Scanning ultraviolet two-step laser mass spectroscopy of polycyclic aromatic hydrocarbon distributions on creosote-contaminated soil particles.

The distribution of polycyclic aromatic hydrocarbons (PAHs) on creosote-contaminated soil has been examined with scanning ultraviolet two-step laser desorption/laser ionization mass spectroscopy (UV-L2MS). The instrument has been constructed in-house by modifying a reflectron time-of-flight mass spectrometer. Two-dimensional chemical maps were accurately generated from model patterned PAH distributions. From examination of three-dimensional substrates, the depth of field of the experiment allows surfaces with roughness of up to 120 microm to be treated as a two-dimensional system and still achieve an accurate representation of the surface deposits. Soil was obtained from a former wood treatment facility. Individual particles of 100-1000 microm were mounted on indexed sample plates and examined by reflectance infrared microscopy, optical microscopy, and imaging UV-L2MS. The most intense PAH signals were associated with regions on the particles where clay/organic carbon deposits were found.

Rational materials design of sorbent coatings for explosives: applications with chemical sensors.

A series of chemoselective polymers had been designed and synthesized to enhance the sorption properties of polymer coated chemical sensors for polynitroaromatic analytes. To evaluate the effectiveness of the chemoselective coatings, a polynitroaromatic vapor test bed was utilized to challenge polymer coated surface acoustic wave (SAW) devices with different explosive vapors. Dinitrotoluene detection limits were determined to be in the <100 parts per trillion ranges. ATR-FTIR studies were used to determine the nature of the polymer-polynitroaromatic analyte interactions, and confirm the presence of hydrogen-bonding between polymer pendant groups and the nitro functional groups of polynitroaromatic explosive materials.

Guidelines for quality assurance in multicenter trials: a position paper.

In the wake of reports of falsified data in one of the trials of the National Surgical Adjuvant Project for Breast and Bowel Cancer supported by the National Cancer Institute, clinical trials came under close scrutiny by the public, the press, and Congress. Questions were asked about the quality and integrity of the collected data and the analyses and conclusions of trials. In 1995, the leaders of the Society for Clinical Trials (the Chair of the Policy Committee, Dr. David DeMets, and the President of the Society, Dr. Sylvan Green) asked two members of the Society (Dr. Genell Knatterud and Dr. Frank Rockhold) to act as co-chairs of a newly formed subcommittee to discuss the issues of data integrity and auditing. In consultation with Drs. DeMets and Green, the co-chairs selected other members (Ms. Franca Barton, Dr. C.E. Davis, Dr. Bill Fairweather, Dr. Stephen George, Mr. Tom Honohan, Dr. Richard Mowery, and Dr. Robert O'Neill) to serve on the subcommittee. The subcommittee considered "how clean clinical trial data should be, to what extent auditing procedures are required, and who should conduct audits and how often." During the initial discussions, the subcommittee concluded that data auditing was insufficient to achieve data integrity. Accordingly, the subcommittee prepared this set of guidelines for standards of quality assurance for multicenter clinical trials. We include recommendations for appropriate action if problems are detected.

Methods, statistical features, and baseline results of a standardized, multicentered ophthalmologic surgical trial: the Silicone Study.

This article describes the trial design and baseline results for the Silicone Study, a multicenter, randomized surgical trial designed to compare the effectiveness of silicone fluid versus long-acting gas in the treatment of proliferative vitreoretinopathy (PVR). Design features include (1) standardization of the surgical protocol to reduce intersurgeon variability, (2) formulation of a PVR clinical classification system relevant to modern vitreoretinal surgery, and (3) creation of a photographic protocol to document PVR pathology. Statistical issues affecting the analysis of the outcome data include (1) the addition of a second group of patients with more severely diseased eyes after the trial began, (2) the change to a different long-acting gas during the course of the trial, and (3) recurrent retinal detachments that require reoperations with the randomized treatment, and, in some instances, a crossover from the randomized to the alternate treatment. Demographic and baseline ocular characteristics are presented for the two groups under study.

Operational aspects of terminating randomization in the Multicenter Trial of Cryotherapy for Retinopathy of Prematurity. Cryotherapy for Retinopathy of Prematurity Cooperative Group.

The Multicenter Trial of Cryotherapy for Retinopathy of Prematurity (CRYO-ROP) is a randomized clinical trial sponsored by the National Eye Institute (NEI) designed to test whether cryotherapy applied to eyes of premature infants with a specified extent of stage 3+ ROP significantly decreases the incidence of an unfavorable outcome. An unfavorable outcome is defined as either retinal detachment or a retinal fold and was determined at 3 months posttreatment by the use of a masked photographic system. Enrollment into the trial was terminated on recommendation of the Data and Safety Monitoring Committee 9 months before the scheduled closing date for enrollment because of demonstrated treatment benefit. The purpose of this article is to discuss the operations involved in the orderly termination of enrollment and dissemination of results from this trial. These activities included preparation of trial participants and staff, release of trial information, continuing patient care, data collection and coding, and publication of trial results.

Screening and surgical intervention results from cataract-free-zone projects in Campinas, Brazil and Chimbote, Peru.

Two cataract-free-zone projects, one in Brazil and the other in Peru, were designed to provide surgery to all those who need and want it within a defined geographic area. In-home visual acuity screening was accepted by three-fourths of the enumerated population aged 50 years or more. Those with reduced bilateral visual acuity were referred to a community health post for ophthalmic examination. Among those diagnosed as bilaterally blind (less than or equal to 20/200), comprising 5% of the screened population, two-thirds were thought to be blind from cataract. Because of other ocular pathology and general health conditions, surgery was not indicated for 30-50%. Two-thirds of those recommended for out-patient surgery accepted. Motivational efforts to convince the refusers were uniformly unsuccessful. The average age of those accepting and those refusing surgery was in the mid-seventies. Those already aphakic were 7-8 years younger. Post-operative acuity was greater than or equal to 20/50 for only one-half of those operated. A significant number of cases had previously undetected macular degeneration and other causes of decreased vision. These projects have given increased attention to cataract blindness and the need for further operational research to develop effective methods for its control using outpatient surgery.

Krypton laser for proliferative diabetic retinopathy: the Krypton Argon Regression of Neovascularization Study.

The Krypton Argon Regression of Neovascularization Study (KARNS) is a multicenter, randomized, controlled clinical trial designed to determine the efficacy of red krypton laser photocoagulation in the treatment of proliferative diabetic retinopathy.

Lessons from the Visual Acuity Impairment Survey pilot study.

The Visual Acuity Impairment Survey (VAIS) pilot study was carried out in three large metropolitan areas of the United States to determine whether it would be feasible to conduct a large two-stage survey of the prevalence of visual acuity impairment and its causes. The study was conducted in conjunction with the Health Interview Survey (HIS), performed by the National Center for Health Statistics and the Census Bureau. In the first stage, a simple vision screening test was administered to 1,868 adults in their homes by specially trained Census Bureau interviewers. All those who failed the test, and a sample of those who passed it, were invited to a local clinic for a check on the accuracy of the screen and a detailed eye examination to establish the cause of the impairment. About 89 per cent of the HIS interviewees took the vision screening test in the home and agreed to have the results released, making it possible for the clinic to invite them for an examination. The principal obstacle to the success of the feasibility study was a low rate (less than 50 per cent) of participation in the clinic examination by the target population. Such low participation would leave the survey open to a serious question about its representativeness. The methods and findings of the pilot study are presented because the lessons may be of value to those attempting similar studies in the future. Suggestions are made for methodological modifications that may enhance the chances for success.

Plasma high-density lipoprotein cholesterol and socioeconomic status. The Lipid Research Clinics Program Prevalence Study.

The relationship between high-density lipoprotein (HDL) cholesterol and educational level was examined in 2182 white females and 2368 white males ages 20-59 years in nine North American populations surveyed by the Lipid Research Clinics Program. Mean HDL cholesterol values were positively associated with reported educational achievement. Among females of all ages and males ages 20-39 years, a gradient of HDL cholesterol levels from lowest to highest educational stratum was found. A similar trend of lower magnitude was noted among older males. The positive association between educational and HDL cholesterol levels was statistically significant in both sexes (p < 0.002) and was consistent for each of the study populations. Differences in mean HDL cholesterol between educational strata were in part explained statistically by education-related differences in body mass, alcohol consumption, cigarette smoking, age and, in women, gonadal hormone use. These findings indicate that socioeconomic status and lifestyle, as measured by level of educational achievement, are associated with HDL cholesterol concentrations in adult populations.

Common methods, different populations. The Lipid Research Clinics Program Prevalence Study.

The salient characteristics of the Lipid Research Clinics (LRC) Program Prevalence Study are presented, including an overview of its structure, the populations included and the common procedures used. Highlighted are the two sequential screening examinations that included 68,317 participants in 12 LRCs in the U.S. Canada and the U.S.S.R. for the first examination and 15,816 for the second. Several thousand more will be added as the thirteenth LRC completes its screening in Israel. Major data items are described briefly, as are data quality enhancement procedures. Procedures for plasma lipid determination, lipoprotein cholesterol, other clinical chemistries, nutritional intake assessment, and resting and stress electrocardiography are discussed. A discussion of the methodologic strengths and weaknesses of the findings of the LRC Program Prevalence Study is also included. This paper provides a frame of reference for the individual papers in this volume.

Plasma high-density lipoprotein cholesterol, total cholesterol and triglyceride levels in 17-year-old Jewish residents of Jerusalem: a preliminary report. The Lipid Research Clinics Program Prevalence Study.

Preliminary data on plasma high-density lipoprotein (HDL) cholesterol, total cholesterol and triglyceride levels in 2565 teenage Jerusalem residents attending a military medical examination were analyzed. Mean HDL cholesterol levels were highest among male and female subjects whose fathers had immigrated from Europe and the Americas and lowest in those of Asian and of North African origin. Second-generation Israelis ranked intermediate between the Europeans and the other two groups. Total cholesterol levels were lowest in teenagers of both sexes whose fathers had come from North Africa, highest in subjects of European and of Israeli origin and intermediate in the Asians. Triglyceride levels were also lowest among North Africans of both sexes, but the Asian and Israeli groups had higher mean values than the Europeans. These findings show that patterns of lipid and lipoprotein levels previously observed in adult immigrants persist in a generation of native-born Israelis.

Plasma cholesterol and triglyceride distributions in 13,665 children and adolescents: the Prevalence Study of the Lipid Research Clinics Program.

The age-, race-, sex-specific distributions for plasma cholesterol (CH) and triglyceride (TG) are described for the 13,655 individuals under 20 years of age who were examined at the first visit (visit I) of the Prevalence Study of the Lipid Research Clinics (LRC) Program. Composite findings are presented from the seven North American LRC's where children were included in the target population. Cholesterol values are higher for blacks than for whites, but triglyceride values are higher for whites than for blacks. In both the CH and TG distributions for the combined races, the mean values for females are generally higher than for males. For cholesterol, consistent age-associated differences occur. On average, the CH values peak in late childhood and decline during adolescence. The decrease in mean values for CH is most marked for white males. The values for TG tend to increase in early adolescence. This report expands the available information about lipid distributions in young populations and describes the extent of the variation in plasma lipids associated with race and sex for each year of age, 0 to 19 years.

Aspects of clinic monitoring in large-scale multiclinic trials.

Monitoring the implementation of large-scale and the adherence of clinical centers to a common protocol should be an integral part of the study design and a primary responsibility of the coordinating center for the study. There are four basic concepts in external clinic monitoring: (1) the maintenance of open lines of communication between all study facilities, (2) "responsibility and accountability" for study implementation and for the integrity of the data, (3) evaluation of clinic operations, and (4) analysis of data quality. A monitoring scheme consisting of regular telephone calls to the screening centers. periodic visits to the screening centers, and continuing review of the data collected can be effectively used by the coordinating center.