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Biomedical subjects

J A Wright

Publications and source records attributed to J A Wright.

At least 37 records · Page 2Linked to original sources
PubMed1999

fas-mediated lysis of chronic lymphocytic leukaemia cells: role of type I versus type II cytokines and autologous fasL-expressing T cells.

Given the known role of the fas cytolytic pathway in B-cell regulation, we evaluated whether fas-fasL interactions might induce chronic lymphocytic leukaemia (CLL) cell death. De novo CLL cells expressed a low level of surface fas, and were not lysed by fasL-bearing cells. CLL cells cultured in media containing the type I cytokines interleukin (IL)-12 or interferon (IFN)-alpha had increased fas expression, and were readily lysed by fasL-bearing cells. In contrast, the type II cytokine IL-4 did not increase CLL cell fas, and abrogated type I cytokine-induced fas up-regulation. With prolonged culture, IL-4 exposed CLL cells expressed an intermediate level of fas; however, such CLL cells were resistant to fas-mediated lysis. These results indicate that IL-4 inhibits fas-mediated killing of CLL cells at the level of both fas receptor expression and post-receptor events. Additionally, we have defined in vitro culture conditions which generate fasL-bearing T cells from CLL patients; such T cells efficiently mediated fas-based lysis of autologous fas-positive CLL cells. We therefore conclude that type I and type II cytokines differentially regulate the fas pathway in CLL cells, and that a combination of type I cytokines and fasL-expressing T cells may represent a new approach to the immunotherapy of CLL.

Apoptosis↗
PubMed1999

Is greater continuity of care associated with less emergency department utilization?

BACKGROUND: The benefits of continuity of care (COC) have not been firmly established for pediatric patients. OBJECTIVE: To assess whether greater COC is associated with lower emergency department (ED) utilization. SETTING: Outpatient teaching clinic at Children's Hospital and Regional Medical Center, Seattle, WA. PATIENTS: All 785 Medicaid managed care children ages 0 to 19 years followed at Children's Hospital and Regional Medical Center between 1993 to 1997 who had at least four outpatient visits. METHODS: Retrospective claims-based analysis. COC was quantified based on the number of different care providers in relation to the number of clinic visits. RESULTS: Attending COC was significantly greater than resident COC. In a multiple event survival analysis, compared with those patients in the lowest tertile of attending COC, those in the middle tertile had 30% lower ED utilization (hazard ratio 0.70 [0.53-0.93]) and those in the highest tertile had 35% lower ED use (hazard ratio 0.65 [0.50-0.80]). Resident COC was not significantly associated with ED use. CONCLUSION: Greater COC with attending physicians in outpatient teaching clinics is associated with lower ED utilization.

Adolescent↗
PubMed1999

Organization of chromatin in cancer cells: role of signalling pathways.

The role of mechanical and chemical signalling pathways in the organization and function of chromatin is the subject of this review. The mechanical signalling pathway consists of the tissue matrix system that links together the three-dimensional skeletal networks, the extracellular matrix, cytoskeleton, and nuclear matrix. Intermediate filament proteins are associated with nuclear DNA, suggesting that intermediate filaments may have a role in the organization of chromatin. In human hormone-dependent breast cancer cells, the interaction between cytokeratins and chromatin is regulated by estrogens. Transcription factors, histone acetyltransferases, and histone deacetylases, which are associated with the nuclear matrix, are components of the mechanical signalling pathway. Recently, we reported that nuclear matrix-bound human and chicken histone deacetylase 1 is associated with nuclear DNA in situ, suggesting that histone deacetylase has a role in the organization of nuclear DNA. Chemical signalling pathways such as the Ras/mitogen-activated protein kinase (Ras/MAPK) pathway stimulate the activity of kinases that modify transcription factors, nonhistone chromosomal proteins, and histones. The levels of phosphorylated histones are increased in mouse fibroblasts transformed with oncogenes, the products of which stimulate the Ras/MAPK pathway. Histone phosphorylation may lead to decondensation of chromatin, resulting in aberrant gene expression.

Amino Acid Sequence↗
PubMed1998

Ras-associated nuclear structural change appears functionally significant and independent of the mitotic signaling pathway.

An altered nuclear morphology has been previously noted in association with Ras activation, but little is known about the structural basis, functional significance, signaling pathway, or reproducibility of any such change. We first tested the reproducibility of Ras-associated nuclear change in a series of rodent fibroblast cell lines. After independently developing criteria for recognizing Ras-associated nuclear change in a Papanicolaou stained test cell line with an inducible H(T24)-Ras oncogene, two cytopathologists blindly and independently assessed 17 other cell lines. If the cell lines showed Ras-associated nuclear change, a rank order of increasing nuclear change was independently scored. Ras-associated nuclear changes were identified in v-Fes, v-Src, v-Mos, v-Raf, and five of five H(T24)-Ras transfectants consisting of a change from a flattened, occasionally undulating nuclear shape to a more rigid spherical shape and a change from a finely textured to a coarse heterochromatic appearance. Absent or minimal changes were scored in six control cell lines. The two cytopathologists' independent morphologic rank orders were similar (P < .0002). The mitogen signaling pathway per se does not appear to transduce the change since no morphologic alterations were identified in cell lines with activations of downstream components of this pathway--MAPKK or c-Myc--and the rank orders did not correlate with markers of mitotic rate (P > .11). The rank order correlated closely with metastatic potential (P < .0014 and P < .0003) but not with histone H1 composition or global nuclease sensitivity. Based on published studies of five of the cell lines, there may be a correlation between increases in certain nuclear matrix proteins and the Ras-associated nuclear change.

3T3 Cells↗
PubMed1998

Protein kinase mutants of human ATR increase sensitivity to UV and ionizing radiation and abrogate cell cycle checkpoint control.

In fission yeast, the rad3 gene product plays a critical role in sensing DNA structure defects and activating damage response pathways. A structural homologue of rad3 in humans (ATR) has been identified based on sequence similarity in the protein kinase domain. General information regarding ATR expression, protein kinase activity, and cellular localization is known, but its function in human cells remains undetermined. In the current study, the ATR protein was examined by gel filtration of protein extracts and was found to exist predominantly as part of a large protein complex. A kinase-inactivated form of the ATR gene was prepared by site-directed mutagenesis and was used in transfection experiments to probe the function of this complex. Introduction of this kinase-dead ATR into a normal fibroblast cell line, an ATM-deficient fibroblast line derived from a patient with ataxia-telangiectasia, or a p53 mutant cell line all resulted in significant losses in cell viability. Clones expressing the kinase-dead ATR displayed increased sensitivity to x-rays and UV and a loss of checkpoint control. We conclude that ATR functions as a critical part of a protein complex that mediates responses to ionizing and UV radiation in human cells. These responses include effects on cell viability and cell cycle checkpoint control.

Ataxia Telangiectasia Mutated Proteins↗
PubMed1998

The mammalian ribonucleotide reductase R2 component cooperates with a variety of oncogenes in mechanisms of cellular transformation.

Ribonucleotide reductase, which is composed of the two protein components R1 and R2, is a highly regulated enzyme activity that is essential for DNA synthesis and repair. Recent studies have shown that elevated expression of the rate-limiting R2 component increases Raf-1 protein activation and mitogen-activated protein kinase activity and acts as a novel malignancy determinant in cooperation with H-ras and rac-1. We show that R2 cooperation in cellular transformation extends to a variety of oncogenes with different functions and cellular locations. Anchorage-independent growth of cells transformed with v-fms, v-src, A-raf, v-fes, c-myc, and ornithine decarboxylase was markedly enhanced when the R2 component of ribonucleotide reductase was overexpressed. In addition, we observed that elevated R2 expression conferred on c-myc-transformed NIH 3T3 cells an increased tumorigenic potential in immunoincompetent mice. Taken together, these observations demonstrate that the R2 protein is not only a rate-limiting component for ribonucleotide reduction but that it is also capable of acting in cooperation with a variety of oncogenes to determine transformation and tumorigenic potential.

3T3 Cells↗
PubMed1998

Gonadotropin-releasing hormone agonist (GnRH-a) therapy alters activity of plasminogen activators, matrix metalloproteinases, and their inhibitors in rat models for adhesion formation and endometriosis: potential GnRH-a-regulated mechanisms reducing adhesion formation.

OBJECTIVE: To evaluate the effects of a gonadotropin-releasing hormone agonist (GnRH-a) on plasminogen activator (PA), matrix metalloproteinase (MMP), plasminogen activator inhibitor (PAI) and matrix metalloproteinase inhibitor (MMPI) activities in peritoneal fluid relative to GnRH-a-induced reduction of adhesion formation. DESIGN: Continuation of prospective randomized study using surgical models for adhesion formation. SETTING: Department of Obstetrics and Gynecology research laboratory at the University of Missouri School of Medicine. PATIENT(S): Forty reproductively cycling female Sprague-Dawley rats. INTERVENTION(S): Female rats were injected with depot GnRH-a or diluent and randomly assigned to adhesion and endometriosis surgeries. Peritoneal fluid was collected prior to (time 1) and 7 weeks from (time 2) initial surgery. MAIN OUTCOME MEASURE(S): Peritoneal fluid was analyzed for PA, PAI, MMP, and MMPI activities. RESULT(S): At time 1, MMP and MMPI activities were similar in all rats; however, PA and PAI activities were less in rats pretreated with GnRH-a than with diluent. Between time 1 and time 2, GnRH-a-treated rats showed an increase in PAI and MMPI activities without significant changes in PA or MMP activities, whereas rats receiving diluent showed a significant increase in PAI and MMP activities but no significant changes in PA or MMPI activities. At time 2, rats receiving GnRH-a had less PA and MMP activities than those receiving diluent. Adhesion scores showed a positive correlation with MMP activity. CONCLUSION(S): In the absence of GnRH-a therapy, surgical tissue manipulation increased peritoneal fluid MMP and PAI activity. Gonadotropin-releasing hormone agonist therapy decreased PA and MMP activities and also increased PAI and MMPI activities. This GnRH-a-induced shift to a less invasive phenotype may alter fibrinolysis and extracellular matrix remodeling and thereby play a role in the mechanism of GnRH-a-induced reduction in adhesion formation.

Animals↗
PubMed1998

Gestational diabetes and the risk of offspring obesity.

BACKGROUND: Intrauterine exposure to the metabolic alterations of maternal diabetes may increase the risk of later obesity. We determined whether offspring of mothers with diet-treated, gestational diabetes mellitus (GDM) have an increased risk of childhood obesity and examined the relationship between childhood obesity and metabolic markers of GDM. METHODS: At a health maintenance organization in Seattle, WA, we reviewed medical records to obtain the life-time height and weight measurements of 524, 8- to 10-year-old children whose mothers had been screened for GDM. Maternal plasma glucose and triglyceride levels were obtained in midgestation 1 hour after ingestion of 50 g of glucose. Those with glucose screening levels >/=7.77 mmol/L (140 mg/dL) underwent a 3-hour, 100-g, oral glucose tolerance test to determine GDM status. Cord serum insulin levels also were obtained at birth. Obesity was defined as an average body mass index between 5 and 10 years of age at or above the 85th percentile for age and sex. RESULTS: The prevalence of obesity was 19% in the 58 offspring of mothers with diet-treated GDM and 24% in the 257 offspring of mothers with negative glucose screen values. There also was no difference in mean body mass index (adjusted for age and sex) between these two groups of offspring. Among all 524 offspring, there was no significant increase in the rate of offspring obesity according to the quartile of maternal screening glucose, triglyceride, oral glucose tolerance test, or cord serum insulin level. CONCLUSION: Prenatal exposure to the metabolic effects of mild, diet-treated GDM does not increase the risk of childhood obesity.

Adult↗
PubMed1998

Early adiposity rebound and the risk of adult obesity.

OBJECTIVE: At 5 to 6 years of age, body fatness normally declines to a minimum, a point called adiposity rebound (AR), before increasing again into adulthood. We determined whether a younger age at AR was associated with an increased risk of adult obesity and whether this risk was independent of fatness at AR and parent obesity. DESIGN: A retrospective cohort study using lifelong height and weight measurements recorded in outpatient medical records. SETTING: Group Health Cooperative of Puget Sound (GHC), a health maintenance organization based in Seattle, Washington. PARTICIPANTS: All 390 GHC members (and their parents) born at GHC between January 1, 1965, and January 1, 1971, who had at least one recorded adult height and weight measurement plus two visits with recorded height and weight measurements in each of three age intervals: 1.5 to 4, 4 to 8, and 8 to 16 years. MAIN OUTCOME MEASURES: We calculated the mean body mass index (BMI) of each subject during young adulthood (age 21 to 29 years) and the BMI of the parents when each subject was 1.5 years of age. Adult obesity was defined as a BMI >/=27.8 for males and >/=27. 3 for females. Curves were fit to each subject's BMI values between ages 1.5 and 16 years, and the age and BMI at AR were calculated from these curves. Subjects were divided into tertiles of age at AR (early, middle, and late), BMI at AR, and parent BMI (heavy, medium, and lean). RESULTS: The mean age at AR was 5.5 years, and 15% of the cohort was obese in young adulthood. Adult obesity rates were higher in those with early versus late AR (25% vs 5%), those who were heavy versus lean at AR (24% vs 4%), those with heavy versus lean mothers (25% vs 5%), and those with heavy versus lean fathers (21% vs 5%). After adjusting for parent BMI and BMI at AR, the odds ratio for adult obesity associated with early versus late AR was 6.0 (95% CI, 1.3-26.6). CONCLUSION: An early AR is associated with an increased risk of adult obesity independent of parent obesity and the BMI at AR. Future research should examine the biological and behavioral determinants of AR.

Adipose Tissue↗
PubMed1998

Collaborative working practices in schools for children with physical disabilities.

Questionnaires were sent to speech and language therapists (SLTs) and teachers in 83 special schools catering specifically for children with physical disabilities. Sixty two teachers and 47 SLTs responded. The results indicated that there were different patterns of collaborative working in these special schools than had been found in a previous study in schools for children with severe learning disabilities (SLD). The majority of SLTs and teachers were using alternative and augmentative communication systems (AAC) with the children and, in the main, the SLTs introduced the aids to the children and their families. These findings have implications for the specialist training of speech and language therapists.

Child↗
PubMed1998

Myc-epitope tagged proteins detected with the 9E10 antibody in immunofluorescence and immunoprecipitation assays but not in western blot analysis.

A human Myc epitope is frequently used to tag proteins for expression experiments in nonhuman cells. We used the monoclonal 9E10 antibody specific for this epitope to analyse the expression of four proteins carrying the Myc tag in cells transfected with expression vectors. While all four proteins can be detected by immunofluorescence and immunoprecipitation assays, surprisingly, only two proteins could be detected in Western blot analysis, indicating that epitope recognition by the monoclonal antibody can be blocked in some membrane-retained ectopic proteins. Other techniques such as immunofluorescence and immunoprecipitation assays can be successfully used with the 9E10 antibody to determine potential expression of Myc-tagged proteins.

Animals↗
PubMed1997

The R1 component of mammalian ribonucleotide reductase has malignancy-suppressing activity as demonstrated by gene transfer experiments.

Our recent studies have shown that deregulated expression of R2, the rate-limiting component of ribonucleotide reductase, enhances transformation and malignant potential by cooperating with activated oncogenes. We now demonstrate that the R1 component of ribonucleotide reductase has tumor-suppressing activity. Stable expression of a biologically active ectopic R1 in ras-transformed mouse fibroblast 10T(1/2) cell lines, with or without R2 overexpression, led to significantly reduced colony-forming efficiency in soft agar. The decreased anchorage independence was accompanied by markedly suppressed malignant potential in vivo. In three ras-transformed cell lines, R1 overexpression resulted in abrogation or marked suppression of tumorigenicity. In addition, the ability to form lung metastases by cells overexpressing R1 was reduced by >85%. Metastasis suppressing activity also was observed in the highly malignant mouse 10T(1/2) derived RMP-6 cell line, which was transformed by a combination of oncogenic ras, myc, and mutant p53. Furthermore, in support of the above observations with the R1 overexpressing cells, NIH 3T3 cells cotransfected with an R1 antisense sequence and oncogenic ras showed significantly increased anchorage independence as compared with control ras-transfected cells. Finally, characteristics of reduced malignant potential also were demonstrated with R1 overexpressing human colon carcinoma cells. Taken together, these results indicate that the two components of ribonucleotide reductase both are unique malignancy determinants playing opposing roles in its regulation, that there is a novel control point important in mechanisms of malignancy, which involves a balance in the levels of R1 and R2 expression, and that alterations in this balance can significantly modify transformation, tumorigenicity, and metastatic potential.

Animals↗
PubMed1997

Ribonucleotide reductase R2 gene expression and changes in drug sensitivity and genome stability.

Ribonucleotide reductase is a highly regulated, cell cycle-controlled activity that plays an important role in DNA synthesis and repair. Recent studies have shown that elevated expression of the rate-limiting R2 component of ribonucleotide reductase increases Raf-1 protein activation and mitogen-activated protein kinase activity and acts as a novel malignancy determinant in cooperation with activated oncogenes like H-ras. We show that hydroxyurea-resistant mouse L cells with elevated R2 gene expression and increased ribonucleotide reductase activity exhibit significantly decreased sensitivities to the chemotherapeutic compounds N-(phosphonacetyl)-L-aspartate (PALA) and methotrexate (MTX). Furthermore, BALB/c 3T3 cells containing a retroviral expression vector encoding the R2 sequence also showed decreased sensitivity to PALA and MTX when compared to cells containing the same vector but without the R2 coding region. Colonies that developed in the presence of PALA or MTX contained amplifications of the CAD or dihydrofolate reductase genes and exhibited wild-type p53 function as determined in sequence-specific p53 binding activity assays. NIH-3T3 cells containing the R2 retroviral expression vector also showed significantly decreased sensitivity to hydroxyurea and MTX but not to PALA. Furthermore, NIH-3T3 cells transfected with a vector containing the R2 sequence in antisense orientation exhibited increased sensitivity to hydroxyurea, PALA, and MTX. Similarly, mouse 10T1/2 cells that are highly transformed and drug resistant due to alterations in H-ras and a mutant oncogenic form of p53 exhibited significant increases in sensitivity to hydroxyurea, PALA, and MTX when transfected with a vector containing the R2 sequence in antisense orientation and compared to cells containing the same vector without the antisense sequence. These results indicate that altered expression of the R2 component is capable of significantly modifying drug sensitivity properties of tumor cells. We hypothesize that this occurs, at least in part, through a mechanism of increased genetic instability that is independent of direct p53 mutation or loss and involves R2 stimulation of the mitogen-activated protein kinase signal pathway.

3T3 Cells↗
PubMed1997

Predicting obesity in young adulthood from childhood and parental obesity.

BACKGROUND: Childhood obesity increases the risk of obesity in adulthood, but how parental obesity affects the chances of a child's becoming an obese adult is unknown. We investigated the risk of obesity in young adulthood associated with both obesity in childhood and obesity in one or both parents. METHODS: Height and weight measurements were abstracted from the records of 854 subjects born at a health maintenance organization in Washington State between 1965 and 1971. Their parents' medical records were also reviewed. Childhood obesity was defined as a body-mass index at or above the 85th percentile for age and sex, and obesity in adulthood as a mean body-mass index at or above 27.8 for men and 27.3 for women. RESULTS: In young adulthood (defined as 21 to 29 years of age), 135 subjects (16 percent) were obese. Among those who were obese during childhood, the chance of obesity in adulthood ranged from 8 percent for 1- or 2-year-olds without obese parents to 79 percent for 10-to-14-year-olds with at least one obese parent. After adjustment for parental obesity, the odds ratios for obesity in adulthood associated with childhood obesity ranged from 1.3 (95 percent confidence interval, 0.6 to 3.0) for obesity at 1 or 2 years of age to 17.5 (7.7 to 39.5) for obesity at 15 to 17 years of age. After adjustment for the child's obesity status, the odds ratios for obesity in adulthood associated with having one obese parent ranged from 2.2 (95 percent confidence interval, 1.1 to 4.3) at 15 to 17 years of age to 3.2 (1.8 to 5.7) at 1 or 2 years of age. CONCLUSIONS: Obese children under three years of age without obese parents are at low risk for obesity in adulthood, but among older children, obesity is an increasingly important predictor of adult obesity, regardless of whether the parents are obese. Parental obesity more than doubles the risk of adult obesity among both obese and nonobese children under 10 years of age.

Adolescent↗
PubMed1997

Histone H1b phosphorylation is dependent upon ongoing transcription and replication in normal and ras-transformed mouse fibroblasts.

We have previously shown that mouse phosphorylated histone H1b (pH1b) was localized near nuclear sites that contained splicing factors. This observation suggested to us that pH1b was associated with transcribing chromatin. Here we investigated the relationship between phosphorylation of H1b and transcription. We demonstrate that treatment of normal or ras-transformed mouse fibroblasts with the transcription inhibitor actinomycin D for 70 min results in a dramatic decrease in the level of pH1b. Similar results were observed when transcription was inhibited by 5, 6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB). When DRB was removed, the level of pH1b was restored after 2 h. Treatment of the cells with aphidicolin, a potent inhibitor of replication, resulted in a marked decrease in the level of pH1b after 30 min. This is the first report showing a dependence of histone modification upon ongoing transcription and replication. Inhibition of transcription or replication may hinder accessibility of H1b to the H1 kinase, supporting the idea that pH1b is associated with transcribing chromatin. Phosphorylation of H1b may be required to maintain a more decondensed chromatin structure to facilitate transcription and replication processes.

Animals↗
PubMed1997

Additive impact of in-hospital cardiac arrest on the functioning of children with heart disease.

OBJECTIVE: This study examined the impact of a sudden cardiac arrest (CA) on the neurodevelopmental and adaptive functioning of young children with congenital heart disease (CHD). METHODOLOGY: Sixteen children with CHD who had sustained an in-hospital CA were compared with a medically similar group of children with CHD who had not incurred a CA. The contribution of CA, disease severity, and family socioeconomic status on the prediction of developmental outcome variables was evaluated. RESULTS: Children in the CA group displayed more impairments in general cognitive, motor, and adaptive behavior functioning as well as greater disease severity as measured by a cumulative medical risk index. With respect to all children in the study, a higher socioeconomic status was related to higher scores on cognitive functioning, lower levels of child maladjustment, and lower levels of stress within the parent-child relationship. Although the occurrence of a CA alone did not contribute to the prediction of outcome measures, a significant interactional effect between CA and cumulative medical risk index was found. Specifically, among children who had incurred a CA, as disease severity increased, decrements in abilities were observed. Few significant correlations between specific CA-related variables (eg, length of CA) and outcome indices were found. CONCLUSIONS: Results from this study indicate that the impact of cardiac arrest on neuropsychological functioning may be mediated by the child's overall disease severity. These findings have implications for the identification of CA survivors at greatest risk for developmental difficulties.

Case-Control Studies↗