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At least 523 records · Page 29Linked to original sources
PubMed2006

Kinetics of in vitro lysozyme deposition on silicone hydrogel, PMMA, and FDA groups I, II, and IV contact lens materials.

We sought to compare the kinetics of in vitro lysozyme deposition on silicone hydrogel (SH), polymethyl methacrylate (PMMA), and FDA groups I, II, and IV contact lenses. Lenses were incubated in 125I-labeled lysozyme for time periods ranging from 1 hr to 28 days, and radioactive counts were determined. SH lenses and PMMA deposited less lysozyme than conventional hydrogel lenses (p < 0.05). Lysozyme accumulation on group IV lenses reached a maximum on the seventh day and then plateaued, whereas on groups I, II, and SH lenses, deposition continued to increase across all time periods, reiterating that kinetics of lysozyme deposition is highly material dependent.

Biocompatible Materials↗
PubMed2001

Migraine and tension-type headache reduction through pericranial muscular suppression: a preliminary report.

Migraine and tension-type headaches have always plagued mankind. In spite of all the research dollars spent trying to determine the etiologies of these headaches, the neurology community still has not established a known cause of migraine and tension type headaches. This paper describes a study that was conducted for the U.S. Food and Drug Administration in which the efficacy of the Nociceptive Trigeminal Inhibition Tension Suppression System was evaluated and proved safe and efficacious in the reduction of medically diagnosed migraine and tension-type headache.

Analgesics↗
PubMed2007

Statistical and regulatory issues with the application of propensity score analysis to nonrandomized medical device clinical studies.

Propensity score analysis is a versatile statistical method used mainly in observational studies for improving treatment comparison by adjusting for up to a relatively large number of potentially confounding covariates. Recently, there has been an increased interest in applying this method to nonrandomized medical device clinical studies. In the application of the methodology, some statistical and regulatory issues arise in both study design and analysis of study results, such as the need for pre-specifying clinically relevant covariates to be measured, appropriate patient populations, and the essential elements of statistical analysis, planning sample size in the context of propensity score methodology, handling missing covariates in generating propensity scores, and assessing the success of the propensity score method by evaluating treatment group overlap in terms of the distributions of propensity scores. In this paper, the advantages and limitations of this methodology will be revisited, and the above issues will be discussed and illustrated with examples from a regulatory perspective.

Algorithms↗
PubMed2001

Why and how to avoid stenting during brachytherapy.

Intracoronary radiation is a promising therapy to reduce restenosis after percutaneous coronary intervention. It may be anticipated that radiation and intracoronary stents - the current standard coronary revascularization procedure - have a synergic antirestenosis effect. However, this potential benefit has not been proven in the clinical scenario. Indeed, this combined approach (stenting plus brachytherapy) may even be harmful. Delayed endothelialization and late stent malapposition are important drawbacks of implanting a metallic prosthesis in the setting of radiation therapy. Owing to the relatively high frequency of late thrombosis after stenting irradiated coronary arteries, the Food and Drug Administration required that the labeling of both gamma- and beta-radiation devices recently approved for clinical use explicitly advise avoidance of the placement of new stents. The pathophysiologic aspects as well as the clinical implications of the implantation of a new stent in association with radiation delivered by radioactive stents or catheter-based systems are discussed in this paper.

Journal Article↗
PubMed2001

Validation and regulation of medical neural networks.

Using artificial neural networks (ANNs) in medical applications can be challenging because of the often-experimental nature of ANN construction and the "black box" label that is frequently attached to them. In the US, medical neural networks are regulated by the Food and Drug Administration. This article briefly discusses the documented FDA policy on neural networks and the various levels of formal acceptance that neural network development groups might pursue. To assist medical neural network developers in creating robust and verifiable software, this paper provides a development process model targeted specifically to ANNs for critical applications.

Device Approval↗
PubMed2004

Home telehealth reduces healthcare costs.

The aim of this study was to determine whether home telehealth, when integrated with the health facility's electronic medical record system, reduces healthcare costs and improves quality-of-life outcomes relative to usual home healthcare services for elderly high resource users with complex co-morbidities. Study patients were identified through the medical center's database. Intervention patients received home telehealth units that used standard phone lines to communicate with the hospital. FDA-approved peripheral devices monitored vital signs and valid questionnaires were used to evaluate quality-of-life outcomes. Out-of-range data triggered electronic alerts to nurse case managers. (No live video or audio was incorporated in either direction.) Templated progress notes facilitated seamless data entry into the patient's electronic medical record. Participants (n = 104) with complex heart failure, chronic lung disease, and/or diabetes mellitus were randomly assigned to an intervention or control group for 6-12 months. Parametric and nonparametric analyses were performed to compare outcomes for (1) subjective and objective quality-of-life measures, (2) health resource use, and (3) costs. In contrast to the control group, scores for home telehealth subjects showed a statistically significant decrease at 6 months for bed-days-of-care (p < 0.0001), urgent clinic/emergency room visits (p = 0.023), and A1C levels (p < 0.0001); at 12 months for cognitive status (p < 0.028); and at 3 months for patient satisfaction (p < 0.001). Functional levels and patient-rated health status did not show a significant difference for either group. Integrating home telehealth with the healthcare institution's electronic database significantly reduces resource use and improves cognitive status, treatment compliance, and stability of chronic disease for homebound elderly with common complex co-morbidities.

Aged↗
PubMed2001

High failure rate after laparoscopic adjustable silicone gastric banding for treatment of morbid obesity.

OBJECTIVE: To report the results from one of the eight original U.S. centers performing laparoscopic adjustable silicone gastric banding (LASGB), a new minimally invasive surgical technique for treatment of morbid obesity. SUMMARY BACKGROUND DATA: Laparoscopic adjustable silicone gastric banding is under evaluation by the Food & Drug Administration in the United States in an initial cohort of 300 patients. METHODS: Of 37 patients undergoing laparoscopic placement of the LASGB device, successful placement occurred in 36 from March 1996 to May 1998. Patients have been followed up for up to 4 years. RESULTS: Five patients (14%) have been lost to follow-up for more than 2 years but at last available follow-up (3-18 months after surgery) had achieved only 18% (range 5-38%) excess weight loss. African American patients had poor weight loss after LASGB compared with whites. The LASGB devices were removed in 15 (41%) patients 10 days to 42 months after surgery. Four patients underwent simple removal; 11 were converted to gastric bypass. The most common reason for removal was inadequate weight loss in the presence of a functioning band. The primary reasons for removal in others were infection, leakage from the inflatable silicone ring causing inadequate weight loss, or band slippage. The patients with band slippage had concomitant poor weight loss. Bands were removed in two others as a result of symptoms related to esophageal dilatation. In 18 of 25 patients (71%) who underwent preoperative and long-term postoperative contrast evaluation, a significantly increased esophageal diameter developed; of these, 13 (72%) had prominent dysphagia, vomiting, or reflux symptoms. Of the remaining 21 patients with bands, 8 currently desire removal and conversion to gastric bypass for inadequate weight loss. Six of the remaining patients have persistent morbid obesity at least 2 years after surgery but refuse to undergo further surgery or claim to be satisfied with the results. Overall, only four patients achieved a body-mass index of less than 35 and/or at least a 50% reduction in excess weight. Thus, the overall need for band removal and conversion to GBP in this series will ultimately exceed 50%. CONCLUSIONS: The authors did not find LASGB to be an effective procedure for the surgical treatment of morbid obesity. Complications after LASGB include esophageal dilatation, band leakage, infection, erosion, and slippage. Inadequate weight loss is common, particularly in African American patients. More study is required to determine the long-term efficacy of the LASGB

Adult↗
PubMedDate not supplied

Transcranial magnetic stimulation: a possible treatment for TBI.

The purpose of this article is to outline the principles of transcranial magnetic stimulation (TMS), to summarize the existing use of TMS as a prognostic indicator and as a therapeutic device in clinical populations, and to highlight the potential of repetitive TMS (rTMS) as an intervention for traumatic brain injury. TMS is a painless method to stimulate the human brain. Repeated applications of TMS can influence brain plasticity and cortical reorganization through stimulation-induced alterations in neuronal excitability. Existing evidence has demonstrated positive outcomes in people with motor disorders and psychiatric conditions who have received rTMS as a therapeutic intervention. These findings suggest that rTMS may be a promising treatment for people with traumatic brain injury.

Brain↗
PubMed2006

Data withholding and the next generation of scientists: results of a national survey.

PURPOSE: To provide the first national data on the nature, extent, and consequences of withholding among life science trainees. METHOD: In 2003, the authors surveyed 1,077 second-year doctoral students and postdoctoral fellows in life sciences at 50 U.S. universities, with a comparison group of trainees in computer science and chemical engineering. The study variables examined trainees' exposure to and the consequences of data withholding. RESULTS: Two hundred forty-six trainees (23.0%) reported that they had asked for and been denied access to information, data, materials, or programming associated with published research and 221 (20.6%) to unpublished research. Eighty-five trainees (7.9%) reported that they had denied another academic scientist's request(s) related to their own published research. Five hundred thirty-three trainees (50.8%) reported that withholding had had a negative effect on the progress of their research, 508 (48.5%) on the rate of discovery in their lab/research group, 472 (45.0%) on the quality of their relationships with academic scientists, 346 (33.0%) on the quality of their education, and 299 (28.5%) on the level of communication in their lab/research group. Trainees denied access to research were significantly more likely to report that data withholding had had a negative effect on several aspects of the educational experience. CONCLUSIONS: Data withholding had demonstrated negative effects on trainees. The life sciences, more so than chemical engineering or computer science, will have to address this issue among its trainees. Failure to do so could result in delayed research, inefficient training, and a culture of withholding among future life scientists.

Access to Information↗
PubMedDate not supplied

Push-pull sorbent based pheresis for treatment of acute hepatic failure: the BioLogic-detoxifier/plasma filter System.

The BioLogic-DT (detoxifier) System is an extracorporeal blood treatment device that uses the membranes of a cellulosic plate dialyzer to propel blood in and out through a single lumen access (on a 12 sec cycle) and circulates a suspension of powdered charcoal and cation exchanger through the dialysate spaces to absorb many soluble toxins in the treatment of hepatic failure. The BioLogic-DTPF (detoxifier/plasma filter) System adds two Gambro plasma filters downstream from the plate dialyzer, which allows most of the blood plasma to pass out of the blood, contact powdered charcoal in a suspension, and then return to the blood during each 12 sec cycle (creating push-pull sorbent based pheresis). A roller pump exchanges charcoal suspension between the plasma filter case and a 700 ml bag of powdered charcoal suspension. At a blood flow rate of 150-200 ml/min, 100 ml/min of plasma moves bidirectionally through the plasma filter membranes. Direct contact of plasma with charcoal outside the plasma filter membranes removes creatinine with a clearance rate equal to plasma flow (100 ml/min); clearance of strongly protein bound toxins, such as unconjugated bilirubin, is lower (10-40 ml/min). In this article, the authors explain the mechanisms of operation of this system and present in vitro tests that define its chemical efficiency. Also described are potential problems, tests that indicate the severity of these problems, and monitors and algorithms to detect or avoid these problems in clinical use of the system. The results of the treatment of two patients with acute hepatic failure and coma using the BioLogic-DTPF System are reviewed.

Aged↗
PubMed2000

Microkeratomes.

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Device Approval↗