Experimental non-alcoholic steatohepatitis in Göttingen Minipigs: consequences of high fat-fructose-cholesterol diet and diabetes.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease in humans, and ranges from steatosis to non-alcoholic steatohepatitis (NASH), the latter with risk of progression to cirrhosis. The Göttingen Minipig has been used in studies of obesity and diabetes, but liver changes have not been described. The aim of this study was to characterize hepatic changes in Göttingen Minipigs with or without diabetes, fed a diet high in fat, fructose, and cholesterol to see if liver alterations resemble features of human NAFLD/NASH. METHODS: Fifty-four male castrated minipigs (age 6 to 7 months) were distributed into four groups and diet-fed for 13 months. Groups were: lean controls fed standard diet (SD, n = 8), a group fed high fat/fructose/cholesterol diet (FFC, n = 16), a group fed high fat/fructose/cholesterol diet but changed to standard diet after 7 months (diet normalization, FFC/SD, n = 16), and a streptozotocin-induced diabetic group fed high fat/fructose/cholesterol diet (FFCDIA, n = 14). At termination, blood samples for analyses of circulating biomarkers and liver tissue for histopathological assessment and analyses of lipids and glycogen content were collected. RESULTS: In comparison with SD and FFC/SD, FFC and FFCDIA pigs developed hepatomegaly with increased content of cholesterol, whereas no difference in triglyceride content was found. FFC and FFCDIA groups had increased values of circulating total cholesterol and triglycerides and the hepatic circulating markers alkaline phosphatase and glutamate dehydrogenase. In the histopathological evaluation, fibrosis (mainly located periportally) and inflammation along with cytoplasmic alterations (characterized by hepatocytes with pale, granulated cytoplasm) were found in FFC and FFCDIA groups compared to SD and FFC/SD. Interestingly, FFC/SD also had fibrosis, a feature not seen in SD. Only two FFC and three FFCDIA pigs had > 5% steatosis, and no hepatocellular ballooning or Mallory-Denk bodies were found in any of the pigs. CONCLUSIONS: Fibrosis, inflammation and cytoplasmic alterations were characteristic features in the livers of FCC and FFCDIA pigs. Overall, diabetes did not exacerbate the hepatic changes compared to FFC. The limited presence of the key human-relevant pathological hepatic findings of steatosis and hepatocellular ballooning and the variation in the model, limits its use in preclinical research without further optimisation.

Platelet function in lung cancer patients undergoing lobectomy.

A growing interest concerns arterial thromboembolic disease in cancer patients. As platelets may be key players in this process, investigation of platelet aggregation in cancer patients is of importance. We aimed to investigate platelet aggregation in patients with lung cancer prior to surgery and during video-assisted thoracoscopic surgery (VATS) lobectomy compared with lobectomy performed through a thoracotomy. We included 93 patients (VATS + low molecular weight heparin (LMWH), n = 32; VATS no LMWH, n = 31; thoracotomy + LMWH, n = 30). Data obtained from 121 healthy individuals were used for comparison prior to surgery. Platelet aggregation was analysed by impedance aggregometry using adenosine diphosphate 6.5 µM (ADPtest) and collagen 3.2 µg/mL (COLtest) as agonists. Prior to surgery, platelet aggregation was significantly increased in both VATS-patients (ADPtest, p < .0001; COLtest, p = .0002) and patients undergoing thoracotomy (ADPtest, p < .0001; COLtest, p < .0001) compared with healthy individuals. Platelet aggregation did not differ between VATS-patients and thoracotomy patients prior to surgery (p-values >.11). At the first postoperative day, VATS-patients demonstrated significantly higher collagen-induced platelet aggregation than preoperatively (p = .001), but the increase in platelet aggregation did not differ significantly between VATS and thoracotomy patients (p-values ≥.24). At the second postoperative day, platelet aggregation was significantly reduced in thoracotomy patients compared with the preoperative level (ADPtest, p = .002; COLtest, p = .05). In conclusion, platelet aggregation was significantly increased in patients with primary lung cancer prior to surgery compared with healthy individuals. At the first postoperative day, platelet aggregation was significantly higher than the preoperative level in VATS-patients; however, this increase did not differ between patient groups.

Video-assisted Thoracoscopic surgery (VATS) lobectomy for lung cancer does not induce a procoagulant state.

BACKGROUND: Changes in the coagulation system in patients undergoing surgery for lung cancer have been sparsely investigated and the impact of the surgical trauma on the coagulation system is largely unknown in these patients. An increased knowledge could potentially improve the thromboprophylaxis regimes. The aim of this study was to assess the coagulation profile evoked in patients undergoing curative surgery by Video-Assisted Thoracoscopic Surgery (VATS) lobectomy for primary lung cancer. METHODS: Thirty-one patients diagnosed with primary lung cancer undergoing VATS lobectomy were prospectively included. The coagulation profile was assessed preoperatively and in the first two days postoperatively using a wide range of standard coagulation tests, dynamic whole blood coagulation measured by rotational thromboelastometry (ROTEM®) and thrombin generation evaluated by calibrated automated thrombography. Patients did not receive thromboprophylactic treatment. Data was analyzed using repeated measures one-way ANOVA. RESULTS: The standard coagulation parameters displayed only subtle changes after surgery and the ROTEM® and thrombin generation results remained largely unchanged. CONCLUSIONS: Patients undergoing VATS lobectomy are normocoagulable in the preoperative state and a VATS lobectomy does not significantly influence the coagulation. TRIAL REGISTRATION: The trial is registered at ClinicalTrials.gov (Identifier: NCT01741506) and at EudraCTno. 2012-002409-23. Registered December 2012.

Effect of captopril on post-infarction remodelling visualized by light sheet microscopy and echocardiography.

Angiotensin converting enzyme inhibitors, among them captopril, improve survival following myocardial infarction (MI). The mechanisms of captopril action remain inadequately understood due to its diverse effects on multiple signalling pathways at different time periods following MI. Here we aimed to establish the role of captopril in late-stage post-MI remodelling. Left anterior descending artery (LAD) ligation or sham surgery was carried out in male C57BL/6J mice. Seven days post-surgery LAD ligated mice were allocated to daily vehicle or captopril treatment continued over four weeks. To provide comprehensive characterization of the changes in mouse heart following MI a 3D light sheet imaging method was established together with automated image analysis workflow. The combination of echocardiography and light sheet imaging enabled to assess cardiac function and the underlying morphological changes. We show that delayed captopril treatment does not affect infarct size but prevents left ventricle dilation and hypertrophy, resulting in improved ejection fraction. Quantification of lectin perfused blood vessels showed improved vascular density in the infarct border zone in captopril treated mice in comparison to vehicle dosed control mice. These results validate the applicability of combined echocardiographic and light sheet assessment of drug mode of action in preclinical cardiovascular research.

Monitoring variables affecting positron emission tomography measurements of cerebral blood flow in anaesthetized pigs.

BACKGROUND: Positron emission tomography (PET) imaging of anaesthetized pig brains is a useful tool in neuroscience. Stable cerebral blood flow (CBF) is essential for PET, since variations can affect the distribution of several radiotracers. However, the effect of physiological factors regulating CBF is unresolved and therefore knowledge of optimal anaesthesia and monitoring of pigs in PET studies is sparse. The aim of this study was therefore to determine if and how physiological variables and the duration of anaesthesia affected CBF as measured by PET using [15O]-water in isoflurane-N2O anaesthetized domestic female pigs. First, we examined how physiological monitoring parameters were associated with CBF, and which parameters should be monitored and if possible kept constant, during studies where a stable CBF is important. Secondly, we examined how the duration of anaesthesia affected CBF and the monitoring parameters. RESULTS: No significant statistical correlations were found between CBF and the nine monitoring variables. However, we found that arterial carbon dioxide tension (PaCO2) and body temperature were important predictors of CBF that should be observed and kept constant. In addition, we found that long-duration anaesthesia was significantly correlated with high heart rate, low arterial oxygen tension, and high body temperature, but not with CBF. CONCLUSIONS: The findings indicate that PaCO2 and body temperature are crucial for maintaining stable levels of CBF and thus optimizing PET imaging of molecular mechanisms in the brain of anaesthetized pigs. Therefore, as a minimum these two variables should be monitored and kept constant. Furthermore, the duration of anaesthesia should be kept constant to avoid variations in monitoring variables.

Coagulation profile in open and video-assisted thoracoscopic lobectomies: a cohort study.

OBJECTIVES: Lung cancer patients are perceived to have a relatively high risk of venous thromboembolic events due to an activation of the coagulation system. In terms of activation of the coagulation system, the difference between video-assisted thoracoscopic surgery (VATS) and open lobectomies for primary lung cancer has not been investigated. The aim of this study was to compare the impact on the coagulation system in patients undergoing curative surgery for primary lung cancer by either VATS or open lobectomies. METHODS: In total, 62 patients diagnosed with primary lung cancer were allocated to either VATS (n = 32) or open lobectomies (n = 30). All patients received subcutaneous injections with dalteparin (Fragmin®) 5000 IE once daily. The coagulation was assessed pre- and intraoperatively, and the first 2 days postoperatively by standard coagulation blood tests, thromboelastometry (ROTEM®) and thrombin generation. RESULTS: The open lobectomies bled more than the VATS group and had a significantly lower platelet count (109/l) on postoperative Days 1 and 2 (198 vs 231 and 194 vs 243, respectively). The open group also had a higher international normalized ratio on postoperative Days 1 and 2 compared with the VATS group (1.21 vs 1.14 and 1.17 vs 1.09, respectively). There were no differences in thromboelastometry (ROTEM®) and thrombin generation parameters. None of the included patients developed venous thromboembolic events. CONCLUSIONS: In patients undergoing curative surgery for early-stage primary lung cancer, we observed a statistical non-significant difference and a similar-sized minor impact on the coagulation system.

Coagulation profile in patients undergoing video-assisted thoracoscopic lobectomy: A randomized, controlled trial.

BACKGROUND: Knowledge about the impact of Low-Molecular-Weight Heparin (LMWH) on the coagulation system in patients undergoing minimal invasive lung cancer surgery is sparse. The aim of this study was to assess the effect of LMWH on the coagulation system in patients undergoing Video-Assisted Thoracoscopic Surgery (VATS) lobectomy for primary lung cancer. METHODS: Sixty-three patients diagnosed with primary lung cancer undergoing VATS lobectomy were randomized to either subcutaneous injection with dalteparin (Fragmin®) 5000 IE once daily or no intervention. Coagulation was assessed pre-, peri-, and the first two days postoperatively by standard coagulation blood test, thromboelastometry (ROTEM®) and thrombin generation. RESULTS: Patients undergoing potential curative surgery for lung cancer were not hypercoagulable preoperatively. There was no statistically significant difference in the majority of the assessed coagulation parameters after LMWH, except that the no intervention group had a higher peak thrombin and a shorter INTEM clotting time on the first postoperative day and a lower fibrinogen level on the second postoperative day. A lower level of fibrin d-dimer in the LMWH group was found on the 1. and 2.postoperative day, although not statistical significant. No differences were found between the two groups in the amount of bleeding or number of thromboembolic events. CONCLUSIONS: Use of LMWH administered once daily as thromboprophylaxis did not alter the coagulation profile per se. As the present study primarily evaluated biochemical endpoints, further studies using clinical endpoints are needed in regards of an optimized thromboprophylaxis approach.

A PET Tracer for Renal Organic Cation Transporters, ¹¹C-Metformin: Radiosynthesis and Preclinical Proof-of-Concept Studies.

UNLABELLED: Organic cation transporters (OCTs) in the kidney proximal tubule (PT) participate in renal excretion of drugs and endogenous compounds. PT function is commonly impaired in kidney diseases, and consequently quantitative measurement of OCT function may provide an important estimate of kidney function. Metformin is a widely used drug and targets OCT type 2 located in the PT. Thus, we hypothesized that (11)C-labeled metformin would be a suitable PET tracer for quantification of renal function. METHODS: (11)C-metformin was prepared by (11)C-methylation of 1-methylbiguanide. In vitro cell uptake of (11)C-metformin was studied in LLC-PK1 cells in the presence of increasing doses of unlabeled metformin. In vivo small-animal PET studies in Sprague-Dawley rats were performed at baseline and after treatment with OCT inhibitors to evaluate renal uptake of (11)C-metformin. Kidney and liver pharmacokinetics of (11)C-metformin was investigated in vivo by dynamic (11)C-metformin PET/CT in 6 anesthetized pigs, and renal clearance of (11)C-metformin was compared with renal clearance of (51)Cr-ethylenediaminetetraacetic acid (EDTA). Formation of (11)C metabolites was investigated by analysis of blood and urine samples. RESULTS: The radiochemical yield of (11)C-metformin was 15% ± 3% (n= 40, decay-corrected), and up to 1.5 GBq of tracer were produced with a radiochemical purity greater than 95% in less than 30 min. Dose-dependent uptake of (11)C-metformin in LLC-PK1 cells was rapid. Rat small-animal PET images showed (11)C-metformin uptake in the kidney and liver, the kinetics of which were changed after challenging animals with OCT inhibitors. In pigs, 80% of the injected metformin dose was rapidly present in the kidney, and a high dose of metformin caused a delayed renal uptake and clearance compared with baseline consistent with transporter-mediated competition. Renal clearance of (11)C-metformin was approximately 3 times the renal clearance of (51)Cr-EDTA. CONCLUSION: We successfully synthesized an (11)C-metformin tracer, and PET studies in rats and pigs showed a rapid kidney uptake from the blood and excretion into the bladder similar to other radiopharmaceuticals developed for γ-camera renography.