PubMed Health⌕ Search

Biomedical subjects

Igor M Sauer

Publications and source records attributed to Igor M Sauer.

At least 19 recordsLinked to original sources
PubMed2006

Extended surgical resection for xanthogranulomatous cholecystitis mimicking advanced gallbladder carcinoma: A case report and review of literature.

Xanthogranulomatous cholecystitis (XGC) is a destructive inflammatory disease of the gallbladder, rarely involving adjacent organs and mimicking an advanced gallbladder carcinoma. The diagnosis is usually possible only after pathological examination. A 46 year-old woman was referred to our center for suspected gallbladder cancer involving the liver hilum, right liver lobe, right colonic flexure, and duodenum. Brushing cytology obtained by endoscopic retrograde cholangiography (ERC) showed high-grade dysplasia. The patient underwent an en-bloc resection of the mass, consisting of right lobectomy, right hemicolectomy, and a partial duodenal resection. Pathological examination unexpectedly revealed an XGC. Only six cases of extended surgical resections for XGC with direct involvement of adjacent organs have been reported so far. In these cases, given the possible coexistence of XGC with carcinoma, malignancy cannot be excluded, even after cytology and intraoperative frozen section investigation. In conclusion, due to the poor prognosis of gallbladder carcinoma on one side and possible complications deriving from highly aggressive inflammatory invasion of surrounding organs on the other side, it seems these cases should be treated as malignant tumors until proven otherwise. Clinicians should include XGC among the possible differential diagnoses of masses in liver hilum.

Cholecystitis↗
PubMed2006

Evaluation of primary human liver cells in bioreactor cultures for extracorporeal liver support on the basis of urea production.

Primary human liver cells from donor organs unsuitable for transplantation were cultivated in bioreactors developed for extracorporeal liver support. Because each system contains cells originating from an individual organ, each bioreactor culture must be individually characterized. The objective of this study was to identify suitable decisive parameters for the evaluation of cell culture performance. We analyzed the data from 47 bioreactor cultures containing 437 +/- 110 g of cells. Choosing urea production as the decisive parameter, the bioreactor cultures were divided into high-performance (daily urea production > or = 110 mg per bioreactor between culture days 3 and 14) and low-performance cultures. Comparing the mean courses of the groups revealed a significant distinction in most other investigated biochemical parameters. In conclusion, urea production seems to be an appropriate parameter for evaluating the performance of liver cell cultures in bioreactors because it corresponds to all other evaluated parameters of cell function.

Adult↗
PubMed2005

A novel system for efficient gene transfer into primary human hepatocytes via cell-permeable hepatitis B virus-like particle.

Protein transduction domains (PTDs) have been used to deliver a variety of biologically active cargo across cellular membranes. However the potential of PTDs to mediate transport of nanoparticular structures into the cytoplasm bypassing the endosomal compartment remains unclear. Cell-permeable virus-like particles (VLPs) harboring a marker gene based on hepatitis B virus nucleocaspids were established. Cell permeability was achieved by fusion with translocation motif (TLM)-PTD. Electron and confocal microscopy revealed that these VLPs translocate as complete particles across the plasma membrane and transverse the cytoplasm toward the nucleus. Inhibition of endocytosis did not affect translocation of these VLPs into the cytoplasm. Based on these particles, a gene transfer system was developed. To this end the particles were loaded with DNA-encoding small hepatitis B virus surface antigen (SHBs) or green fluorescence protein (eGFP) that served as marker genes. Although the DNA-packaging efficiency was very low, applying the appropriate number of VLPs to primary human hepatocytes a gene transfer efficiency of approximately 95% was observed. In conclusion, the TLM-PTD has the potential to mediate efficient transfer of assembled particles and its cargo, nucleic acids, into primary human hepatocytes. This provides the basis for development of novel transducible therapeutic or diagnostic particles.

Cells, Cultured↗
PubMed2005

"Blogs" and "wikis" are valuable software tools for communication within research groups.

Appropriate software tools may improve communication and ease access to knowledge for research groups. A weblog is a website which contains periodic, chronologically ordered posts on a common webpage, whereas a wiki is hypertext-based collaborative software that enables documents to be authored collectively using a web browser. Although not primarily intended for use as an intranet-based collaborative knowledge warehouse, both blogs and wikis have the potential to offer all the features of complex and expensive IT solutions. These tools enable the team members to share knowledge simply and quickly-the collective knowledge base of the group can be efficiently managed and navigated.

Communication↗
PubMed2005

In vitro evaluation of the transportability of viable primary human liver cells originating from discarded donor organs in bioreactors.

BACKGROUND: The use of primary human liver cells obtained from discarded donor organs is increasingly favored for cell-based extracorporeal liver support systems. However, as cryopreservation of primary human hepatocytes causes a significant loss of metabolic activity, the transport of bioreactors with viable liver cells is required. The aim of this study was to evaluate the impact of two major potential threats to viable cells during transport: temperature changes and mechanical stress. METHODS: In each experiment three hollow fiber-based bioreactors were charged with primary human liver cells originating from the same discarded donor organ and were simultaneously kept under culture conditions for 8 days. In total, 18 bioreactors were evaluated. On the fifth day the bioreactors were exposed to hypothermia (4 degrees C, n = 3), to hyperthermia (42 degrees C, n = 3), or served as normothermic controls (37 degrees C, n = 3). In a second test series bioreactors were exposed to vibration (21 Hz for 20 min, thereafter 7 Hz for 160 min, n = 3), or were operated as control cultures (n = 6). The release of hepatocyte-specific enzymes was determined as an indicator for cell damage. RESULTS: Hypothermic stress resulted in a significant release of transaminases and led to disturbances of the histological integrity, all indicating a high degree of cell damage. When compared with the control cultures, hyperthermia and mechanical stress in terms of vibration had no significant effect on the cells. CONCLUSION: The transport of hollow fiber bioreactors charged with viable primary human liver cells appears to be feasible in transport monitors for perfusion and temperature control.

Bioreactors↗
PubMed2005

The SlideReactor--a simple hollow fiber based bioreactor suitable for light microscopy.

Most bioartificial liver support systems are based on hollow fiber capillaries within modified dialysis cartridges or more sophisticated bioreactor constructions. Due to their design microscopic follow-up of reorganization and growth of tissue between the hollow fibers is not possible. The SlideReactor is a simple hollow fiber based bioreactor construction suitable for light microscopy and time-lapse video observation. The SlideReactor offers a cell compartment separated from a medium inflow and outflow compartment. Cell compartment access ports enable easy filling of the cell compartment with cell suspension, as well as fixation of the tissue. For more complex procedures or full access to all the cells, the bioreactor can be opened easily by cutting the silicone seal with a scalpel. Due to its simple design and the utilization of standard materials, it could serve as a suitable, cost-efficient tool to evaluate the behavior of cells cultured between hollow fiber capillaries. The paper describes the production process: similar to open source projects in software engineering, we would like to propose the concept as an open platform to anyone interested in hollow fiber based cell culture.

Bioreactors↗
PubMed2005

The European artificial organ scene: present status.

This article summarizes the current evolutions regarding artificial organs in Europe. The review emanates from the activities by four of the work groups of the European Society for Artificial Organs (ESAO) and is essentially based on the reports by these work groups at the latest ESAO meeting in Warsaw, Poland (2004). The topics are: apheresis, heart support, liver support, uremic toxins.

Artificial Organs↗
PubMed2004

In vitro comparison of the molecular adsorbent recirculation system (MARS) and single-pass albumin dialysis (SPAD).

The detoxification capacities of single-pass albumin dialysis (SPAD), the molecular adsorbents recirculation system, (MARS) and continuous veno-venous hemodiafiltration (CVVHDF) were compared in vitro. In each experiment 4,100 mL of toxin-loaded human plasma was processed for 6.5 hours. MARS treatment (n = 6) was undertaken in combination with CVVHDF. For SPAD (n = 6) and CVVHDF (n = 6) a high-flux hollow fiber hemodiafilter (identical to the MARS filter) was used. Levels of ammonia, urea, creatinine, bilirubin, and bile acids were determined. Concentrations before and after application of detoxification procedures were expressed as differences and were compared using the Kruskal-Wallis test. Post hoc comparisons for pairs of groups were adjusted according to Bonferroni-Holm. Time, group, and interaction effects were tested using the nonparametric ANOVA model for repeated measurements. SPAD and CVVHDF induced a significantly greater reduction of ammonia levels than MARS. No significant differences were found among SPAD, MARS, and CVVHDF with respect to other water-soluble substances. SPAD induced a significantly greater reduction in bilirubin levels than MARS. Reductions in bile acid levels were similar for SPAD and MARS. When operating MARS in continuous veno-venous hemodialysis mode, as recommended by the manufacturer, no significant differences in the removal of bilirubin, bile acids, urea, and creatinine were found. However, MARS in continuous veno-venous hemodialysis mode was significantly less efficient in removing ammonia than MARS in CVVHDF mode. In conclusion, the detoxification capacity of SPAD is similar to or even greater than that of MARS.

Hemodialysis Solutions↗
PubMed2003

Use of primary human liver cells originating from discarded grafts in a bioreactor for liver support therapy and the prospects of culturing adult liver stem cells in bioreactors: a morphologic study.

INTRODUCTION: The development of a bioreactor providing a three-dimensional network of interwoven capillary membranes with integrated oxygenation and decentralized mass exchange enables the culture of primary human liver cells from discarded donor organs for extracorporeal liver support. METHODS: Primary liver cells were isolated from 54 discarded organs (donor age 56.7+/-13.2 years). Between 2.8x10(10) and 6.4x10(10) parenchymal cells (PC) were cocultured with nonparenchymal cells (NPC) of the same organ in bioreactors (n=36). The metabolic activity of the cells was regularly determined during culture. The cell morphology and ultrastructure were investigated after culture periods of 1 to 5 weeks. RESULTS: Cell metabolism was maintained over at least 3 weeks after a phase of adaptation lasting 2 to 3 days. Through the use of transmission electron microscopy and immunohistochemistry, it was demonstrated that PC and NPC spontaneously formed tissue-like structures. Vascular cavities (CD 31 immunoreactivity [IR]) and bile duct-like channels (CK 19 IR), both exhibiting proliferation activity (Ki-67 IR), were regularly distributed. Some of the bile duct-like channels showed similarities to the Canals of Hering found in the natural liver. Cells expressing morphologic and antigenic characteristics of adult liver stem cells (CD 34 IR and c-kit IR) and areas with cells that showed both hepatocyte and biliary characteristics were detected. CONCLUSION: The results show that primary human liver cells obtained from discarded donor organs recover and can be maintained in bioreactors for clinical liver support therapy. In addition, initial observations on adult liver stem-cell culture in bioreactors are presented.

Aged↗
PubMed2003

Successful infliximab treatment of steroid and OKT3 refractory acute cellular rejection in two patients after intestinal transplantation.

Acute rejection resistant to established immunosuppressive rescue protocols remains the most prominent risk factor after intestinal transplantation. In two patients presenting with steroid-resistant severe acute cellular rejection 9 months and 2 years after intestinal transplantation, complete resolution was not achieved despite 5 and 10 days of OKT3 treatment, respectively, and high-dose triple baseline immunosuppression with tacrolimus, rapamycin, and steroids. There was a dissociated course of rejection with persistent moderate to severe rejection in the terminal portion of the graft despite complete recovery from rejection in the proximal parts. Both patients were treated with four subsequent infusions of infliximab (3 mg/kg body weight), a chimeric anti-tumor necrosis factor-alpha antibody. There was an immediate response regarding macroscopic appearance, graft histology, and clinical symptoms. Both patients recovered. In conclusion, infliximab has proven to be an effective rescue therapy in a selected group of patients with steroid and OKT3 refractory severe acute rejection after intestinal transplantation.

Acute Disease↗
PubMed2003

Extracorporeal liver support based on primary human liver cells and albumin dialysis--treatment of a patient with primary graft non-function.

METHODS: Following liver transplantation, a 26-year old female suffered from primary non-function of the transplant. The patient was subsequently treated with a modular extracorporeal liver support concept until a suitable organ became available. A bioreactor was charged with human liver cells, obtained from a discarded cadaveric graft (470 g, viability: 60%). The bioreactor was integrated into an extracorporeal circuit with continuous single pass albumin dialysis and continuous veno-venuous hemodiafiltration for detoxification and fluid reduction. RESULTS: Over the total system application time of 79 h, a significant reduction of the plasma levels of total bilirubin (21.1 mg/dl at start, 10.1 mg/dl at end of therapy) and ammonia (100 versus 22.7 micromol/l) was achieved. During treatment the patient's neurological status significantly improved from coma stage IV to I permitting extubation. Recovery of kidney function with a urine output of 1325 ml/24 h compared to 45 ml/24 h prior to system application, was noted. Over the treatment period, an improvement of coagulation status was observed. Adverse events were absent. CONCLUSIONS: This first successful clinical treatment of a patient with liver failure suggests that a modular approach combining both primary human liver cell bioreactor technology and detoxification methods is promising.

Adult↗
PubMed2003

Porcine endogenous retroviruses: no infection in patients treated with a bioreactor based on porcine liver cells.

BACKGROUND: Acute liver failure (ALF) remains a disease with high mortality. Bioartificial liver support systems, which combine living cells of the liver in an extracorporeal circuit, have been successfully used in first clinical trials. The shortage of human organs to be used for bioreactors and the lack of safe and effective human liver cell lines have resulted in pigs becoming an important hepatic cell source. However, using these cells may be associated with the risk of transmission of porcine endogenous retroviruses (PERVs). PERVs are present in the genome of all pigs and are able to infect human cells in vitro. However, it remains unclear whether PERVs infect transplant recipients in vivo and, if so, whether they are pathogenic. OBJECTIVES: To detect antibodies directed against specific epitopes from PERVs in seven individuals who were treated with porcine liver cell bioreactor therapy prior to liver transplantation. METHODS: Sera from seven patients treated with a hybrid liver support system based on porcine liver cells for ALF who survived the treatment and were discharged from hospital were investigated for antibodies against PERV. For this in addition to methods already reported (Xenotransplantation (2001) 125), new immunological detection methods were developed. RESULTS: PERV-specific antibodies were found in none of the patients using Western blot assays based on purified virus or recombinant viral core and envelope proteins or ELISA based on synthetic diagnostic peptides. CONCLUSION: The assays used are specific and sensitive, and correlated in their diagnostic value. The data indicate that no PERV infection had occurred in none of the patients treated with the CellModule bioreactor containing porcine cells.

Adult↗
PubMed2003

Late graft loss after intestinal transplantation in an adult patient as a result of necrotizing enterocolitis.

A 50-year-old recipient of an intestinal and coecal graft with sudden onset of abdominal distention and pain, lack of bowel movements, and vomiting after closure of the diagnostic ostomy 7 months after transplantation is reported. A plain abdominal radiograph revealed pneumatosis intestinalis. An angiography excluded obstruction of large vessels, however, with absent microcirculation of the intestine. Upper gastrointestinal endoscopy showed extensive ulcerative enteritis with several spontaneous perforations. The patient underwent exploration demonstrating a nonviable intestine. The entire necrotic intestine was removed. Vascular thrombosis was excluded. Clinical data, and macroscopic and histologic features of the intestinal graft were diagnostic for necrotizing enterocolitis (NEC). Though there has been evidence for the occurrence of NEC not only in premature infants but even in older infants, children and adolescents, the presented case is, to our knowledge, the first report of NEC as etiology of late graft loss after intestinal transplantation in an adult recipient.

Enterocolitis, Necrotizing↗
PubMed2002

Extracorporeal liver perfusion as hepatic assist in acute liver failure: a review of world experience.

BACKGROUND: There are almost no prospective, controlled and randomized clinical trials comparing different approaches towards hepatic assist. In order to create a basis for comparing the value of the existing different hepatic assist methods this article offers a systematic review of the world experience with allogeneic or xenogeneic extracorporeal liver perfusion (ECLP). METHODS: An Internet-assisted search was conducted in the international literature published from 1964 to 2000. Only articles with a clear description of methodology and outcome of patients were included. For multivariate analysis of variance the general linear method (GLM) procedure was used. Differences within the groups were analyzed by chi-square test. Data of 198 patients were included into the statistical analysis for systematic review. RESULTS: The long-term survival rate (SVR) of these patients was 26%, thus not exceeding published data concerning SVR under standard intensive care. Age below 40 years (P<0.029), coma stage lower than III-IV (P<0.003), total perfusion time over 10 hours (P<0.024), hepatitis B as cause for acute liver failure (ALF) (P<0.05) as well as use of baboon and human livers (P<0.02) were identified as independent positive prognostic markers for improved survival. ECLP as bridging therapy to liver transplantation was successful in 12 of 14 patients. CONCLUSION: ECLP using pig livers did not surpass the success of conventional intensive care treatment. An additional effect of transgenic expression of human regulators of complement regulation in porcine livers has not yet been proven. ECLP with human livers not suitable for liver transplantation might prove effective and practicable for temporary hepatic support. Bridging to liver transplantation by long-term ECLP using porcine and human livers appears to have comparable efficacy as bioartificial support methods.

Acute Disease↗
PubMed2002

Modular extracorporeal liver support.

Modular extracorporeal liver support (MELS) is an integrative concept for the treatment of hepatic failure with appropriate extracorporeal therapy units tailored to suit the actual clinical needs of each patient. The CellModule is a specific bioreactor charged with primary human liver cells harvested from human donor livers found to be unsuitable for transplantation due to steatosis, cirrhosis, or traumatic injury. The DetoxModule enables albumin dialysis for the removal of albumin-bound toxins, reducing the biochemical burden of the liver cells and replacing the bile excretion of hepatocytes in the bioreactor. A DialysisModule for continuous venovenous hemofiltration can be added to the system if required in hepatorenal syndrome.

Bioreactors↗
PubMed2002

Donor evaluation, donor risks, donor outcome, and donor quality of life in adult-to-adult living donor liver transplantation.

Right lobe living donor liver transplantation (LD-LTx) is currently performed at an increasing number of transplant centers. Donor selection, donor safety, donor recovery, and postdonation psychological impairment are essential criteria to determine whether and under which conditions LD-LTx is justifiable. Before commencing the LD-LTx program, approval was obtained from the local ethics committee. Potential donors underwent a comprehensive multistep evaluation protocol to exclude any conditions that could lead to an increased operative risk. Each donation was approved by the local Living Donation Commission. Follow-up investigations were performed after 6 and 12 months. Liver regeneration was assessed by computed tomography scan and magnetic resonance imaging scan derived volumetries. Quality of life (QOL) was investigated according to the Anamnestic Comparative Self-Assessment Scale (ACSA) before donation, and 6 and 12 months after donation. As of December 2001, 43 right lobe living donations have been performed at the Charité, Campus Virchow, Berlin. None of the donors died or has suffered life-threatening or persisting complications. All patients recovered completely. Complications occured in 8 donors (18%). The incidence of perioperative surgical complications was 9%, comprising temporary biliary leakages (n = 3; 6.8%) as well as postoperative bleeding (n = 1). Liver volume regeneration approximated 72% +/- 15% of predonation volume by 6 months and 85% +/- 18% (mean +/- SD) by 12 months. There was no evidence of significant psychological impairment after donation. QOL increased after donation compared with the preoperative state (P < .05). In our experience, LD-LTx has proven to be a practicable and safe procedure. However, there is a considerable risk of postoperative complications. The donor selection process plays a pivotal role in preventing complications. The discussion of potential risks, especially potential life-threatening risks, must be an integral part of informed consent.

Adult↗
PubMedDate not supplied

Time course of primary liver cell reorganization in three-dimensional high-density bioreactors for extracorporeal liver support: an immunohistochemical and ultrastructural study.

To enable extracorporeal liver support based on the use of primary liver cells, culture models supporting the maintenance of cell integrity and function in vitro are required. In this study the cell organization and ultrastructure of primary porcine hepatocytes cocultured with nonparenchymal cells in three-dimensional high-density bioreactors were analyzed after 10, 20, and 30 days of culture by immunohistochemistry and transmission electron microscopy. Biochemical data showed that metabolic activity of the cells in the system was relatively stable over at least 20 days. Immunohistochemical studies were performed in comparison with donor organ biopsies. They showed that hepatocytes and nonparenchymal cells reaggregated in bioreactors, forming structures partly resembling natural liver parenchyma. Bile duct-like structures characterized by cytokeratin 7 (CK-7) immunoreactivity (IR) were regularly detected. Nonparenchymal cells (vimentin IR) formed sinusoidal-like structures within parenchymal cell aggregates. Proliferative activity (Ki-67 IR) increased over time. The detection of collagen I and laminin indicated the production of extracellular matrix components within bioreactors. The results showed that primary liver cell reorganization and long-term maintenance of their differentiated state were achieved within the bioreactors The findings on cell proliferation indicated that the culture model is also of interest for further in vitro studies on cell regeneration and tissue formation.

Adaptation, Physiological↗