Differing field methods and site conditions lead to varying bias in suspended sediment concentrations in the Lower Mississippi and Atchafalaya Rivers.

At sites that have been sampled for decades, changes in field and laboratory methods happen over time as instrumentation and protocols improve. Here, we compare the influence of depth- and point-integrated sampling on total, fine (< 0.0625 mm), and coarse (≥ 0.0625 mm) suspended sediment (SS) concentrations in the Lower Mississippi and Atchafalaya Rivers. Using historical field method information, we identified seven sites to test such differences. We found SS samples collected using point-integration tended to have higher concentrations than those collected using depth-integration. However, the presence and magnitude of the bias were inconsistent across sites. Bias was present at the site with less-than-ideal conditions (i.e., non-trapezoidal channel, non-uniform flow) and non-existent at the ideal site location, indicating the bias between sampling methods depends on site sampling conditions. When present, the bias is greater at higher concentrations and at moderate to high flows. At the less-than-ideal site, point-integrated samples can have 16% (total) and 34% (coarse) higher concentrations than depth-integrated samples. When flow effects are removed, this translates to a bias of 19, 9, and 8 mg per liter for total, fine, and coarse SS. When a change in field methods occurs, comparison samples and a rigorous evaluation of those samples are warranted to determine the proper course of action for a particular site. Often, the effect and solution will not be known until several years of comparison samples have been collected under a variety of hydrologic conditions.

Meta-analysis of the effectiveness of HIV prevention interventions for women.

The present study is a meta-analysis of the effectiveness of HIV prevention interventions for women in the USA. Twenty-four articles from 1989-1997 were included. We evaluated five ethnic groupings (All Ethnicities Combined, African-American, White, Hispanic and a Mixed Ethnicity group) over four time periods (post-test, less than two months after the intervention, 2-3 months after the intervention and 6-24 months after the intervention) on three HIV-related sexuality outcome variables (HIV/AIDS knowledge, self-efficacy and sexual risk reduction behaviour). The HIV interventions appear effective at improving knowledge about HIV/AIDS and increasing sexual risk reduction behaviours for all ethnicities examined at all follow-up periods, with one exception. The findings for self-efficacy are less consistent. The interventions were less consistently effective for African-American women, for whom significant improvements in feelings of self-efficacy were only seen six months or longer after the intervention. The present analysis elucidates ethnic differences which may have previously been obscured while demonstrating convincingly that HIV interventions are generally effective for women of many different ethnicities.

Effect of sterilization on cyclic fatigue of rotary nickel-titanium endodontic instruments.

The ability of heat treatment as a result of autoclave sterilization to extend the life of nickel-titanium rotary endodontic instruments by reducing the effect of cyclic fatigue was evaluated using 280 size 40 Lightspeed instruments. Instruments were cycled in artificial canals with angles of curvature of 30 degrees and either 2 or 5 mm radii of curvature. In a pilot study, instruments were sterilized or not sterilized and cycled to failure to obtain mean cycles-to-failure values for each group. In the first experimental protocol, instruments were cycled to either 25%, 50%, or 75% of the mean cycles-to-failure limit determined in the pilot study, then sterilized or not sterilized before being cycled to failure. In the second experimental protocol, instruments were cycled to 25% of the mean cycles-to-failure determined in the pilot study, and sterilized or not sterilized. The sequence of cycling to 25% of the predetermined cycles-to-failure limit followed by sterilization was repeated until the instruments failed. No significant increases in cycles to failure were observed between groups for either experimental protocol when instruments were evaluated at a similar radius. Significant differences in cycles to failure were only observed when instruments cycled to failure in the artificial canal with 2 mm radius were compared with instruments cycled to failure in the artificial canal of 5 mm radius. Scanning electron microscopic photos showed crack initiation and propagation in all instruments that were cycled to a percentage of the predetermined cycles-to-failure limit. It is concluded that heat treatment as a result of autoclave sterilization does not extend the useful life of nickel-titanium instruments.

Clinical evaluation of a new in-line continuous blood gas monitor.

Two methodologies for obtaining accurate blood gas and electrolyte values during cardiopulmonary bypass (CPB) are traditional laboratory analyzers, which use an electrochemical technology, and continuous in-line monitoring systems, which use a fluorometric and/or spectrophotometric technology. The purpose of the present study was to evaluate the accuracy of a new continuous in-line monitor, the 3M CDI Blood Parameter Monitoring System 500, which provides continuous in-line measurements of pH, PCO2, PO2, potassium (K+), oxygen saturation, hematocrit, hemoglobin, and temperature, during partial or complete CPB. Study parameters included arterial pH, PCO2, PO2, and K+ values. Overall performance was analyzed by calculating the mean difference (expressed as the bias) between the CDI system 500 and the laboratory analyzer for each parameter. The accuracy of the arterial pH, PCO2, and K+ values provided by the CDI system 500 was then evaluated using target values established in the acceptable performance standards for laboratory analyzers from the Clinical Laboratory Improvement Act of 1988 (CLIA '88). The accuracy of the PO2 value provided by the CDI system 500 was evaluated using a target value of +/- 10% of the reference, or laboratory analyzer, value. A prospective multi-center trial was conducted following Institutional Review Board approval. A total of 75 cases was included in the analyses, with over 200 data points from 4 clinical locations. Results for pH, PCO2, and K+ were within the target values established by CLIA '88. pH bias was 0.00 +/- 0.02 pH units. PCO2 bias was -0.3 +/- 3.3 mm Hg. K+ bias was approximately +0.12 +/- 0.31 mmole/l. Results for PO2 were within 10% of the reference value. PO2 bias was 7.5 +/- 13.8 mm Hg. The results of this clinical trial show that the CDI System 500 continuous in-line monitoring system provides values that meet the accuracy standards for laboratory analyzers for arterial pH, PCO2, PO2, and K+.

The challenge of follow-up for clinical trials of somatic gene therapy.

Although extensive efforts have been made to optimize the safety of vectors for somatic gene transfer and somatic gene therapy, the safety of these agents must ultimately be assessed in clinical trials. A statistically significant assessment of safety will be complicated by the relatively small number of patients who will be enrolled in initial clinical trials, the need for long-term longitudinal follow-up of patients and perhaps their progeny, and the traditionally poor participation in long-term follow-up by many patients. This article reviews the potential risks of retroviral-mediated gene transfer, the statistical power required to assess the true incidence of potential complications, the number of patients who may participate in clinical trials involving retroviral vectors, and the factors that make thorough follow-up and uniform data ascertainment difficult. The role of the FDA in assessing the safety of retroviral vectors and the potential role of registries for patient tracking and data ascertainment are discussed.

Aid to the evaluation of therapeutic studies.

Physicians are often faced with conflicting recommendations from therapeutic studies. An evaluation form is proposed to facilitate the evaluation of the quality of therapeutic studies and the resulting treatment or management recommendations in any area of medicine. Twelve major topics for evaluation include sample size determination, randomization, selection of control group(s), "blinding," and support for treatment recommendations. Emphasis is placed on study design and performance rather than data analysis. Thirty-four primary criteria based on accepted research standards are designated as most important, and examples from the literature are provided to illustrate their use. The form provides a comprehensive set of well-accepted standards of research in a format that encourages detailed, consistent, and thoughtful evaluation of therapeutic studies. The evaluation form is recommended as a tool for physicians who wish to develop and exercise skill in evaluating therapeutic studies.

ReCAP: the Registry of Cytogenetic Abnormalities and Phenylketonuria.

The Registry of Cytogenetic Abnormalities and Phenylketonuria (ReCAP) is a multicenter collaborative registry of information on patients with constitutional cytogenetic abnormalities or hyperphenylalaninemia (HPA). Data are entered by microcomputer at four contributing centers. Records are then electronically transmitted to the coordinating center, where the composite cytogenetic and hyperphenylalaninemia databases are maintained on a mainframe computer. A set of programs, known as the ReCAP ISCN Translator, is used to create additional database records describing in detail the chromosome abnormalities present in each patient. The ReCAP computer system permits rapid and flexible retrieval of cases on the basis of any combination of laboratory, clinical, psychometric, or genetic characteristics contained within the databases. Special procedures protect patient confidentiality and assure that ReCAP data are of consistently high quality. Qualified investigators may use ReCAP as a resource for a variety of scientific studies.

Moxalactam therapy for neonatal meningitis due to gram-negative enteric bacilli. A prospective controlled evaluation.

Moxalactam and ampicillin sodium therapy were compared with amikacin sulfate and ampicillin therapy for meningitis due to gram-negative enteric bacilli in 63 infants enrolled in the Third Neonatal Meningitis Cooperative Study. The population characteristics and causative organisms were comparable for the two treatment groups. Cultures of CSF were positive for approximately three days in both study groups. Case-fatality rates were 23% and 15% for moxalactam-treated infants and ampicillin- and amikacin-treated infants, respectively. Developmental or neurological abnormalities were found in about 40% of survivors, and the rates were comparable for both treatment groups. Computed tomograms in 44 infants were interpreted as normal in 13 (30%); hydrocephalus, abscesses, and low-density areas were the most frequent abnormalities. We conclude that moxalactam is a suitable alternative for treatment of meningitis due to gram-negative enteric bacilli.

Intraventricular gentamicin therapy in gram-negative bacillary meningitis of infancy. Report of the Second Neonatal Meningitis Cooperative Study Group.

In a multicentre controlled trial in the U.S.A. and Latin America 52 infants with meningitis and ventriculitis were randomly assigned to receive either systemic ampicillin and gentamicin or intraventricular gentamicin plus systemic antimicrobial agents. The aetiological agents most often encountered were Escherichia coli in the U.S. infants and Salmonella spp. in Latin American infants. Infants receiving systemic antibiotics plus intraventricular gentamicin had a significantly higher mortality rate (42.9%) than those who received systemic therapy only (12.5%). Duration of positive CSF cultures and morbidity rates were not significantly different in the two treatment groups. The concentrations of gentamicin in ventricular and lumbar CSF 1--6 h after an intraventricular dose of 2.5 mg gentamicin were 10--130 microgram/ml and 8--85 microgram/ml, respectively. The study was terminated early because of the higher mortality rate in the intraventricular-therapy group. Intraventricular gentamicin should not be used as routine treatment for neonatal meningitis caused by gram-negative enteric bacilli.

Government regulations and other influences on the medical use of computers.

This paper presents points brought out in a panel discussion held at the 12th Hawaiian International Conference on System Sciences, January 1979. The session was attended by approximately two dozen interested parties from various segments of the academic, government, and health care communities. The broad categories covered include the specific problems of government regulations and their impact on specific clinical information systems installed at The University of Texas Health Science Center at Dallas, opportunities in a regulated environment, problems in a regulated environment, vendor-related issues in the marketing and manufacture of computer-based information systems, rational approaches to government control, and specific issues related to medical computer science.

Impact of government regulations on two management and clinical information systems in a medical school environment.

Administrative and legal requirements and, in particular, federal and state government health care assistance and social services program regulations all combine to add complexity to the management and operation of ambulatory and inpatient health programs. This paper describes how constantly changing government regulations and differences in interpretations and definitiions have been expensive, time-consuming and sometimes detrimental to health care delivery for two large management and clinical computer-based information systems.

An automated clinic management system for a family planning network.

The medical information, financial, and logistic aspects of a comprehensive computer-based Appointment, Registration, Information System, and Evaluation (ARISE) are analyzed for the management of a family planning program serving 30,000 patients annually. An overview of the existing computer system network is presented with descriptions of the interactive master patient index, the batch appointment process, the management statistics package, and Department of Health, Education, and Welfare (HEW) reporting. Emphasis is placed on the financial management control system which includes 1) procedures for third-party submission of claims for payment, in particular Titles IVA, XX, and XIX (Social Security Act), together with discussion of related administrative requirements; 2) technics of auditing data integrity including systematic sampling of collected data; and 3) the process of billing and receipts collection. Methodology and implementation aspects of ARISE may have wide applicability to other family planning and similarly structured clinical programs.

Rentran. An on-line computer-based regional kidney transplant matching system.

An interactive on-line computerized renal transplant matching system called RENTRAN which serves the Southwest Kidney Transplant Region is described. The region consists of one transplant center in Arkansas, two in Oklahoma, and six in Texas. The computer used is the DECsystem-10 located in the Medical Computing Resources Center at Dallas. RENTRAN participants have remotely located standard interactive computer terminals and gain access to the computer by dialing over normal telephone lines. Functions provided by RENTRAN include obtaining instructions, performing a donor-recipient match, obtaining a list of potential recipients, making a user comment or adding, updating or deleting a potential recipient record. Either long or short formats for dialog with the computer system are available for inexperienced and experienced and users, respectively. In the time period from August 1,1973, when the system went into production on February 1, 1976, there have been in excess of 232 matches attempted and approximately 142 kidneys have been transplanted according to RENTRAN results. There are about 361 recipients currently on the data base. The system was developed with funds provided by the Texas Regional Medical Program. Expenses of maintaining the system as well as occasional programmed improvements as deemed appropriate by the Southwest Kidney Transplant Region Registry Committee on the basis of user comments are provided through a $25 per year charge to patients for being listed on the data base.

A controlled study of intrathecal antibiotic therapy in gram-negative enteric meningitis of infancy. Report of the neonatal meningitis cooperative study group.

Eighteen institutions collaborated in evaluating the comparative efficacy of combined ampicillin and gentamicin therapy with and without intrathecal administration of gentamicin on the clinical and bacteriologic responses of 117 infants with meningitis caused by gram-negative enteric bacteria. There was a random distribution of patients within the two study groups with regard to age on enrollment, birth weight, sex, race, number of infants greater than 30 days of age, the etiologic agent, and their antimicrobial susceptibilities. There were no statistically significant differences (P greater than 0.05) in mortality, morbidity, or days that cerebrospinal fluid cultures remained positive among the infants in the two treatment groups. The case fatality rate for all patients was 32%; that for full-term infants (18%) was significantly lower (P less than 0.01) than that for low-birth-weight infants (45%) or for the patients greater than 30 days of age (48%). Fifty-one of the 80 (64%) survivors were assessed as normal on follow-up examinations performed up to four years after illness.