Search PubMed⌕ Search

Biomedical subjects

J W Hoyt

Publications and source records attributed to J W Hoyt.

At least 19 recordsLinked to original sources
PubMed1997

Pleomorphic xanthoastrocytoma: DNA flow cytometry and outcome analysis of 12 patients.

BACKGROUND: Pleomorphic xanthoastrocytoma (PXA) is an astrocytic tumor occurring primarily in childhood and adolescence with some malignant histologic features but a relatively slow clinical course. However, some tumors progress more rapidly and can undergo malignant degeneration. The authors attempted to determine whether various histologic features or tumor cell proliferative indices might help identify lesions at risk for early progression and distinguish PXAs from malignant gliomas. METHODS: In a retrospective study of 12 patients with PXA, the tumor's histologic features and DNA flow cytometric parameters were compared with their clinical course. DNA flow cytometry values for the S- and G2-phase of the PXAs also were compared with control group samples of malignant and low grade astrocytomas. RESULTS: Of the 12 tumors at initial diagnosis, 5 were considered typical PXAs whereas 7 had some atypical features (4 with paucity of reticulin fibers, 1 with focal necrosis, and 2 with both atypical reticulin and focal necrosis). During the follow-up period (range, 3.75-11 years; mean, 6.8 years), 2 patients had recurrences; 1 atypical reticulin PXA progressed to glioblastoma after 6.5 years and the 1 tumor with focal necrosis recurred at 6 months and again at 2 years with typical histologic features. DNA flow cytometry parameters of the typical PXA group were similar to values for malignant astrocytoma and significantly higher than values for control specimens of low grade astrocytomas. There were no distinctive DNA flow cytometric features that could distinguish this last tumor from others with a more benign clinical course. CONCLUSIONS: Measurements of the S-phase and G2-phase obtained from DNA flow cytometry and atypical histologic features cannot reliably identify PXA patients at risk for early progression and overall are significantly higher than values obtained for low grade gliomas. Therefore, frequent (i.e., two to three times per year) postoperative clinical and radiologic examinations are necessary to judge the appropriateness of adjuvant therapy in patients with PXA. The paradox of slow growth but DNA flow cytometry consistent with aggressive malignant lesions may represent a cell-cycle arrest mechanism in these lesions that could be verified in subsequent studies.

Adolescent↗
PubMed1996

Ethics consultation.

This article comprehensively addresses the composition, role, and functions of a hospital ethics committee (HEC). HECs are of particular interest to critical care specialists because they often participate in or lead such committees, extending their commitment to communication and caring beyond the borders of the intensive care unit (ICU). This article also demonstrates that a well-run ICU in a hospital with a strong HEC automatically will include many of the services that the HEC normally would provide, without the need for HEC assistance.

Committee Membership↗
PubMed1995

Analysis of proliferative grade in glial neoplasms using antibodies to the Ki-67 defined antigen and PCNA in formalin fixed, deparaffinized tissues.

In an effort to optimize immunocytochemical methods to evaluate cell kinetics in brain tumors, we studied two newly-developed antibodies which react with formalin resistant epitopes of Proliferating Cellular Nuclear Antigen (PCNA) and Ki-67. These results were compared with standard flow cytometric cell cycle data from the same tumor specimens to determine if these methods correlate with each other, and whether retrospective analysis using these antibodies is feasible for cell kinetic analysis of brain tumors. Thirty-one specimens of glial tumors submitted for flow cytometry during 1992 were also reacted with antibodies to PCNA (PC-10) and Ki-67 (MIB-1). Flow cytometry scores for S-phase Fraction were compared with immunocytochemical scores for both antibodies, using an arbitrary rating of 1 (low, < 4%), 2 (intermediate, 4-6%), 3 (high, > 6%), and 1 (< 25% positive), 2 (26-75% positive), 3 (> 75% positive), respectively. MIB-1 results were found to correlate significantly with the S-phase fraction as determined by flow cytometry. The MIB-1 data showed a trend toward underestimating, i.e., lower scores, the proliferative index compared with flow cytometry. There was less of a correlation between PC-10 antibody scores and flow cytometry S-phase fraction, as PC-10 immunostaining typically overestimated the proliferative rate of brain tumors when compared with flow cytometry. There was an exact correlation between PC-10 and MIB-1 in only 4 cases, whereas in the remaining specimens, PC-10 results were always higher than MIB-1.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Monoclonal↗
PubMed1995

Medical futility.

Explore the source record for details and available documents.

Ethics, Medical↗
PubMed1994

Persistent paralysis in critically ill patients after the use of neuromuscular blocking agents.

Neuromuscular blocking agents (NMBAs), an important part of the pharmacologic armamentarium of the intensivist, have a long and admirable history of safety when used in the operating room for periods of time (almost always < 12 hrs). Since 1985, dozens of medical journals have reported a multitude of studies on persistent paralysis when these same agents are exported from the operating room to the ICU. Most of these reports are case presentations of patients who failed to move for days to weeks after discontinuation of NMBAs. These reports have led to concern about the appropriate use of NMBAs in the ICU. This article sorts through the issues surrounding persistent paralysis, and defines it as a short-term and a long-term problem. The short-term problem seems to have a pharmacologic explanation that is not difficult to correct. The long-term problem is much more complex and may have a toxic explanation that may also be more difficult to manage.

Critical Care↗
PubMed1994

Objective data and quality assurance programs. Current and future trends.

As CCM has grown, the diversity of ICU patients, as well as that of ICU organization and structure, has grown. This growth has led to numerous questions regarding health care delivery in the ICU. These questions contributed to the development of systems that objectively evaluate the quality of health care delivery in ICUs. Severity of disease scoring systems have been developed and allow for a valid analysis of ICU performance at several levels. These systems should help intensivists determine how health care delivery can be optimized in ICUs. Despite the controversy that surrounds severity of disease scoring and prognostic systems, it is not unreasonable to suggest that, because of the feedback these systems would provide, health care delivery in the ICU would be improved through more extensive use of them at the present time. The information acquired through the use of objective scoring systems ultimately must be used to improve the efficiency of ICUs. The structure and organization of ICUs in the United States, as well as the training of those who treat ICU patients, are excessively diverse, and a more standardized approach to health care delivery in the ICU ultimately will be required. Present information suggests that decentralized ICUs with part-time ICU physicians result in poorer outcomes. The APACHE III study intends to explore these relationships in more detail. Certainly, more studies looking at these issues are needed, but we are at least beginning to answer the questions that resulted from the rapid growth of critical care in the 1980s. The SCCM data suggest two possible alternatives, not necessarily exclusive of each other: (1) A large percentage of ICUs may be obligated to undergo structural changes in the near future. (2) Regionalization of critical care, already present, may continue. Certain rural areas may find it more expedient to send the most critically ill patients to tertiary centers in nearby cities, as opposed to a wholesale upgrading of the delivery of care in their own ICUs. Ultimately, all hospitals will be obligated to provide patients access to the highest quality of critical care.

Certification↗
PubMed1992

Pulmonary artery catheterization.

After two decades, hemodynamic invasive monitoring using a flow-directed, balloon-tipped, pulmonary artery (PA) catheter has established itself as a significant component of acute clinical care. In spite of continued recommendations for limitations, restrictions, moratoria, and even abandonment, growth in catheter use continues. Attempts to replace it by competing technologies for routine clinical practice have not been successful thus far. More than one million PA catheters are inserted in the United States annually. The clinical utility and value of the pulmonary artery catheter depend largely on the interpretation of information obtained. Clinical interpretation of data is influenced by an understanding of cardiopulmonary hemodynamics, technical skills, and professional integrity of the physician using the device. After a brief history, this article focuses on the technical aspects of the insertion procedure, choice of hardware, and acquisition and analysis of information. Indications, contraindications, and clinical utility are briefly described. Major complications from PA catheterization reported in the literature since clinical introduction of the catheter are summarized.

Cardiac Output↗
PubMed1990

Pain: theory, anatomy, and physiology.

Pain is a common experience of the ICU patient, with a diverse clinical manifestation. To manage pain we must understand its anatomic pathways and physiology. This article reviews the development of our understanding of the theory of pain from Descartes to the gate theory of Melzack and Wall. We will review the anatomy of the pathways of pain and the interrelationship of "A" and "C" fibers and the unique nature of the opiate receptor.

Humans↗