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Biomedical subjects

C L Young

Publications and source records attributed to C L Young.

At least 37 records · Page 2Linked to original sources
PubMed1990

Chondrosarcoma of bone in children.

Chondrosarcoma of bone rarely occurs in children. This report analyzes the clinicopathologic features in a series of 47 patients with conventional chondrosarcoma who were less than 17 years of age. Of the 47 cases, 14 were from the Mayo Clinic files, and 33 were from our consultation files. Most of the lesions occurred in the trunk and upper ends of the long bones, with the humerus being the most frequent skeletal site. Twelve of the 47 tumors were secondary. The radiographic findings were the same as those seen in adult chondrosarcoma. Pathologically, the tumors were low grade. En bloc resection is the treatment of choice because of the high incidence of local recurrence with lesser surgical margins. Prognosis in childhood chondrosarcoma is no different from that in adult chondrosarcoma. None of the patients with follow-up data had metastasis.

Adolescent↗
PubMed1990

Kinetics of the interaction of a 41-kilodalton macrophage capping protein with actin: promotion of nucleation during prolongation of the lag period.

A 41-kilodalton macrophage capping protein (MCP) has been isolated which is capable of forming complexes with actin monomers in addition to capping the barbed ends of actin filaments (Southwick & DiNubile, 1986). The protein is calcium activated in a fully reversible manner. Using kinetic assays, we determined a capping constant, defined here as a modified Kd, of 1 nM and a Kd of 3-4 microM for MCP-actin monomer complex formation. MCP weakly nucleates actin polymerization: more than 0.5 microM MCP is necessary to shorten the lag period, and 1 microM MCP at an actin/MCP ratio of 10 reduces the average length of actin filaments to about 200 molecules per filament. We determined that the actin nucleus that survives MCP inactivation contains a minimum number of five actin molecules. These experiments also make a point with respect to the interpretation of the prolongation of the lag period. We directly demonstrate that in the presence of an actin binding protein a prolongation of the lag period can be associated with increased nucleation, contrary to the usual interpretation in the literature that it indicates no or decreased nucleation by the actin binding protein.

Acrosome↗
PubMed1990

Efficacy, toxicity, pharmacokinetics, and in vitro metabolism of the enantiomers of ifosfamide in mice.

The enantiomers of the anticancer drug ifosfamide, (+)-(R)-IFF and (-)-(S)-IFF, were prepared from the racemic compound rac-IFF using enantioselective liquid chromatographic techniques. The efficacy, toxicity, and pharmacokinetics of the individual enantiomers and rac-IFF were studied in mice. The results of the studies indicate that there were no statistically significant differences between the efficacy of (+)-(R)-IFF, (-)-(S)-IFF, and rac-IFF against childhood rhabdomyosarcoma (HxRh28) maintained in vivo as a xenograft in immune-deprived female CBA/CaJ mice. Similar results were found in toxicity and pharmacokinetic studies conducted in non-tumor-bearing female CBA/CaJ mice. The production of two major metabolites, aldoifosfamide and isophosphoramide mustard, by mice hepatic microsomes from non-tumor-bearing female CBA/CaJ mice was also investigated. There were no statistically significant differences in the calculated kinetic parameters, Vmax and Km, of the production of these two metabolites when the separate enantiomers or the racemic mixture were used as substrate.

Animals↗
PubMed1990

The actin released from profilin--actin complexes is insufficient to account for the increase in F-actin in chemoattractant-stimulated polymorphonuclear leukocytes.

Chemoattractant stimulation of polymorphonuclear leukocytes is associated with a nearly two-fold rise in actin filament content. We examined the role of the actin monomer sequestering protein, profilin, in the regulation of PMN actin filament assembly during chemoattractant stimulation using a Triton extraction method. Poly-L-proline-conjugated Sepharose beads were used to assess the relative concentration of actin bound to profilin with high enough affinity to withstand dilution (profilin-actin complex) and DNase I-conjugated beads to measure the relative concentration of actin in the Triton-soluble fraction not bound to profilin. Actin associated with the Triton-insoluble fraction (F-actin) was also measured. In unstimulated PMN, the relative concentration of actin bound to profilin was maximum. After FMLP stimulation, profilin released actin monomers within 10 s, with the profilin-actin complex concentration reaching a nadir by 40 s and remaining low as long as the cells were exposed to chemoattractant (up to 30 min). If FMLP was dissociated from PMN membrane receptors using t-BOC, actin reassociated with profilin within 20 s. Quantitative analysis of these reactions, however, revealed that profilin release of and rebinding to actin could account for only a small percentage of the total change in F-actin content. Determination of the total profilin and actin concentrations in PMN revealed that the molar ratio of profilin to actin was 1 to 5.2. When purified actin was polymerized in PMN Triton extract containing EGTA, removal of profilin from the extract minimally affected (12% reduction) the high apparent critical concentration at which actin began to assemble. Although profilin released actin at the appropriate time to stimulate actin assembly during exposure to chemoattractants, the concentration of profilin in PMN was insufficient to explain the high unpolymerized actin content in unstimulated PMN and the quantity of actin released from profilin too small to account for the large shifts from unpolymerized to polymerized actin associated with maximal chemoattractant stimulation.

Actins↗
PubMed1989

The determination of (-)-(S)- and (+)-(R)-ifosfamide in plasma using enantioselective gas chromatography: a validated assay for pharmacokinetic and clinical studies.

An enantioselective gas chromatographic method has been developed and validated for the determination of the plasma concentration of the enantiomers of the anticancer drug ifosfamide (IFF). In this approach, the IFF enantiomers are separated from the plasma matrix by solid phase extraction, chromatographically resolved by gas chromatography on a chiral stationary phase, and detected by mass selective detection using selective ion monitoring. The assay has been validated for routine clinical and pharmacokinetic use and has a limit of detection in plasma of 250 ng/ml of each isomer.

Chromatography, Gas↗
PubMed1989

Adolescent third-trimester enrollment in prenatal care.

This study reports the demographic and reproductive characteristics of 87 adolescents (11-19 years of age) who entered prenatal care during the third trimester of pregnancy at a publicly funded program during a 6-month period of 1987-1988, as well as their self-reported reasons for delayed prenatal care. The findings suggest that concealment of the pregnancy was the primary reason for younger adolescents (11-17 years), while poor motivation to attend prenatal care was often cited by the older adolescents (18-19 years). Older adolescents appeared to be particularly at risk for poor pregnancy outcome: 63% were mothers; the identified pregnancy was the third child for 20%; 42% smoked during pregnancy; and 22% entered care during the period from 36 to 41 weeks of gestation. The apparently poor motivation to attend prenatal care and the closely spaced pregnancies of this age group suggest that the second and third children of adolescent mothers may be a particularly vulnerable pediatric population.

Adolescent↗
PubMed1989

Psychosocial influences on research subject recruitment, enrollment and retention.

Psychosocial factors may profoundly affect the successful implementation of a research study. The purpose of this paper is to describe psychosocial influences on the researcher-participant interaction during: (1) recruitment, (2) enrollment, and (3) retention and to provide guidelines for effective implementation of a study within a clinical health care setting. An interdisciplinary teamwork approach was used to identify and to resolve psychosocial issues. A study of 4781 family planning patients will be used as the case example.

Adolescent↗
PubMed1988

Primary leiomyosarcoma of bone.

Adequate treatment of primary leiomyosarcoma of bone requires surgical ablation with the goals being those for any malignant tumor of bone--eradication of the lesion and preservation of as much function as possible. Careful preoperative staging will determine whether amputation is necessary or whether successful limb-saving resection is possible.

Aged↗
PubMed1988

Afraid of death.

Explore the source record for details and available documents.

Attitude of Health Personnel↗
PubMed1987

Family planning utilization by black and white women: public health social work implications.

Black infant mortality is one of the most serious and long-standing public health problems in the United States. This article reports the findings of a study of the family planning records of 1143 residents of a city with one of the highest black infant mortality rates. The importance of increased social work involvement in the federally funded family planning system and specific social work strategies are discussed as methods to reduce black infant mortality.

Adolescent↗
PubMed1986

Rehabilitation team and family assessment of the initial home pass.

Brain-injured individuals may have neurologic damage resulting in physical, cognitive and personality sequelae. Rehabilitation promotes recovery for these patients by restoring cognitive and social functions and focusing attention on medical-physical and cognitive-social intervention. A major component in rehabilitation is to teach family members to understand the process of recovery and their role in teaching and reinforcing desired behaviors at home. To investigate the utility of the family's role, we studied the effects of allowing patients to return to the home/family environment for short stays (therapeutic pass). By comparing functional ratings obtained from family and rehabilitation team members, we found families rated brain-injured patients higher in medical-physical areas and more equally in cognitive-social areas. Although we do not control for the family's frame of reference regarding the patient's premorbid status, we conclude that impaired cognitive functioning has a profound impact on family members who, like the patient, must make adjustments because of the disability. We recommend therapeutic passes as a meaningful tool in the process of educating families about the disability, its scope and impact, as well as its accompanying effects on cognitive and social functioning.

Brain Injuries↗
PubMed1986

Social work roles in collaborative research.

Social workers in health care settings may be most effective in the development and implementation of collaborative research studies which jointly involve academic and health service institutions. This article describes: organizational issues significant to the integration of research into a health service system; interpersonal issues that effect the perspectives of research and service professionals in the daily operation of the research project; and social work skills for collaborative research studies. An on-going 5-year collaborative research study of approximately 7,000 participants will be used as a case example.

Data Collection↗