CPR during COVID-19: Use of Expert-driven Rapid Cycle Deliberate Practice to Implement PALS Guidelines.

The American Heart Association (AHA) and other national institutions have endorsed modifications to resuscitation guidelines given the risk of healthcare workers' (HCWs) exposure to COVID-19. Institutional implementation of the COVID-19-focused guidelines requires both proof of feasibility and education of HCW. Pediatric critical care medical directors at The University of Texas Southwestern/Children's Health System of Texas (UTSW/CHST) created a guideline for the resuscitation of COVID-19 patients. The simulation team used in situ simulation to demonstrate guideline feasibility and to create educational materials. METHODS: A UTSW/CHST guideline incorporated COVID-19-focused AHA and other national organizational recommendations to fit the institutional needs. A high-fidelity in situ simulation helped test the feasibility and optimize the UTSW/CHST guideline. We developed a novel form of rapid cycle deliberate practice (RCDP), expert-driven RCDP, in which all simulation participants are experts, to debrief the simulation. RESULTS: In situ simulation with expert-driven RCDP demonstrated guideline feasibility in the resuscitation of a COVID-19 patient while balancing the protection of HCW. Expert-driven RCDP allowed for real-time alterations to the guideline during the simulation event. Video recording and dissemination of the simulation allowed for the education of over 300 staff on the new recommendations. CONCLUSIONS: High-fidelity in situ simulation with expert-driven RCDP created a rapid consensus among expert critical care providers to develop the UTSW/CHST guideline and quickly adopt the new AHA recommendations. This debriefing method helped minimize the risk of HCW exposure by minimizing the number of required participants and time for simulation. We recommend using this distinctive, expert-driven RCDP debriefing method for expeditious testing of COVID-19-focused processes at other institutions.Video Abstract available at: [link forthcoming].

Sensitizing acute myeloid leukemia cells to induced differentiation by inhibiting the RIP1/RIP3 pathway.

Tumor necrosis factor-α (TNF-α)-induced RIP1/RIP3 (receptor-interacting protein kinase 1/receptor-interacting protein kinase 3)-mediated necroptosis has been proposed as an alternative strategy for treating apoptosis-resistant leukemia. However, we found that most acute myeloid leukemia (AML) cells, especially M4 and M5 subtypes, produce TNF and show basal level activation of RIP1/RIP3/MLKL signaling, yet do not undergo necroptosis. TNF, through RIP1/RIP3 signaling, prevents degradation of SOCS1, a key negative regulator of interferon-γ (IFN-γ) signaling. Using both pharmacologic and genetic assays, we show here that inactivation of RIP1/RIP3 resulted in reduction of SOCS1 protein levels and partial differentiation of AML cells. AML cells with inactivated RIP1/RIP3 signaling show increased sensitivity to IFN-γ-induced differentiation. RIP1/RIP3 inactivation combined with IFN-γ treatment significantly attenuated the clonogenic capacity of both primary AML cells and AML cell lines. This combination treatment also compromised the leukemogenic ability of murine AML cells in vivo. Our studies suggest that inhibition of RIP1/RIP3-mediated necroptotic signaling might be a novel strategy for the treatment of AML when combined with other differentiation inducers.

Nlrp12 mutation causes C57BL/6J strain-specific defect in neutrophil recruitment.

The inbred mouse strain C57BL/6J is widely used in models of immunological and infectious diseases. Here we show that C57BL/6J mice have a defect in neutrophil recruitment to a range of inflammatory stimuli compared with the related C57BL/6N substrain. This immune perturbation is associated with a missense mutation in Nlrp12 in C57BL/6J mice. Both C57BL/6J and NLRP12-deficient mice have increased susceptibility to bacterial infection that correlates with defective neutrophil migration. C57BL/6J and NLRP12-deficient macrophages have impaired CXCL1 production and the neutrophil defect observed in C57BL/6J and NLRP12-deficient mice is rescued by restoration of macrophage NLRP12. These results demonstrate that C57BL/6J mice have a functional defect in NLRP12 and that macrophages require NLRP12 expression for effective recruitment of neutrophils to inflammatory sites.

Clinical and genetic findings in a family with NMNAT1-associated Leber congenital amaurosis: case report and review of the literature.

BACKGROUND: Leber congenital amaurosis (LCA) is a severe retinal dystrophy, typically manifesting in the first year of life. Mutations in more than 18 genes have been reported to date. In recent studies, biallelic mutations in NMNAT1 encoding nicotinamide mononucleotide adenylyltransferase 1 have been found to cause LCA. PURPOSE: To broaden the knowledge regarding the phenotype of NMNAT1-associated LCA. METHODS: Clinical ophthalmologic examinations were performed in two sisters with LCA. Whole exome sequencing was performed in one of the affected girls, with subsequent segregation analysis in the affected sister and unaffected parents. The literature was reviewed for reports of NMNAT1-associated LCA. RESULTS: Exome sequencing revealed the known NMNAT1 mutation c.25G>A (p.Val9Met) in a homozygous state. Segregation analysis showed the same homozygous mutation in the affected younger sister. Both parents were found to be heterozygous carriers of the mutation. The two girls both presented with severe visual impairment, nystagmus, central atrophy of the pigment epithelium, and pigment clumping in the periphery before the age of 6 months. Retinal vessels were attenuated. Both children were hyperopic. In the older sister, differential diagnosis included an inflammatory origin, but electrophysiology in her as well as her sister confirmed a diagnosis of LCA. Pallor of the optic nerve head was not present at birth but developed progressively. CONCLUSIONS: We confirmed a diagnosis of NMNAT1-associated LCA in two siblings through identification of the mutation (c.25G>A [p. Val9Met]) in a homozygous state. In infants with non-detectable electroretinogram (ERG), along with severe congenital visual dysfunction or blindness and central pigment epithelium atrophy with pigment clumping resembling scarring due to chorioretinitis, LCA due to NMNAT1 mutations should be considered.

[Lichtenstein's hernia repair]. / Lichtenstein's Hernia Repair.

AIM: Lichtenstein's hernia repair (LHR) is presented as a technically feasible procedure for inguinal hernia. INDICATION: LHR is a standard procedure for open mesh techniques with very good postoperative results. METHOD: We demonstrate an LHR step by step with preservation of the iliohypogastricus and ilioinguinalis nerves. CONCLUSION: LHR is a technically feasible and safe procedure which should have a firm place in a general surgical education.

ROS-containing endosomal compartments: implications for signaling.

The endogenous generation of reactive oxygen species (ROS), previously perceived as a detrimental by-product of cellular processes, is now recognized as a critical component of intracellular signaling. Exploration of these biological signaling functions requires understanding the complex redox biochemistry and recognizing the compartment-specific elements of ROS generation. The endosomal compartment is increasingly recognized as a source for NADPH oxidase (NOX)-generated signaling ROS. Despite this growing understanding, there are significant limitations to the available detection and measurement systems for endogenous ROS. This chapter provides information about specific methodologies and redox-sensitive probes to guide the investigator and define the critical limitations for many of the available approaches. Although measurement continues to be challenging, the rapid growth and development of new detection systems suggests that our capacity to assign specific signaling roles to endosomal ROS will expand markedly in the next several years.

[Recurrent colorectal liver metastases: who benefits from a second hepatic resection?]. / Rezidivlebermetastasen kolorektaler Karzinome: Wer profitiert von einer zweiten Leberresektion?

BACKGROUND: Hepatic recurrence is seen in approximately 40 % of patients undergoing hepatectomy for colorectal metastases. The authors assessed the benefit and the main prognostic factors for a second liver resection of recurrent colorectal metastases. METHODS: This study reports the experience with second liver resections for recurrent liver metastases at a German University Hospital. A total of 39 parameters from 60 patients were identified from a prospective database and analysed as to their influence on recurrence-free survival and overall survival. RESULTS: At a median follow-up of 26 months (range: 2-173 months) after second hepatic resection, recurrence-free survival at 3 and 5 years were 50 % and 37 %, respectively. The overall survival at three and five years were 61 % and 52 %, respectively. Recurrence was identified in 58.3 % of the patients. Recurrences involved exclusively the liver in 19 patients (31.6 %). By multivariate analysis (Cox proportional hazard model), a time interval between diagnosis of the liver metastases of less than 24 months after operation for colorectal primary carcinoma (HR: 6.47, p = 0.002), a CEA level of 4.0 ng/mL or more (HR: 3.48, p = 0.004) at the time of first liver metastases and a size of second liver metastases of 80 mm or more (HR: 4.73, p = 0.007) were independent prognostic factors for a reduced recurrence-free survival. A repeat recurrence of liver metastases without the option of curative resection was the only risk factor for overall survival after second hepatic resection (p = 0.009). In these cases, mortality risk was 4.51-fold, however, when the second liver recurrence was resectable, the mortality risk increased only 1.4-fold. CONCLUSIONS: Technically resectable recurrent colorectal hepatic metastases should be resected the same as the first metastases. Characteristics of the primary metastasis as well as parameters of the hepatic recurrence are shown to influence the prognosis of patients after resection of recurrent liver metastases. Repeat resection of colorectal liver metastases allows for improved survival in patients even after two previous liver operations.

Truncating mutations in FUS/TLS give rise to a more aggressive ALS-phenotype than missense mutations: a clinico-genetic study in Germany.

BACKGROUND AND PURPOSE: Mutations in the FUS/TLS have been associated with amyotrophic lateral sclerosis (ALS) in a few percent of patients. METHODS: We screened 184 familial (FALS) and 200 sporadic German patients with ALS for FUS/TLS mutations by sequence analysis of exons 5, 6 and 13-15. We compared the phenotypes of patients with different FUS/TLS mutations. RESULTS: We identified three missense mutations p.K510R, p.R514G, p.R521H, and the two truncating mutations p.R495X and p.G478LfsX23 in samples from eight pedigrees. Both truncating mutations were associated with young onset and very aggressive disease courses, whereas the p.R521H, p.R514G and in particular the p.K510R mutation showed a milder phenotype with disease durations ranging from 3 years to more than 26 years, the longest reported for a patient with a FUS/TLS mutation. Also, in a pair of monozygous twins with the p.K510R mutation, a remarkable similar disease course was observed. CONCLUSIONS: Mutations in FUS/TLS account for 8.7% (16 of 184) of FALS in Germany. This is a higher prevalence than reported from other countries. Truncating FUS/TLS mutations result in a more severe phenotype than most missense mutations. The wide phenotypic differences have implications for genetic counselling.

Meningioma progression in mice triggered by Nf2 and Cdkn2ab inactivation.

Aggressive variants of meningiomas (WHO grade II and III) represent up to 30% of those tumors that are among the most common primary central nervous system tumors in adults. Currently, there is no effective treatment for grade-II and -III meningiomas, the main treatment remaining surgical excision. Genetic studies have highlighted two main events associated with meningioma progression: an increase of chromosomal instability in tumors with NF2 inactivation and homozygous deletions or point mutations of the CDKN2AB locus. In this study we demonstrated that in mice, in addition to bi-allelic Nf2 inactivation, homozygous and heterozygous Adenovirus Cre-mediated Cdkn2ab deletions lead to increased meningioma frequency (72% and 50%, respectively) with a shorter latency (3.5 and 7.8 months, respectively) compared with control cohorts and induce grade II/III meningioma progression with an incidence of 34% and 28%, respectively. Moreover, Cdkn2ab inactivation in arachnoidal cells was associated with decreased senescence compared with Nf2(-/-) and wild-type arachnoidal cells in vitro. We have established three mouse meningioma cell lines and generated a syngenic orthotopic meningioma mouse model with 50-100% grade-II/III meningiomas after reimplantation. Comparative genomic hybridization of four meningiomas from Cdkn2ab homozygous mice and three cell cultures revealed the absence of unbalanced chromosomal segments in tumors and several chromosome imbalances in cell cultures. In addition, we were able to detect meningiomas by using bioluminescence and to evaluate tumor vascular permeability by dynamic magnetic resonance imaging. These results show that Nf2 and Cdkn2ab cooperate to promote meningioma progression in mice. The short latency of tumor development and the ability to derive grade II/III meningioma cell cultures are key aspects of this model to promote its use in pre-clinical drug testing.

Circulating natriuretic peptide concentrations in hyperthyroid cats.

OBJECTIVES: To assess the influence of thyroid function on natriuretic peptide concentration in hyperthyroid cats before and after treatment. METHODS: Serum natriuretic peptide concentration was measured in 61 hyperthyroid cats recruited from first-opinion clinics before and after treatment. RESULTS: Following successful treatment, total thyroxine, heart rate, systolic blood pressure and packed cell volume all decreased and bodyweight and creatinine concentrations increased. Furthermore, a significant (P < 0·001) decline in NT-proBNP concentration but not NT-proANP was identified. CLINICAL SIGNIFICANCE: Thyroid function has a modest but significant effect on NT-proBNP concentration. Thyroid status should be taken into account when interpreting NT-proBNP concentrations in cats.

Endotoxin priming of neutrophils requires endocytosis and NADPH oxidase-dependent endosomal reactive oxygen species.

NADPH oxidase 2 (Nox2)-generated reactive oxygen species (ROS) are critical for neutrophil (polymorphonuclear leukocyte (PMN)) microbicidal function. Nox2 also plays a role in intracellular signaling, but the site of oxidase assembly is unknown. It has been proposed to occur on secondary granules. We previously demonstrated that intracellular NADPH oxidase-derived ROS production is required for endotoxin priming. We hypothesized that endotoxin drives Nox2 assembly on endosomes. Endotoxin induced ROS generation within an endosomal compartment as quantified by flow cytometry (dihydrorhodamine 123 and Oxyburst Green). Inhibition of endocytosis by the dynamin-II inhibitor Dynasore blocked endocytosis of dextran, intracellular generation of ROS, and priming of PMN by endotoxin. Confocal microscopy demonstrated a ROS-containing endosomal compartment that co-labeled with gp91(phox), p40(phox), p67(phox), and Rab5, but not with the secondary granule marker CD66b. To further characterize this compartment, PMNs were fractionated by nitrogen cavitation and differential centrifugation, followed by free flow electrophoresis. Specific subfractions made superoxide in the presence of NADPH by cell-free assay (cytochrome c). Subfraction content of membrane and cytosolic subunits of Nox2 correlated with ROS production. Following priming, there was a shift in the light membrane subfractions where ROS production was highest. CD66b was not mobilized from the secondary granule compartment. These data demonstrate a novel, nonphagosomal intracellular site for Nox2 assembly. This compartment is endocytic in origin and is required for PMN priming by endotoxin.

High frequency of autosomal-recessive DFNB59 hearing loss in an isolated Arab population in Israel.

Autosomal-recessive non-syndromic hearing impairment (DFNB) is usually of prelingual onset with a moderate to profound degree of hearing loss. More than 70 DFNB loci have been mapped and ~40 causative genes have been identified. Non-syndromic hearing impairment caused by mutations of DFNB59 (encoding pejvakin) has been described in a couple of families in which affected individuals presented with either auditory neuropathy or hearing loss of cochlear origin. We have identified and clinically evaluated three consanguineous families of Israeli Arab origin with prelingual non-syndromic hearing impairment and absent otoacoustic emissions in a total of eight affected individuals. All the families originate from the same village and bear the same family name. We have identified a c.406C>T (p.R136X) nonsense mutation in the DFNB59 gene in affected individuals from these families. Among the inhabitants of the village, we found an exceptionally high carrier frequency of ~1 in 12 individuals (7/85; 8.2%). The high prevalence of hearing impairment can be explained by a founder effect and the high consanguinity rate among the inhabitants of this village.

Priming of neutrophils and differentiated PLB-985 cells by pathophysiological concentrations of TNF-α is partially oxygen dependent.

Activation of polymorphonuclear leukocytes (PMN) can be modulated to intermediate 'primed' states characterized by enhanced responsiveness to subsequent stimuli. We studied priming in response to TNF-α in human PMN and PLB-985 cells, a myeloid cell line differentiated to a neutrophilic phenotype (PLB-D). PMN generated reactive oxygen species (ROS) in response to TNF-α alone, and NADPH oxidase activity increased in response to stimulation with formyl-Met-Leu-Phe after priming. PLB-D cells also demonstrated priming of NADPH oxidase activity. Similar to priming by endotoxin, priming of the respiratory burst by TNF-α was predominantly oxygen dependent, with marked attenuation of ROS generation if primed anaerobically. Both PMN and PLB-D cells displayed significant increases in cell surface CD11b and gp91(phox) expression after TNF-α priming and PMN displayed activation of MAPK. In response to TNF-α priming, neither mobilization of intracellular proteins nor activation of MAPK pathways was NADPH oxidase dependent. Priming of PMN and PLB-D cells by low TNF-α concentrations enhanced chemotaxis. These data demonstrate that pathophysiological concentrations of TNF-α elicit NADPH oxidase-derived ROS and prime cells for enhanced surface protein expression, activation of p38 and ERK1/2 MAPK pathways, and increased chemotaxis. Furthermore, PLB-D cells undergo TNF-α priming and provide a genetically modifiable model to study priming mechanisms.

Bolus-tracking MRI with a simultaneous T1- and T2*-measurement.

The aim of this study was to propose and evaluate a methodology to analyze simultaneously acquired T2*-weighted dynamic susceptibility contrast (DSC) MRI and T(1)-weighted dynamic contrast enhanced (DCE) MRI data. Two generalized models of T2*-relaxation are proposed to account for tracer leakage, and a two-compartment exchange model is used to separate tracer in intra- and extravascular spaces. The methods are evaluated using data extracted from ROIs in three mice with subcutaneously implanted human colorectal tumors. Comparing plasma flow values obtained from DCE-MRI and DSC-MRI data defines a practical experimental paradigm to measure T2*-relaxivities, and reveals a factor of 15 between values in tissue and blood. Comparing mean transit time values obtained from DCE-MRI and DSC-MRI without leakage correction, indicates a significant reduction of susceptibility weighting in DSC-MRI during tracer leakage. A one-parameter gradient correction model provides a good approximation for this susceptibility loss, but redundancy of the parameter limits the practical potential of this model for DSC-MRI. Susceptibility loss is modeled more accurately with a variable T2*-relaxivity, which allows to extract new parameters that cannot be derived from DSC-MRI or DCE-MRI alone. They reflect the cellular and vessel geometry, and thus may lead to a more complete characterization of tissue structure.

ClC-3 and IClswell are required for normal neutrophil chemotaxis and shape change.

Polymorphonuclear leukocytes undergo directed movement to sites of infection, a complex process known as chemotaxis. Extension of the polymorphonuclear leukocyte (PMN) leading edge toward a chemoattractant in association with uropod retraction must involve a coordinated increase/decrease in membrane, redistribution of cell volume, or both. Deficits in PMN phagocytosis and trans-endothelial migration, both highly motile PMN functions, suggested that the anion transporters, ClC-3 and ICl(swell), are involved in cell motility and shape change ( Moreland, J. G., Davis, A. P., Bailey, G., Nauseef, W. M., and Lamb, F. S. (2006) J. Biol. Chem. 281, 12277-12288 ). We hypothesized that ClC-3 and ICl(swell) are required for normal PMN chemotaxis through regulation of cell volume and shape change. Using complementary chemotaxis assays, EZ-TAXIScantrade mark and dynamic imaging analysis software, we analyzed the directed cell movement and morphology of PMNs lacking normal anion transporter function. Murine Clcn3(-/-) PMNs and human PMNs treated with anion transporter inhibitors demonstrated impaired chemotaxis in response to formyl peptide. This included decreased cell velocity and failure to undergo normal cycles of elongation and retraction. Impaired chemotaxis was not due to a diminished number of formyl peptide receptors in either murine or human PMNs, as measured by flow cytometry. Murine Clcn3(-/-) and Clcn3(+/+) PMNs demonstrated a similar regulatory volume decrease, indicating that the ICl(swell) response to hypotonic challenge was intact in these cells. We further demonstrated that ICl(swell) is essential for shape change during human PMN chemotaxis. We speculate that ClC-3 and ICl(swell) have unique roles in regulation of PMN chemotaxis; ICl(swell) through direct effects on PMN volume and ClC-3 through regulation of ICl(swell).

Ischemic preconditioning improves postoperative outcome after liver resections: a randomized controlled study.

BACKGROUND: Clamping of the portal triad (Pringle maneuver) prevents blood loss during liver resection, but leads to liver injury upon reperfusion. Ischemic preconditioning (IP) has been shown to protect the liver against prolonged ischemic injury in animal models. However, the clinical value of this procedure has not yet been established. METHODS: 61 Patients undergoing hepatic resection under inflow occlusion were randomized to either to receive (Group-A n = 30) or not to receive (Group-B n = 31) an IP (10 minutes of ischemia followed 10 minutes of reperfusion). RESULTS: Mean (+/- SD)/ Group-A vs. Group-B. Pringle time of 34 +/- 14 and 33 +/- 12 minutes and the extent of resected liver tissue (2.7 +/- 1.3 vs. 2.7 +/- 1.1 segments) were comparable in both groups. Complications, including death, severe liver dysfunction and biliary leakage occurred in 6 patients of Group-A vs. 14 patients of Group-B (p<0.05). Intraoperative blood loss was significantly lower in Group-A (1.28 +/- 0.91 l vs. 1.94 +/- 0.76 l; p<0.001) with 5 vs. 15 patients requiring transfusions (p<0.01). In a multivariate analysis the duration of the Pringle maneuver (p<0.05) and the absence of preconditioning (p<0.05) were independent predictors for the occurrence of postoperative complications. CONCLUSIONS: IP protects against reperfusion injury, reduces the incidence of complications after hepatic resection under inflow occlusion and is simple to use in clinical practice.

CNTO 530: molecular pharmacology in human UT-7EPO cells and pharmacokinetics and pharmacodynamics in mice.

CNTO 530 is a 58 kD antibody Fc domain fusion protein, created using Centocor's MIMETIBODY platform, that contains two EMP1 sequences as a pharmacophore. CNTO 530 has no sequence homology with EPO but acts as a novel erythropoietin receptor agonist. In UT-7(EPO) cells, CNTO 530 caused protein phosporylation of the erythropoietin receptor associated signaling pathway (Jak2, STAT5, AKT and ERK1/2). CNTO 530 also rescued these cells from apoptosis and mediated proliferation. In mice, pharmacokinetic analysis showed that CNTO 530 was slowly cleared from circulation with a t(1/2) approximately 40 h. Pharmacodynamic analysis in mice showed that a single sc dose of CNTO 530 caused a long-lived stimulation of erythropoiesis that translated into increases in red blood cell counts and hemoglobin values that were maintained for at least 28 d. In conclusion, CNTO 530 is a long-lived EPO-R agonist that stimulates erythropoiesis in a manner similar to epoetin-alpha. These data suggest that CNTO 530 may be an effective treatment of anemia in humans.

Expression of human tissue factor under the control of the mouse tissue factor promoter mediates normal hemostasis in knock-in mice.

BACKGROUND: Tissue factor (TF) is expressed widely at the subluminal surface of blood vessels and serves as the primary cellular initiator of the extrinsic pathway of blood coagulation. Lack of TF in mice resulted in lethality in utero, but human TF (huTF) expressed at low levels from a human minigene rescued null mice from prenatal death. Although these low-TF expressing transgenic mice developed to term, they had a significantly shorter life span and exhibited hemorrhage and fibrosis in the heart. METHODS: Human TF knock-in (TFKI) mice were generated by replacing the first two exons of the mouse (murine) TF (muTF) gene with the huTF complete coding sequence, thus placing it under the control of the endogenous muTF promoter. RESULTS: Expression of huTF in the TFKI mice was similar to muTF in wild-type (wt) mice. The TFKI mice showed no microscopic evidence of spontaneous hemorrhage in the heart, nor cardiac fibrosis at up to 18 months of age. Immunohistochemistry showed that huTF was expressed in cells surrounding blood vessels in TFKI mice. Coagulation activity of brain homogenates from TFKI mice was comparable with that from wt brain. Cardiac hemorrhage similar to that of the low-TF transgenic mice occurred in the TFKI mice when huTF was blocked by a neutralizing anti-huTF monoclonal antibody. CONCLUSION: We generated a transgenic mouse line that expresses huTF under the control of the endogenous muTF promoter at physiological levels. Our results suggest that huTF can fully reconstitute the murine coagulation system and mediate normal hemostasis.

Ischemic preconditioning attenuates portal venous plasma concentrations of purines following warm liver ischemia in man.

BACKGROUND/AIMS: Degradation of adenine nucleotides to adenosine has been suggested to play a critical role in ischemic preconditioning (IPC). Thus, we questioned in patients undergoing partial hepatectomy whether (i) IPC will increase plasma purine catabolites and whether (ii) formation of purines in response to vascular clamping (Pringle maneuver) can be attenuated by prior IPC. METHODS: 75 patients were randomly assigned to three groups: group I underwent hepatectomy without vascular clamping; group II was subjected to the Pringle maneuver during resection, and group III was preconditioned (10 min ischemia and 10 min reperfusion) prior to the Pringle maneuver for resection. Central, portal venous and arterial plasma concentrations of adenosine, inosine, hypoxanthine and xanthine were determined by high-performance liquid chromatography. RESULTS: Duration of the Pringle maneuver did not differ between patients with or without IPC. Surgery without vascular clamping had only a minor effect on plasma purine concentrations. After IPC, plasma concentrations of purines transiently increased. After the Pringle maneuver alone, purine plasma concentrations were most increased. This strong rise in plasma purines caused by the Pringle maneuver, however, was significantly attenuated by IPC. When portal venous minus arterial concentration difference was calculated for inosine or hypoxanthine, the respective differences became positive in patients subjected to the Pringle maneuver and were completely prevented by preconditioning. CONCLUSION: These data demonstrate that (i) IPC increases formation of adenosine, and that (ii) the unwanted degradation of adenine nucleotides to purines caused by the Pringle maneuver can be attenuated by IPC. Because IPC also induces a decrease of portal venous minus arterial purine plasma concentration differences, IPC might possibly decrease disturbances in the energy metabolism in the intestine as well.