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Biomedical subjects

J A Meyer

Publications and source records attributed to J A Meyer.

At least 19 recordsLinked to original sources
PubMed2001

A federal tax credit to encourage employers to offer health coverage.

Many firms that employ low-wage workers cannot afford to offer an employee health plan, and many of the uninsured work for such firms. This article makes the case for an employer tax credit, administered by the Internal Revenue Service, as a way to extend health coverage to uninsured workers and their families. The permanent, fixed-dollar, refundable credit would be available to all low-wage employers (those with average wages of $10 per hour and less), including those already offering coverage. The credit would be graduated depending on average wage: the maximum credit would equal 50% of the cost of a standard benefit package; the minimum would equal 30% of the package. It also would vary by family size and could be used to cover part-time and temporary workers. Participating employers would be required to pay at least 50% of the health insurance premium, proof of which would be shown on firms' tax returns. The paper provides justification for this approach. It closes with a discussion of strengths and weaknesses of this approach and alternative design features.

Adult↗
PubMed2000

Animat navigation using a cognitive graph.

This article describes a computational model of the hippocampus that makes it possible for a simulated rat to navigate in a continuous environment containing obstacles. This model views the hippocampus as a "cognitive graph", that is, a hetero-associative network that learns temporal sequences of visited places and stores a topological representation of the environment. Calling upon place cells, head direction cells, and "goal cells", it suggests a biologically plausible way of exploiting such a spatial representation for navigation that does not require complicated graph-search algorithms. Moreover, it permits "latent learning" during exploration, that is, the building of a spatial representation without the need of any reinforcement. When the rat occasionally discovers some rewarding place it may wish to rejoin subsequently, it simply records within its cognitive graph, through a series of goal and sub-goal cells, the direction in which to move from any given start place. Accordingly, the model implements a simple "place-recognition-triggered response" navigation strategy. Two implementations of place cell management are studied in parallel. The first one associates place cells with place fields that are given a priori and that are uniformly distributed in the environment. The second one dynamically recruits place cells as exploration proceeds and adjusts the density of such cells to the local complexity of the environment. Both implementations lead to identical results. The article ends with a few predictions about results to be expected in experiments involving simultaneous recordings of multiple cells in the rat hippocampus.

Animals↗
PubMed2000

HLA-B*4012: a new allele with unique serological features.

We have defined the new allele HLA-B*4012, which had been isolated from a black individual. It was initially recognized as a serologically unique allele when typing her father for renal transplantation. The HLA class I phenotype was A*0201,*6602; B*4001,*4012; Bw6; Cw*0304,*1505. Sequencing from exon 1 through intron 3 of B*4012 was performed. B*4012 is identical to B*4001 and B*4010 in exon 3, and in the 3' part of exon 2, but it is unique in that exon 1 and the 5' part of exon 2 are identical to B*1503, B*1509, B*1510, B*1518, B*1523, and B*1529. The generation of this allele is best explained by a recombination event in exon 2 (break point between nucleotides 205 and 222 from the beginning of the coding region) of B*4001 or B*4010 with one of these B*15 variants as a donor allele. Its unique serological feature (B48, B60, B70, and B72 reactivity) is consistent with the sequence data of its donor alleles.

Alleles↗
PubMed2000

Presence-absence sequential sampling plan for northern fowl mite, Ornithonyssus sylviarum (Acari: Macronyssidae), on caged-layer hens.

Caged-layer hens were scored as infested or uninfested by visual examination of the vent region, and the number of northern fowl mite, Ornithonyssus sylviarum (Canestrini & Fanzago), per hen was estimated. The proportion infested and average number of mites per hen were shown to have a highly significant, positive relationship (r = 0.936). Sampling among houses within a flock, and rows and sections within houses were analyzed to determine the reliability of sampling a representative portion of a flock. Low- and moderate-tolerance treatment thresholds, based on percentage of hens infested with mites, were developed from sampling 1 wk before and 1 wk after acaricide treatments determined necessary by the producer. These thresholds were used to compare a fixed (single) sampling plan, a curtailed procedure of the fixed sampling plan, and a sequential sampling plan based on a sequential probability ratio test, by sampling 174 hens (the maximum number needed for the single sampling plan). The sequential sampling plan required fewer hen examinations on average to reach a treatment decision than did the other plans, depending on the infestation tolerance limits. Using a low tolerance approach in which infestations below 15% are considered noneconomic (safe threshold) and infestations above 25% are considered economically important (action threshold), as few as 5 hens required examination to reach a treatment decision. Sequential sampling plan graphs are presented for 2 tolerance threshold scenarios (a 15% safe-threshold paired with a 25% action threshold and a 35% safe-threshold paired with a 45% action threshold). These sequential sampling plans using presence absence assessments should greatly facilitate monitoring and treatment decisions for this important pest.

Animals↗
PubMed1998

Biocatalytic sulfur removal from fuels: applicability for producing low sulfur gasoline.

Environmental regulations are driving R&D efforts to produce low sulfur fuels, including diesel fuel and gasoline for motor vehicles. Biocatalytic sulfur removal from fuels has potential applicability for producing low sulfur gasoline. Microbial biocatalysts have been identified that can biotransform sulfur compounds found in fuels, including ones that selectively remove sulfur from dibenzothiophene heterocyclic compounds. Most attention is give to the 4S pathway of Rhodococcus, which can remove sulfur from substituted and unsubstituted dibenzothiophenes, including sulfur compounds that hinder chemical catalysis and that resist removal by mild hydrotreatment. Various bioreactor and bioprocess designs are being tested for use with biocatalysts, including recombinant biocatalysts, for use in removing sulfur from fuels and feedstocks within the petroleum refinery stream. With bioprocess improvements that enhance biocatalyst stability, achieve faster kinetics, improve mass transfer limitations, temperature and solvent tolerance, as well as broaden substrate specificity to attack a greater range of heterocyclic compounds, biocatalysis may be a cost-effective approach to achieve the production of low sulfur gasoline. The challenge will be to accomplish these improvements by the time the regulations for low sulfur gasoline and other vehicle fuels go into effect in order to be competitive with emerging nonbiological desulfurization technologies.

Fossil Fuels↗
PubMed1997

Biologically based artificial navigation systems: review and prospects.

Diverse theories of animal navigation aim at explaining how to determine and maintain a course from one place to another in the environment, although each presents a particular perspective with its own terminologies. These vocabularies sometimes overlap, but unfortunately with different meanings. This paper attempts to define precisely the existing concepts and terminologies, so as to describe comprehensively the different theories and models within the same unifying framework. We present navigation strategies within a four-level hierarchical framework based upon levels of complexity of required processing (Guidance, Place recognition-triggered Response, Topological navigation, Metric navigation). This classification is based upon what information is perceived, represented and processed. It contrasts with common distinctions based upon the availability of certain sensors or cues and rather stresses the information structure and content of central processors. We then review computational models of animal navigation, i.e. of animats. These are introduced along with the underlying conceptual basis in biological data drawn from behavioral and physiological experiments, with emphasis on theories of "spatial cognitive maps". The goal is to aid in deriving algorithms based upon insights into these processes, algorithms that can be useful both for psychobiologists and roboticists. The main observation is, however, that despite the fact that all reviewed models claim to have biological inspiration and that some of them explicitly use "Cognitive Map"-like mechanisms, they correspond to different levels of our proposed hierarchy and that none of them exhibits the main capabilities of real "Cognitive Maps"--in Tolman's sense--that is, a robust capacity for detour and shortcut behaviors.

Animals↗
PubMed1997

Fluoride tolerance of laying hens.

1. One thousand Silver Grey Hyline hens were given drinking water containing 5 concentrations of added sodium fluoride (0, 6, 10, 14 and 20 mg/l) over a 17-week growth and 57-week laying period. The natural fluoride content of the water was 0.21 mg/l during the growing period and 0.29 mg/l throughout lay. 2. During the rearing phase, efficiency of food utilisation and mortality were not significantly affected by the fluoride concentration of the water. Weight gain and food intake decreased in the 10 and 14 mg/l fluoride treatments. 3. During the laying period, the fluoride content of the water had a significant effect on egg production, but eggshell breaking strength was not significantly influenced. 4. Post mortem analyses, carried out at the end of lay (74 weeks of age), showed that carcase weight and the fluoride content of the os femur increased significantly as the fluoride concentration in the water increased; the increase in bone fluoride followed a linear pattern. 5. Histopathology showed no evidence of changes in the livers or kidneys; liver weights and breaking strength of the os femur were unaffected by the amount of fluoride consumed. 6. The data showed that under commercial conditions, laying birds can tolerate ingesting 4.453 mg fluoride/day for up to 74 weeks.

Animals↗
PubMed1994

Solubilized HLA class I antigen enzyme-linked immunoassay to identify HLA-typing reagents.

The objective of this study was to evaluate the use of sHLA in a solid-phase EIA as a rapid and sensitive way to identify potential IgG HLA class-I-typing reagents. To evaluate the efficacy of the sHLA EIA, we used the assay to screen 259 HLA-A, -B, and -C antisera that our laboratory had procured using the standard NIH LCA. A positive result obtained by the sHLA EIA, which was defined as an EIA ratio of 3 SD above the mean of 91 anti-HLA-negative sera, revealed that 91% (79 of 87) of the A-locus-typing reagents were positive, 96% (150 of 156) of the B-locus antisera were positive, and only 75% (12 of 16) of the C-locus reagents were positive. The typing reagents that were negative by EIA (n = 18) fell into two categories. First, 38% (7 of 18) were negative by sHLA EIA, as they were IgM-typing reagents (NIH LCA reactivity ameliorated by DTT). The second group of the 11 remaining typing reagents had a mean EIA ratio of 1.0 +/- 0.246 (mean +/- 1 SD), which was significantly (P < 0.001) higher than the mean of the 91 negative controls that were used to establish the negative cutoff. The overall sensitivity of the sHLA EIA to detect HLA class-I-directed IgG was 97.2%.

Female↗
PubMed1991

Tuberculosis, the Adirondacks, and coming of age for thoracic surgery.

"The Captain of all these men of death," wrote John Bunyan in 1680, "that came against him to take him away, was the Consumption, for it was that that brought him down to the grave." Until the twentieth century tuberculosis, or the Consumption, was the foremost cause of death among adults. It had not been recognized as a specific infectious process until 1882. The sanatorium movement for segregation and treatment of tuberculous patients originated in the late nineteenth century. Locations in the mountains were thought to be especially favorable, for the sake of fresh air, sunshine, and the aromas of pine and spruce. Long before the epidemic of lung cancer, or the possibilities of correction for cardiac disease, development of thoracic surgery was closely intertwined with the history of the sanatoriums. All of them had disappeared, however, soon after the middle of the twentieth century.

Health Resorts↗
PubMed1991

Residual activity of microencapsulated permethrin against stable flies on lactating dairy cows.

Emulsifiable concentrate and microencapsulated formulations of permethrin were evaluated for residual activity against stable flies on lactating dairy cows. Cows were treated in the field with each formulation and hair was clipped from the leg and shoulder area, and bioassayed at 1, 2, 3, 4, 7 and 14 days after treatment. Significantly more stable flies died when exposed to hair sampled 3, 4 and 7 days after treatment from the shoulder than from the lower leg. Analysis with gas chromatography of hair samples showed no detectable permethrin residues on shoulder or leg hair 72 h after treatment with the emulsifiable concentrate formulation. Microencapsulated permethrin was still detectable on hair sampled from both locations 7 days after treatment. The permethrin concentration on the leg hair was approximately 50% of the shoulder hair concentration after 3 days, with the leg hair residue dropping to 31% of shoulder level after 7 days.

Animals↗
PubMed1991

Universal access to health care. A comprehensive tax-based approach.

More than 30 million Americans lack health insurance, and millions more are "underinsured." Meanwhile, the cost of health care in the United States is escalating, and some of our care is of questionable value. This article presents a health care reform strategy that addresses these three fundamental problems in the US health care system. The strategy, designed to empower consumers to make cost-conscious health care choices, combines a universal tax credit that enables all Americans to purchase basic health coverage; insurance reforms including pooling and reinsurance mechanisms; requirements that all employers make insurance available to their employees and that all consumers purchase coverage; and efforts to measure and improve the quality and efficiency of health care services. This strategy would help us to achieve universal health insurance coverage, while creating the proper incentives for cost control. In addition, it can be largely internally financed through savings automatically triggered by its implementation.

Cost Control↗
PubMed1990

Friedrich Trendelenburg and the surgical approach to massive pulmonary embolism.

A surgical approach to embolectomy from the pulmonary artery had been worked out in laboratory animals prior to 1908 by Friedrich Trendelenburg, professor of surgery and director of the University Surgical Clinic at Leipzig, Germany. His technique was based on limited opening of the left side of the chest directly over the common or undivided pulmonary artery and encircling the proximal aorta and pulmonary artery together through the transverse sinus of the pericardium. Both vessels were to be occluded by traction on the encircling band. Emboli were to be extracted through a small pulmonary arteriotomy, which then was to be controlled by a tangentially applied clamp, while occlusion of the great blood vessels was released. Unfortunately, during the first clinical trial of the technique, the patient died because of technical difficulties. Not until 1924 was a surviving patient described, by Trendelenburg's former trainee, Martin Kirschner.

Aged↗
PubMed1990

Werner Forssmann and catheterization of the heart, 1929.

Invasive study of cardiac anatomy and function traces its origin to the work of a 25-year-old surgical trainee in a provincial German town in the pre-Depression years of 1929 and 1930. Only 1 year out of medical school and undeterred by the medical profession's fear of tampering with the heart, Dr Werner Forssmann explored methods for a more direct access to the cardiac chambers, finding it necessary to make the observations on himself. Later he was able to show that the right-sided cardiac chambers could be visualized radiographically after injection of iodinated contrast materials through a catheter into the right atrium, and again he tried the method on himself.

Cardiac Catheterization↗