Population pharmacokinetics of fluconazole in critically ill patients receiving extracorporeal membrane oxygenation and continuous renal replacement therapy: an ASAP ECMO study

This multicenter study describes the population pharmacokinetics (PK) of fluconazole in critically ill patients receiving concomitant extracorporeal membrane oxygenation (ECMO) and continuous renal replacement therapy (CRRT) and includes an evaluation of different fluconazole dosing regimens for achievement of target exposure associated with maximal efficacy. Serial blood samples were obtained from critically ill patients on ECMO and CRRT receiving fluconazole. Total fluconazole concentrations were measured in plasma using a validated chromatographic assay. A population PK model was developed and Monte Carlo dosing simulations were performed using Pmetrics in R. The probability of target attainment (PTA) of various dosing regimens to achieve fluconazole area under the curve to minimal inhibitory concentration ratio (AUC0-24/MIC) >100 was estimated. Eight critically ill patients receiving concomitant ECMO and CRRT were included. A two-compartment model including total body weight as a covariate on clearance adequately described the data. The mean (±standard deviation, SD) clearance and volume of distribution were 2.87 ± 0.63 L/h and 15.90 ± 13.29 L, respectively. Dosing simulations showed that current guidelines (initial loading dose of 12 mg/kg then 6 mg/kg q24h) achieved >90% of PTA for a MIC up to 1 mg/L. None of the tested dosing regimens achieved 90% of PTA for MIC above 2 mg/L. Current fluconazole dosing regimen guidelines achieved >90% PTA only for Candida species with MIC <1 mg/L and thus should be only used for Candida-documented infections in critically ill patients receiving concomitant ECMO and CRRT. Total body weight should be considered for fluconazole dose.

Antimicrobial Exposures in Critically Ill Patients Receiving Extracorporeal Membrane Oxygenation

Rationale: Data suggest that altered antimicrobial concentrations are likely during extracorporeal membrane oxygenation (ECMO). Objectives: The primary aim of this analysis was to describe the pharmacokinetics (PKs) of antimicrobials in critically ill adult patients receiving ECMO. Our secondary aim was to determine whether current antimicrobial dosing regimens achieve effective and safe exposure. Methods: This study was a prospective, open-labeled, PK study in six ICUs in Australia, New Zealand, South Korea, and Switzerland. Serial blood samples were collected over a single dosing interval during ECMO for 11 antimicrobials. PK parameters were estimated using noncompartmental methods. Adequacy of antimicrobial dosing regimens were evaluated using predefined concentration exposures associated with maximal clinical outcomes and minimal toxicity risks. Measurements and Main Results: We included 993 blood samples from 85 patients. The mean age was 44.7 ± 14.4 years, and 61.2% were male. Thirty-eight patients (44.7%) were receiving renal replacement therapy during the first PK sampling. Large variations (coefficient of variation of ⩾30%) in antimicrobial concentrations were seen leading to more than fivefold variations in all PK parameters across all study antimicrobials. Overall, 70 (56.5%) concentration profiles achieved the predefined target concentration and exposure range. Target attainment rates were not significantly different between modes of ECMO and renal replacement therapy. Poor target attainment was observed across the most frequently used antimicrobials for ECMO recipients, including for oseltamivir (33.3%), piperacillin (44.4%), and vancomycin (27.3%). Conclusions: Antimicrobial PKs were highly variable in critically ill patients receiving ECMO, leading to poor target attainment rates. Clinical trial registered with the Australian New Zealand Clinical Trials Registry (ACTRN12612000559819).

Conventional and Novel Approaches to Immunosuppression in Lung Transplantation

Most therapeutic advances in immunosuppression have occurred over the past few decades. Although modern strategies have been effective in reducing acute cellular rejection, excess immunosuppression comes at the price of toxicity, opportunistic infection, and malignancy. As our understanding of the immune system and allograft rejection becomes more nuanced, there is an opportunity to evolve immunosuppression protocols to optimize longer term outcomes while mitigating the deleterious effects of traditional protocols.

Multispecies Outbreak of Nocardia Infections in Heart Transplant Recipients and Association with Climate Conditions, Australia

Extreme weather conditions, coupled with greater susceptibility to opportunistic infection, could explain this outbreak.

A multispecies outbreak of Nocardia occurred among heart transplant recipients (HTR), but not lung transplant recipients (LTR), in Sydney, New South Wales, Australia, during 2018–2019. We performed a retrospective review of 23 HTR and LTR who had Nocardia spp. infections during June 2015–March 2021, compared risk factors for Nocardia infection, and evaluated climate conditions before, during, and after the period of the 2018–2019 outbreak. Compared with LTR, HTR had a shorter median time from transplant to Nocardia diagnosis, higher prevalence of diabetes, greater use of induction immunosuppression with basiliximab, and increased rates of cellular rejection before Nocardia diagnosis. During the outbreak, Sydney experienced the lowest monthly precipitation and driest surface levels compared with time periods directly before and after the outbreak. Increased immunosuppression of HTR compared with LTR, coupled with extreme weather conditions during 2018–2019, may explain this outbreak of Nocardia infections in HTR.

Population pharmacokinetics of ciprofloxacin in critically ill patients receiving extracorporeal membrane oxygenation (an ASAP ECMO study)

INTRODUCTION

This study aimed to describe the pharmacokinetics (PK) of ciprofloxacin in critically ill patients receiving ECMO and recommend a dosing regimen that provides adequate drug exposure.

METHODS

Serial blood samples were taken from ECMO patients receiving ciprofloxacin. Total ciprofloxacin concentrations were measured by chromatographic assay and analysed using a population PK approach with Pmetrics®. Dosing simulations were performed to ascertain the probability of target attainment (PTA) represented by the area under the curve to minimum inhibitory concentration ratio (AUC_0-24/MIC) ≥ 125.

RESULTS

Eight patients were enrolled, of which three received concurrent continuous venovenous haemodiafiltration (CVVHDF). Ciprofloxacin was best described in a two-compartment model with total body weight and creatinine clearance (CrCL) included as significant predictors of PK. Patients not requiring renal replacement therapy generated a mean clearance of 11.08 L/h while patients receiving CVVHDF had a mean clearance of 1.51 L/h. Central and peripheral volume of distribution was 77.31 L and 90.71 L, respectively. ECMO variables were not found to be significant predictors of ciprofloxacin PK. Dosing simulations reported that a 400 mg 8 -hly regimen achieved > 72% PTA in all simulated patients with CrCL of 30 mL/min, 50 mL/min and 100 mL/min and total body weights of 60 kg and 100 kg at a MIC of 0.5 mg/L.

CONCLUSION

Our study reports that established dosing recommendations for critically ill patients not on ECMO provides sufficient drug exposure for maximal ciprofloxacin activity for ECMO patients. In line with non-ECMO critically ill adult PK studies, higher doses and therapeutic drug monitoring may be required for critically ill adult patients on ECMO.

Systemic inflammation affects reperfusion following transient cerebral ischaemia

Reperfusion after stroke is critical for improved patient survival and recovery and can be achieved clinically through pharmacological (recombinant tissue plasminogen activator) or physical (endovascular intervention) means. Yet these approaches remain confined to a small percentage of stroke patients, often with incomplete reperfusion, and therefore there is an urgent need to learn more about the mechanisms underlying the no-reflow phenomenon that prevents restoration of adequate microvascular perfusion. Recent evidence suggests systemic inflammation as an important contributor to no-reflow and to further investigate this here we inject interleukin 1 (IL-1) i.p. 30 min prior to an ischaemic challenge using a remote filament to occlude the middle cerebral artery (MCA) in mice. Before, during and after the injection of IL-1 and occlusion we use two-dimensional optical imaging spectroscopy to record the spatial and temporal dynamics of oxyhaemoglobin concentration in the cortical areas supplied by the MCA. Our results reveal that systemic inflammation significantly reduces oxyhaemoglobin reperfusion as early as 3h after filament removal compared to vehicle injected animals. CD41 immunohistochemistry shows a significant increase of hyper-coagulated platelets within the microvessels in the stroked cortex of the IL-1 group compared to vehicle. We also observed an increase of pathophysiological biomarkers of ischaemic damage including elevated microglial activation co-localized with interleukin 1α (IL-1α), increased blood brain barrier breakdown as shown by IgG infiltration and increased pyknotic morphological changes of cresyl violet stained neurons. These data confirm systemic inflammation as an underlying cause of no-reflow in the post-ischaemic brain and that appropriate anti-inflammatory approaches could be beneficial in treating ischaemic stroke.

Open-label, dose-escalation, safety, pharmacokinetic, and pharmacodynamic study of intravenously administered CNF1010 (17-(allylamino)-17-demethoxygeldanamycin [17-AAG]) in patients with solid tumors

BACKGROUND

17-(Allylamino)-17-demethoxygeldanamycin (17-AAG) is a benzoquinone ansamycin that binds to and inhibits the Hsp90 family of molecular chaperones leading to the proteasomal degradation of client proteins critical in malignant cell proliferation and survival. We have undertaken a Phase 1 trial of CNF1010, an oil-in-water nanoemulsion of 17-AAG.

METHODS

Patients with advanced solid tumors and adequate organ functions received CNF1010 by 1-h intravenous (IV) infusion, twice a week, 3 out of 4 weeks. Doses were escalated sequentially in single-patient (6 and 12 mg/m(2)/day) and three-to-six-patient (≥25 mg/m(2)/day) cohorts according to a modified Fibonacci's schema. Plasma pharmacokinetic (PK) profiles and biomarkers, including Hsp70 in PBMCs, HER-2 extracellular domain, and IGFBP2 in plasma, were performed.

RESULTS

Thirty-five patients were treated at doses ranging from 6 to 225 mg/m(2). A total of 10 DLTs in nine patients (2 events of fatigue, 83 and 175 mg/m(2); shock, abdominal pain, ALT increased, increased transaminases, and pain in extremity at 175 mg/m(2); extremity pain, atrial fibrillation, and metabolic encephalopathy at 225 mg/m(2)) were noted. The PK profile of 17-AAG after the first dose appeared to be linear up to 175 mg/m(2), with a dose-proportional increase in C max and AUC0-inf. Hsp70 induction in PBMCs and inhibition of serum HER-2 neu extracellular domain indicated biological effects of CNF1010 at doses >83 mg/m(2).

CONCLUSION

The maximum tolerated dose was not formally established. Hsp70 induction in PBMCs and inhibition of serum HER-2 neu extracellular domain indicated biological effects. The CNF1010 clinical program is no longer being pursued due to the toxicity profile of the drug and the development of second-generation Hsp90 molecules.

ASAP ECMO: Antibiotic, Sedative and Analgesic Pharmacokinetics during Extracorporeal Membrane Oxygenation: a multi-centre study to optimise drug therapy during ECMO

Background

Given the expanding scope of extracorporeal membrane oxygenation (ECMO) and its variable impact on drug pharmacokinetics as observed in neonatal studies, it is imperative that the effects of the device on the drugs commonly prescribed in the intensive care unit (ICU) are further investigated. Currently, there are no data to confirm the appropriateness of standard drug dosing in adult patients on ECMO. Ineffective drug regimens in these critically ill patients can seriously worsen patient outcomes. This study was designed to describe the pharmacokinetics of the commonly used antibiotic, analgesic and sedative drugs in adult patients receiving ECMO.

Methods/Design

This is a multi-centre, open-label, descriptive pharmacokinetic (PK) study. Eligible patients will be adults treated with ECMO for severe cardiac and/or respiratory failure at five Intensive Care Units in Australia and New Zealand. Patients will receive the study drugs as part of their routine management. Blood samples will be taken from indwelling catheters to investigate plasma concentrations of several antibiotics (ceftriaxone, meropenem, vancomycin, ciprofloxacin, gentamicin, piperacillin-tazobactum, ticarcillin-clavulunate, linezolid, fluconazole, voriconazole, caspofungin, oseltamivir), sedatives and analgesics (midazolam, morphine, fentanyl, propofol, dexmedetomidine, thiopentone). The PK of each drug will be characterised to determine the variability of PK in these patients and to develop dosing guidelines for prescription during ECMO.

Discussion

The evidence-based dosing algorithms generated from this analysis can be evaluated in later clinical studies. This knowledge is vitally important for optimising pharmacotherapy in these most severely ill patients to maximise the opportunity for therapeutic success and minimise the risk of therapeutic failure.

Trial registration

ACTRN12612000559819

Medication Error Minimization Scheme (MEMS) in an adult tertiary intensive care unit (ICU) 2009-2011

INTRODUCTION

The Medication Error Minimisation Scheme (MEMS) is a locally based ongoing multidisciplinary, multifaceted quality improvement (QI) project within an Australian adult tertiary level Intensive Care Unit (ICU). The project commenced in 2009. Its primary aim is to enhance medication safety within this ICU by utilising existing resources. The aim of this paper is to provide a descriptive account of the various activities, interventions and results of this project within the first three years.

METHODS

The research design for this project was based upon Plan-Do-Study-Act (PDSA) cycles associated with QI projects. Medication error rates and audits of: intravenous infusions, incompatible intravenous medications and incorrect documentation of withheld medications were analyzed according to simple statistical techniques. Initial and follow up medication safety surveys were compared using basic statistical analysis. Focus groups exploring barriers and enablers of medication incident reporting were analyzed according to qualitative techniques associated with focus group discussions. Other interventions included: regular education sessions; discussions within other departmental meetings such as nursing staff meetings and Morbidity and Mortality meetings; and bedside discussions and demonstrations. Promotion of medication safety occurred within a number of forums; activities and findings were advertised and displayed; a recognizable Logo for MEMS was employed; and incentives were provided for staff.

RESULTS

Reported Medication Incidents (MIs) increased from 6.2 to 14.9 MIs per 1000 patient days. Audits and chart reviews confirmed that more MIs are uncovered by employing a variety of techniques in addition to incident reporting. Staff surveys provided a rich source of information regarding medication safety. Audits of intravenous infusions revealed a reduced error rate from 38/331 (11.5%) to 15/468 (3.2%). Chart review of incorrect documentation of omitted medications decreased from 105/347 (30.3%) to 104/486 (21.4%). Focus groups provided information that was able to be used in a number of hospital forums in order to explain the impact of existing systems upon ICU staff.

CONCLUSION

This ongoing QI project was able to achieve its targeted goals. The MI reporting rate was increased. This project demonstrated that measurable, "non-incident report" errors can be reduced by focusing upon and promoting medication safety in the ICU. These activities demonstrated a workplace that values medication safety, the discovery of shortfalls and the benefits of ongoing improvement.

P3-16-14: Effect of TG02, a Multikinase Inhibitor, on Triple Negative Breast Cancer Cells

Background

Breast cancer is the most common neoplasia in women. Formerly, we reported that the MAPK Erk5 participates in the proliferation of breast cancer cells in vitro, it is overexpressed in the tumours of a number of breast cancer patients, and its overexpression is an independent prognostic marker for disease-free survival. In addition, inhibition of Erk5 sensitized cells to treatments commonly used in the breast cancer clinic. Therefore, Erk5 may represent a novel therapeutic target in breast cancer. Here we describe the preclinical activity of TG02, a novel multi-kinase inhibitor being developed by Tragara Pharmaceuticals, in triple negative breast cancer (TNBC). TG02 presents a unique kinase inhibitory spectrum, combining Erk5 inhibitory properties with inhibition of CDKs and certain receptor tyrosine kinases.

Material and methods: The action of TG02 on cell proliferation of TNBC cell lines was carried out by the MTT-based assay, and its action on cell death and cell cycle progression was analyzed by flow cytometry. The expression of different kinases and other proteins implicated in cell cycle, apoptosis and DNA damage responses were analyzed by western blotting. Studies on the action of TG02 in combination with chemotherapy were performed in MDAMB231 and HBL100 cells, and the potency of the combination was quantitated with the Calcusyn software. In vivo studies on the action of TG02 were performed in mice xenografted with the TNBC cell line MDA-MB231.

Results: The TNBC cell lines analyzed showed high levels of Erk5 expression, and Erk5 was active under resting conditions in some of them. TG02 inhibited the kinase activity of Erk5 even though TG02 did not affect the Erk5 upstream activating kinase Mek5. TG02 showed an inhibitory effect of phosphorylation of residue Thr732 in the C-terminal tail of Erk5 without affecting the phosphorylation of the activation loop TEY motif. Cell proliferation studies indicated that one group of TNBC cells were very sensitive to the action of this compound (IC50 ≤100 nM) and another group were more resistant. TG02 induced cell cycle arrest at the early G1 and G2 phases of cell cycle, and triggered cell death in MDAMB231 (representative cell line of the most resistant group), and induced a strong effect of apoptosis and a DNA damage response in HCC1187(representative of the most sensitive group). In vitro studies indicated that TG02 sensitizes TNBC cells to chemotherapy, showing additive or synergistic effects depending of the doses. In vivo studies indicated that TG02 exerted a strong antitumoral action in mice bearing MDA-MB231-derived tumours.

Conclusions: TNBC cells are very sensitive to TG02, both in vitro and in vivo. The inhibits the kinase activity of Erk5, which, together with the targeting of other kinases, may contribute to the induction of cell cycle arrest or apoptosis in response to the compound in TNBC cells. TG02 synergized with chemotherapy, supporting the possibility of using this drug in combination therapy. Taken together, these preclinical studies establish the bases for the clinical development of this compound for the treatment of TNBC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-16-14.

Preclinical antitumor activity and mechanisms of action of apricoxib, a clinical COX-2 inhibitor

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Background: Apricoxib, a selective COX-2 inhibitor, is currently in phase II trials, but its anticancer mechanisms of action could be better defined. Apricoxib inhibits COX-2 enzymatic activity and suppresses production of PGE2 and VEGF at low nanomolar concentrations but also directly inhibits tumor cell proliferation and survival with 10-20μM potency. In this study we characterized the in vivo activity of apricoxib in xenograft models of lung, breast and colorectal carcinoma. Also, we examined the relationship between the PK, PD and antitumor activity and the effect of the drug on both tumor cell-autonomous functions and aspects of the tumor-host relationship in the HT29 model.

Methods: Human tumor xenografts were grown in nude mice and apricoxib was given daily PO. Drug levels were quantified by LC-MS and VEGF levels by ELISA. Vessel density, apoptosis, proliferation and EMT were assessed by immunohistochemistry.

Results: Apricoxib significantly retarded tumor growth in NSCLC models and also enhanced the efficacy of SOC drugs in breast and lung tumors. In the HT29 model, the drug was active at both doses tested. Drug concentrations in plasma and tumors peaked at 2-10 μM within an hour and decreased rapidly to submicromolar levels but concentrations persisted above the active concentration for inhibition of PGE2 production for >24h. This strongly indicates that apricoxib exerts its in vivo activity via blockade of COX-2-dependent PGE2 production. Plasma VEGF levels decreased to zero for 6h post-dose, but returned to baseline by 24h. CD31 and Endomucin staining revealed no drug effect on microvessel density, although the percentage of immature vessels was reduced, as determined by pericyte coverage/NG2 expression. Apoptosis was significantly increased by TUNEL in apricoxib-treated tumors. PCNA analysis revealed a decrease in proliferating cells. ECAD expression was significantly increased in treated animals, whereas ZEB1 expression was lower, suggesting that COX-2 activity also plays an important role in EMT.

Conclusions: Apricoxib possesses antitumor activity as a single agent and in combination. In the HT29 model, apricoxib inhibits tumor proliferation and survival, normalizes tumor vasculature and reverses EMT.

[Table: see text]

Phase I study of CNF1010 (lipid formulation of 17-(allylamino)-17-demethoxygeldanamycin: 17-AAG) in patients with advanced solid tumors

10062

Background: 17-AAG is a benzoquinone ansamycin that binds to and inhibits the HSP90 family of molecular chaperones leading to the proteasomal degradation of client proteins critical in malignant cell proliferation and survival. We have undertaken a Phase 1 trial of CNF1010, an oil-in-water nanoemulsion of 17-AAG. Methods: Patients (pts) with advanced solid tumors, ECOG PS 0–2, and adequate hematologic, hepatic, renal and cardiac functions received CNF1010 by 1 h intravenous infusion, twice-a-week, three weeks out of four, starting at 6 mg/m2 per dose. Doses were escalated sequentially in single pts (6 and 12 mg/m2) and 3–6 pts (≥ 25 mg/m2) cohorts according to a modified Fibonacci’s schema. Plasma pharmacokinetic (PK) profiles were obtained on days 1 and 18. Biomarkers were measured in PBMC’s (HSP70) and plasma (HER-2 ectodomain (HER-2 ECD)). Results: 30 pts (M/F: 14/16; median age 63, range 48–78) with colorectal cancer (11), pancreatic cancer (5), melanoma (5), ovarian (2), others (7) were treated with a median of 2 courses (range: 1–10). There was no dose-limiting toxicity up to 175 mg/m2. One pt at 175 mg/m2 died on study, but drug relation was unclear. Grade 1–2 gastrointestinal toxicities (nausea, vomiting, diarrhea) and serum creatinine elevation were observed. Severe toxicities (grade 3 but no grade 4) consisted of reversible hepatic enzyme elevation, hyperbilirubinemia, fatigue, anemia and hyperglycemia. There were no hematological toxicities. Plasma 17-AAG PK appeared dose-proportional (AUC, Cmax); CL (17 L/h/m2) and t1/2 (5.2 h) were dose independent and unchanged after repeated dosing (day 18). Post-treatment increases in HSP70 were observed in PBMCs and decreases in plasma HER-2 ECD were observed at doses ≥ 83 mg/m2. Minor tumor regressions were seen in 1 pt with duodenal cancer (83 mg/m2), 1 pt with gastric carcinoid (175 mg/m2) and 1 pt with melanoma (175 mg/m2). Conclusion: The threshold of biologic activity for CNF1010 administered by a twice a week schedule appears to be 83 mg/m2. This dosing regimen appears to be optimal and supported by the pharmacokinetic and pharmacodynamic data. The MTD has not yet been determined. Dose escalation of CNF1010 continues at 225 mg/m2.

[Table: see text]

Induction of melanoma-associated antigen systemic immunity upon intratumoral delivery of interferon-gamma retroviral vector in melanoma patients

A total of 17 patients with metastatic melanoma were treated with intratumoral interferon-gamma (IFN-gamma) retroviral vector in a phase I clinical trial. A cycle of treatment consisted of five daily injections every 2 weeks. Patients were divided into two treatment arms that involved a single course (one cycle) of treatment (group I; n = 9) and multiple cycles (six cycles) of treatment (group II; n = 8). Patients received intratumoral injections of IFN-gamma (10(7) plaque-forming units/mL administered at 0.3, 0.5, and 1.0 mL per cohort of patients). All patients receiving multiple injections either maintained stable disease (n = 5) or achieved a partial or complete response (n = 3) of the injected lesion, whereas in patients receiving a single cycle of treatment, only one of nine patients had a response. Patients were assessed for immunoglobulin G antibody (Ab) responses to the melanoma-associated antigens (MAA) tyrosinase, gp100, TRP-2, and MAGE-A1 by affinity enzyme-linked immunosorbent assay. Anti-MAGE-A1 and tyrosinase Ab were significantly elevated from baseline (day 0) to week 16 during treatment (P = .005; P = .002, respectively) in patients who received multiple injections. Patients undergoing treatment who had a clinical response (stable disease or better) also had significantly more elevated Ab responses to a greater number of MAA (P = .0004). The induction of systemic Ab responses to multiple MAA also correlated with systemic clinical responses. These studies suggest that multiple anti-MAA Ab responses are associated with clinical responses to IFN-gamma retroviral treatment and may be used as surrogate response markers.

Phase I trial of interferon gamma retroviral vector administered intratumorally with multiple courses in patients with metastatic melanoma

The purpose of this study was to determine the safety and antitumor activity of IFN-gamma retroviral vector in patients with advanced melanoma. Seventeen patients (9 single courses, 8 multiple courses) received a total of 363 intratumor injections of IFN-gamma retroviral vector (1 x 10(7) PFU/ml administered at 0.3, 0.5, and 1.0 ml per cohort). No grade III/IV adverse events were attributed to study medication. Replication-competent retrovirus was not detected in any of the 17 patients by polymerase chain reaction studies. Eight patients showed elevated anti-tumor antibody responses in comparison with baseline by ELISA. One of nine patients treated with a single course had an optimal response of stable disease, compared with eight of eight multiple-injected patients. Median survival of single-injected patients was 150 days, and patients who received multiple injections have still not achieved median survival duration, with four of eight still living (p = 0.0462, Wilcoxon; p = 0.0273, log rank). We conclude that intratumor injection of IFN-gamma is safe and well tolerated. Evidence of antitumor activity is suggested in patients with advanced malignancy that received multiple injections.

Heparin therapy during cardiopulmonary bypass in children requires ongoing quality control

Heparin therapy for children undergoing cardiopulmonary bypass (CPB) is monitored in the operating room by automated whole blood activated clotting times (ACT). For many years our institution used Hemochron (HC) ACT machines but changed to HemoTec (HT) ACT machines because they required a smaller blood sample and provided results in duplicate. When HemoTec ACT machines were introduced at our institution, the surgical team was concerned that increased amounts of heparin were being administered to our patients during CPB. This study was conducted to investigate the potential mechanisms responsible for these clinical observations. First, we compared ACT values on ex vivo blood samples from 20 consecutive pediatric patients (6 samples each) during CPB. The HC ACT values were significantly and systematically increased over HT ACT values (HC: 750 +/- 40 vs HT: 418 +/- 26, Mean +/- SEM, p < 0.01). 94% of all HC ACT values were above 450 s compared to only 27% of HT ACT values. If HT ACT values had been used for patient monitoring, all patients would have received more heparin to achieve ACT values above 450 s. The two machines reported similar ACT values when heparin was added in vitro to whole blood (0.1-5.0 units/ml), (HC: Y = 98X + 104, r2 = 0.93 HT: Y = 82X + 109, r2 = 0.94). Heparin concentrations in our patients following a bolus of 300 U/kg of heparin, but prior to CPB were 3.2 +/- 0.07 units/ml. Following the initiation of CPB, heparin concentrations decreased to 1.3 +/- 0.05, reflecting, in part hemodilution by the pump prime (1 U of heparin/ml).(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of the biliary tract after liver transplantation: T tube cholangiography or IODIDA scanning

Biliary tract obstruction or anastomotic leakage are common problems following liver transplantation. In a sequential study, 31 patients with a liver transplant were investigated by 99mTc-IODIDA (IODIDA) scanning and T tube cholangiography (TTC) and the results were compared with clinical outcome. Seven patients had an extrahepatic biliary obstruction and one patient had a biliary leak. In the detection of biliary complications TTC and IODIDA scanning were similar in terms of sensitivity (63 per cent for both) but TTC had a better specificity (79 per cent versus 60 per cent) and accuracy (74 per cent versus 60 per cent) than IODIDA scanning. When liver function was taken into account, the diagnostic efficacy of both tests in patients with bilirubin levels of less than 200 mumol/l was similar. With levels greater than 200 mumol/l there was a greater number of false positive results with IODIDA scanning (12 per cent versus 54 per cent). The only significant biliary leak was clearly detected by TTC but not IODIDA scanning. TTC remains the more effective way of evaluating the biliary tract after transplantation. IODIDA scanning has limited value when bilirubin levels are elevated, but may provide additional information about blood supply, hepatocyte function and intrahepatic cholestasis.

The nodular duodenum in chronic renal failure

A retrospective study of barium meals in 120 patients with chronic renal failure demonstrated duodenal abnormalities in 38 cases (31%). Multiple nodular filling defects were shown in 28 patients (23%), while in 10 cases (8%) peptic ulceration was found on a background of smooth duodenal mucosa. There was no common cause for the renal failure in the group with nodules. The nodular changes were a direct consequence of the uraemia and were unrelated to dialysis, renal transplantation or drug therapy. They were found almost exclusively in males, and in the more severe degrees of uraemia. Associated dyspeptic symptoms were infrequent and there was no apparent relationship between the nodules and peptic ulceration. Radiologically the nodules were typical of Brunner's gland hyperplasia while endoscopic and histological assessment excluded ulceration, infection, duodenitis and malignancy. Hyperplasia of Brunner's glands is commonly associated with chronic uraemia.

Evaluation of ricin A chain-containing immunotoxins directed against the CD30 antigen as potential reagents for the treatment of Hodgkin's disease

Five monoclonal CD30 antibodies and two Fab' fragments were linked to deglycosylated ricin A chain (dgA), and their potential as immunotoxins for the treatment of Hodgkin's disease was evaluated. Cross-blocking experiments demonstrated that HRS-1, HRS-3, HRS-4, and Ber-H2 recognize the same epitope on the CD30 antigen and that Ki-1 binds to a different epitope. Scatchard analyses showed that HRS-3, HRS-4, and Ber-H2 bound strongly to L540 Hodgkin cells (Kd 15, 7, and 14 nM, respectively), whereas HRS-1 and Ki-1 bound more weakly (Kd 160 and 380 nM, respectively). The different affinities of the antibodies correlated closely with their cytotoxic potency as immunotoxins. HRS-3.dgA, HRS-4.dgA, and Ber-H2.dgA inhibited the protein synthesis of L540 cells by 50% at concentrations of 0.9-2.0 x 10(-10) M, whereas HRS-1.dgA and Ki-1.dgA were about 100 times less potent with 50% inhibitory concentrations of 0.8-1.0 x 10(-8) M. The most effective immunotoxins, HRS-3.dgA and HRS-4.dgA, were only 15 times less toxic than ricin itself. HRS-3 Fab'.dgA and HRS-4 Fab'.dgA were 7.8 and 3 times less potent than their IgG.dgA counterparts with 50% inhibitory concentrations of 7 x 10(-10) and 3 x 10(-10) M, respectively. Staining of human tissues revealed an unexpected cross-reactivity of HRS-4 with pancreatic cells of malignant and nonmalignant origin. HRS-1, HRS-3, Ber-H2, and Ki-1 showed very little cross-reactivity with any normal human tissues. It is concluded that HRS-3.dgA and HRS-3 Fab'.dgA are the immunotoxins of choice for in vivo therapy.

Identification of risk factors for spinal cord ischemia by the use of monitoring of somatosensory evoked potentials during coarctation repair

The infrequency of spinal cord infarction and paraplegia after occlusion of the descending thoracic aorta has effectively precluded statistical identification of risk factors. Reversible spinal cord ischemia (SCI), however, is more common, can be detected by intraoperative neurophysiologic monitoring, and can lead to irreversible spinal cord damage. Spinal somatosensory evoked potentials (SEPs) were monitored intraoperatively in 38 patients (18 days to 18 years) undergoing coarctation repair (1982-1986). Although no patients sustained perioperative neurologic dysfunction, 10 of 38 (26%) patients developed reversible SCI, as reflected by greater than 75% loss of SEP N1-P1 interpeak amplitude during aortic occlusion (mean clamp time, 29.1 +/- 1.1 min). During occlusion, seven of 38 (18%) sustained complete loss of the SEP; uniform and prompt (1 to 6 min after clamp release) recovery of the signal occurred in these patients with reperfusion following completion of the repair (n = 6), or temporary institution of partial occlusion (n = 1). By multiple regression analysis the degree of SCI was negatively related to the distal aortic pressure (mean 32.4 +/- 2.4 mm Hg, p = .03), and the occlusion PCO2 (mean 33.1 +/- 1.1 mm Hg; p = .013), and positively related to the change in proximal systolic pressure with aortic occlusion (mean 19.8 +/- 3 mm Hg, p = .003). We conclude that: (1) distal hypotension and SCI commonly occur during aortic occlusion for coarctation repair, and (2) intraoperative interventions that can potentially influence distal aortic perfusion and/or PCO2 should be used judiciously.

Albendazole--objective evidence of response in human hydatid disease

Thirty-two patients with cysts caused by Echinococcus granulosus were treated with albendazole in a dosage of 10 mg/kg/day. Reversible abnormalities in liver-cell function tests were seen in five patients. Some radiological evidence of remission (on serial computed tomographic or ultrasound scanning) was seen in 15 of 22 patients undergoing a therapeutic course of albendazole (as opposed to those treated before or after surgery). In five patients, the cysts virtually disappeared. Apart from reduction in size, the appearance of a halo around the cysts and the apparent disappearance of daughter cysts has been seen. Serological findings have not correlated well with radiological or clinical improvement. Serum and cyst concentrations of albendazole sulfoxide (the principal metabolite) have been measured.