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.

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.

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.

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.

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.