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S Childress

Publications and source records attributed to S Childress.

34 records · Page 2Linked to original sources
PubMed1995

Calcification can shorten T2, but not T1, at magnetic resonance imaging fields. Results of a relaxometry study of calcified human meningiomas.

RATIONALE AND OBJECTIVES: Water content and water-proton relaxation rates are reported for fresh, histologically characterized, surgical specimens of calcified human intracranial meningiomas and compared with results for noncalcified meningiomas from an earlier study and with calcium hydroxyapatite (CaHA) suspensions to elucidate the influence of calcification on magnetic resonance imaging (MRI) signal intensity of calcified meningiomas. METHODS: The magnetic field dependence of 1/T1 of water protons (nuclear magnetic relaxation dispersion profile) and dry weights are reported for 38 calcified nonhemorrhagic and 3 hemorrhagic specimens of known histologic subtype, a subset of the 67 specimens measured earlier. Calcification was considered mild or heavy when the dry weight was within or above the range for noncalcified meningiomas. Preliminary 1/T1 profiles for pure CaHA and a single high-field 1/T2 value also are reported. RESULTS: The ranges of dry weights and of low-field 1/T1 values were twice as large for calcified as for noncalcified meningiomas. No correlation was found between low-field 1/T1 and either histologic subtype or dry weight. Mild calcification produced the highest low-field 1/T1 values; the most heavily calcified tumor had slightly increased low-field 1/T1. Calcium hydroxyapatite increases low-field 1/T1 significantly but not high-field 1/T1; high-field 1/T2 is large. For calcified hemorrhagic meningiomas, increases in both low-field and high-field 1/T1 were seen. CONCLUSION: For mild calcification, MRI signal voids result from an increased high-field 1/T2; for heavier calcification, reduced proton density (from excluded water) becomes of increasing importance. Cellular CaHA appears to brighten the signal in T1-weighted MRI in the presence of hemorrhage.

Adolescent↗
PubMed1994

Comparison of colony stimulation factors on in vitro rat and human neutrophil function.

The effects of rhCSFs on in vitro polymorphonuclear leukocyte (PMN) function were studied in Sprague-Dawley neonatal and adult rats and adult and umbilical cord derived human PMN to compare species response. Following in vitro exposure to buffer or rhCSFs (50-100 micrograms/ml), PMN oxidative burst, chemotactic activity and adherence protein expression were measured. RhG-CSF increased the oxidative burst of adult rat PMN as measured by chemiluminescence and altered CD11b/CD18 in resting neonatal rat but not adult rat cells. RhGM-CSF had no effect on adult rat PMN function in vitro, but led to modest changes in adult rat PMN diapedesis across rat peritoneum. No responses were noted to rhM-CSF. Human PMN responded best to GM-CSF (particularly in the neonate), intermediately to G-CSF and none to M-CSF. These experiments show that the profile of cytokine effects is not similar in adult and neonatal rat PMN when compared to human cells. The diversity of actions in other species must be considered when using rhCSFs in animal models.

Animals↗
PubMed1984

A model of cell sorting.

Voronoi polygons are introduced as a suitable representation for a two-dimensional cell sheet. These polygons are defined in terms of a finite number of points, making numerical simulations tractable and yet allowing cells to change neighbors and their shape in response to deforming forces without leaving gaps in the tissue. Using this geometry and an extension of the equilibrium theory proposed by Steinberg to drive the motion, simulations of rounding of uneven tissue and engulfment of two intact tissues are carried out.

Amphibians↗
PubMed1984

Models of cell interaction based on differential adhesion.

Recent efforts to model the mechanical interaction of aggregates of biological cells are reviewed. Differential adhesion is discussed as a means of creating a field of stress equivalent to tension elements at interfaces between unlike cell types. Several numerical algorithms are described and applied to shortening and folding of cell sheets, three-dimensional monolayers, and two-dimensional cell aggregates.

Biomechanical Phenomena↗
PubMed1980

Lichen growth.

Explore the source record for details and available documents.

Carbohydrates↗
PubMedDate not supplied

Air medical transport for the trauma patient requiring cardiopulmonary resuscitation: a 10-year experience.

INTRODUCTION: Air medical response and transport for the injured patient in cardiopulmonary arrest remain controversial. This study is a large, single-program experience. METHODS: A retrospective chart review and descriptive study of all injured patients requiring cardiopulmonary resuscitation (CPR) immediately before or during air medical transport. The crew functioned under advanced cardiac life support/advanced trauma life support protocols. SETTING: The patients, when transported, went to a variety of facilities, with the majority of patients transported to a level-I trauma center. The service area was primarily rural. RESULTS: During 1985 to 1994, inclusive, there were 12,518 completed missions. A total of 320 injured patients required CPR (284 with blunt injury and 36 with penetrating injury), six of the 320 patients (1.9%) survived. Survivors and nonsurvivors did not differ significantly in age, mechanism of injury, time from initiation of CPR to arrival in the emergency department (ED), year of injury or initial cardiac rhythm. All survivors did, however, present to the ED in normal sinus rhythm with a palpable blood pressure. CONCLUSION: Air medical transport for the injured patient without signs of life following prehospital intervention appears futile.

Air Ambulances↗
PubMedDate not supplied

Trauma and nontrauma cardiopulmonary arrest: a national survey.

INTRODUCTION: This survey attempts to identify the current standard of care for the air medical transport of the patient in cardiopulmonary arrest. METHOD: An Association of Air Medical Services/National Flight Nurses Association-approved survey by a single mailing with an anonymous response. SETTING: All rotor-craft programs with current memberships in AAMS. RESULTS: Fifty-three of the 178 questionnaires mailed were returned. Program demographics, crew composition and transport volumes were typical of other reported national experiences. The majority of programs (84%) had standing operational protocols for trauma and non-trauma cardiopulmonary arrests. The indications for not initiating or discontinuing CPR, the transport of the patient in cardiopulmonary arrest, triage and financial considerations varied widely between air medical programs. CONCLUSIONS: This study provides some insight on the current air medical management of the patient in cardiopulmonary arrest. National practice guidelines should be developed and tested prospectively in future studies.

Air Ambulances↗