Umwelteinflüsse medizinisch bewerten

Bundesgesundheitsblatt - Gesundheitsforschung - Gesundheitsschutz -     

Glycocholic acid and glycodeoxycholic acid but not glycoursocholic acid inhibit bile acid synthesis in the rabbit.

Feedback regulation of derepressed hepatic bile acid biosynthesis was studied individually with glycocholic, glycodeoxycholic, and glycoursocholic acids by infusion into bile acid-depleted rabbits. Construction of a bile fistula drained the endogenous bile acid pool (90% glycodeoxycholic acid, 10% glycocholic acid) within 24 hours and elicited maximal bile acid synthesis after about 72 hours, at which time glycocholic acid became the only biliary bile acid (greater than 98%). Replacement of the bile acid pool with glycocholic acid or glycodeoxycholic acid at a rate equivalent to the hepatic endogenous bile acid flux inhibited endogenous biosynthesis by 40%. In contrast, glycoursocholic acid, the 7 beta-hydroxy epimer of glycocholic acid, failed to suppress synthesis. Hepatic bile acid depletion increased hydroxymethyglutary coenzyme A (HMG-CoA) reductase activity fourfold and cholesterol 7 alpha-hydroxylase activity threefold, which were reduced 48% and 51%, respectively, from their maximum levels during replacement with glycocholic acid. Glycodeoxycholic acid infusion depressed cholesterol 7 alpha-hydroxylase activity by 59% without reducing HMG-CoA reductase activity significantly. There was no significant change in the activity of either enzyme during glycoursocholic acid infusion. Biliary cholesterol and cholestanol secretion declined 13% and 53%, respectively, during glycocholic acid infusion, were not affected by glycodeoxycholic acid infusion, but increased 19% and 43%, respectively, during glycoursocholic acid infusion. These results show that in rabbits the feedback regulation of hepatic bile acid synthesis depends on the hepatic flux of the normally present endogenous bile acids glycocholic acid and glycodeoxycholic acid but does not respond to the 7 beta-hydroxy glycoursocholic acid. Glycocholic acid inhibits both HMG-CoA reductase and cholesterol 7 alpha-hydroxylase while glycodeoxycholic acid affects primarily cholesterol 7 alpha-hydroxylase. Thus, the regulation of bile acid synthesis may be mediated by both the availability of cholesterol substrate and the activity of the rate-determining enzyme for bile acid synthesis.     

A humanised tissue‐engineered bone model allows species‐specific breast cancer‐related bone metastasis in vivo

Bone metastases frequently occur in the advanced stages of breast cancer. At this stage, the disease is deemed incurable. To date, the mechanisms of breast cancer‐related metastasis to bone are poorly understood. This may be attributed to the lack of appropriate animal models to investigate the complex cancer cell–bone interactions. In this study, two established tissue‐engineered bone constructs (TEBCs) were applied to a breast cancer‐related metastasis model. A cylindrical medical‐grade polycaprolactone‐tricalcium phosphate scaffold produced by fused deposition modelling (scaffold 1) was compared with a tubular calcium phosphate‐coated polycaprolactone scaffold fabricated by solution electrospinning (scaffold 2) for their potential to generate ectopic humanised bone in NOD/SCID mice. While scaffold 1 was found not suitable to generate a sufficient amount of ectopic bone tissue due to poor ectopic integration, scaffold 2 showed excellent integration into the host tissue, leading to bone formation. To mimic breast cancer cell colonisation to the bone, MDA‐MB‐231, SUM1315, and MDA‐MB‐231BO breast cancer cells were cultured in polyethylene glycol‐based hydrogels and implanted adjacent to the TEBCs. Histological analysis indicated that the breast cancer cells induced an osteoclastic reaction in the TEBCs, demonstrating analogies to breast cancer‐related bone metastasis seen in patients.     

Abnormal septal Q waves in sickle cell disease. Prevalence and causative factors

Electrocardiograms and M-mode echocardiograms were obtained prospectively from 72 patients with hemoglobin SS (n = 55) or SC (n = 17) disease to assess the prevalence of abnormal Q waves in sickle cell disease and to determine if such Q waves could be explained by, or related to, echocardiographically determined anatomic or functional abnormalities. The mean age (+/- SD) of the population under study was 28 +/- 9 years, and the mean hematocrit reading was 28 +/- 5 percent; 43 male and 29 female patients were evaluated. No patient had a history of systemic arterial hypertension, valvular heart disease, or congestive heart failure. Abnormal septal Q waves (amplitude greater than or equal to 0.30 mV; duration less than or equal to 29 msec) were noted in leads V4, V5, or V6 in 15 of 72 patients, and 50 percent (36) of the population under study demonstrated electrocardiographic voltage changes consistent with left ventricular hypertrophy. M-mode echocardiography showed that 29 of 72 patients had a thickened interventricular septum (greater than or equal to 1.2 cm), 16 of 72 had an abnormally thickened left ventricular posterior wall (greater than or equal to 1.2 cm), and 31 of 72 had increased left ventricular mass (greater than 215 g). The prevalence of electrocardiographic and echocardiographic abnormalities was not significantly different between patients with hemoglobin SS and SC disease. Septal excursion was decreased in 11 of the patients, and global left ventricular function (percent fractional shortening) was slightly decreased in three patients. Regional wall motion was normal in all 72 patients. Six percent (four) of the patients met echocardiographic criteria for asymmetric septal hypertrophy. Linear regression analysis yielded significant positive correlations between septal dimension (r = 0.38; p less than 0.001) and left ventricular mass (r = 0.37; p less than 0.005) when each was compared with Q-wave amplitude. A significant negative correlation (r = 0.40; p less than 0.001) was noted between hematocrit reading and Q-wave amplitude. We conclude that abnormal septal Q waves are common in sickle cell disease and are related, in part, to septal thickness, as well as left ventricular mass and degree of anemia.     

Chemoradiation-induced changes in systemic inflammatory markers and their prognostic significance in oesophageal squamous cell carcinoma

Objective:Chemoradiation (CRT) may induce a change in systemic inflammatory state which could affect clinical outcomes in oesophageal cancer. We aimed to evaluate the changes and prognostic significance of systemic inflammatory markers following definitive CRT in oesophageal squamous cell carcinoma.Methods:A total of 53 patients treated with concurrent CRT were included in this retrospective analysis. We compared neutrophils, lymphocytes, platelets, neutrophil–lymphocyte ratio (NLR) and platelet–lymphocyte ratio (PLR) before and after CRT using Wilcoxon signed-rank test. Overall survival (OS) and progression-free survival (PFS) were calculated. Univariable and multivariable survival analysis were performed using Cox regression analysis. Clinical univariable survival prognostic factors with p < 0.1 were included in a multivariable cox regression analysis for backward stepwise model selection.Results:Both NLR (median ∆+2.8 [IQR −0.11, 8.62], p < 001) and PLR (median ∆+227 [81.3–523.5], p < 0.001) increased significantly after CRT. Higher levels of pre-CRT, post-CRT and change (∆) in NLR and PLR were associated with inferior OS and PFS. Post-CRT NLR (HR 1.04, 95% CI 1.02–1.07, p < 0.001), post-CRT platelets (HR 1.03, 95% CI 1.01–1.05, p = 0.005), cT-stage (HR 3.83, 95% CI 1.39–10.60, p = 0.01) and RT dose (HR 0.41, 95% CI 0.21–0.81, p = 0.01) were independent prognostic factors for OS in multivariable analysis. Change in NLR (HR 1.04, 95% CI 1.01–1.06, p = 0.001), post-CRT platelets (HR 1.03, 95% CI 1.01–1.05, p = 0.002), cT-stage (HR 3.98, 95% CI 1.55–10.25, p = 0.004) and RT dose (HR 0.41, 95% CI 0.21–0.80, p = 0.009) were independent prognostic factors for PFS.Conclusion:Both NLR and PLR increased following definitive CRT. Post-CRT NLR and ∆NLR were associated with adverse survival in oesophageal SCC.Advances in knowledge:We showed that CRT increased PLR and NLR, possibly reflecting a systemic inflammatory state which were associated with poor clinical outcomes in oesophageal SCC.     

siRNA Mediated Knockdown of Tissue Factor Expression in Pigs for Xenotransplantation

Acute vascular rejection (AVR), in particular microvascular thrombosis, is an important barrier to successful pig‐to‐primate xenotransplantation. Here, we report the generation of pigs with decreased tissue factor (TF) levels induced by small interfering (si)RNA‐mediated gene silencing. Porcine fibroblasts were transfected with TF‐targeting small hairpin (sh)RNA and used for somatic cell nuclear transfer. Offspring were analyzed for siRNA, TF mRNA and TF protein level. Functionality of TF downregulation was investigated by a whole blood clotting test and a flow chamber assay. TF siRNA was expressed in all twelve liveborn piglets. TF mRNA expression was reduced by 94.1 ± 4.7% in TF knockdown (TFkd) fibroblasts compared to wild‐type (WT). TF protein expression in PAEC stimulated with 50 ng/mL TNF‐α was significantly lower in TFkd pigs (mean fluorescence intensity TFkd: 7136 ± 136 vs. WT: 13 038 ± 1672). TF downregulation significantly increased clotting time (TFkd: 73.3 ± 8.8 min, WT: 45.8 ± 7.7 min, p < 0.0001) and significantly decreased thrombus formation compared to WT (mean thrombus coverage per viewing field in %; WT: 23.5 ± 13.0, TFkd: 2.6 ± 3.7, p < 0.0001). Our data show that a functional knockdown of TF is compatible with normal development and survival of pigs. TF knockdown could be a valuable component in the generation of multi‐transgenic pigs for xenotransplantation.