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Biomedical subjects

M A Alexander

Publications and source records attributed to M A Alexander.

At least 19 recordsLinked to original sources
PubMed1992

Intervention program for obese school children.

The purpose of this study was to implement and evaluate a program for obese school children. A pretest-posttest design was utilized. Data was collected related to weight status, skinfold measurements, self-esteem, and nutritional knowledge. A convenience sample of 26 children, in the fourth to sixth grades, completed this 9-week program. The results indicate that self-esteem increased significantly (p less than .001) between the pretest and posttest interval. Weight status and nutritional knowledge showed no improvement. Exercise was difficult to assess on self-report, therefore no conclusions were were drawn in relation to this variable. Future research will be directed toward refining this intervention program.

Child↗
PubMed1992

Early detection of heterotopic ossification in young patients with traumatic brain injury.

Heterotopic ossification (HO) is frequently a complication in patients with severe head injury, impeding the rehabilitation process. Detection of HO is often delayed until the appearance of clinical manifestations. To better characterize the frequency and distribution of HO, a three-year prospective study at a pediatric brain injury rehabilitation unit was done. Triple-phase bone scans were performed routinely on all patients. Early intervention followed, with intensive physical therapy and indomethacin. We report an incidence of HO in 25 of 111 cases (22.5%). Of 55 sites identified, the hip was most commonly affected. Clinically significant heterotopic bone impeded the rehabilitation process in five patients (20%), although none of these patients required surgical intervention. Bone scanning identified HO in patients whose symptoms were clinically silent, as well as in those who were symptomatic. In addition, multiple sites of involvement were found in areas not clinically suspect. This study suggests that HO may be more prevalent in young, traumatically brain injured patients than previously suspected.

Adolescent↗
PubMed1992

Postoperative heterotopic ossification in the child with cerebral palsy: three case reports.

Three children with cerebral palsy and mental retardation showed irritability after surgical procedures. They were subsequently diagnosed as having heterotopic ossification. Heterotopic ossification developed around the hip in all cases--two after bilateral adductor releases at the operative site and the third after spinal fusion at a site unrelated to the surgery.

Adult↗
PubMed1991

Correlation between CD8 dependency and determinant density using peptide-induced, Ld-restricted cytotoxic T lymphocytes.

We have taken advantage of some unique properties of H-2Ld to investigate the determinant density requirements for cytotoxic T lymphocyte (CTL) priming versus effector function and to correlate the determinant density requirements with CD8 dependency. In a previous study (Lie, W.-R., N. B. Myers, J. Gorka, R. J. Rubocki, J. M. Connolly, and T. H. Hansen. 1990. Nature [Lond.]. 344:439), we demonstrated that culturing normal cells with peptides known to be restricted by H-2Ld led to a two- to fourfold increase in surface Ld expression. In the present study, we demonstrate the generation of Ld-restricted, peptide-specific in vitro primary CTL by culturing spleen cells with murine cytomegalovirus or tum- peptide at concentrations previously shown to result in maximum induction of Ld expression. Target cells can be sensitized for recognition by these CTL with lower dose of peptide than are required for the primary sensitization. This demonstrates differences in the determinant density requirements for priming versus effector function. The in vitro primary CTL generated with peptide can weakly lyse target cells that express the determinant endogenously, and CTL lines and clones capable of strong lysis of endogenous expressors are easily obtained. In both cases, target cells treated with exogenous peptide are lysed better than target cells expressing antigen endogenously. This suggested that there are differences in the determinant density of peptide-fed versus endogenous targets. This interpretation was substantiated when it was observed that the level of lysis of target cells expressing endogenous determinants correlated inversely with the amount of peptide required to sensitize targets for recognition by various tum- -specific CTL clones. Furthermore, simultaneous titration of both the peptide used to treat target cells and the antibody to CD8 revealed that the various CTL clones analyzed displayed widely disparate CD8 dependencies. In each case, the CD8 dependency correlated inversely with the determinant density requirement. Therefore, CD8 dependency of CTL is relative, but shows an absolute and quantitative correlation with their dependency on determinant density. These findings suggest that under physiologic conditions, where only low determinant densities are likely to be encountered, all CTL clones will show at least partial CD8 dependency.

Amino Acid Sequence↗
PubMed1991

Metabolism of ethanol by rat hepatocytes results in generation of a lipid chemotactic factor: studies using a cell-free system and role of oxygen-derived free radicals.

We have reported that liver cells metabolizing ethanol release a lipid that has chemotactic activity for human polymorphonuclear leukocytes. The purpose of the present study was to investigate the role of ethanol and of oxygen-derived free radicals in generation of this activity. A cell-free, ethanol-metabolizing system consisting of rat liver cytosol was found to generate a polar lipid which possessed a chemotactic activity identical to the activity from intact cells. The importance of acetaldehyde in this process was established by the findings that (i) an inhibitor of the metabolism of ethanol to acetaldehyde, 4-methylpyrazole, blocked production of the chemotactic lipid; (ii) acetaldehyde could substitute for ethanol; and (iii) cytosol alone incubated with ethanol in the absence of mitochondrial acetaldehyde metabolism generated the activity. Acetaldehyde can serve as a substrate for cytosolic oxidases in reactions that generate radicals (e.g., superoxide anion) which have been shown to attack unsaturated lipids to yield lipid hydroperoxides. When scavengers of oxygen-derived free radicals (superoxide dismutase, catalase, and dimethylsulfoxide) were added to the ethanol-metabolizing system they prevented generation of the activity. The data are consistent with a mechanism of chemotactic factor generation by ethanol-metabolizing liver cytosol in which acetaldehyde causes formation of oxygen-derived free radicals that attack unsaturated cytosolic lipid to generate a polar chemotactic compound.

Animals↗
PubMed1991

Obesity in Mexican-American preschool children--a population group at risk.

This research built on our previous work focusing on the Mexican-American population as one group at risk for the development of obesity. The purpose of this study was to explore the relationship among knowledge of nutrition, feeding practices, values, and select demographic variables of Mexican-American mothers and obesity in their preschool children. One hundred forty-three mothers of children were recruited to participate. Each mother was interviewed and asked to complete questionnaires regarding maternal nutrition knowledge, maternal feeding practices, weight locus of control, and ideal infant body habitus. Compared to thin infants and their mothers, obese children had a significantly greater mean birth weight and their mothers had a significantly greater body mass index. Analysis of responses to the ideal infant body habitus scale revealed that mothers of obese children selected a chubby baby as ideal significantly more often than mothers of nonobese children. The data collected from this study can alert public health nurses to children at risk for obesity.

Chi-Square Distribution↗
PubMed1991

Factors associated with obesity in school children.

Factors associated with obesity in school children, based on current research in the field, are described. Both family environment and individual characteristics have been shown to relate to children's weight status. Research to date supports the complex interrelationships between nutritional knowledge, feeding practices, values, and select demographic variables and the development of obesity in school children. An example of an ethnic group at risk for the development of obesity is provided. The present study suggests implications for school nursing practice in relation to the problem of obesity in children.

Child↗
PubMed1990

Obesity in children: a research update.

Factors associated with obesity in children are described based on current research in the field. Consideration is given to the family environment as well as to individual characteristics that have been shown to relate to children's weight status. Research to date supports the complex interrelationships between nutritional knowledge, feeding practices, values, and select demographic variables and the development of obesity in children. This article suggests areas for further research to advance understanding of obesity in children.

Child↗
PubMed1989

Defective antigen presentation by human melanoma cell lines cultured from advanced, but not biologically early, disease.

The present studies were undertaken to characterize Ag presentation by cultured human melanoma cell lines. Cell lines established from "biologically early" lesions of malignant melanoma were able to present the soluble Ag tetanus toxoid (TT) to autologous and HLA-DR-matched allogeneic, TT-immune T cell clones. Proliferation of T cell clones in response to Ag presented by primary melanoma peaked on day 2 of culture with Ag. Ag presentation was blocked by pretreatment of TT-pulsed and fixed melanoma cells with mAb against HLA-DR, but not HLA-DQ, HLA-DP, or HLA-ABC. Ag processing and presentation were inhibited by treating the melanoma cells with ammonium chloride. In parallel with previous findings from this laboratory demonstrating the inability of cell lines cultured from "advanced" primary or metastatic melanoma to induce autologous T cell proliferation, such cell lines also failed to present this exogenous Ag despite the presence of cell-surface HLA-class II molecules. Thus, in contrast to the finding in biologically early melanoma, none of the multiple TT-immune, T cell clones from autologous patients or HLA-DR matched donors was able to respond to TT presented by melanoma cells cultured from advanced disease. Co-incubation studies revealed that metastatic melanoma cells did not secrete inhibitory substances during the APC assay, however, they were able to process TT, rendering it "immunogenic" in the presence of fixed, autologous non-T cells. When fixed, autologous melanoma cells were assayed for their ability to present processed Ag; fixed cells of early but not advanced disease were able to present Ag in this setting, indicating that the presenting limb becomes flawed in the evolution of the metastatic phenotype. Finally, studies of chloroquine inhibition of the capacity of melanoma cells derived from early primary disease to stimulate autologous peripheral blood T cells suggest that such cells process and present tumor-associated Ag in the same fashion as the "model" Ag TT.

Ammonium Chloride↗
PubMed1989

Myelomeningocele: comprehensive treatment.

The management of children born with myelomeningocele is now extended over an entire lifespan. Rehabilitation specialists managing these children must understand the initial anatomic dysfunction, its interaction with normal child development, and the effect of normal aging on pediatric-onset disabilities. A model for an interdisciplinary process that keeps the final goals of any child-onset disability in mind is discussed. A review of current medical, surgical, and behavioral interventions for these children is also presented.

Adolescent↗
PubMed1988

Treatment of adult lower extremity lymphedema with the Wright linear pump: statistical analysis of a clinical trial.

Seventy-three adult lymphedema patients with 78 affected lower extremities were treated with the Wright Linear Pump. All patients were admitted for a 48-hour clinical trial. Comparison of circumferential limb measurements before and after a 48-hour treatment period using a repeated measures analysis of variance showed statistically significant improvement (p less than 0.00005). Although the improvement appeared to be somewhat more pronounced for men than for women, both sexes experienced an important reduction in leg circumference after therapy. Other factors such as age, etiology, previous use of the Jobst pump, or duration of lymphedema did not appear to influence the extent of improvement. These data clearly indicate that the Wright Linear Pump is an effective treatment for lower extremity lymphedema in adults.

Adolescent↗
PubMed1987

Interferon-gamma regulates the T cell response to precursor nevi and biologically early melanoma.

To examine the potential regulatory role of interferon-gamma in the cellular immune response to melanoma and its precursor lesions, we have tested the capacity of this lymphokine to enhance HLA class II antigen-dependent T lymphocyte blastogenesis, its in vitro production by autologous T cells stimulated by melanoma, and its presence in melanocytic lesions in situ. Cell lines derived from a dysplastic nevus, a radial growth phase primary tumor, a vertical growth phase primary, and metastatic lesions were induced by recombinant interferon-gamma to express increased amounts of HLA class II antigens. Such cells were then examined in radioimmunoassay for expression of HLA-DR antigens and in co-culture for their ability to stimulate proliferation of autologous T cells. Interferon-gamma treatment of melanocytic cells increased their expression of HLA-DR antigens threefold to sixfold. In parallel with these findings, co-culture of T cells with interferon-treated cells of a dysplastic nevus and a radial phase melanoma led to augmented T cell incorporation of tritiated thymidine, and this stimulation was inhibited with a monoclonal antibody to HLA-DR antigens. Despite augmented expression of HLA class II antigens (HLA-DR, -DQ, and -DP), vertical growth phase and metastatic melanoma cells failed to stimulate autologous T cells. When T cells were co-cultured with stimulating melanoma cells, culture supernatants contained significantly increased amounts of interferon-gamma (12 U/ml) in comparison with supernatants of T cells alone (4 U/ml). No interferon was detectable in cultures of melanoma cells alone. To link these in vitro phenomena to in situ events, we used murine monoclonal antibodies to interferon-gamma, the interleukin 2 receptor, and HLA-DR antigens in an immunoperoxidase system to detect interferon production and lymphocyte activation in frozen sections of lesions representative of melanocytic tumor progression. In these studies, precursor dysplastic nevi and radial phase melanomas contained the highest numbers of activated lymphocytes and stained positively for interferon-gamma. These results suggest that interferon-gamma plays a central role in the regulation of the cellular immune response to melanoma. It is produced by T cells, likely activated by tumor antigens seen in the context of HLA class II antigens. In turn, interferon-gamma production enhances expression of HLA class II antigens by melanoma and precursor cells, and such enhancement is associated with additional T cell activation in a positive feed-back loop.

Antigens, Neoplasm↗
PubMed1987

Small-airways disease in recipients of allogeneic bone marrow transplants. An analysis of 11 cases and a review of the literature.

In a retrospective review of 116 consecutive allogeneic bone marrow transplants (BMT), severe obstructive airways disease was identified in 11 patients. Lung pathology demonstrated bronchiolitis in 9 patients and physiologic studies showed small-airways disease consistent with bronchiolitis in the other 2. None of the 5 patients with associated infection survived, while 3 of the 6 patients without an identified pathogen stabilized or improved. Analysis of the 11 cases presented and all 25 cases reported in the literature (1982 to 1985) supports the conclusion that graft-versus-host disease is a major risk factor for bronchiolitis in BMT recipients. Among the proposed mechanisms for the development of bronchiolitis after allogeneic BMT, the 2 most likely are graft-versus-host disease directly causing bronchiolitis, and increased immunosuppressive therapy given for graft-versus-host disease predisposing to viral bronchiolitis. The available evidence would suggest that it is prudent to obtain serial pulmonary function tests even in asymptomatic patients post-BMT, and particularly in those with chronic graft-versus-host disease, in the hope that early detection will allow for early intervention that will arrest or reverse the progression of the obstructive airways disease.

Adolescent↗