PubMed Health⌕ Search

Biomedical subjects

J A Meyer

Publications and source records attributed to J A Meyer.

At least 19 recordsLinked to original sources
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↗
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↗
PubMed1990

A practical mechanical respirator, 1929: the "iron lung".

No satisfactory mechanical respirator existed before 1929, when Philip Drinker and Louis Shaw described an apparatus of their own design. This machine was in the form of a cylindrical tank enclosing the patient's body and chest, leaving the head outside the chamber under atmospheric pressure. Air pumps, later a bellows, raised and lowered pressure within the tank to assume the entire work of breathing. Popularly named the iron lung, the Drinker respirator supported thousands of patients afflicted with respiratory paralysis during the polio era. It was being superseded by positive-pressure airway ventilators just as the polio era came to a close. Today the Drinker respirator has disappeared virtually without a trace. Although its disadvantage was its cumbersome size, we must concede that it supported patients over the long term with fewer complications than do the respirators of today.

Disease Outbreaks↗
PubMed1990

Commercial and naturally occurring fly parasitoids (Hymenoptera: Pteromalidae) as biological control agents of stable flies and house flies (Diptera: Muscidae) on California dairies.

Filth fly parasites reared by commercial insectaries were released on two dairies (MO, DG) in southern California to determine their effect on populations of house flies, Musca domestica L., and stable flies, Stomoxys calcitrans (L.). Spalangia endius Walker, Muscidifurax raptorellus Kogan and Legner, and Muscidifurax zaraptor Kogan and Legner were released on the MO dairy from 1985 to 1987 in varying quantities. Parasitism by Muscidifurax zaraptor on the MO dairy was significantly higher (P less than 0.05) from the field-collected stable fly (4.4%) and house fly (12.5%) pupae, compared with a control dairy (0.1%, stable fly; 1.3%, house fly). Muscidifurax zaraptor, released from April through October during 1987 on the DG dairy (350,000 per month), was not recovered in a significantly higher proportion from either fly species relative to the corresponding control dairy. No specimens of Muscidifurax raptorellus were recovered from the MO dairy. Parasite treatments had no apparent effect on adult populations of either fly species or on overall parasitism rate of field-collected stable fly (16.8%, MO; 17.2%, DG) and house fly (23.3%, MO; 20.9%, DG) pupae. Spalangia spp. were the predominant parasites recovered from field-collected stable fly and house fly pupae on all four dairies. Sentinel house fly pupae placed in fly-breeding sites on both release dairies were parasitized at a significantly higher rate, as compared with sentinel pupae on control dairies. The generic composition of parasites emerging from sentinel house fly pupae was 20.6% Spalangia spp. and 73.2% Muscidifurax spp., whereas in field-collected house fly pupae, Spalangia spp. and Muscidifurax spp. constituted 74.3 and 19.6% of the parasites, respectively.

Animals↗
PubMed1990

Filth fly resistance to pyrethrins associated with automated spray equipment in poultry houses.

Resistance to pyrethrins plus piperonyl butoxide (PB) in a population of Fannia canicularis (L.) (BR strain) at a broiler-breeder facility was determined (in F2 laboratory generation) to be 109.1-fold the median lethal dose (LD50), apparently having been influenced by twice-daily treatments with automatic spray equipment during the previous 2 years. By contrast, resistance was only 12-fold the normal LD50 in a population of Musca domestica L. (DH strain) at an egg-production facility that was subjected during a comparable period to treatments twice per week with synergized pyrethrins with the identical automatic pyrethrin-spray system. The automated application of a nonpersistent chemical at frequent intervals, obviously, provides continuity of selection pressure leading to high levels of resistance. Other factors such as enclosed poultry housing and the elimination of refugia have also contributed to the enhancement of resistance. The resistance level in Strain BR regressed to 31.7-fold after remaining unselected for an additional generation in the laboratory. Other bioassays on the F2 generation revealed limited resistance toward permethrin of 3.7-fold the normal LD50.

Aerosols↗
PubMed1989

Gotthard Bülau and closed water-seal drainage for empyema, 1875-1891.

Optimal treatment of pleural empyema remains controversial to the present day. In the preantibiotic era, surgical thinking favored early and aggressive drainage of closed-space infections, but the dynamics of the pleural space were poorly understood and open pneumothorax generally was considered the necessary price of surgical drainage. Against bitter opposition, revision of the dogma of early open drainage was achieved in 1918 by Evarts Graham and his associates on the US Army's Empyema Commission. Unacceptable mortality rates for early drainage were brought under control through a treatment program of repeated tapping, with surgical drainage only after loculation had occurred. Paradoxically, closed water-seal drainage for empyema had been used by a German internist, Gotthard Bülau, as early as 1875. His technique was published in 1891, 27 years before the report of the Empyema Commission. As a closed system, it would have been suited to empyema drainage in either the early diffuse or the loculated stages. Thoracotomy was not possible at the time, and Bülau probably could not foresee the future importance of his method to surgery.

Drainage↗
PubMed1988

Claude Beck and cardiac resuscitation.

The problem of sudden death due to derangement of the cardiac mechanism remained poorly defined into the 20th century. The physiologist Carl J. Wiggers proposed maintenance of the circulation by manual massage of the heart, followed by electrical defibrillation at a suitable time. His surgical colleague Claude S. Beck, with several associates, defined a precise sequence of steps for management of cardiac arrest in the operating room and was able to apply them clinically with complete success. Subsequently, patients were resuscitated outside the operating room as well; and finally, massage and defibrillation across the intact chest have made cardiac resuscitation available at any place or time.

France↗
PubMed1988

Hugh Morriston Davies and lobectomy for cancer, 1912.

The report of a lobectomy for bronchogenic carcinoma in 1912, by Hugh Morriston Davies of London, and without precedent, describes a surgical technique strikingly similar to that of today. Unfortunately, Davies' patient died because postoperative management of the pleural space was not yet well understood. The tumor had been identified by radiographic examination and the diagnosis confirmed by cytological examination of the sputum. The operative technique included individual ligation of hilar vessels and suture closure of the bronchus, neither of which was to be reported again for more than 20 years. More effective management of the pleural space was described, without special emphasis, by Harold Brunn of San Francisco 17 years later.

History, 20th Century↗