AF IDE is a prospective, non-randomized, multi-center clinical study which enrolled 355 subjects worldwide. Enrollment in the main study began on June 26, 2020 and completed on June 18, 2021. Subjects underwent de novo Pulmonary Vein Isolation (PVI) and, if indicated, a Cavotricuspid Isthmus ablation (CTI line) for CTI-dependent atrial flutter.

Results

Subjects were divided into two as treated subgroups: High Standard Power (HSP, n=189), defined as subjects with 100% of left atrial lesions ablated at ≥40 W, and Low Standard Power (LSP, n=119), defined as subjects with at least one left atrial lesion ablated at &lt;40W. First pass success, defined as isolation of all pulmonary veins (PVs) confirmed after a minimum 20 min waiting period was achieved in 93.5% (175/186) and 84.5% (98/116) of HSP and LSP subjects, respectively (p=0.0104). Significant decreases in the HSP versus LSP procedures were also seen in total procedure time (112.0 min [89.0, 139.5] and 149.0 [115.0, 182.0], respectively [p&lt;0.001]), total RF time for PV ablation (14.0 min [11.0, 19.0] and 29.0 [19.0, 41.0], respectively [p&lt;0.0001]), total fluoroscopy time (4.0 min [0.0, 11.0] and 8.0 [3.0, 17.0], respectively [p&lt;0.0001]) and irrigation fluid volume (378.0 mL [310.0, 466.0] and 636.0 [476.0, 829.0], respectively [p&lt;0.0001]) (values given as Median [Q1, Q3]), see Figure 1. Both HSP and LSP subjects had a low rate of repeat procedures (1.6% [3/182] and 4.3% [5/115], respectively [p=0.2684]) and primary safety endpoint events (4.8% [9/189] and 4.2% [5/119], respectively [p=0.8182]) through 90 days post-index procedure.

Conclusion

The acute data on the TactiFlex SE catheter demonstrates safe and effective treatment of PAF using either a HSP or LSP ablation strategy. Ablation procedures performed using a HSP strategy were shorter and required less irrigation fluid and fluoroscopy. It is anticipated these results will be reflected in the 12-month safety and effectiveness primary endpoints.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): Abbott

Phase Stability and Electronic Properties of Hybrid Organic-Inorganic Perovskite Solid Solution (CH(NH2)2) x (CH3NH3)1-x Pb(Br y I1-y )3 as a Function of Composition

Compositional mixing provides the means to maintain the structural stability of a hybrid organic-inorganic perovskite for efficient and robust photovoltaic applications. Here we present a theoretical, first-principles study of the electronic and energetic properties of the solid solution (CH(NH₂)₂) _x (CH₃NH₃)_1-x PbBr _y I_1-y , the mixing of two organic molecules with various orientations, formamidinium and methylammonium, and two halides, bromide and iodide. Our results show the variation in the band gap as a function of composition (x and y) provides several candidates that exceed the 27.5% Schockley-Queisser efficiency. The variation in the composition of hybrid perovskite shows specific regions where either the hexagonal or cubic phase dominates. We discuss the balance between the band gap and phase stability and indicate regions where the phase transition temperature between cubic and hexagonal phases is far from room temperature, indicating that these compositions are more robust at room temperature against phase transitions.

Acute results of a novel flexible tip radiofrequency catheter incorporating contact force sensing

Funding Acknowledgements

Type of funding sources: Private company. Main funding source(s): Abbott

Background

Catheter ablation is an established therapy for paroxysmal atrial fibrillation (PAF). The TactiFlex Ablation Catheter, Sensor-Enabled (TactiFlex SE) is a next-generation radiofrequency ablation catheter incorporating highly accurate fiber optics-based contact force sensing technology with a flexible, laser-cut tip. This is the first report of results from the TactiFlex IDE clinical study.

Purpose

To demonstrate that ablation with TactiFlex SE is safe and effective for the treatment of drug refractory, symptomatic PAF.

Methods

The TactiFlex IDE (NCT04356040) is a prospective, non-randomized, multi-center clinical study which enrolled 305 subjects worldwide in the main study. Enrollment in the main study began on June 26, 2020 and completed on June 8, 2021. Subjects underwent de novo Pulmonary Vein Isolation (PVI) and, if indicated, a Cavotricuspid Isthmus ablation (CTI line) for CTI-dependent atrial flutter.

Results

Acute procedural success was achieved in 98.6% (274/278) of the main study cohort who underwent an ablation procedure using the TactiFlex SE. First pass success, defined as isolation of all pulmonary veins (PVs) confirmed after a minimum 20 min waiting period was achieved in 89.6% (249/278) of subjects. This was a significant improvement versus the TactiSense IDE trial (TactiCath Ablation Catheter, Sensor-Enabled). Significant decreases were also seen in total procedure time (123 min [101.0, 163.5]), total PV ablation time (55.5 min [35.0, 81.0]), total fluoroscopy time (6.0 min [0.0, 13.0]) and irrigation fluid volume (450.0 mL [346.0, 636.0]) (values given as Median [Q1, Q3]), see FIGURE. All subjects have completed at least 90 days of follow-up. Only 2.6% (7/271) of subjects required a repeat procedure during the 90-day blanking period. The primary safety and effectiveness endpoints will be evaluated at 12-months. At 90 days, 4.3% (12/281) subjects had experienced a primary safety endpoint event.

Conclusions

The acute data from the TactiFlex IDE clinical study demonstrate safety and effectiveness of the TactiFlex SE catheter in the treatment of PAF. Ablation procedures performed using the next-generation TactiFlex SE catheter were shorter and had improved acute clinical effectiveness outcomes versus the TactiSense IDE. It is anticipated these results will also be reflected in the 12-month safety and effectiveness endpoints.

Combining current knowledge on DNA methylation-based age estimation towards the development of a superior forensic DNA intelligence tool

The estimation of chronological age from biological fluids has been an important quest for forensic scientists worldwide, with recent approaches exploiting the variability of DNA methylation patterns with age in order to develop the next generation of forensic 'DNA intelligence' tools for this application. Drawing from the conclusions of previous work utilising massively parallel sequencing (MPS) for this analysis, this work introduces a DNA methylation-based age estimation method for blood that exhibits the best combination of prediction accuracy and sensitivity reported to date. Statistical evaluation of markers from 51 studies using microarray data from over 4000 individuals, followed by validation using in-house generated MPS data, revealed a final set of 11 markers with the greatest potential for accurate age estimation from minimal DNA material. Utilising an algorithm based on support vector machines, the proposed model achieved an average error (MAE) of 3.3 years, with this level of accuracy retained down to 5 ng of starting DNA input (~ 1 ng PCR input). The accuracy of the model was retained (MAE = 3.8 years) in a separate test set of 88 samples of Spanish origin, while predictions for donors of greater forensic interest (< 55 years of age) displayed even higher accuracy (MAE = 2.6 years). Finally, no sex-related bias was observed for this model, while there were also no signs of variation observed between control and disease-associated populations for schizophrenia, rheumatoid arthritis, frontal temporal dementia and progressive supranuclear palsy in microarray data relating to the 11 markers.

Incidence and location of residual gaps identified by a high-density grid-style catheter after PVI is confirmed by pacing the ablation lines

Funding Acknowledgements

Type of funding sources: None.

Background

The continual pursuit of more durable pulmonary vein isolation (PVI) has led ablationists to evaluate many different techniques for confirming isolation. One such technique involves using the ablation catheter to pace along the ablation lines, ensuring loss of pace capture. Initial observations from a small cohort of patients suggested that a high-density, grid style mapping catheter (HD Grid) enabling simultaneous recording of adjacent bipolar EGMs in two directions (HD Wave) may identify residual gaps that are missed when using the technique of pacing the ablation line in isolation. The true incidence of these residual gaps as identified in a large patient population has not been previously reported.

Purpose

To quantify in a large cohort of AF ablation patients, the presence of residual gaps identified by HD Grid which are missed by a technique of pacing along the ablation lines with the ablation catheter.

Methods

Self-reported data was prospectively collected in AF radiofrequency ablation procedures in which PVI was first confirmed by pacing along the ablation line followed by assessment using the HD Grid. Procedural characteristics and acute outcomes, including the incidence and location of gaps post-ablation, were analyzed.

Results

Data was collected in 111 AF ablation procedures performed in 18 centers across the United States and Europe. Paroxysmal (PAF), persistent (PersAF), and longstanding persistent AF (LsPersAF) accounted for 60.4%, 33.3%, and 6.3% of cases, respectively. Overall, 64.0% of ablations were de novo procedures. Following ablation, PVI was confirmed in all cases by pacing the ablation line with an average output of 9.1 ± 2.6mA and pulse width of 2.1 ± 0.5ms. Adenosine was administered in 3.6% of cases, isoproterenol in 3.6%, and a combination in 0.9%. PVI was then reassessed with HD Grid using a variety of techniques including exit block (91.0%), voltage mapping (82.0%), loss of pace capture along the ablation lines (47.7%), and entrance block (27.0%); note: total exceeds 100% as more than one technique may be used in a single case. A second dose of adenosine was administered in 2.7% of cases; isoproterenol in 2.7%. The HD Wave configuration was used in 96.4% of cases. HD Grid identified a total of 130 gaps in 65 (58.6%) patients, which were missed by pacing the ablation line (Figure 1).

Conclusions

In over half of the patients evaluated, the HD Grid identified residual PVI gaps that were missed when isolation was confirmed by using the ablation catheter to pace the ablation lines. These results suggest that the pacing technique, used in isolation, is not sufficient for complete gap detection. One limitation of this analysis was the use of a workflow which consistently assessed PVI with the HD Grid following confirmation of isolation by pacing the ablation lines. Despite this limitation, the rate at which residual gaps were identified is noteworthy and likely warrants additional study. Abstract Figure.

Clinicopathological comparison of VHL expression as a prognostic tumor marker in renal cell carcinoma: A single center experience

AIM

To assess the VHL gene expression as a prognostic marker in Renal Cell Carcinoma (RCC) and compare it with clinicopathologic features.

MATERIALS AND METHODS

This retrospective observational study was conducted in the department of Urology and Renal Transplantation in Sri Ramachandra Institute of Higher Education and Research, Chennai from August 2016 to August 2018. Thirty patients who have undergone a radical/partial nephrectomy with biopsy proven histological diagnosis of RCC during the study period were included in the study. Data was analyzed using Statistical package for Social Sciences version 17.

RESULTS

A complete loss and retained VHL expression were noted in 60% and 40% of the RCC specimens. Association between smoking and VHL expression was found to be statistically significant. There was no statistical significance found between age group, sex, chief complaints, BMI. ECOG score, hypertension, family history, location of tumor, calcification, venous system or lymphnode involvement. However, rT staging, nature of lesion and cut surface, HPE type, pT staging, HPE grade, necrosis and lympho-vascular invasion were also found to be statistically significant.

CONCLUSION

Complete loss of VHL expression was noted in majority of the specimens that leads to the development of RCC. Smoking has been found to be statistically significant in tumors that retain VHL expression which may contributes to more aggressive form of tumor. Association between rT staging, nature of lesion and cut surface, HPE type, pT staging, HPE grade, necrosis and lympho-vascular invasion were also found to be statistically significant.

Society of pediatric liver transplantation: Current registry status 2011-2018

BACKGROUND

SPLIT was founded in 1995 in order to collect comprehensive prospective data on pediatric liver transplantation, including waiting list data, transplant, and early and late outcomes. Since 2011, data collection of the current registry has been refined to focus on prospective data and outcomes only after transplant to serve as a foundation for the future development of targeted clinical studies.

OBJECTIVE

To report the outcomes of the SPLIT registry from 2011 to 2018.

METHODS

This is a multicenter, cross-sectional analysis characterizing patients transplanted and enrolled in the SPLIT registry between 2011 and 2018. All patients, <18 years of age, received a first liver-only, a combined liver-kidney, or a combined liver-pancreas transplant during this study period.

RESULTS

A total of 1911 recipients from 39 participating centers in North America were registered. Indications included biliary atresia (38.5%), metabolic disease (19.1%), tumors (11.7%), and fulminant liver failure (11.5%). Greater than 50% of recipients were transplanted as either Status 1A/1B or with a MELD/PELD exception score. Incompatible transplants were performed in 4.1%. Kaplan-Meier estimates of 1-year patient and graft survival were 97.3% and 96.6%. First 30 days of surgical complications included reoperation (31.7%), hepatic artery thrombosis (6.3%), and portal vein thrombosis (3.2%). In the first 90 days, biliary tract complications were reported in 13.6%. Acute cellular rejection during first year was 34.7%. At 1 and 2 years of follow-up, 39.2% and 50.6% had normal liver tests on monotherapy (tacrolimus or sirolimus). Further surgical, survival, allograft function, and complications are detailed.

Pathological changes in ureterovesical and ureteropelvic junction obstruction explained by fetal ureter histology

The etiology of ureterovesical junction obstruction (UVJO) and ureteropelvic junction obstruction (UPJO) is obscure with an adynamic narrow segment causing the obstruction. In this study, the authors compared interstitial cells of Cajal (ICC) and collagen-to-muscle ratio (CM ratio) between UVJO, UPJO, and fetal ureters to investigate whether a maturational arrest of the fetal ureter could explain both clinical pathologies.

METHODS

Group 1 (control) involved specimens of the normal ureter (nephrectomy for trauma/tumor; n = 20), while group 2, specimens of UVJO (n = 14); group 2 was further divided into group 2a, the dilated megaureter above UVJO, and group 2b, UVJO narrow segment; group 3, UPJO narrow segment excised during pyeloplasty (n = 31); and group 4, normal fetal ureters (n = 12). The specimens were analyzed for ICC using immunohistochemistry and CM ratio on Masson's trichrome (stains collagen in blue and muscle in red).

RESULTS

The median ICC/10 high-power field was 16.1 (8.3) in the normal and 17.3 (7.9) in the dilated segment of the megaureter, with no significant difference, but was significantly less in the narrow segment of UVJO at 4.5 (2.0), narrow segment of UPJO at 5.1 (2.3), and fetal ureter at 5.0 (2.3). The median CM ratio was 0.75 (0.29) in the normal and 0.65 (0.2) in the dilated segment of the megaureter, with no significant difference between them (figure), but was significantly higher in the narrow segment of UVJO at 3.0 (0.8), narrow segment of UPJO at 2.5 (0.71), and fetal ureter at 3.1 (0.61). Overall UVJO, UPJO, and fetal ureter segment had significantly less ICC density and more collagen compared with the normal ureter (P < 0.001 by Mann-Whitney U test).

DISCUSSION

There are conflicting reports on the etiopathogenesis of UVJO and UPJO, with several authors showing decreased ICC and increased collagen in the narrow segment. In this study, the authors found that the pathological changes at UVJ and UPJ segments resemble fetal ureter morphology. We also found that in fetal ureters, as the gestation progressed, there was an increase in the ICC density/smooth muscle, whereas the collagen content decreased. While the entire ureter has uniform embryological origin, it essentially remains an epithelial tube until the late gestation. The maturational process involves differentiation of smooth muscles cells/ICC to establish the peristaltic machinery required to functionally connect the ureter at both ends. This process, probably, starts at the mid ureter during fetal life and extends toward the UPJ and UVJ, and its failure, probably, results in UPJO or UVJO. The study's limitations are small numbers, and further larger studies are required to validate this hypothesis.

Time-restricted feeding mitigates high-fat diet-enhanced mammary tumorigenesis in MMTV-PyMT mice

Erratic eating behavior disrupts the daily feeding and fasting pattern and leads to metabolic dysfunction and chronic diseases including cancer. In the present study, we tested the hypothesis that time-restricted feeding of a high-fat diet (HFD) to the dark phase does not enhance mammary tumorigenesis in MMTV-PyMT mice. Female mice were assigned to 3 groups and fed the standard AIN93G diet or an HFD with or without dark phase restricted feeding (12 hours). The duration of restricted feeding was 8 weeks. The HFD group had 24% more body fat mass than the AIN93G group; the body fat mass of the restricted group remained similar to that of the AIN93G group. Energy intake of the restricted group was similar to that of the HFD and AIN93G groups. The median mammary tumor latency was 5.8, 7.0, and 6.4 weeks for the AIN93G, HFD, and restricted groups, respectively. Mammary tumor progression was 241% higher in the HFD group than that in the AIN93G group; there was no significant difference in tumor progression between the restricted and AIN93G groups. Plasma concentrations of leptin, monocyte chemoattractant protein-1, plasminogen activator inhibitor-1, angiopoietin-2, vascular endothelial growth factor, and hepatocyte growth factor were significantly higher in the HFD group than those in the control group; these measurements were similar between the restricted and control groups. In conclusion, feeding restricted to the dark phase mitigates the HFD-enhanced mammary tumorigenesis; this may be related to the lower body adiposity and associated inflammatory and angiogenic signals.

Polymyxin-B Stimulates Tumor Necrosis Factor-α Production by Human Peripheral Blood Mononuclear Cells

Gram-negative bacterial lipopolysaccharide (LPS) is a well known stimulus for cytokine production, particularly interleukin-1 (IL-1) and tumor necrosis tactor alpha (TNFα). Polymyxin B (PMX-B) is a cationic polypeptide that binds to LPS, neutralizing its biological effects. PMX-B also disrupts gram-negative bacterial cell membrane phospholipids but is highly toxic to mammalian cells, therefore is of limited use. PMX-B is used as additive to media, as a way to handle LPS contamination. To derive benefit from the ability of PMX-B to neutralize lipid A in vivo while avoiding its systemic toxicity, PMX-B was covalently bound to polystyrene-derivative fibers, creating a hemoperfusion column (PMX-F) for the selective removal of circulating ET In vitro PMX-F hemoperfusion studies have demonstrated effective ET removal, using either the Limulus amebocyte lysate assay or TNFα production by peripheral blood mononuclear cells (PBMC) as an index of ET removal. However, the question whether PMX-B itself could stimulate human PBMC to produce cytokines has not been adequately addressed. We examined the effect of increasing concentrations of PMX-B on cytokine production by PBMC in vitro. PBMC harvested from healthy volunteers were incubated for 24 hours at 37°C with control (tissue culture media RPMI), or 5 µg/ml, 10 µg/ml, 20 µg/ml or 100 µg/ml PMX-B. At the end of 24 hours, PBMC were subjected to three freeze-thaw cycles, and total TNFα production (pg/2.5x106 PBMC) was measured by radioimmunoassay. Total TNFα production by PBMC was 163 ± 3 pg, 171 ± 9 pg, 164 ± 4 pg, 323 ± 63 pg and 331 ± 58 pg, in the control, PMX-B 5 µg/ml, 10 µg/ml, 20 µg/ml and 100 µg/ml conditions, respectively. Compared to controls (RPMI), the percentage increase in TNFα production by PBMC was 5 ± 6% (P=0.23), 1 ± 3% (P=0.45), 99 ± 40% (P=0.03) and 103 ± 36% (P=0.02) in the presence of 5 µg/ml, 10 µg/ml, 20 µg/ml and 100 µg/ml of PMX-B, respectively. Furthermore, total TNFα production correlated significantly with increasing concentrations of PMX-B (R=0.53, P=0.007). We conclude that the use of PMX-B in in vitro studies as an LPS-neutralizing agent, or in the experimental treatment of endotoxic or septic shock can lead to erroneous interpretations of cytokine production by PBMC, and should be used cautiously in in vitro systems at high concentrations.

Patterns of Blood Response during Cardiopulmonary Bypass

Monitoring of cardiopulmonary bypass (CPB) in terms of alterations to the concentrations of selected blood constituents leads to contrasting patterns of response. This has been verified by determining the influence of CPB on the activation of fibrinolysis, complement, leucocytes and the contact phase of coagulation.

Fibrinolytic activity was determined by fibrin degradation products (X-FDP's), complement activation by C3a and C5a, leucocyte activation by granulocyte elastase and contact activation by factor XII-like activity (FXIIA). Five patients undergoing elective coronary artery surgery using a bubble oxygenator and pulsatile perfusion were studied. X-FDP's rose gradually during CPB and remained elevated. Similar patterns were observed for elastase and FXIIA. In contrast, C3a rose sharply with peak values at 1½-2h of bypass while C5a did not show significant changes during bypass. The data obtained have enabled the establishment of response patterns for parameters in CPB which will provide information relevant to the clinical application of biomaterials.

Cytokine Production by Human Peripheral Blood Mononuclear Cells Stimulated by a Pseudomonas Aeruginosa Culture Filtrate: Role of Plasma and Polymyxin B

The lack of consensus regarding the significance of transmembrane passage of bacterial products across hemodialysis membranes can be related to several methodological differences in the various studies, including the choice of circulating fluid in the blood compartment of the model, nature and concentration of the bacterial products employed to challenge the dialysate compartment and whether cytokine production by PMBC or the limulus amebocyte lysate (LAL) assay was used as the index of transfer and the cytokine used as the read-out. In this study, we examined the production of interleukin-1 alpha (IL-1α), interieukin-1 receptor antagonist (IL-1Ra) and interleukin-8 (IL-8) by peripheral blood mononuclear cells (PBMC) incubated with a Pseudomonas aeruginosa culture filtrate. Further, the effects of 10% autologous human plasma and Polymyxin B sulfate (PmB) on cytokine production by PBMC were also characterized. The results of our study indicate that the Ps. aeruginosa culture filtrate had both PmB suppressible and PmB non-suppressible components and that the addition of 10% human plasma significantly enhanced cytokine production by both PmB suppressible and PmB non-suppressible components. The enhancing effect of plasma was most evident at low concentrations of the filtrate. The inhibitory effect of PmB was most evident in samples cultured in the presence of 10% plasma. There was a direct correlation between the production of IL-1α and IL-1Ra suggesting that both pro-inflammatory cytokines and cytokine-specific inhibitory proteins are concurrently produced. There results have direct relevance to selection of study conditions for in vitro models used to study the transmembrane passage of bacterial products across hemodialysis membranes

Biocompatibility of Cardiopulmonary Bypass: Influence on Blood Compatibility of Device Type, Mode of Blood Flow and Duration of Application

The biocompatibility of artificial organs is recognised as an area presenting difficulties in terms of the complexity of the situation. The nature of the blood response involving interactions of systems, pattern and extent of change, patient status and the influence of the whole device contribute to the complexity. Recognising these, the profile of the blood response to cardiopulmonary bypass (CPB), with respect to type of device, mode of blood flow, duration of the procedure and patient status, has been evaluated by monitoring contact phase activation [Factor XII-like activity (FXIIA)], fibrinolytic activity [Fibrin degradation products (X-FDP's)], complement activation (C3a, C5a), leucocyte activation [Granulocyte elastase (GE)] and platelet and white cell imaging. FXIIA, X-FDP's, and GE rose gradually during CPB, with levels remaining elevated post-operatively for up to 48 h. In contrast, C3a levels rose sharply with no significant elevation in the post-operative period, while C5a did not show significant changes during bypass. The use of pulsatile perfusion resulted in lesser activation of the parameters, although these were significantly less only for GE. The alterations in FXIIA, X-FDP's, C3a and GE correlated positively with the duration of CPB, with this effect pronounced in the post-operative period for FXIIA, X-FDP's and GE. However, these changes had no apparent influence on clinical outcome and the majority of patients had uncomplicated post-operative recoveries. With respect to the use of bubble/membrane oxygenators, platelet and white cell deposition and the patterns of change for FXIIA and C3a were similar in the two groups. The investigation has enabled a broad perspective of biocompatibility in CPB relevant to the clinical application of biomaterials.