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At least 883 records · Page 49Linked to original sources
PubMed2003

Influence of VEGF on the viability of encapsulated pancreatic rat islets after transplantation in diabetic mice.

After pancreatic islet transplantation, insufficient blood supply is responsible for the loss of islet viability. The aim of our study was: 1) to determine the influence of vascular endothelial growth factor (VEGF) on the survival of encapsulated rat islets transplanted into healthy and diabetic mice and 2) to evaluate the metabolic efficiency of the VEGF-supplemented grafts. Twenty-four hours after culture, 50 rat islets immobilized into collagen in the presence of VEGF (100 ng/ml) and encapsulated (AN69 membrane, HOSPAL) were grafted in the peritoneal cavity of healthy or streptozotocin-induced diabetic mice (n = 6). Seven, 14, and 28 days after implantation, the encapsulation device and tissue surrounding the device were removed and the following parameters were analyzed: the number and the diameter of buds, the distance between devices and buds, the amount of cellular adhesion on the capsule surface, and the level of insulin secreted by encapsulated islet. For reversal of diabetes, 1000 rat islets encapsulated in the presence of VEGF were implanted in the peritoneal cavity of diabetic mice and fasting glycemia was analyzed. After 7 days of islet implantation in the absence of VEGF, the bud diameter was 16.1 +/- 6.9 microm in diabetic mice and 34.4 +/- 3.9 microm in healthy mice. However, the number of buds increased by a factor 2.5 in the presence of VEGF in both types of mice. Furthermore, when islets were transplanted in the presence of VEGF, the distance between the device and the buds was significantly decreased in both types of mice (p < 0.001) after 7, 14, and 28 days of islet implantation. Capsule analysis showed a decrease in cellular adhesion when the islets were encapsulated in the presence of VEGF. Insulin secretion of the islets was higher in the presence of VEGF compared with islets alone at all steps of the study. When 1000 rat islets were transplanted in the presence of VEGF, the glycemia level decreased to 6.2 +/- 0.8 mmol/L after 3 days and remained stable until at least 28 days. In contrast, in the absence of VEGF, the initial decrease in the glucose level was rapidly followed by a relapse in hyperglycemia. In summary, VEGF increased the viability of engrafted encapsulated islets, increasing the duration of a normalized glycemia in diabetic mice following transplantation. Local adjunction of VEGF may therefore improve the clinical outcome of islet transplantation.

Animals↗
PubMed1996

Medical device recall authority--FDA. Final rule.

The Food and Drug Administration (FDA) is establishing procedures for implementing the medical device recall authority provided in the Safe Medical Devices Act of 1990 (the SMDA). This statutory authority protects the public health by permitting FDA to remove dangerous devices from the market promptly. This authority complements other provisions of the device law, including tracking and notification.

Device Approval↗
PubMed1984

Intensification of milk somatic cell response to intramammary device.

Treatments consisting of copper-impregnated polyethylene intramammary device (PIMD-Cu), PIMD-Cu which had been abraded to ensure exposure of surface copper (APIMD-Cu), PIMD which had been abraded in an identical manner (APIMD), and an untreated control were established in mammary quarters of 2 cows. Quarters selected were bacteria free and had milk somatic cell counts (MSCC) in strippings of less than 240 X 10(3) ml. Milk somatic cell counts were determined from strippings immediately after milking and 6 hours later. Cows were monitored for 4 weeks after devices were inserted. Milk samples (250 ml) were collected and analyzed for free fatty acids, a measure of hydrolytic rancidity, at 14 days. The devices were removed from mammary quarters after 4 weeks and examined with a scanning electron microscope. Surfaces of the devices were assessed for plaque buildup and presence of leukocytes. Immediately after and 6 hours later, geometric mean MSCC for APIMD, APIMD-Cu, PIMD-Cu, and control quarters average 946/1,556, 1,479/2,882, 512/1,148, and 161/190 X 10(3) ml, respectively. There was no difference in free fatty acid values of samples from treated and control quarters. Plaque formation was observed over the entire surface of APIMD. Numerous leukocytes were found associated with plaque and appeared to initiate development of plaque. Smaller amounts of plaque were found on APIMD-Cu, and minimal amounts were found on PIMD-Cu. Results indicate that modification of PIMD by abrading or addition of copper will increase MSCC to concentrations (greater than 900 X 10(3) ml) that should be protective against establishment of infection by mastitis pathogens.

Animals↗
PubMed1991

Quantitative blood cultures in candidemia.

The relationship between quantitative data on peripheral blood cultures and source of infection was studied in 172 episodes of candidemia that occurred in 169 patients. Clinically, the source of candidemia was an intravascular device in 67 episodes, an extravascular source in 73 episodes, and endocarditis in 2 patients; no source was identified for the other 30 episodes. Colony counts were determined in peripheral blood specimens on the first day of candidemia by the lysis-centrifugation system. High-grade and low-grade candidemia were defined as 25 colony-forming units or more per 10 ml and 10 colony-forming units or fewer per 10 ml of blood, respectively. Of 48 episodes of high-grade candidemia, 43 (90%) were associated with an infected intravascular device; therefore, the presence of high-grade candidemia should prompt the removal of intravascular devices. In contrast, 92 of the 112 episodes of low-grade candidemia (82%) had an extravascular or an unidentified source of candidemia. In patients with infections associated with an intravascular device, colony counts declined significantly within 72 hours after removal of the device in the absence of antifungal therapy; failure to decline suggests an alternative source of persistent infection. Quantitative data from peripheral blood cultures may help distinguish intravascular from extravascular sources of candidemia and aid in assessing the response to the removal of infected intravascular devices.

Academic Medical Centers↗
PubMed1993

A new device for blockout procedures in rotational path removable partial dentures.

The rationale of a rotation axis is discussed and on this basis a blockout device is designed for rotational path removable partial dentures. This device has three basic components, which are (1) the acrylic resin block, (2) the rotation axis, and (3) the functional part. In the blockout procedures for removable partial dentures with tilted mandibular molars, the rotation axis of the prosthesis is first localized by the blockout device. A knife edge, made of Duralay resin that corresponds to the survey lines of teeth to be used as supports, is constructed and is joined to the functional part of the blockout device. Blockout regions are determined by the rotational movement of the Duralay resin knife edge along the rotation axis of the blockout device. In addition to the function of blockout, the device can also be used to analyze diagnostic casts for critical undercuts. Internal and external types of blockout devices are also discussed.

Acrylic Resins↗
PubMedDate not supplied

Development of ambulatory arterio-venous carbon dioxide removal (AVCO2R): the downsized gas exchanger prototype for ambulation removes enough CO2 with low blood resistance.

We are developing an ultra compact gas exchanger to allow ambulation during arterial-venous CO2 removal (AVCO2R). The ambulatory AVCO2R gas exchanger (135 ml prime volume and 1.3 M2 gas exchange surface area) is made of polymethylpentene hollow fibers. The gas exchanger was attached to sheep carotid artery (12F) and jugular vein (14F) by percutaneous cannulae for 6 hours (n = 5). Device CO2 removal was measured and calculated at a constant blood flow rate of 1 L/min coupled with varying sweep gas from 1 to 15 L/min, and at constant sweep gas flow of 2 L/min coupled with varying blood flow from 0.5 to 1.25 L/min to determine capacity of CO2 removal at Pa CO2 = 40-50 mm Hg. Blood gases, CO2 removal and hemodynamics were recorded at 0, 3, and 6 hours. CO2 removal increased with sweep gas flow rate and with increase of device blood flow. Hemodynamics remained unchanged throughout study. Gas exchanger resistance remained stable at 2.3 +/- 0.53 mm Hg/L/min. CO2 removal with 1 L/min blood flow and 2 L/min sweep gas was 110 +/- 12 then stabilized at 85 +/- 14 mL/min to 6 hours. The compact ambulatory AVCO2R gas exchanger achieves stable, near total CO2 removal for at least 6 hours with a simple arteriovenous shunt.

Animals↗
PubMed1982

Observation of orthopedic force distribution produced by maxillary orthodontic appliances.

A three-dimensional anatomic model was duplicated from a human skull, using different birefringent materials to simulate the various craniofacial structures. Individual bones of the midface were fabricated separately and then articulated in their correct sutural relation. One removable and four fixed maxillary appliances were used. The fixed appliances included the Haas, Minne-expander, Hyrax, and quad helix devices. The removable appliance incorporated an expansion screw in a full acrylic palate with appropriate retentive clasps. After the insertion of each appliance, intraoral forces were produced by incremental activation. The model was examined and photographed in the field of a transmission polariscope. Each appliance used produced a different range of load-activation characteristics. This was reflected by the differences in the stresses transmitted through the bones of the craniofacial complex and the effect on the various sutures. Stresses produced by the fixed appliances were concentrated in the anterior region of the palate, progressing posteriorly toward the palatine bone. The Haas, Minne-expander, and Hyrax appliances produced stresses that radiated superiorly along the perpendicular plates of the palatine bone to deeper anatomic structures, such as the lacrimal, nasal, and malar bones, as well as the pterygoid plates of the sphenoid. Similar stress characteristics were seen with the removable appliance. However, increased activation decreased retention of the appliance, thereby lessening the stress. The quad helix appliance proved to be the least effective orthopedic device. Although the effects of palate separation were seen with increased activation, this appliance primarily affected the posterior teeth.

Equipment Design↗
PubMed1998

Measuring line-related bacteraemia in intensive care patients.

All patients with an intravascular device in the intensive care units at Prince of Wales and Prince Henry Hospitals between July and September 1995 were followed for the development of line-related bacteraemia per 1000 line days. Cases of sepsis related to an intravascular device were identified using a case definition which incorporated clinical and laboratory parameters. Data were collected prospectively for the dates of insertion and removal of devices for 188 lines inserted in 69 patients. The majority (90%) of lines had both date of insertion and removal documented allowing the calculation of the rate of primary bacteraemia over 832 at-risk line days. Multiple concurrent lines were more common (88.4%) than single lines, with one central and one or two peripheral lines being the most common (42.3%) combination. Five cases of bacteraemia were diagnosed clinically and confirmed microbiologically. The incidence density of primary bacteraemia was 6.0 per 1000 line days (CI 95% 5.7-6.3).

APACHE↗
PubMedDate not supplied

Orthopaedic implants in children: survey results regarding routine removal by the pediatric and nonpediatric specialists.

The role of orthopaedic implant removal in children is controversial. Some children later require adult reconstruction; implant removal may be difficult or may adversely affect the outcome. The purpose of this study is to compare the opinions of the pediatric and nonpediatric specialists regarding routine implant removal in children. Participants were asked to complete a Web-based questionnaire containing demographics, general opinions, and a series of specific case scenarios related to implant removal/retention. The study group consisted of 273 pediatric, and 99 nonpediatric specialists, with an average of 17-year experience. Regarding asymptomatic, stainless steel implants in children, 41% indicated removal most or all of the time, 36% reported sometimes, and the remaining 22% reported almost never or never. Implant location was the only important factor in the decision to remove or retain the implant. A greater percentage of pediatric specialists endorsed implant retention in the hip or pelvis in older children compared with nonpediatric specialists. More experienced surgeons, regardless of specialty area, recommended implant removal. Pediatric specialists may wish to reconsider their preference to retain large hip implants in older children because their nonpediatric colleagues, who presumably are faced with the removal from these children when they reach adulthood, recommend implant removal once they have served their purpose. The number of such cases and the role of early removal in improving the long-term outcome need further study.

Adult↗
PubMed2002

Factors leading to the removal of the intrauterine implant Gynefix.

OBJECTIVE: The objective of this study was to determine the incidence of expulsion of the Gynefix intrauterine implant, to analyze the variables associated with the above and to examine the efficacy of this intrauterine contraceptive model in users at the Municipal Family Planning Center-SERGAS in A Coruña, Spain. METHODS: A prospective observational study was performed on all women (n = 358) who had a Gynefix implant inserted from March 1998 to September 2000. RESULTS: The accumulated incidence of implant expulsion was 6.7% (95% confidence interval (CI) 4.4-9.9) with a pregnancy rate of 0.6% (95% CI 0.09-2.2). The probability of implant removal decreases with the rise in the number of implants that have been inserted by the professional. A multivariate analysis adjusted for age, number of implants and uterine position showed that the position of the uterus was the variable that independently determined the probability of removal. CONCLUSIONS: It is concluded that retroflexion of the uterus increases the probability of removal.

Adolescent↗
PubMed2005

Left ventricular apical infection and rupture complicating left ventricular assist device explantation in 2 women with postpartum cardiomyopathy.

Postpartum cardiomyopathy is rare form of cardiac failure, with the potential for cardiac function to recover to normal. When medical therapy fails to control symptoms or haemodynamic stability, circulatory support with a ventricular assist device may be considered as a bridge to cardiac transplantation. We describe 2 patients with severe postpartum cardiomyopathy, in whom cardiac function recovered sufficiently during mechanical circulatory assistance to enable device explantation. Bacteremia during device support was treated with chronic suppressive antibiotics, yet after cannula explantation and ventricular repair, residual infection led to destruction of the primary repair, with formation of a left ventricular pseudoaneurysm. This is a complication of device support not previously reported. Surgery was necessary to repair the infected ventricular cannula site. Both patients recovered; however one patient developed recurrent cardiomyopathy 4 months later.

Adult↗
PubMed2004

Bridging to transplant with the HeartMate left ventricular assist device: The Columbia Presbyterian 12-year experience.

OBJECTIVE: Implantation of a left ventricular assist device as a bridge to transplantation has become an acceptable approach for patients with end-stage heart failure. Our long-term results with 3 Thoratec HeartMate devices are presented to outline improvements in successful bridging to transplantation and post-transplant survival. METHODS: From August 1990 through January 2003, 243 patients underwent implantation of Thoratec HeartMate devices as a bridge to transplantation. This included 52 (21.4%) pneumatic devices, 17 (7.0%) dual-lead vented electric devices, and 174 (71.6%) single-lead vented electric devices. RESULTS: Mean age was 49.7 +/- 13.7 years. Mean support time was 78.1 +/- 82.9 days (0-541). Bridging success increased from 63.5% (n = 33) for pneumatic devices to 64.7% (n = 11) for dual-lead vented electric devices and 72.4% (n = 126) for single-lead vented electric devices (P =.005). Posttransplant 1-, 3-, and 5-year actuarial survival increased from 87.5%, 78.1%, and 71.9% in patients with pneumatic devices to 91.5%, 86.9%, and 81.3%, respectively, for patients with single-lead vented electric devices. Device infection and malfunction occurred in 17.7% (n = 43) and 12.8% (n = 31) of patients, respectively. CONCLUSIONS: Successful bridging to transplantation and posttransplant survival has improved over time. Left ventricular assist devices have become increasingly more effective in bridging patients with end-stage heart failure to transplantation. This is likely due to a combination of better patient selection, improvements in clinical practice, and evolution in device design.

Device Removal↗
PubMed2000

Recurrent remodeling after ventricular assistance: is long-term myocardial recovery attainable?

BACKGROUND: Long-term left ventricular assist devices (LVAD) have been used both as a bridge to heart transplantation and to recovery of native myocardial function. Despite much evidence for reversal of some of the structural and functional changes present in the failing heart during LVAD support, clinical evidence for sustained myocardial recovery is scant. We describe 2 patients in whom myocardial recovery during LVAD support led to device explanation only to have heart failure recur. This necessitated a second LVAD implantation, a process that we have termed recurrent remodeling. METHODS: The medical records of 2 patients with cardiomyopathy supported with HeartMate LVADs (Thermo Cardiosystems, Inc, Woburn, MA) were retrospectively reviewed. RESULTS: One patient was supported with an LVAD for 2 months, at which time the LVAD was explanted. Progressive deterioration of cardiac function followed, requiring a second LVAD 19 months after LVAD explanation. After 2 months of further LVAD support, a second episode of apparent myocardial recovery was observed during a period of device malfunction. The other patient was supported with an LVAD for 12 months, at which time the LVAD was explanted. The patient experienced progressive hemodynamic deterioration and required a second LVAD 6 months after LVAD explantation. Heart transplantations of both patients were successful. CONCLUSIONS: Our understanding of myocardial recovery in the setting of hemodynamic unloading with LVAD support has not yet progressed to the point where we are able to accurately predict successful long-term LVAD explantation. The evolution of reliable predictors of sustainable myocardial recovery will help to avoid further cases of recurrent remodeling requiring repeat LVAD implantation.

Adult↗