Biomedical subjects

C Plank

Publications and source records attributed to C Plank.

At least 19 recordsLinked to original sources

PubMed2006

Intrauterine growth retardation aggravates the course of acute mesangioproliferative glomerulonephritis in the rat.

Intrauterine growth retardation (IUGR) aggravates the course of acute mesangioproliferative glomerulonephritis (GN) in the rat. Observational studies in children suggest that IUGR may be associated with a severe course of kidney diseases such as IgA nephropathy. We tested the hypothesis that IUGR leads to aggravation of acute mesangioproliferative GN in former IUGR rats. IUGR was induced in Wistar rats by isocaloric protein restriction in pregnant dams. Litter size was reduced to six male neonates in low protein animals (LP) and normal protein animals (NP). At 8 weeks GN was induced by injection of an anti-Thy-1.1 antibody. Rats were killed on days 4 and 14 after induction of GN and kidneys were investigated for inflammation and sclerosis using real-time polymerase chain reaction and histological methods. On day 4 after induction of GN, LP animals showed more glomerulosclerosis and tubulointerstitial lesions. On day 14, inflammatory markers (expression of monocyte chemoattractant protein 1, osteopontin, tumor necrosis factor and interleukin-6), extracellular matrix accumulation and markers of sclerosis (plasminogen activator inhibitor-1 expression, transforming growth factor-beta1 expression, score for glomerulosclerosis, glomerular deposition of collagen I and collagen IV) were more severe in LP animals. Some degree of induction of inflammatory and profibrotic markers was also present in non-nephritic LP animals. However, these rats did not display marked glomerulosclerosis or interstitial fibrosis. We conclude that after IUGR inflammatory damage is aggravated and the reparation of the kidney is impaired during the course of acute mesangioproliferative GN, leading to more sclerotic lesions.

Animals↗

PubMed2006

Using magnetic forces to enhance non-viral gene transfer to airway epithelium in vivo.

We have assessed whether magnetic forces (magnetofection) can enhance non-viral gene transfer to the airways. TransMAG(PEI), a superparamagnetic particle was coupled to Lipofectamine 2000 or cationic lipid 67 (GL67)/plasmid DNA (pDNA) liposome complexes. In vitro transfection with these formulations resulted in approximately 300- and 30-fold increase in reporter gene expression, respectively, after exposure to a magnetic field, but only at suboptimal pDNA concentrations. Because GL67 has been formulated for in vivo use, we next assessed TransMAG(PEI) in the murine nasal epithelium in vivo, and compared this to naked pDNA. At the concentrations required for in vivo experiments, precipitation of magnetic complexes was seen. After extensive optimization, addition of non-precipitated magnetic particles resulted in approximately seven- and 90-fold decrease in gene expression for naked pDNA and GL67/pDNA liposome complexes, respectively, compared to non-magnetic particles. Thus, whereas exposure to a magnetic field improved in vitro transfection efficiency, translation to the in vivo setting remains difficult.

Animals↗

PubMed2006

[Pancreas. Part I: congenital changes, acute and chronic pancreatitis].

The pancreas develops from ventral and the dorsal buds, which undergo fusion. Failure to fuse results in pancreas divisum, which is defined by separate pancreatic ductal systems draining into the duodenum. Risk of developing pancreatitis is increased in pancreas divisum because of insufficient drainage. MR cholangiopancreatography (MRCP) is the technique of choice for detecting pancreas divisum non-invasively. Annular pancreas is the result of incomplete rotation of the pancreatic bud around the duodenum with the persistence of parenchyma or a fibrous band encircling (and sometimes stenosing) the duodenum. Acute pancreatitis is usually caused by bile duct stones or alcohol abuse. The Atlanta classification differentiates between mild acute and severe acute pancreatitis associated with organ failure and/or local complications such as necrosis, abscess or pseudocyst. Contrast-enhanced multi-detector row CT is the method of choice to assess the extent of disease. Balthazar et al.'s CT severity index assesses the risk of mortality and morbidity. In acute pancreatitis, the role of MRCP is mainly limited to finding bile duct stones in patients with suspected biliary pancreatitis. Chronic pancreatitis results in relentless and irreversible loss of exocrine (and sometimes endocrine) function of the pancreas. MDCT even shows subtle calcifications. MRCP is the method of choice for non-invasive assessment of the duct. Inflammatory pseudotumor in chronic pancreatitis and groove pancreatitis are difficult to differentiate from pancreatic cancer. In these cases, multiple imaging methods such as MDCT, MRI and endosonography including biopsy may be used to make a diagnosis.

Acute Disease↗

PubMed2006

[Pancreas. Part II: Tumors].

Adenocarcinoma is the most common malignant pancreatic tumor, affecting the head in 60-70% of cases. By the time of diagnosis, approximately 80% of tumors are unresectable. Helical CT is very effective in detection and staging of adenocarcinoma, with a sensitivity of 76-92% for detection and an accuracy of 80-90% for staging, but it has limitations in the detection of small cancers (< or =2 cm). Multidetector CT (MDCT) has brought substantial improvements with its inherent 3D imaging capability. Mangafodipir-enhanced MRI is a problem-solving tool in the depiction of small cancers following an equivocal CT imaging result. Gadolinium-enhanced 3D gradient-echo MRI is helpful in the assessment of vascular invasion of cancer and in determining the etiology of cystic lesions. Serous cystadenoma is benign, has a lobulated contour and contains innumerable small cysts of 0.1-2 cm in diameter. Mucinous cystic neoplasms are unilocular or multilocular (fewer than six cysts), and the cyst diameter exceeds 2 cm. The presence of solid nodular components should alert the radiologist to suspect cystadenocarcinoma. Neuroendocrine tumors are mostly hypervascular. Diagnosis of insulinoma is a challenge: they are <2 cm in 90% of cases and mostly hypervascular at CT or MRI. A combination of contrast-enhanced MDCT, MRI, endosonography, and/or somatostatin receptor scintigraphy is used to detect these small tumors. This review summarizes the imaging features of the most common pancreatic tumors and discusses the limitations of CT, MRI and endosonography.

Adenocarcinoma↗

PubMed2006

Fibrillin-1 regulates mesangial cell attachment, spreading, migration and proliferation.

The microfibrillar protein fibrillin-1 is present in many organs, including the vasculature, eye, and dermis, and is thought to convey structural anchorage and elastic strength. Fibrillin-1 is also a component of the mesangial matrix. To assess the functional relevance of fibrillin-1 for cell-matrix interactions in the glomerulus, we studied the attachment, spreading, migration and proliferation of mesangial cells on fibrillin-1 and the regulation of fibrillin-1 in experimental anti-Thy1.1 nephritis displaying mesangial cell migration and proliferation in vivo. During the acute phase of experimental Thy1.1 nephritis, glomerular fibrillin-1 messenger ribonucleic acid expression and protein immunoreactivity were significantly induced as compared to controls. In a hexosaminidase-based adhesion assay, mesangial cells showed concentration-dependent attachment to fibrillin-1, similar to what was observed for fibronectin. The cell attachment was Arg-Gly-Asp dependent. Further, fibrillin-1 significantly promoted spreading and focal contact formation detected by immunostaining for vinculin. Mesangial cell migration, assessed by a transmigration assay, and proliferation, measured by a 5-bromo-2'-deoxy-uridine incorporation assay, were augmented by fibrillin-1. In diabetic mice underexpressing fibrillin-1, glomerular cell proliferation, determined by counting proliferating cell nuclear antigen-positive cells in renal sections, was significantly lower than in diabetic control mice. We conclude that fibrillin-1 promotes mesangial cell attachment, spreading, migration, and proliferation. We speculate that fibrillin-1 may thus contribute to mesangial hypercellularity during glomerular disease.

Animals↗

PubMed2006

No effect of homocysteine-lowering therapy on vascular inflammation and haemostasis in peripheral arterial occlusive disease.

BACKGROUND: Although peripheral arterial occlusive disease (PAOD) is significantly associated with elevated homocysteine levels, the clinical relevance of hyperhomocysteinaemia for the prevention and progression of PAOD is still unknown. MATERIALS AND METHODS: A total of 65 patients suffering from symptomatic PAOD with elevated homocysteine levels were randomized onto placebo or B-vitamins (50 mg thiaminhydrochlorid, 50 mg pyridoxine, and 0.05 mg cyanocobalamin), plus 5 mg folic acid daily for 6 weeks. Serum levels of folic acid, vitamin B12, creatinine, ultra-sensitive C-reactive protein (usCRP), interleukin (IL)-6, IL-8, IL-18, monocyte-chemo-attractant-protein-1 (MCP-1) and plasma levels of homocysteine, tissue factor (TF) and tissue factor pathway inhibitor (TFPI) were determined on the 1st day and 42nd day. Primary outcome was reduction of homocysteine, secondary outcomes were reduction of usCRP, IL-6, IL-8, Il-18, MCP-1, TF and TFPI. RESULTS: The mean reduction of homocysteine concentration was 33% (95%CI 33.36-55.76, or 18.9+/-5.4 micromol L-1-12.6+/-2.8 micromol L-1, P=0) in the B-vitamin group compared with 1% in the placebo group. Folic acid (P=0) and vitamin B12 (P=0) increased significantly in the verum group, but both remained unchanged in the control group. No treatment effect of lowering of homocysteine on any markers of haemostasis (TF, TFPI) or inflammation (usCRP, IL-6, IL-8, IL-18 and MCP-1) was observed. CONCLUSION: Although homocysteine is associated with vascular disease risk in the general population and in particular with PAOD, marked lowering of homocysteine concentrations by folic acid and B-vitamin supplementation does not influence inflammatory responses involving usCRP, IL-6, IL-8, IL-18 and MCP-1, nor tissue factor. These results provide evidence against a major effect of hyperhomocysteinaemia on vascular chronic inflammation or coagulation in patients with symptomatic peripheral arterial occlusive disease.

Aged↗

PubMed2005

Matrix-based autologous chondrocyte implantation for cartilage repair with HyalograftC: two-year follow-up by magnetic resonance imaging.

OBJECTIVE: Monitoring of articular cartilage repair after matrix-associated autologous chondrocyte implantation with HyalograftC by a new grading system based on non-invasive high-resolution magnetic resonance imaging. PATIENTS AND METHODS: In 23 patients, postoperative magnetic resonance imaging (MRI) was performed between 76 and 120 weeks. In nine of these patients, five MRI examinations were performed at 4, 12, 24, 52 and 104 weeks after HyalograftC implant. The repair tissue was described with separate variables: degree of defect repair in width and length, signal intensity of the repair tissue and status of the subchondral bone. For these variables a grading system with point scale evaluation was applied. RESULTS CONCLUSION: High-resolution MRI provides a non-invasive tool for monitoring the development of cartilage repair tissue following HyalograftC technology, shows a good correlation with clinical outcome and may help to differentiate abnormal repair tissue from a normal maturation process.

Adult↗

PubMed2005

Methodological optimization of polyethylenimine (PEI)-based gene delivery to the lungs of mice via aerosol application.

BACKGROUND: Polyethylenimine (PEI) has been successfully used for gene delivery to the lungs of mice via aerosol application using a whole body nebulization device. In this report we optimized the design of such an aerosol device. METHODS: Aerosol devices were constructed as either serial inhalation apparatus or as a whole body nebulization chamber connected to an aerosol spacer placed in a horizontal or vertical position. PEI-based gene vectors were nebulized using a standard jet nebulizer and luciferase gene expression of various tissues was examined. RESULTS: Using a whole body aerosol device resulted in luciferase gene expression in the lungs of mice at the same level as compared with a serial inhalation apparatus. Whereas gene expression was enhanced in the presence of 5% CO(2)-in-air, anesthesia of mice strongly decreased gene expression even when mice were intubated with an intravascular cannula. Reduction of the median mass aerodynamic diameter (MMAD) of the aerosol from 3.4 to 0.27 microm by interposition of an aerosol spacer increased gene expression significantly 3-fold. Drying of the aerosol by silica gel additionally increased gene delivery significantly 3-fold. Reporter gene expression mediated by branched PEI 25 kDa was 9- and 15-fold higher as compared with linear PEIs of 22 and 25 kDa, respectively, and was dependent on the DNA concentration. Gene expression was detectable as soon as 6 h after gene vector application and reached a maximum after 72 h but was still detectable after 14 days. The presence of Zn(2+) did not increase gene expression. CONCLUSION: We propose aerosol drying as a novel and simple method of optimizing PEI-based gene delivery to the lungs.

Aerosols↗

PubMed2005

A randomized clinical trial of valacyclovir in multiple sclerosis.

OBJECTIVE: The human Herpesvirus type-6 (HHV-6) has been implicated in multiple sclerosis (MS). Valacyclovir is an antiviral agent with an excellent safety profile. A two-year placebo-controlled, double-blind study was conducted to (1) ascertain if high-dose, prolonged treatment with valacyclovir would be safe and (2) observe if valacyclovir would delay the progression of MS clinically or by magnetic resonance imaging (MRI). DESIGN/METHODS: Fifty-eight patients were stratified as to severity and randomly assigned to receive valacyclovir (3000 mg/day) or placebo for a period of two years. Patients were followed clinically over the two-year period by means of the Expanded Disability Status Scale (EDSS), the Ambulation Index (AI) and brain MRI scans. Patients underwent routine lab studies every three months. Patients continued on the medication for two years unless they had a sustained progression or repeated exacerbations. RESULTS: No patient discontinued the study due to side effects or toxicity. In Relative Ranking of Progression, time to first attack, attack rate, and time to withdrawal there were trends (but not statistically significant) toward drug effect over placebo in the Severe clinical category. MRI evaluation showed no significant drug effect. CONCLUSIONS: Although not statistically significant, positive trends were detected for acyclovir by clinical measures, but not by MRI.

Acyclovir↗

PubMed2004

[Diagnostic imaging of cartilage replacement therapy].

Over the past decade a number of surgical interventions for durable cartilage repair have been developed. For the long-term follow-up of this procedures clinical scores and the morphological and biochemical evaluation of biopsies taken during arthroscopy are used.Magnetic resonance imaging is a useful noninvasive tool for the evaluation of the morphologic status of the cartilage repair tissue throughout the postoperative period. The MR imaging appearance of the most important cartilage transplantation techniques, such as autologous osteochondral transplantation, autologous chondrocyte implantation and matrix-based autologous chondrocyte implantation are described and possible complications of each technique are mentioned. The importance of new MR techniques such as high-resolution morphologic imaging and possible visualization of biochemical information of cartilage repair tissue is discussed.

Cartilage Diseases↗

PubMed2004

Inducible nonviral gene expression in the treatment of osteochondral defects.

OBJECTIVE: The repair of osteochondral defects with chondrocytes genetically modified to express desired growth factors promises great potential in orthopaedic therapy. Controlled expression of the transgenes is required in many instances. The objective of the present study was to demonstrate the inducibility of tetracycline-responsive transgene expression in osteochondral defects in the knee joint filled with genetically modified chondrocyte implants. METHODS: An expression plasmid containing the lacZ gene under the control of the minimal CMV promoter fused to the Tet-responsible element (TRE) as well as the reverse transactivator (rtTA2s-M2) was constructed and used to transfect isolated articular chondrocytes from New Zealand white rabbits. rtTA2s-M2 binds to the TRE in the presence of tetracycline and leads to the transcription of the transgene. Different concentrations of DNA and various DNA:lipid ratios were tested to determine best transfection conditions. Transfection efficiency and inducibility were analysed by histochemical analysis and flow-cytometry. To evaluate the system in vivo, collagen-sponges were seeded with transfected autologous chondrocytes and implanted in osteochondral defects in the knees of NZW-rabbits. Gene expression was induced by doxycycline and 3 weeks later, LacZ-expression in isolated knee joints was evaluated in histological sections by X-gal staining. RESULTS: In vitro 13.5% (+/-1.32) of induced primary chondrocytes were LacZ-positive, while non-induced controls showed a background-staining in 0.6% (+/-0.2). In vivo, upon doxycycline treatment, induction of lacZ-gene-expression could be demonstrated in chondrocytes in 3-week-old, well-integrated implants. CONCLUSION: For the first time, tetracycline-inducible gene expression is demonstrated to work in the treatment of osteochondral defects. This demonstrates the feasibility for a gene therapy-assisted approach using controlled expression of therapeutic growth factors from transplanted genetically modified chondrocytes.

3T3 Cells↗

PubMed2002

Nonviral gene delivery to the lung with copolymer-protected and transferrin-modified polyethylenimine.

Polyethylenimine (PEI) has been shown to efficiently mediate topical gene transfer to the lungs after either direct intratracheal instillation or nebulisation. Recently, the protection of polyplexes with novel copolymers of poly(ethylene glycol) (PEG) via electrostatic interaction has been reported. In this study, such coated PEI polyplexes were investigated for their stability and interaction with human plasma and bronchoalveolar lavage fluid (BALF). Further, their potential for gene delivery to the mouse lungs in vivo was examined. Plasma protein and mucin adsorption was effectively inhibited when polyplexes were coated with the novel copolymers. Gene transfer efficiency of the coated PEI polyplexes decreased as compared with uncoated PEI polyplexes when administered intratracheally to the lung. The higher the molecular weight of the copolymerized PEG was, the stronger the observed gene transfer reduction. Gene transfer decreased presumably due to reduced interaction of the coated gene vectors with the cell surface. To circumvent this problem, transferrin was combined with PEI/DNA polyplexes for specific binding to the cell surface. In this case, gene transfer efficiency decreased. Gene transfer of the copolymer-protected and transferrin-modified gene vectors increased as compared with the copolymer-protected gene vectors alone but did not reach the level of uncoated gene vectors. These data show that copolymers could be used to effectively shield polyplexes from interaction with components of the airway surface liquid (ASL). Increased gene delivery was found upon transferrin modification of the coated PEI polyplexes suggesting a targeting effect.

Animals↗

PubMed2002

Magnetofection: enhancing and targeting gene delivery by magnetic force in vitro and in vivo.

Low efficiencies of nonviral gene vectors, the receptor-dependent host tropism of adenoviral or low titers of retroviral vectors limit their utility in gene therapy. To overcome these deficiencies, we associated gene vectors with superparamagnetic nanoparticles and targeted gene delivery by application of a magnetic field. This potentiated the efficacy of any vector up to several hundred-fold, allowed reduction of the duration of gene delivery to minutes, extended the host tropism of adenoviral vectors to nonpermissive cells and compensated for low retroviral titer. More importantly, the high transduction efficiency observed in vitro was reproduced in vivo with magnetic field-guided local transfection in the gastrointestinal tract and in blood vessels. Magnetofection provides a novel tool for high throughput gene screening in vitro and can help to overcome fundamental limitations to gene therapy in vivo.

Adenoviridae↗

PubMed2000

Overexpression of hypoxia-inducible factor 1alpha is a marker for an unfavorable prognosis in early-stage invasive cervical cancer.

Hypoxia-inducible factor 1alpha (HIF-1alpha) is a transcriptional factor that regulates genes involved in response to hypoxia and promotes neoangiogenesis, which are considered essential for tumor growth and progression. Using immunohistochemistry, we investigated the influence of HIF-1alpha expression on prognosis in 91 patients with cervical cancer stage pT1b. In univariate and multivariate analysis, patients with strong expression of HIF-1alpha had a significantly shorter overall survival time (P = 0.0307, log-rank test) and disease-free survival time (P < 0.0001, log-rank test) compared with those with moderate to absent HIF-1alpha expression. HIF-1alpha expression is a strong independent prognostic marker in early stage cervical cancer.

Adult↗

PubMed2000

Protective copolymers for nonviral gene vectors: synthesis, vector characterization and application in gene delivery.

Uncontrolled interactions of gene vectors and drug carriers in and with an in vivo environment pose serious limitations to their applicability. In order to reduce such interactions we have designed, synthesized and applied novel copolymers of poly(ethylene glycol) and reactive linkers which are derivatized with anionic peptides after copolymerization. The anionic copolymer derivatives are used to coat positively charged nonviral gene vectors by electrostatic interactions. The copolymer coat confers to polyelectrolyte colloids of DNA and polycations steric stabilization in their minimal size and prevents salt- and serum albumin-induced aggregation. Furthermore, complement activation and the interaction with serum proteins are drastically reduced or abolished in contrast to unprotected DNA complexes. The designed vectors are compatible with the intracellular steps of gene delivery and can even enhance transfection efficiency as demonstrated with various adherent and nonadherent cell lines in culture. The synthetic concept is amenable to the principles of combinatorial chemistry and the copolymeric products may be applicable beyond gene delivery in targeted drug delivery. Gene Therapy (2000) 7, 1183-1192.

Cells, Cultured↗

PubMed2000

European Society of Gene Therapy (ESGT) Seventh Meeting. 26-28 November 1999, Munich, Germany.

This meeting gave an excellent overview of the recent developments in gene therapy. Much research effort has focused on the improvement and de novo construction of gene vectors, on characterizing their mechanisms of action and on their interactions with, and in, living organisms. The continual improvements in understanding disease at a molecular level and the progress in cell biology, immunology and related fields have opened the way for novel gene therapy approaches. The gene therapeutic strategy has proven to be feasible and efficient in numerous preclinical (animal) models of a variety of diseases. On the other hand, applying this experience to humans has turned out to be difficult. Currently, the field is rapidly moving into clinical applications. No major limiting side effects have been observed in patients in the phase I and later stage trials presented. Nonetheless, years of preclinical and clinical research will be required before gene therapy can be considered a reliable and efficient therapeutic approach with broad applicability.

Journal Article↗

PubMed1999

Branched cationic peptides for gene delivery: role of type and number of cationic residues in formation and in vitro activity of DNA polyplexes.

To examine the suitability of synthetic peptides as DNA-binding and -compacting agents for receptor-mediated gene delivery, we have synthesized and characterized a series of branched oligocationic peptides that differ in the number and type (lysine, arginine, ornithine) of cationic amino acids in the DNA-binding moiety. The peptides were designed as branched molecules to provide a coupling site via a spacer for the attachment of effectors at a flexible distance from the DNA-binding moiety. This design provides torsional flexibility in the peptide backbone of the DNA-binding moiety to maximize cation-DNA phosphate interactions and also minimizes the potential for interference by the effector with DNA binding. The branched peptides bind DNA with affinities that increase with the number of cationic groups. The peptides compact DNA into microparticulate structures as judged by an ethidium bromide displacement assay, dynamic light scattering, and electron microscopy. In general, differences in DNA binding and compaction owing to variation in the cationic side chain were modest, with the rank order being arginyl > lysyl approximately ornithyl. Incorporation of tryptophans into the DNA-binding moiety had no major effect on apparent binding affinity but clearly reduced the DNA-compacting potency of the peptides. Compared with polylysine, the peptides and their DNA complexes are weak activators of the complement system. Complement activation by an octaarginyl peptide was stronger than that induced by an octalysyl peptide. The microparticulate peptide-DNA complexes are suitable for receptor-mediated gene delivery as evidenced by transferrinfection of K562 cells in the presence of chloroquine. The results obtained in gene delivery in vitro suggest that a minimum chain length of six to eight cationic amino acids is required to compact DNA into structures active in receptor-mediated gene delivery.

Binding, Competitive↗

PubMed1998

Application of membrane-active peptides for drug and gene delivery across cellular membranes.

Naturally occurring peptides and protein domains with amphipathic sequences play a dominant role in physiological, lipid membrane-reorganizing processes like fusion, disruption, or pore formation. More recently this capacity to modulate membrane integrity has been exploited for drug delivery into cells. Incorporation of synthetic membrane-active peptides into delivery systems has been found to enhance intracellular delivery of drugs including oligonucleotides, peptides, or plasmid DNA. In the majority of applications, the amphipathic peptides are designed to act after uptake by endocytosis, releasing the delivered agent from intracellular vesicles to the cytoplasm. Alternatively, peptides might mediate direct drug transfer across the plasma membrane. Although encouraging results have been obtained with the use of synthetic peptides to enhance cellular delivery of various compounds, the naturally evolved mechanisms observed in the entry of viruses or protein toxins are still far more efficient. For the development of improved synthetic peptides and carrier systems a better understanding of the molecular details of membrane-destabilization and reorganization will be essential.

Journal Article↗