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Biomedical subjects

J A Snyder

Publications and source records attributed to J A Snyder.

At least 19 recordsLinked to original sources
PubMed1995

Cytochalasin J affects chromosome congression and spindle microtubule organization in PtK1 cells.

PtK1 cells were treated with 10 micrograms/ml cytochalasin J (CJ) for 15 min at various stages of mitosis. When applied at nuclear envelope breakdown (NEB) chromosome congression was blocked or substantially slowed, and chromosomes failed to show organization patterns typical of prometaphase. Spindle microtubule (MT) numbers appeared unaffected as judged by the pattern of birefringent retardation. However, ultrastructural analysis showed MTs to be reorganized within the spindle domain with some exhibiting fragmentation and others failing to interact with poorly defined kinetochore laminae. The spindle domain took on a curved, almost banana-like shape, as related to the position of the centrosomes and lack of orientation of chromosomes. Serial section analysis of kinetochore regions showed reduced contour length and maturation of the kinetochore plate with few MTs associated with this structure. Cells similarly treated with 10 micrograms/ml CJ at NEB for 15 min and then released into conditioned medium for 15 min showed the most chromosomes resumed congression to the metaphase plate. Ultrastructural analysis revealed a more normal organization of spindle MTs, but kinetochore structure remained affected. CJ treatment of cells in prometaphase slightly affected chromosomes congression with most chromosomes aligning at the metaphase plate after 10-15 min of treatment. Ultrastructural analysis showed that astral MTs were disrupted and spindle MTs were fragmented; few MTs coursed from kinetochore to pole. Kinetochore structure was also affected with only small numbers of short MTs seen associated with kinetochores. Application of CJ at anaphase onset had little effect on anaphase A and B, but cytokinesis failed to occur. Anti-tubulin staining of a monolayer of cells treated with 10 micrograms/ml CJ for 15 min showed that over 60% of mitotic figures exhibited changes in MT organization. Cells showing the greatest effect of treatment had several foci of bundles of MTs, as if the spindle were multipolar. Chromosomes were arranged near the periphery of the spindle which could be a result of abnormalities of kinetochore structure. Improper association of spindle MTs with kinetochores and, thus, changes in kinetochore position could account for these changes in spindle architecture.

Actins↗
PubMed1995

Emergency medical service system development: results of the statewide emergency medical service Technical Assessment Program.

STUDY OBJECTIVE: The National Highway Traffic Safety Administration developed the EMS (emergency medical services) Technical Assessment Program to assist states in developing and improving their EMS systems. The main goals of this evaluation were to document the level of improvement in EMS system development following completion of the Technical Assessment Program and to identify necessary program improvements at the National Highway Traffic Safety Administration. DESIGN: Independent investigators retrospectively reviewed the information in Technical Assessment Program reports from 35 states that participated in the program during a 5-year period. RESULTS: Training and certification programs for prehospital personnel were the most well-developed elements of EMS systems. Conversely, comprehensive quality management and EMS system evaluation programs were almost uniformly absent (89% of states). Areas of need targeted for improvement included enabling legislation for EMS (60%) or trauma system development (69%), an improved mechanism to assess system resources (71%), an established or updated state EMS plan (80%), aging and unreliable communications equipment (89%), fully operational prehospital data collection systems (89%), and consistent medical oversight for all prehospital providers (92%). CONCLUSION: Program evaluation revealed that significant recommendation-based changes occurred in all components of EMS systems. The Technical Assessment Program is one tool that states can use to promote EMS system improvements.

Certification↗
PubMed1994

In vitro characteristics of white cell-reduced single-unit platelet concentrates stored in syringes.

BACKGROUND: Platelet concentrates (PCs) for premature infants may be subjected to filtration, centrifugation, and various storage conditions before transfusion. STUDY DESIGN AND METHODS: As there are few data on the cumulative effect of these procedures on PCs, platelet properties (including biochemical and functional in vitro assays) were evaluated after the processing of single units of PCs through a 1-unit-capacity high-efficiency white cell (WBC)-reduction filter followed by syringe storage at either 22 or 37 degrees C for 6 hours. Two- and 5-day-old PCs, volume-reduced PCs, and prestorage WBC-reduced PCs were evaluated. RESULTS: WBC filtration consistently resulted in a 3 to 4 log10 reduction in WBCs, with less than 15-percent platelet loss. No adverse effects of platelet function or evidence of increased platelet activation as determined by the percentage of P-selectin positivity were noted. A decrease in pH associated with increased lactate production and consumption of glucose was observed following syringe storage under all conditions tested. Such changes were most pronounced, however, with volume-reduced PCs stored at 37 degrees C (pH 6.31 +/- 0.15, lactate 23.0 +/- 3.06 mmol/L). All pH levels at the end of storage were above the minimum Food and Drug Administration requirement (pH 6.0). CONCLUSION: The in vitro data suggest that single units of PCs can undergo WBC filtration followed by syringe storage for up to 6 hours and still maintain acceptable storage characteristics. The practice of maintaining volume-reduced PCs in syringes for 6 hours at 37 degrees C in isolettes during transfusion should, however, be avoided.

Blood Component Removal↗
PubMed1994

Emergency department programs for patients with chest pain.

The development and implementation of specialized ED programs for patients with chest pain are continually evolving, although the initial goals of "chest pain centers" may vary dramatically. ED nursing staff play an important role in the delivery of rapid cardiac care and support of community education programs, both of which are intended to decrease the time between recognition of clinically significant chest pain and initiation of appropriate interventions.

Chest Pain↗
PubMed1994

Special protocols for patients with trauma.

The ED care of the patient with trauma can be facilitated by the establishment of protocols to ensure prompt access to lifesaving and limb-saving procedures and care. Specific protocols for patients with trauma support assessment and treatment in both the emergency and long-term phases of care.

Clinical Protocols↗
PubMed1993

Depression of macrophage respiratory burst capacity and arachidonic acid release after Fc receptor-mediated phagocytosis.

The phagocytosis of IgG-coated erythrocytes (ElgG) by macrophages results in a subsequent depression of macrophage phagocytic function, respiratory burst capacity, and bactericidal activity. Our study was carried out to determine the importance of impaired arachidonic acid release in the depression of the respiratory burst after ElgG phagocytosis. The depression of triggered H2O2 production after ElgG phagocytosis was not due to cyclooxygenase products because indomethacin or aspirin did not modify the depression. Further studies revealed that the depression of triggered H2O2 production after ElgG phagocytosis was associated with a depression in the ability of macrophages to release arachidonic acid in response to PMA, zymosan, or calcium ionophore. The addition of exogenous arachidonic acid partially prevented the depression of triggered H2O2 production after ElgG phagocytosis. Unlike phagocytosis mediated by FcR, complement receptor-mediated phagocytosis did not alter H2O2 production or arachidonic acid release. Ligation of FcR was not sufficient to depress triggered H2O2 production and arachidonic acid release because these functions were not depressed when phagocytosis was inhibited with cytochalasin D. Thus, it was found that the depression of triggered H2O2 production by macrophages after FcR-mediated phagocytosis was associated with impaired release of arachidonic acid and that H2O2 production could be partially restored by the addition of arachidonic acid. These results suggest that the impairment of arachidonic acid release after FcR-mediated phagocytosis contributes to the depression of macrophage respiratory burst capacity after FcR-mediated phagocytosis.

Animals↗
PubMed1993

Analysis of spindle microtubule organization in untreated and taxol-treated PtK1 cells.

Taxol, a microtubule stabilizing agent, has been used to study changes in spindle microtubule organization during mitosis. PtK1 cells have been treated with 5 micrograms/ml taxol for brief periods to determine its effect on spindle architecture. During prophase taxol induces microtubules to aggregate, particularly evident in the region between the nucleus and cell periphery. Taxol induces astral microtubule formation in prometaphase and metaphase cells concomitant with a reduction in spindle length. At anaphase taxol induces an increase in length in astral microtubules and reduces microtubule length in the interzone. Taxol-treated telophase cells show a reduction in the rate of furrowing and astral microtubules lack a discrete focus and are arranged more diffusely on the surface of the nuclear envelope. In summary, taxol treatment of cells prior to anaphase produces an increase in astral microtubules, a reduction in kinetochore microtubules and a decrease in spindle length. Brief taxol treatments during anaphase through early G1 promotes stabilization of microtubules, an increase in the length of astral microtubules and a delayed rate of cytokinesis.

Animals↗
PubMed1993

Documentation of nursing care for patients who have been restrained.

The care of patients who require restraints in the emergency department presents a challenge, not only for the amount and quality of behavioral interventions but also for the level of monitoring and documentation required. Special forms created to facilitate serial documentation of nursing care for patients who require restraints are designed to meet the unique needs of each emergency care facility.

Emergency Nursing↗
PubMed1992

Survival of implanted fetal dopamine cells and neurologic improvement 12 to 46 months after transplantation for Parkinson's disease.

BACKGROUND AND METHODS: Patients with Parkinson's disease tend to have a reduced response to levodopa after 5 to 20 years of therapy, with "on-off" fluctuations consisting of dyskinesia alternating with immobility. In an effort to modify the motor disability of advanced Parkinson's disease, we implanted embryonic mesencephalic tissue containing dopamine cells into the caudate and putamen of seven patients. Two patients received unilateral grafts in the caudate and the putamen on the side opposite the side with worse symptoms. Five patients received bilateral grafts implanted in the putamen only. In six of the seven patients, the fetal tissue was obtained from a single embryo with a gestational age of seven to eight weeks. The tissue was injected by means of 10 to 14 needle passes. There were no surgical complications. Four of the seven patients underwent immunosuppression with cyclosporine and prednisone. RESULTS: All patients reported improvement according to the Activities of Daily Living Scale when in the on state 3 to 12 months after surgery (P < 0.01). Neurologic examination according to the Unified Disease Rating Scale showed that five of the seven patients improved when in the on state six months after surgery. The mean group Hoehn-Yahr score improved from 3.71 to 2.50 (P < 0.01). Computer and videotape testing in the home supported these findings. Fluctuations in clinical state were moderated, and periods of dyskinesia and off episodes were shorter and less severe than before implantation. Drug doses were reduced by an average of 39 percent (P < 0.01; maximum, 58 percent). The results of clinical evaluation and fluorodopa positron-emission tomography in one patient were compatible with transplant survival for as long as 46 months. Both immunosuppressed and nonimmunosuppressed patients improved. CONCLUSIONS: Fetal-tissue implants appear to offer long-term clinical benefit to some patients with advanced Parkinson's disease.

Activities of Daily Living↗
PubMed1992

Specialized services for psychiatric patients in the emergency department.

The care of the psychiatric patient in the emergency department offers yet another opportunity for emergency nurses to draw on specialty nursing resources or to create expanded roles for emergency practitioners themselves. As our emergency departments continue to encounter increasing numbers of patients, the need for concise and expeditious psychiatric consultation protocols becomes even more clear.

Emergency Nursing↗
PubMed1991

UV-microbeam irradiations of the mitotic spindle: spindle forces and structural analysis of lesions.

Mitotic PtK1 spindles were UV irradiated (285 nm) during metaphase and anaphase between the chromosomes and the pole. The irradiation, a rectangle measuring 1.4 x 5 microns parallel to the metaphase plate, severed between 90 and 100% of spindle microtubules (MTs) in the irradiated region. Changes in organization of MTs in the irradiated region were analyzed by EM serial section analysis coupled with 3-D computer reconstruction. Metaphase cells irradiated 2 to 4 microns below the spindle pole (imaged by polarization optics) lost birefringence in the irradiated region. Peripheral spindle fibers, previously curved to focus on the pole, immediately splayed outwards when severed. We demonstrate via serial section analysis that following irradiation the lesion was devoid of MTs. Within 30 s to 1 min, recovery in live cells commenced as the severed spindle pole moved toward the metaphase plate closing the lesion. This movement was concomitant with the recovery of spindle birefringence and some of the severed fibers becoming refocused at the pole. Ultrastructurally we confirmed that this movement coincided with bridging of the lesion by MTs presumably growing from the pole. The non-irradiated half spindle also lost some birefringence and shortened until it resembled the recovered half spindle. Anaphase cells similarly irradiated did not show recovery of birefringence, and the pole remained disconnected from the remaining mitotic apparatus. Reconstructions of spindle structure confirmed that there were no MTs in the lesion which bridged the severed spindle pole with the remaining mitotic apparatus. These results suggest the existence of chromosome-to-pole spindle forces are dependent upon the existence of a MT continuum, and to a lesser extent to the loss of MT initiation capacity of the centrosome at the metaphase/anaphase transition.

Anaphase↗