Ernst von Dobschuetz

Orthogonal polarization spectral imaging as a tool for the assessment of hepatic microcirculation: A validation study

Background. Quantitative analysis of liver microcirculation using intravital fluorescence microscopy in animals has increased our knowledge about ischemia-reperfusion injury. However, because of the size of the instrumentation and the necessity of fluochromes for contrast enhancement, human liver microcirculation cannot be observed. Orthogonal Polarization Spectral (OPS) imaging is a recently introduced technique that can be used to visualize the microcirculation without the need for fluorescent dyes. It is a small, hand-held device and could potentially be used to study the microcirculation of the human liver in a clinical setting. However, before implementation into clinical use its ability to quantitatively measure microcirculatory parameters must be validated. Methods. The livers of Spraque-Dawley rats (n=9) were exteriorized, and images were obtained using OPS imaging and intravital fluorescence microscopy of the identical microvascular regions before and after the induction of a 20-min warm lobar ischemia. Images were videotaped for later computer-assisted off-line analysis. Results. OPS imaging can be used to accurately quantify the sinusoidal perfusion rate, vessel diameter, and venular red blood cell velocity. Correlation parameters were significant and Bland-Altman analyses showed good agreement for data obtained from the two methods at baseline as well as during reperfusion. Conclusion. OPS imaging can be used to quantitatively measure microcirculatory parameters in the rat liver under both physiological and pathophysiological conditions. Thus, OPS imaging has the potential to be used to make quantitative measurements of the microcirculation in the human liver.

Antimetastatic Effects of Liposomal Gemcitabine and Empty Liposomes in an Orthotopic Mouse Model of Pancreatic Cancer

Objectives: Test the efficacy of liposomal gemcitabine (GemLip) on primary tumor and metastases using the pancreatic tumor cell line AsPC1 implanted orthotopically into nude mice. Methods: The efficacy of gemcitabine and GemLip cells was tested on luciferase-transduced AsPC1 cells in vitro as well as implanted orthotopically into the pancreata of nude mice. Results: In vitro, the IC50s for GemLip and gemcitabine were 20 nM and 140 nM, respectively. However, when applied against established tumors, GemLip (8 mg/kg) blocked tumor growth for 5 consecutive weeks according to bioluminescence measurements in vivo. Gemcitabine (240 mg/kg) had no effect on luciferase-monitored tumor growth. When analyzed at the time of necropsy, GemLip strongly reduced tumor size (−64% ± [SD] 27%; ***P < 0.0001), whereas gemcitabine only weakly (−36% ± 37%) affected tumor size. Empty liposomes had no effect on the tumor size. GemLip and empty liposomes both significantly interfered with the metastatic spread to the liver, as measured using luciferase assays (GemLip, *P = 0.01; empty liposomes, *P = 0.036). In addition, they showed effects against spleen, as well as peritoneal metastases. Conclusions: GemLip presents an effective new formulation of gemcitabine, combining the targeting and protective features of the liposomes with their antimetastatic effects to target pancreatic cancer.

Long term prognosis of patients with pediatric pheochromocytoma

A third of patients with paraganglial tumors, pheochromocytoma, and paraganglioma, carry germline mutations in one of the susceptibility genes, RET, VHL, NF1, SDHAF2, SDHA, SDHB, SDHC, SDHD, TMEM127, and MAX. Despite increasing importance, data for long-term prognosis are scarce in pediatric presentations. The European-American-Pheochromocytoma-Paraganglioma-Registry, with a total of 2001 patients with confirmed paraganglial tumors, was the platform for this study. Molecular genetic and phenotypic classification and assessment of gene-specific long-term outcome with second and/or malignant paraganglial tumors and life expectancy were performed in patients diagnosed at <18 years. Of 177 eligible registrants, 80% had mutations, 49% VHL, 15% SDHB, 10% SDHD, 4% NF1, and one patient each in RET, SDHA, and SDHC. A second primary paraganglial tumor developed in 38% with increasing frequency over time, reaching 50% at 30 years after initial diagnosis. Their prevalence was associated with hereditary disease (P=0.001), particularly in VHL and SDHD mutation carriers (VHL vs others, P=0.001 and SDHD vs others, P=0.042). A total of 16 (9%) patients with hereditary disease had malignant tumors, ten at initial diagnosis and another six during follow-up. The highest prevalence was associated with SDHB (SDHB vs others, P<0.001). Eight patients died (5%), all of whom had germline mutations. Mean life expectancy was 62 years with hereditary disease. Hereditary disease and the underlying germline mutation define the long-term prognosis of pediatric patients in terms of prevalence and time of second primaries, malignant transformation, and survival. Based on these data, gene-adjusted, specific surveillance guidelines can help effective preventive medicine.

diaspirin Cross-linked Hemoglobin Effectively Restores Pancreatic Microcirculatory Failure in Hemorrhagic Shock

BACKGROUND Microvascular reperfusion failure of splanchnic organs is a crucial hallmark in organ damage induced by hemorrhagic shock, which should be prevented by a resuscitation solution. Because the vasoactive properties of the hemoglobin-based oxygen carrier diaspirin cross-linked hemoglobin (DCLHb) could adversely influence restoration of pancreatic capillary perfusion during resuscitation, the authors investigated its effects on the microcirculation of the rat pancreas in comparison with whole blood and 6% hydroxyethylstarch resuscitation from severe hemorrhagic shock. METHODS Twenty-eight pentobarbital-anaesthetized rats were bled to a mean arterial pressure (MAP) of 40 mmHg and maintained at this level for 1 h. Using an intravital microscope, mean arterial pressure, the length of erythrocyte-perfused pancreatic capillaries per observation area (functional capillary density), the adherence of leukocytes in postcapillary venules, and pancreatic lipid peroxidation, measured as thiobarbituric acid-reactive material in pancreatic tissue, were determined in animals resuscitated by volumes of hydroxyethylstarch, DCLHb, and whole blood (WB) equivalent to the shed blood volume or in control animals without shock induction for a period of 2 h after resuscitation. RESULTS Compared with control animals (366+/-28 cm(-1)), animals resuscitated with DCLHb (294+/-45 cm(-1)), WB (306+/-11 cm(-1)), and hydroxyethylstarch (241+/-34 cm(-1)) showed a significant reduction of functional capillary density after 2 h of resuscitation. DCLHb was as effective as WB and superior to hydroxyethylstarch in restoring functional capillary density and mean arterial pressure. Leukocyte adherence in postcapillary venules was not enhanced by DCLHb (369+/-148/mm2) infusion when compared with hydroxyethylstarch- (615+/-283/mm2) and WB-treated (510+/-415/mm2) animals. Lipid peroxidation of pancreatic tissue was significantly elevated after treatment with both oxygen-carrying solutions compared with hydroxyethylstarch. CONCLUSION DCLHb is as effective as WB for preservation of the pancreatic microcirculation.

Effects of Organ Preservation, Ischemia Time and Caspase Inhibition on Apoptosis and Microcirculation in Rat Pancreas Transplantation

This study was undertaken to examine the impact of ischemia‐reperfusion (I/R) injury on microcirculation and apoptosis in experimental pancreas transplantation. Pancreatic grafts were subjected to different preservation solutions and cold ischemia times (CITs): University of Wisconsin (UW), 6‐h CITs (group U6); UW, 18‐h CITs (group U18); normal saline, 6‐h CITs (group S6); and normal saline, 6‐h CITs with Z‐Asp‐2,6‐dichlorobenzoyloxymethylketone (pan‐caspase inhibitor; group S6 & CI). Nontransplanted animals served as controls. At 1‐ and 2‐h reperfusion microcirculation was assessed by means of intravital microscopy. Apoptosis was detected by in situ nick end‐labeling method (TUNEL) at 2‐h reperfusion. Deterioration of microcirculation was lowest in group U6 and highest in groups S6 and S6 & CI compared with controls. The apoptotic index (cells per high power fields) of groups U6, U18 and S6 correlated well with functional capillary density (r=− 0,70, p < 0.0001) and leucocyte sticking (r= 0,69, p < 0.0001) at 1‐h reperfusion. Caspase inhibition had no impact on microcirculation but significantly reduced AI compared with group S6 (p < 0.001). These data suggest that pancreatic I/R injury‐induced apoptotic cell death well predicts the extent microcirculatory impairment. Caspase inhibition might be a promising strategy in reducing I/R injury in pancreas transplantation.

Recombinant Human Hemoglobin with Reduced Nitric Oxide–scavenging Capacity Restores Effectively Pancreatic Microcirculatory Disorders in Hemorrhagic Shock

Background: Scavenging of nitric oxide by hemoglobin-based oxygen carriers could aggravate microcirculatory failure in splanchnic organs after hemorrhagic shock as a consequence of vasoconstrictive side effects. The aim of this study was to compare the effects of two recombinant human hemoglobin solutions, a second-generation product bearing reduced nitric oxide–scavenging properties (rHb2.0) due to site directed mutagenesis of the heme pocket and a first-generation recombinant hemoglobin (rHb1.1) with scavenging capacity similar to native hemoglobin, on the pancreatic microcirculation after hemorrhagic shock. Methods: Twenty-eight pentobarbital-anesthetized rats were bled to a mean arterial pressure of 40 mmHg and maintained at this level for 1 h. Using an intravital microscope, the length of erythrocyte-perfused pancreatic capillaries per observation area (functional capillary density) were measured in animals resuscitated by volumes of hydroxyethyl starch, rHb1.1, or rHb2.0 equivalent to the shed blood volume. Animals without shock induction served as control. Results: As compared with control (438 ± 10 cm−1), animals treated with hydroxyethyl starch (315 ± 44 cm−1) and rHb1.1 (288 ± 67 cm−1) showed a significant reduction of functional capillary density after 2 h of resuscitation. rHb2.0 was able to restore functional capillary density (410 ± 42 cm−1) and mean arterial pressure to baseline values. Conclusion: rHb2.0 was effectively able to restore pancreatic microcirculation after hemorrhagic shock. This may be related to the compound’s effective lack of nitric oxide–scavenging properties. This hemoglobin solution or ones similar to it might be uniquely valuable for resuscitation from hemorrhagic shock.

Giant ancient schwannoma of pancreatic head treated by extended pancreatoduodenectomy.

We report a case of a 55-year-old woman who was transferred from another center to our university clinic after diagnostic laparotomy with a pancreatic head tumor which was seen to encase the portal vein. Although intraoperative biopsies were performed, a histologic diagnosis of the tumor was not possible before giving suspect to a malignant tumor being resectable only with a vascular resection. In a second operation we performed a pylorus-preserving pancreatoduodenectomy. Due to adhesion of the tumor to the portal vein, a segmental resection and end-to-end anastomosis of the portal vein was necessary. Postoperative histologic diagnosis revealed an ancient schwannoma which was removed in toto being a rare report of this benign tumor in the pancreatic head. Ten months after the operation the patient is without any health problems. Partial resection of the portal vein, which is considered to be a safe procedure in high volume centers, stands in contrary to surgical nihilism of pancreatic head tumors suspecting advanced tumors with vascular involvement.

Brain Death Impairs Pancreatic Microcirculation

Brain death (BD) influences the quality of donor grafts in transplantation. To evaluate the impact of BD on pancreas grafts, we investigated the influence of BD on the microcirculation and histology of the pancreas in a rat model of explosive BD. A group of Wistar rats (n = 7), rendered brain dead by inflating an intracranially inserted Fogarty catheter was compared with controls (CO) using intravital epifluorescence‐microscopy over 4 h after BD induction; functional capillary density (FCD), leukocyte adherence (AL) in post‐capillary venules, histology and pancreatic enzymes were investigated. Four hours after BD, FCD decreased (333 ± 11 vs. baseline 444 cm/cm2± 5 SEM; p < 0.01) and showed lower values than CO (388 ± 9 p < 0.01). In BD, AL was increased (628 cells/mm2± 110 SEM vs. baseline 123 ± 32, and vs. CO 180 ± 33; p < 0.001). BD caused increased histological damage (CO 1.6 score‐points ± 0.7 SD vs. BD 8.3 ± 7.1; p < 0.05). Amylase was higher in BD (p < 0.05) but did not reach pathological values. We show for the first time that BD causes relevant changes in pancreatic microcirculation, histology and leukocyte endothelial interaction which might have a serious impact on the function of grafts. New strategies for preventing this damage are therefore highly desirable in order to improve the outcome of pancreas transplantation.

Postoperative oral glucose tolerance and stimulated insulin secretion: a predictor of endocrine graft function more than 10 years after pancreas-kidney transplantation.

Background. After pancreas transplantation, endocrine function is determined by the insulin secretory capacity of the transplanted pancreas. The authors evaluated the predictive value of postoperative oral glucose tolerance test (OGTT) and stimulated insulin secretion on long-term endocrine function. Methods. Forty-one patients after pancreas-kidney transplantation with systemic venous drainage were studied. Patients were categorized to have normal glucose tolerance (NGT) or impaired glucose tolerance (IGT) (World Health Organization criteria: NGT, <7.8 mM; IGT, 7.8–11.1 mM 120 min after glucose intake) and high or low total insulin secretion. Mean follow-up of graft function and patient outcome was 10.2±0.5 years after OGTT. Results. Patients with IGT had grafts with a longer ischemia time and a significantly worse urine amylase excretion as compared with patients with NGT. Using Kaplan-Meier survival analysis, patients with NGT had better long-term pancreatic function as compared with IGT in the follow-up after performing the first OGTT (mean, 10.9±0.2 vs. 8.8±0.9 years of graft function; P =0.02), but there was no difference in patient survival and kidney graft function. Also, high insulin secretion predicted significantly longer pancreas graft function as compared with low insulin secretion (P =0.04). Conclusions. Although IGT does not lead to poorer long-term patient survival and kidney graft function, it does predict compromised long-term endocrine function of the transplanted pancreas. Therefore, postoperative OGTT are useful tools for identification of patients at risk of long-term endocrine graft failure after pancreas transplantation.

Endotoxin preconditioning in pancreatic ischemia/reperfusion injury.

Objectives Prospective organ donors are exposed to various stress types. The effect of endotoxin pretreatment (ETX) on pancreatic ischemia/reperfusion injury (IRI) is unclear. We investigated, using a rat model of pancreatic IRI of an in situ isolated pancreatic tail segment, the effect of ETX on postischemic microcirculation and organ damage. Methods Twenty-four hours before pancreatic dissection, either intraperitoneal application of ETX (1 mg/kg in 0.9% NaCl) or saline only (control) was performed. Two-hour normothermic ischemia of the pancreatic tail was induced by clamping the splenic vessels and was followed by a reperfusion period of 2 hours. Microcirculatory parameters were measured by intravital epifluorescence microscopy [functional capillary density (FCD), adherent leukocytes (ALs), and histology]. The presented data represent the mean ± SEM/SD as appropriate. Results ETX pretreatment caused a significantly greater decrease in FCD (497 ± 6 cm/cm2 baseline versus 326 ± 15 cm/cm2 2 hours of reperfusion) compared with controls (498 ± 8 versus 258 ± 15 cm/cm2) 2 hours after reperfusion (P < 0.01). Two hours after reperfusion, ALs were significantly decreased in ETX animals compared with controls (ETX: 141 ± 37 versus 273 ± 36 cells/mm2, P < 0.05). Histologic damage was less in ETX (6.4 score points ± 0.32 versus 8.8 ± 0.33 control, P < 0.05). Conclusion ETX preconditioning decreases microcirculatory deterioration caused by IRI by means of less loss of nutritive tissue perfusion, decrease in ALs, and less histologic damage. This indicates a protective effect of ETX preconditioning in pancreatic IRI.