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Biomedical subjects

L H Bryant

Publications and source records attributed to L H Bryant.

10 recordsLinked to original sources
PubMed2003

Combination of transfection agents and magnetic resonance contrast agents for cellular imaging: relationship between relaxivities, electrostatic forces, and chemical composition.

The purpose of this study was to investigate the changes in electrostatic and magnetic resonance (MR) properties observed when MR contrast agents (CAs) (Feridex, MION-46L, or G5-dendrimer-DOTA-Gd) are combined with transfection agents (TAs) under various conditions for use as a CA-TA complex basis for cellular labeling and MRI. CAs were incubated with various classes of TAs for 0-48 hr in solutions of varying concentrations and pH values. NMR relaxation rates (1/T(1), 1/T(2)), MRI and zeta potential (ZP) of CA-TA solutions were measured. TAs decreased the 1/T(1) and 1/T(2) of G5-DOTA-Gd, Feridex, and MION-46L by 0-95%. Altering the pH of G5-DOTA-Gd-TA decreased the T(1)-weighted signal intensity (SI) on MRI from 0 to 78%. Measured ZP values for G5-DOTA-Gd, Feridex, and MION-46L were -51, -41, and -2.0 mV, respectively. The TA LV had a negative ZP, while the other TAs had ZPs ranging from +20 to +65 mV. The alteration of the ZP and NMR relaxivities of the MR CAs, Feridex, MION-46L, and G5-DOTA-Gd by TAs has been demonstrated. These results enhance our understanding of the relationship between electrostatic and MR properties.

Cells, Cultured↗
PubMed2001

Synthesis of DTPA analogues derived from piperidine and azepane: potential contrast enhancement agents for magnetic resonance imaging.

Two DTPA derivatives (PIP-DTPA and AZEP-DTPA) as potential contrast enhancement agents in MRI are synthesized. The T1 and T2 relaxivities of their corresponding Gd(III) complexes are reported. At clinically relevant field strengths, the relaxivities of the complexes are comparable to that of the contrast agent, Gd(DTPA) which is in clinical use. The serum stability of the (153)Gd-labeled complexes is assessed by measuring the release of (153)Gd from the ligands. The radiolabeled Gd chelates are found to be kinetically stable in human serum for up to at least 14 days without any measurable loss of radioactivity.

Contrast Media↗
PubMed1999

Synthesis and relaxometry of high-generation (G = 5, 7, 9, and 10) PAMAM dendrimer-DOTA-gadolinium chelates.

A series of high-generation (G) ethylenediamine-core polyamidoamine (PAMAM) dendrimers corresponding to G = 5, 7, 9, and 10 were conjugated with the bifunctional chelate 2-(4-isothiocyanatobenzyl)- 1,4,7,10-tetraazacyclododecane-N,N',N",N"'-tetraacetate (p-SCN-Bz-DOTA). Gadolinium (III) ion was added to the macromolecules, and the 1/T1 and 1/T2 NMRD profiles were measured at 3 degrees, 23 degrees, and 37 degrees C. The synthesis resulted in preparations that ranged from an average of 127 chelates and 96 Gd3+ ions per G = 5 dendrimer to an average of 3727 chelates and 1860 Gd3+ ions per G = 10 dendrimer. At 20 MHz and 23 degrees C, the 1/T1 ion relaxivity increased from 30 mM(-1) s(-1) for the G = 5 to 35 mM(-1) s(-1) for the G = 7 PAMAM dendrimer-DOTA-Gd, reaching a plateau at 36 mM(-1) s(-1) for the G = 9 and G = 10 dendrimers. A similar plateau was observed for 1/T2 with values of 36 mM(-1) s(-1) for G = 5, 42 mM(-1) s(-1) for G = 7, and 45 mM(-1) s(-1) for the G = 9 and G = 10 dendrimers. This "saturation" of ion relaxivity for high-generation dendrimers occurred over the entire frequency range studied. The 1/T1 and 1/T2 relaxivities decreased as the temperature decreased for each generation of dendrimer studied, implying that slow water exchange of bound water molecules with the bulk solvent limits the relaxivity. In such circumstances, increases in the rotational correlation time of the macromolecules associated with higher generations of dendrimer does not result in significant increases in the ion relaxivity. Although the ion relaxivity does not increase, the total molecular relaxivities increased from 2880 mM(-1) s(-1) to 66960 mM(-1) s(-1) for the G = 5 to the G = 10 dendrimer. The current findings are relevant for the design of high-generation dendrimer-based receptor agents.

Contrast Media↗
PubMed1999

Relaxometry and magnetometry of the MR contrast agent MION-46L.

MION-46L is an ultrasmall monocrystalline superparamagnetic (SPM) iron oxide that is of current interest as an MR contrast agent. It is believed to consist primarily of small maghemite or magnetite crystals that possess a SPM moment, but the exact magnetic properties and related mechanisms of T(1) and T(2) proton relaxation enhancement are not well understood. We have obtained a comprehensive data set consisting of magnetization curves, EPR spectra, and 1/T(1) and 1/T(2) nuclear magnetic relaxation dispersion (NMRD) profiles for this contrast agent. The magnetization curves show a primary curvature consistent with a SPM moment of 10,300 Bohr magnetons (BM) per particle. In addition, there is a secondary high-field curvature that is consistent with a smaller SPM moment of 1600 BM, which may be responsible for the observed high-field increase in 1/T(2). Finally, there appear to be a considerable number of paramagnetic ions present that are needed to account for the high-field increase in magnetization, and that can provide an alternative explanation for the magnitude of the low-field T(1) plateau. This "three-phase model" appears to be successful in explaining in a self-consistent and quantitative manner the combined results of the magnetometry, relaxometry, and EPR studies. Magn Reson Med 42:379-384, 1999. Published 1999 Wiley-Liss, Inc.

Contrast Media↗
PubMed1997

Impact of parental anxiety on child emotional adjustment when a parent has cancer.

PURPOSE/OBJECTIVES: To describe the relationships among parent anxiety, child anxiety, and emotional adjustment in children who have a parent with cancer. DESIGN: Correlational. SETTING: A large cancer center in the southeastern United States. SAMPLE: Thirty-three child/parent with cancer dyads. METHODS: Research packets were mailed to child/parent dyads who agreed to participate in the study. Parents completed a demographic questionnaire, a Spielberger State-Trait Anxiety Scale, and a Personality Inventory for Children (PIC). Children completed the child version of the Spielberger State-Trait Anxiety Scale. MAIN RESEARCH VARIABLES: Parent anxiety, child anxiety, and child adjustment. FINDINGS: Children who have a parent with cancer and parents who have experienced cancer report significantly higher state and trait anxiety compared to a normed population sample. Parental reports on the PIC indicated that latency-aged children (i.e., 6-12 years) showed significantly greater internalization and somatic symptoms compared to the sample norm. Parent state anxiety was negatively correlated with children's internalization and somatic symptoms. Parental anxiety accounted for the greatest variance in child adjustment. IMPLICATIONS FOR NURSING PRACTICE: These study findings may provide nurses with a better understanding of the vulnerability of children who have a parent with cancer and can build a foundation for the development of supportive interventions for these children.

Adaptation, Psychological↗
PubMed1990

The patient/physician relationship in the management of diabetes mellitus.

Patients with Type I diabetes mellitus are most concerned about the possibility of developing complications or disability related to their disease and really have very little concern regarding the pain of insulin injections or blood sugar monitoring. Just understanding patients' primary concerns may enable physicians to devise a more effective therapeutic program as well as enhance the patient-physician relationship.

Adaptation, Psychological↗
PubMedDate not supplied

Proactive psychosocial care of blood or marrow transplant patients.

PURPOSE: The authors describe a proactive model of psychosocial care for patients undergoing blood or marrow transplantation and their families. DESCRIPTION OF PROGRAM: This program for blood or marrow transplantation patients, developed at the Center for Cancer Treatment and Research, Richland Memorial Hospital, and the University of South Carolina School of Medicine in Columbia, South Carolina, involves pretransplant comprehensive psychosocial assessment; development and implementation of an individual psychosocial treatment plan; monitoring and medical management of neuropsychiatric problems; and psychotherapeutic sessions with a psychiatrist. These functions are achieved through the use of a multidisciplinary psychosocial team and ongoing consultation-liaison with the entire blood or marrow transplantation team. CLINICAL IMPLICATIONS: This positive, proactive model demonstrates significant benefit to patients, families, and the blood or marrow transplantation healthcare team. Benefits of this model are derived from psychosocial assessment during work-up, subsequent planning, and communication with the entire team, thus allowing early identification of problems and avoiding escalation and the likelihood of negative outcomes. Less energy is exerted and less resources expended when problems are resolved with early intervention rather than with intensive interventions during transplant. The psychosocial staff members develop strong relationships with patients and families before transplant, increasing the power of interventions and receptivity of the patient. The blood or marrow transplantation team benefits from the ongoing presence of psychosocial staff and the consistency of approaches offered by team members. An integral part of this approach is teaching psychosocial care to all staff members and modeling approaches to problems. Other blood or marrow transplantation centers and centers providing other intensive anticancer therapies may benefit by adapting this model into the day-to-day care of their patients.

Blood Transfusion↗