PubMed Health⌕ Search

Biomedical subjects

R Schiel

Publications and source records attributed to R Schiel.

46 records · Page 3Linked to original sources
PubMed1996

Scanning electron microscopic investigation of catheters for blood access.

Using blood-contacting catheters, infections, thromboses, and stenoses are among the most frequent complications. They are caused by surface properties of the basic material. Ion beam based processes such as ion implantation (silicone rubber) and ion beam assisted deposition (silver-based coatings) affect only the outer micron of the treated material surface; there is little effect on bulk properties. These processes were employed also in the production of large-bore catheters used for extra-corporeal detoxification. In a prospective study in 56 patients, 72 large-bore catheters were inserted into the internal jugular and subclavian veins and investigated after removal for bacterial colonization using a scanning electron microscope. In 24 patients 30 surface-treated catheters (Spi-Argent I n = 14; Spi-Silicone n = 16) were used. 42 untreated catheters used in 32 patients served as controls. Bacterial colonization was observed in 8.9% in contrast to 38.1% in untreated catheters. The scanning electron microscopic investigations showed in all catheters a low thrombogenicity. The ion beam based processes make the surface-treated catheters thrombus and infection resistant.

Catheterization, Central Venous↗
PubMed1995

LDL-apheresis in treatment of two patients with heterozygous familial hypercholesterolemia and extremely elevated lipoprotein (a) levels.

In hyperlipidemia and, in particular, elevated lipoprotein (a) [Lp(a)] levels there appears to be pronounced linkage between the development and progression of atherosclerosis. Our study concerned two Caucasian male patients with heterozygous forms of familial hypercholesterolemia and extremely high Lp(a) concentrations. Maximal diet regimens and the use of lipid lowering drugs achieved a serum total-, LDL-cholesterol and triglyceride reduction of up to 30%, but no reduction of the Lp(a) level was discernible. Both patients suffered three myocardial infarctions and several coronary angiographies with percutaneous transluminal angioplasties (PTCA) were necessary. In 1989, we commenced treatment with LDL-apheresis. At present, after 78 LDL-aphereses in the case of the 41-year-old patient (48 months, dextran sulfate adsorption, KANEKA, Japan) and 38 aphereses in the case of the 35-year old patient (8 months, immunoadsorption, special Lp[a] columns, LIPOPAK, POCARD, Russia), the Lp(a) has dropped an average of 53%, total cholesterol 31%, LDL-cholesterol 40% and triglycerides 42%. During this period neither mycardial infarctions nor cardiac complaints were observed. In the course of treatment, both patients experienced an improvement in general well-being and increased performance. These results are very encouraging: LDL-apheresis may be effective in the treatment of patients, the only risk factor for premature atherosclerosis being an extremely high Lp(a) concentration.

Adult↗
PubMed1995

LDL-apheresis in two patients with extremely elevated lipoprotein (a) levels.

Hyperlipidemia and elevated lipoprotein (a) [Lp(a)] levels have been linked to the development and progression of premature atherosclerosis. Two male caucasian patients (36 and 42 years old) with heterozygous familial hypercholesterolemia and extremely elevated Lp(a) concentrations, resistant to diet regimen and lipid lowering drugs, were treated with LDL-apheresis for 55 months (liposorber system, Kaneka, Japan) and 15 months (immunoadsorption system, special Lp(a) columns, Lipopak, Pocard, Russia). Lp(a) dropped on average by 50%, total cholesterol by 27%, LDL-cholesterol by 42%, triglycerides by 43% and the fibrinogen concentration by 16%. Prior to treatment, both patients had suffered three myocardial infarctions. Four and six coronary angiographies with two and four percutaneous transluminal angioplasties (PTCA) were necessary. Since the treatment with LDL-apheresis neither myocardial infarctions nor cardiac complaints have been observed, and both patients have reported better performance. Available data suggest that LDL-apheresis may be effective in the treatment of patients with extremely high Lp(a) concentration.

Adult↗
PubMed1995

Scanning electron microscopic investigations of surface treated large-bore catheters used for extracorporeal detoxification methods.

Typical complications caused by surface properties of synthetic catheter implants are infection, thrombosis, and stenosis. New methods for surface modification with the aim of reducing such complications are ion beam-based technologies. In our study 109 large-bore catheters without (n = 42) and with treated surfaces with silver (n = 39) or silicone (n = 28) were inserted into the interna jugular and the subclavian veins and were used for extracorporeal detoxification methods. After removal, the catheters were investigated with scanning electron microscopy (SEM) and for bacterial colonization. In 42 large-bore catheters without surface treatment deposits of fibrin, protein and blood cells were seen on the inner and outer surface. Bacterial colonization was observed in 38.1%. In contrast, the catheters with treated outer surfaces showed a very low thrombogenicity and a low contamination rate of 8.9%. The ion beam-based technologies reduce the thrombogenicity and infection rates of the catheter surfaces. In comparison to catheters without treated surfaces, catheters with surface treatment are good alternatives in blood contacting applications ranging from hemodialysis to oncology.

Adsorption↗
PubMed1995

Four years' treatment efficacy of patients with severe hyperlipidemia. Lipid lowering drugs versus LDL-apheresis.

A total of 47 patients suffering from heterozygous hyperlipidemia were treated with LDL-apheresis (24 patients, aged 49.5 +/- 11.5 years), diet and/or lipid-lowering drugs or with diet and lipid-lowering drugs only (23 patients, aged 48.0 +/- 11.9 years). After treatment periods of 44.4 +/- 14.3 (apheresis group) and 33.5 +/- 15.9 (drug group) months, respectively, the ensuing results revealed significant differences (p < 0.0001): total cholesterol decreased from 10.4 to 5.5 vs 9.9 to 8.7 mmol/l, LDL from 7.4 to 3.9 vs 6.6 to 5.2 mmol/l, triglycerides from 5.8 to 3.7 vs 4.8 to 4.1 mmol/l and the LDL/HDL-ratio decreased from 7.1 to 3.4 vs 6.7 to 5.8. In the apheresis group one patient died from myocardial infarction vs one non-fatal myocardial infarction and the manifestation of coronary heart disease in three cases in the drug group. There were no severe side-effects in either group. All patients in the apheresis group experienced an increased clinical performance. On the other hand physological well-being of these patients was lower than that of the drug group (scores 42.3 +/- 8.9 vs 50.2 +/- 9.9, p < 0.002). The present trial suggests that a continuing reduction in serum lipid concentrations may lower in a dose dependent manner the risk of development and progression of coronary heart disease. With respect to clinical and laboratory results, LDL-apheresis seems safe and appears to be the most effective therapy.

Adolescent↗
PubMed1994

Complications and side effects associated with large-bore catheters in the subclavian and internal jugular veins.

Since the introduction of large-bore catheters for acute hemodialysis 30 years ago, many problems with handling, material, and contamination of these catheters exist. Nevertheless, catheterization of the inferior and superior vena cava with a large-bore catheter has proved to be suitable as a rapid connection process for hemodialysis, hemofiltration, hemoperfusion, plasmapheresis, plasmaperfusion, among others. In a retrospective study with 2,741 large-bore catheters in 1,716 patients, the frequency of infections, thrombosis, bleeding, and other side effects was investigated. All complications and side effects are presented dependent on vascular access route. In total, the complication rate was 48.9% higher in subclavian puncture than in internal jugular puncture (24.8%). The highest complication rates for both vascular access routes were infections or septicemia; infections were observed in 19.5% of subclavian catheters versus 10% of internal jugular catheters.

Bacteria↗
PubMed1993

Characterization of two Metabacterium sp. from the gut of rodents. 1. Morphology and histochemical examination of a new Metabacterium sp. from the gut of the European hamster (Cricetus cricetus)

A new giant Gram-negative non-cultivatable symbiotic endospore-forming bacterium was found in the gut of the European hamster. This "Metabacterium" sp., provisionally named "Metabacterium criceti", sp. n., has a length of approximately 20 microns and thickness of 4 microns. It forms 1 to 2 cylindrical endospores, approximately 9 microns long and 1.4 microns thick. TEM-micrographs show a cell wall structure characteristic of Gram-negative bacteria. Vegetative cells are filled with granules 0.3 micron in diameter which resemble starch granules. The reproduction occurs with binary fission and by formation of two endospores. Of thirteen biochemical components sought, four, i.e. glycogen, triacylglycerols, peroxidase and alkaline phosphatase, were not found. Starch, acid mucosubstances, DNA, RNA, lipids, proteins, adenosine triphosphatase and acid phosphatase were found in different patterns, depending on the developmental stage of the bacterium. In the vegetative cell stage all these components, with the exception of starch, were found. In the endospore-bearing cell stage, only the starch-like cell component granules could be detected. In free endospores only DNA, RNA and acid phosphatase were found. Some of the components, i.e. DNA, lipids, starch-like granules, were linked to certain cell substructures, the distribution of others, viz. polysaccharides, RNA, adenosine triphosphatase and proteins was diffuse. The lipids, found only in vegetative cells, were associated with the cell wall.

Animals↗
PubMedDate not supplied

Surface treated large bore catheters with silver based coatings versus untreated catheters for extracorporeal detoxification methods.

Infection, thrombosis, and stenosis are among the most frequent complications associated with blood contacting catheters. Because these problems are usually related to surface properties of the base catheter material, surface treatment processes, such as ion implantation and ion beam assisted deposition (silver based coatings), can be used to mitigate such complications. Because these ion beam based processes affect only the near-surface region (approximately the outer 1 microm), there is little effect on bulk material properties. This study evaluated silver coated large bore catheters used for extracorporeal detoxification. In a 122 patient prospective study, 156 large bore catheters were inserted into the internal jugular or subclavian veins. Seventy-eight surface treated catheters (SPI-ARGENT, Spire Corporation, Bedford, MA; n = 32 acute catheters, n = 45 long-term catheters) were Bambauer inserted in 55 patients. Seventy-eight untreated catheters placed in 67 patients served as controls (n = 35 acute catheters, n = 43 long-term catheters). After removal, the catheters were cultured for bacterial colonization using standard microbiologic assays. They were also examined using a scanning electron microscope (SEM). Bacterial colonization was observed in 15.4% of the treated catheters compared with 44.9% of untreated catheters. The SEM investigations showed all treated catheters to possess low thrombogenicity. Results of the study indicate that ion beam based processes can be used to improve thrombus and infection resistance of blood contacting catheters.

Adult↗
PubMedDate not supplied

LDL-apheresis as long-term treatment in severe hyperlipidemia using differing methods.

In 34 patients (18 women, 16 men) suffering from familial hypercholesterolemia resistant to diet and lipid lowering drugs, low density lipoprotein (LDL) apheresis was performed during 72.8 + 43.2 months. Four different systems (Liposorber, 28 of 34, Kaneka, Osaka, Japan; Therasorb, 2 of 34, Baxter, Germany; Lipopak 2 of 34, Pocard, Moscow, Russia; Dali, 2 of 34, Fresenius, St. Wendel, Germany) were used. With all methods, average reductions of 51.9% for total cholesterol, 49.8% for LDL, 69.8% for lipoprotein (a) (Lp(a)), and 58.8% for triglycerides, and an average increase of 9.8% for HDL were reached. Severe side effects such as shock or allergic reactions were very rare (0.5%) in all methods. In the course of treatment, an improvement in general well-being and increased performance were experienced by 31 of 34 patients. Assessing the different apheresis systems used, at the end of the trial there were no significant differences with respect to the clinical outcome experienced by the patients' total cholesterol, LDL, HDL, and triglyceride concentrations. However, to reduce high Lp(a) levels, the immunoadsorption method with special Lp(a) columns (Lipopak) seems to be most effective: -57% versus -25% (Kaneka), -23% (Baxter), and -29% (Dali). The present data demonstrate that treatment with LDL-apheresis of patients suffering from familial hypercholesterolemia resistant to maximum conservative therapy is very effective and safe, even in long-term application.

Adult↗