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PubMedDate not supplied

[Genetically modified organisms: a new threat to food safety].

This article analyzes all of the food safety-related aspects related to the use of genetically modified organisms into agriculture and food. A discussion is provided as to the uncertainties related to the insertion of foreign genes into organisms, providing examples of unforeseen, undesirable effects and of instabilities of the organisms thus artificially fabricated. Data is then provided from both official agencies as well as existing literature questioning the accuracy and reliability of the risk analyses as to these organisms being harmless to health and discusses the almost total lack of scientific studies analyzing the health safety/dangerousness of transgenic foods. Given all these unknowns, other factors must be taken into account, particularly genetic contamination of the non-genetically modified crops, which is now starting to become widespread in some parts of the world. Not being able of reversing the situation in the even of problems is irresponsible. Other major aspects are the impacts on the environment (such as insects building up resistances, the loss of biodiversity, the increase in chemical products employed) with indirect repercussions on health and/or future food production. Lastly, thoughts for discussion are added concerning food safety in terms of food availability and food sovereignty, given that the transgenic seed and related agrochemicals market is currently cornered by five large-scale transnational companies. The conclusion entails an analysis of biotechnological agriculture's contribution to sustainability.

Animals↗
PubMed1977

[Multiple organic replacement in intensive care medicine seen from anaesthesiological view (author's transl)].

Additional effective methods have to be studied for in order to improve further the treatment of life threatening conditions which are accompanied by reversible breakdown of organic functions. The development and the recent state of different technical and biological replacement functions are presented and their advantages and disadvantages are described. Temporary multiple organic replacement (lung, kidney, liver) by way of peripheral vessels offers a therapeutic procedure capable of development. This procedure is based on the knowledge that in different endogenous and exogenous intoxications, and also after shock symptomatology generally, several vital functions are simultaneously disturbed or become acutely insufficient. This coincidental breakdown requires a simultaneous, effective, multilateral therapy. First partial successes by means of equipment for multiple organic replacement are critically analysed and conclusions for further improvement of its function are discussed.

Artificial Organs↗
PubMed1993

Development of reliable artificial liver support (ALS)--plasma exchange in combination with hemodiafiltration using high-performance membranes.

A new artificial liver support system (ALSS) consisting of plasma exchange (PE) in combination with hemodiafiltration (HDF) using high-performance membranes of polymethyl methacrylate (PMMA) and cellulose triacetate (CTA) was developed to efficiently remove middle molecules from plasma and treat fulminant hepatic failure (FHF) complicated by the onset of hepatic coma. Twenty-seven patients with FHF due to viral hepatitis, two with type A (HA), nine with type B (HB), and 16 with type non-A, non-B (NANB) underwent therapy with this new ALSS over the last five years. Three patients with an exacerbation of chronic HB and 15/16 with type NANB hepatitis were treated with interferon (IFN) also. Of these, 25 patients (92.6%) regained consciousness and 15 (55.6%) [1/2 (50%) with type A, 6/9 (66.7%) with type B and 8/16 (50%) with type NANB hepatitis] survived. Including four patients who survived with intensive care and plasma exchange alone, 19/31 (61.3%) patients survived. Because of its biocompatibility, both survivors and nonsurvivors could be sustained with the ALSS without complications for long periods (19.3 days for the survivors and 32.4 days for nonsurvivors). With this ALSS the ability to sustain life for such prolonged periods allows hepatic regeneration to occur and result in patient survival. It is anticipated that this new ALSS will not only be of value in cases of fulminant hepatic failure but that it may also play a role in sustaining life for those awaiting liver transplantation.

Adult↗
PubMed1992

Femoral arteriovenous extracorporeal carbon dioxide elimination using low blood flow.

BACKGROUND AND METHODS: Conventional extracorporeal CO2 removal systems require blood flow rates of 1 to 2.5 L/min in the extracorporeal circuit. We hypothesized that standard hemofiltration equipment can be combined with a high-performance extracorporeal lung to achieve high rates of CO2 removal at lower blood flow rates. To test this hypothesis, we performed experiments on nine sheep to examine the extent to which CO2 elimination can be achieved at blood flow rates less than 600 mL/min using a 5-m2 hollow fiber membrane lung with countercurrent gas flow, combined with a hemofiltration blood pump, and connected to femoral arterial and venous hemodialysis catheters. RESULTS: CO2 eliminations of 130 to 180 mL/min at standard temperature and pressure were achieved with blood flow rates in the range 470 to 600 mL/min. With a pumpless artery-to-vein shunt, up to 90 mL/min of CO2 at standard temperature and pressure was eliminated. However, in this mode, the resistance of the access catheters and tubing was the main factor limiting CO2 elimination. CONCLUSIONS: Standard hemofiltration equipment may be combined with a hollow fiber membrane lung to remove the equivalent of a high proportion of the basal metabolic CO2 production of an adult human at low blood flow rates. Use of this technology would bring extracorporeal CO2 removal within the budget and capability of more ICUs.

Animals↗
PubMed2006

Uniformity of the fluid flow velocities within hollow fiber membranes of blood oxygenation devices.

A finite volume-based computational model was developed to investigate the uniformity of the fluid flow across the hollow fiber membranes in blood oxygenation devices. A two-dimensional annular cross section of a blood oxygenation device including about 3,300 hollow fiber membranes was used in the computation model. The equations governing the steady incompressible laminar flow in the blood oxygenation device were solved numerically and the results were compared with those obtained from the equivalent porous medium approximation. For the porous medium approximation, the Ergun equation was used for evaluating the permeability. The simulation results showed that the fluid molecules spend about six times longer in the fiber bundle region than that in its equivalent porous medium approximation model. The computational model also provides a more detailed fluid flow pattern in the membrane compartment of the blood oxygenator.

Artificial Organs↗
PubMed1995

Analysis of glucose and insulin mass transfer in a novel 2-channel bioartificial pancreas.

This paper introduces a newly developed 2-channel bioartificial pancreas for the treatment of type I diabetes. In this device, insulin secreting cells (islets of Langerhans) are placed between 2 semi-permeable membranes that form a flat rectangular chamber. One side of the chamber is in contact with blood from an artery and the other side with blood from a vein. In addition to the diffusive transfer of glucose and insulin, the pressure difference between the artery and the vein creates an ultrafiltration flux through the islet chamber. This diffusion and ultrafiltration flux carries glucose from the artery to the islets, and insulin from the islets to the vein. The bioartificial pancreas has a compact geometry and the blood channels were designed to prevent blood clotting. The predicted insulin release in response to a square-wave and a triangular-wave glucose stimulation is given for the bioartificial pancreas of dimensions necessary for implantation in diabetic patients.

Artificial Organs↗
PubMed1990

Experiments on a new hollow fiber membrane for immuno isolated transplantation of islets of Langerhans.

Immunoisolated transplantation of xenogeneic islets could solve problems concerning the immunology of islet transplantation. This study presents results from in vitro and in vivo experiments in rodents by the use of a PEEK-hollow fiber. Glucagon secretion of encapsulated islets during a 48-hour-culture period sustained on the same level from day 2 to 28. There were no significant differences in glucose (16.7 mmol/l)-stimulated insulin release after 6, 14 or 28 days in culture. Contrary, intraperitoneal transplantation of 800 encapsulated islets resulted in a normoglycemia of 3.8 days (medium survival time) which was similar to that of not encapsulated controls. It was concluded that a more open ultrastructure of the membrane tested could result in a minimization of the diffusion distance and overcome principle geometric problems of the hollow fiber model.

Animals↗
PubMed1990

Comparative study of microencapsulated rat islets implanted in different diabetic models in mice.

Microencapsulated rat islets of Langerhans (alginatepolylysine microcapsules) were implanted into the peritoneal cavity of diabetic mice (500 rat islets per mouse) in order 1) to evaluate the ability of this xenograft in correcting hyperglycemia in different models of diabetes and 2) to examine the implanted material recovered from the recipients after several weeks. 1) In the high-dose streptozotocin model in Balb/c mice (n = 14), 6 had a sustained (over one month) decrease in plasma glucose concentration from 401 +/- 7 to 171 +/- 7 mg/dl, with no effect in the other. 2) In the low dose streptozotocin model in C57BL/6J mice (n = 17), plasma glucose levels decreased in 9 mice, from 439 +/- 27 to 180 +/- 30 mg/dl, and remained below 250 mg/dl up to 60 days. In 8 mice, only a transient effect was observed. Empty capsule transplantation had no effect. Plasma insulin in successfully transplanted mice was higher in fed than in fasted state. 3) Microencapsulated rat islets had no effect on plasma glucose in male NOD mice made diabetic by cyclophosphamide treatment (n = 10). Thus, microencapsulated rat islets can improve the diabetic state in some, but not all diabetic mice. In this study, microcapsules were consistently surrounded by an inflammatory reaction, which remains a major concern.

Animals↗
PubMed1984

[Progress on the way to an "artificial liver"].

Recently lipophilic fluid membrane hollow fiber modules have been developed, which allow continuous extracorporal enzymatic detoxification by elimination of endogenous toxins out of the blood in vivo without loss of enzymatic activity and without immunological risks. The clearance for phenol glucuronisation is 6.8 nMol/min/mg enzyme protein/cm2 hollow fiber surface the hydroxylation rate for dodecanic acid using the cytochrome - P-450 system is 0.5 nMol/nMol P450/min/cm2 hollow fiber surface. Detoxification procedures using methyl, sulfat and glutathion transferase are still in an experimental phase. This new enzyme fluid membrane technology in conjunction with modified established techniques like aminoacid dialysis and plasma exchange will make possible the development of partial extracorporal substitution of liver function in the near future.

Amino Acids↗
PubMed1993

Secretion of erythropoietin from microencapsulated rat kidney cells: preliminary results.

Rat kidney epithelial cells were microencapsulated within alginate-poly(L)lysine-alginate membrane. The microencapsulated cells were incubated using a culture media containing cobalt and another without cobalt. The viability was measured by trypan blue exclusion test. Secretion of erythropoietin (EPO) was measured by radioimmunoassay (RIA). Viability of free cells was 53%. The viability of microencapsulated cells increased to 72% after 12 days of incubation and remained at this level. Samples of the culture media were collected every 2 days for RIA. Samples within the microcapsules were collected by breaking the microcapsules open. RIA of these samples showed the following for the media containing cobalt. Between day 16 and day 32 the concentrations of EPO were 5.3 mU/ml inside and 18.3 mU/ml outside the microcapsule. The medium from the same number of free cells contained 21.2 mU/ml of EPO. Culture media without cobalt collected during the same period contained 1.8 mU/ml inside and 9.9 mU/ml outside the microcapsules. The free cell culture with this media during the same period contained 8.3 mU/ml.

Alginates↗
PubMed2005

Performance of ultrafiltration membrane process combined with coagulation/sedimentation.

Effects of coagulation/sedimentation as a pre-treatment on the dead-end ultrafiltration (UF) membrane process were studied in terms of membrane fouling and removal efficiency of natural dissolved organic matter, using Chitose River water. Two types of experiment were carried out. One was a bench scale membrane filtration with jar-test and the other was membrane filtration pilot plant combined with the Jet Mixed Separator (JMS) as a pre-coagulation/sedimentation unit. In the bench scale experiment, the effects of coagulant dosage, pH and membrane operating pressure on the membrane fouling and removal efficiency of natural dissolved organic matter were investigated. In the pilot plant experiment, we also investigated the effect of pre-coagulation/sedimentation on the membrane fouling and the removal efficiency of natural dissolved organic matter. Coagulation/sedimentation prior to membrane filtration process controlled the membrane fouling and increased the removal efficiency of natural dissolved organic matter.

Colloids↗