A novel technique for intraduodenal administration of drug suspensions/solutions with concurrent pH monitoring applied to ibuprofen formulations

2019

Characterization of dissolution of solid suspended drug particles in vivo is important for developing biopredictive in vitro tests. Therefore, methods to gain deeper insights into particle dissolution in vivo are needed. The soft Bioperm intubation method, a well established tool for investigation of permeability, absorption, metabolism, and drug interactions at predefined locations in the gastroinstinal tract, was modified. The novel intubation method involved pump-controlled infusion of pharmaceutical suspensions as well as simultaneous pH monitoring. This technique was used in a proof of concept study in healthy humans. Plasma sampling and non-compartmental analysis allowed comparison of…

Liver fibrosis induced by hepatic overexpression of PDGF-B in transgenic mice

2006

Background/Aims In hepatic fibrogenesis, stellate cells are activated leading to production and deposition of extracellular matrix. To clarify the role of PDGF-B in liver fibrogenesis, we overexpressed PDGF-B in the liver of transgenic mice. Methods Transgenic mice for the conditional overexpression of PDGF-B in the liver under control of an albumin promoter were generated utilising the Cre/loxP system. Constitutive PDGF-B expression was achieved after breeding with mice expressing Cre-recombinase under actin promoter control. Tamoxifen inducible expression was achieved after breeding with mice expressing Cre under transthyretin receptor promoter control. Levels of fibrosis were assessed an…

In vitro prediction of in vivo absorption of ibuprofen from suspensions through rational choice of dissolution conditions

2020

Two ibuprofen suspension formulations were investigated for their dissolution in various bicarbonate, phosphate and acetate buffers. Phosphate and acetate gave faster release than bicarbonate at comparable molarities. Nevertheless, mass transport modelling using the reversible non-equilibrium (RNE) approach enabled the calculation of phosphate molarities that gave good matches to physiological bicarbonate in terms of ibuprofen dissolution. This shows that developing surrogate buffers for bicarbonate that are devoid of the technical difficulties associated with the bicarbonate-CO2 systems is possible. In addition, the intestinal dissolution kinetics of the tested suspensions were determined …

Defer or treat? Reasons for treatment decisions in patients with chronic hepatitis C genotype 1 in the early era of directly acting antiviral agents

2013

Abstract Background In chronic genotype 1 hepatitis C, telaprevir or boceprevir plus peginterferon and ribavirin have become the new standard of care. Aim of this study was to identify factors contributing to the decision whether to defer or treat with the current triple regimens. Methods Prospective assessment of eight parameters on 0-4-point scales by the attending physician at a German tertiary referral centre between 1st September 2011 and 31st December 2012. Results 307 patients were evaluated at least once by one of the 11 hepatologists involved; 267 patients were considered, but only 163 were recommended to receive triple therapy. Multivariate regression analysis revealed that a high…

Hepatic over-expression of TGF-beta1 promotes LPS-induced inflammatory cytokine secretion by liver cells and endotoxemic shock.

2005

Transforming growth factor-beta (TGF-beta) is an important suppressor of inflammation. However, TGF-beta has also been found to promote secretion of inflammatory cytokines, and transgenic mice, which constitutively express TGF-beta in liver, have been found to be more susceptible to endotoxemia. To approach this apparent paradox, we investigated the role of hepatic TGF-beta1 in endotoxemia by utilising inducible TGF-beta1-transgenic mice that express TGF-beta1 under control of the C-reactive protein promoter. In contrast to non-transgenic littermates, administration of lipopolysaccharide (LPS) induced strongly increased expression of TGF-beta and acute phase proteins in the TGF-beta1-transg…

A systems biology perspective on cholangiocellular carcinoma development: focus on MAPK-signaling and the extracellular environment.

2008

Background/Aims Multiple genes have been implicated in cholangiocellular carcinoma (CCC) development. However, the overall neoplastic risk is likely associated with a much lower number of critical physiological pathways. Methods To investigate this hypothesis, we extracted all published genetic associations for the development of CCC from PubMed (genetic association studies, but also studies associating genes and CCC in general, i.e. functional studies in cell lines, genetic studies in humans, knockout mice etc.) and integrated CCC microarray data. Results We demonstrated the MAPK pathway was consistently enriched in CCC. Comparing our data to genetic associations in HCC often successfully …

Prävention im Alter durch Risikovermeidung, Früherkennung und frühe Behandlung

2019

Der wichtigste Risikofaktor fur Brustkrebs ist bei Frauen und Mannern das Alter. Brustkrebs beim Mann ist selten; Untersuchungen zur Fruherkennung werden deshalb nicht empfohlen; diese sind nur bei Veranderungen oder Beschwerden erforderlich (S3-Leitlinie Diagnostik 2018). Fur Frauen liegt das Lebenszeitrisiko fur Brustkrebs bei 12,8 %, d. h. dass jede achte Frau im Verlauf ihres Lebens an Brustkrebs erkrankt. Selten tritt Brustkrebs bei Frauen unter 30 Jahren auf. Der groste Teil der Frauen erkrankt zwischen dem 50. und 70. Lebensjahr; Mitte 60 ist das Risiko am hochsten. Etwa 37 % erkranken nach dem 70. Lebensjahr; Brustkrebs kann jedoch noch bis ins hohe Alter von 90 Jahren und mehr auft…

Liver-specific overexpression of matrix metalloproteinase 9 (MMP-9) in transgenic mice accelerates development of hepatocellular carcinoma.

2010

Matrix metalloproteinase-9 (MMP-9) plays a central role in tumor invasion and development of metastases. Expression of MMP-9 had been shown in human hepatocellular carcinomas (HCCs). However, it remained unclear whether MMP-9 could influence development of HCC. In order to address this issue, we generated transgenic mice overexpressing MMP-9 in the liver. In order to avoid embryonic lethality a Cre-lox system was utilized for conditional overexpression of MMP-9 under control of an albumin enhancer and promoter. Induction of MMP-9 overexpression in transgenic mice was achieved by i.v. injection of an adenovirus coding for the Cre recombinase. Initiation of liver carcinogenesis was achieved b…

Vergleich unterschiedlicher Polypektomieschlingen für die Kaltabtragung kolorektaler Polypen

2019

Spontaneous hepatic fibrosis in transgenic mice overexpressing PDGF-A.

2008

Platelet derived growth factor (PDGF) plays a central role in repair mechanisms after acute and chronic tissue damage. To further evaluate the role of PDGF-A in liver fibrogenesis in vivo, we generated transgenic mice with hepatocyte-specific overexpression of PDGF-A using the CRP-gene promoter. Transgenic but not wildtype mice showed expression of PDGF-A mRNA in the liver. Hepatic PDGF-A overexpression was accompanied by a significant increase in hepatic procollagen III mRNA expression as well as TGF-beta1 expression. Liver histology showed increased deposition of extracellular matrix in transgenic but not in wildtype mice. PDGF-A-transgenic mice showed positive sinusoidal staining for alp…

Liver specific overexpression of platelet-derived growth factor-B accelerates liver cancer development in chemically induced liver carcinogenesis

2010

A genetic basis of hepatocellular carcinoma (HCC) has been well-established and major signaling pathways, such as p53, Wnt-signaling, transforming growth factor-β (TGF-β) and Ras pathways, have been identified to be essential to HCC development. Lately, the family of platelet-derived growth factors (PDGFs) has shifted to the center of interest. We have reported on spontaneously developing liver fibrosis in PDGF-B transgenic mice. Since HCC rarely occurs in healthy liver, but dramatically increases at the cirrhosis stage of which liver fibrosis is a preliminary stage, we investigated liver cancer development in chemically induced liver carcinogenesis in these mice. HCC induction was performe…