Biomedical subjects

P Sioshansi

Publications and source records attributed to P Sioshansi.

9 recordsLinked to original sources

PubMed2000

Surface treated catheters with ion beam based process for blood access.

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 (IBAD) (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 135 patient prospective study, 170 large bore catheters were inserted into the internal jugular or subclavian veins. Seventy-eight surface treated catheters (Spi-Argent, Spire Corporation, Bedford, MA, U.S.A.; n = 32 acute catheters, n = 46 long-term catheters) were inserted in 55 patients. Ninety-two untreated catheters placed in 80 patients served as controls (n = 40 acute catheters, n = 52 long-term catheters). After removal, the catheters were cultured for bacterial colonization using standard microbiologic assays. They also were examined using a scanning electron microscope (SEM). Bacterial colonization was observed in 7% of the treated catheters compared with 35.3% 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↗

PubMed1997

Surface-treated catheters with ion beam-based process evaluation in rats.

Ion beam-based processes such as ion implantation (silicone rubber) and ion beam-assisted deposition (silver-based coatings) affect the outer micron layers of catheter surfaces. These processes were used on the common catheter materials of silicone and polyurethane. In 56 rats, surface (Spi-Silicone and Spi-Argent I and II) catheter segments were implanted for 1, 3, and 6 weeks. After removal, these pieces were investigated for bacterial colonization and fixed for scanning electron microscopic evaluation. As controls, untreated catheter segments were implanted in 28 rats. Bacterial colonization was found in 2.4% in the surface treated catheter pieces versus 7.1% in the control group. The scanning electron microscope investigations showed low thrombogenicity in all of the treated catheters independent of the implantation times.

Animals↗

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

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↗

PubMed1994

New processes for surface treatment of catheters.

Infection, thrombosis, and stenosis are among the most common complications of blood-contacting catheters and are caused by surface properties of the substrate materials. Ion beam-based processes such as ion implantation and ion beam-assisted deposition affect only the outer micron of the treated material surface; there is little effect on bulk properties. These processes were therefore used on common catheter materials, and their biological properties were evaluated. Ion implantation of materials such as silicone rubber resulted in a less tacky, more wettable surface that demonstrated thrombus-resistance in both in vivo and preliminary clinical studies. Ion beam-assisted deposition was used to deposit silver-based coatings, which demonstrated antimicrobial activity in in vitro and clinical studies. Biocompatibility of these processed catheter materials was also demonstrated using simple laboratory studies. These processes, therefore, can be readily applied to blood-contacting catheters to make them thrombus- and infection-resistant.

Catheters, Indwelling↗

PubMed1994

Scanning electron microscopic investigation of catheters for blood access.

Large-bore catheters for extracorporeal detoxification methods without and with treated surface with silver or silicone were investigated after removal with a scanning electron microscope and for bacterial colonization. In 42 large-bore catheters of three different materials, small deposits of fibrin and protein on the inner and outer surface were seen. This second layer covered the entire surface after 3 days and increased to a thickness of 3 to 60 microns during the following days. Bacterial colonization was observed in 38.1%. In contrast to these results, the catheters with the treated outer surface showed a very low thrombogenicity and a low contamination rate of 6.7%.

Bacteria↗

PubMed1992

Frictional coefficients of ion-implanted alumina against ion-implanted beta-titanium in the low load, low velocity, single pass regime.

The frictional coefficients were measured for four wire alloys against the flats of polycrystalline alumina cylinders using a low load, low velocity, single pass device. Ion-implantations of titanium into polycrystalline alumina flats and nitrogen into beta-titanium wires reduced the static and kinetic coefficients from 0.50 and 0.44 before implantation to 0.20 and 0.25 after implantation, respectively. These results are similar in magnitude to frictional coefficients for unimplanted, control couples of stainless steel, cobalt-chromium, and nickel titanium wires against polycrystalline alumina flats. For orthodontic applications, we conclude that more efficient and reproducible appliances can be engineered for tooth movement if ion-implantation is used to reduce the abrasion of beta-titanium by polycrystalline alumina.

Aluminum Oxide↗

PubMedDate not supplied

Low-energy 103Pd gamma (X-ray) source for vascular brachytherapy.

PURPOSE: This article describes the merits of 103Pd, a low energy x-ray emitter, as a new and potentially superior candidate for intraluminal brachytherapy. 103Pd can be ion implanted into different materials, designs, and devices for vascular brachytherapy. METHODS: The mass-analyzed ion implantation process has been used to embed the desired activity of 103Pd into the surface of 316L stainless steel stents. The low-energy, 21-keV x-ray from 103Pd delivers reasonably homogeneous radiation to the vessel wall and loses intensity rapidly beyond the immediate vicinity of the source. Shielding for 103Pd x-rays is trivial and the issues regarding safety, health hazards, storage, and handling are easily manageable. RESULTS: Experimental data on 103Pd ion-implanted stents show a clean gamma-ray spectrum devoid of any radioimpurity. Activity measurements within a batch demonstrate little stent-to-stent variation (approximately 2%), excellent axial and radial uniformity (<10%), and minimal dissolution in a saline environment (approximately 0.02%). The dosimetry shows the focused radiation field for 103Pd stents and rapid fall-off beyond a few millimeters of the stent. Furthermore, the 103Pd dosimetry indicates that a 350 muCi stent will deliver approximately 14 Gy at 1-mm distance, over its lifetime. CONCLUSION: 103Pd is an appropriate source for vascular brachytherapy. It has an appropriate combination of half-life (16.93 days) and energy (21 keV). The half-life of 103Pd delivers the dose with an acceptable dose rate for stent applications while, at the same time, allowing for manageable shipping, storage, and/or disposal.

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↗