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Biomedical subjects

D Cross

Publications and source records attributed to D Cross.

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

The use of observational methods for monitoring sun-protection activities in schools.

Evaluation of health promotion interventions aimed at behavioural or environmental change involves assessing change that occurs as a result of the program. Direct observational methods can be used for this purpose and this paper describes three such methods that we pilot tested for use in a 5-year intervention study aimed at reducing sun exposure in primary school children. (1) Monitoring 'No hat, no play' policies. This method involved video taping children in selected school play areas during lunch time and analysing the content of the videos to assess the proportion of children wearing various types of hats. (2) Assessing shade provision in the playground. This method involved taking aerial photographs of each school and using them to estimate the proportion of shade in play areas available to children at lunchtime. (3) Shade use. This involved children wearing polysulphone film badges to measure the amount of UV-B exposure they received during one lunch period, relative to the total possible dose registered on index badges. Each method was implemented successfully, and we demonstrated that the video and aerial photography methods produced highly reproducible results and that all three methods were feasible. These three methods will be used in our intervention study to assess longitudinal change in schools' sun-protection policy and practice.

Child↗
PubMed1999

Relationship between self-esteem and smoking behavior among Japanese early adolescents: initial results from a three-year study.

Researchers examined the relationship between self-esteem and smoking behavior among Japanese elementary and junior high school students. Students (2,090) in fourth to ninth grade from three elementary schools and two junior high schools in the Hyogo and Niigata prefectures completed an anonymous questionnaire. Self-esteem was measured using the Harter Perceived Competence Scale, the Pope Self-Esteem Scale, and the Rosenberg Self-Esteem Scale. Results indicated that never smokers had higher cognitive, family, and global self-esteem, but lower physical self-esteem than ever smokers. Grade and gender were significantly associated with self-esteem, showing a decrease of self-esteem with increases in grade and a higher level of self-esteem among boys than girls. The results suggest that effective smoking prevention programs for Japanese early adolescents should be integrated into more comprehensive health education or health promotion programs including self-esteem enhancement training.

Adolescent↗
PubMed1999

Choice of management strategy for colorectal cancer based on a diagnostic immunohistochemical test for defective mismatch repair.

BACKGROUND: Despite intensive research into the molecular abnormalities associated with colorectal cancer (CRC), no diagnostic tests have emerged which usefully complement standard histopathological assessments. AIMS: To assess the feasibility of using immunohistochemistry to detect replication error (RER) positive CRCs and determine the incidence of RER positivity within distinct patient subgroups. METHODS: 502 CRCs were analysed for RER positivity (at least two markers affected) and/or expression of hMSH2 and hMLH1. RESULTS: There were 15/30 (50%) patients with metachronous CRCs, 16/51 (31%) with synchronous CRCs, 14/45 (31%) with a proximal colon carcinoma, and 4/23 (17%) who developed a CRC under the age of 50 showed RER positivity. However, 0/54 patients who developed a solitary carcinoma of the rectum/left colon over the age of 50 showed RER positivity. Immunohistochemical analysis revealed that 66/66 (100%) RER positive carcinomas were associated with complete lack of expression of either hMSH2 or hMLH1. This correlation was confirmed using a further 101 proximal colon carcinomas. Patients with a mismatch repair defective carcinoma showed improved survival but a 5.54 times relative risk of developing a metachronous CRC. A prospective immunohistochemical study revealed 13/117 (11%) patients had a mismatch repair defective carcinoma. A fivefold excess of hMLH1 defective cases was noted. CONCLUSIONS: All RER positive carcinomas were identified by the immunohistochemical test. This is the first simple laboratory test which can be performed routinely on all CRCs. It will provide a method for selecting patients who should be investigated for HNPCC, offered long term follow up, and who may not respond to standard chemotherapy regimens.

Adaptor Proteins, Signal Transducing↗
PubMed1999

Measuring community/environmental interventions: the Child Pedestrian Injury Prevention Project.

OBJECTIVES: To assess the effectiveness of community/environmental interventions undertaken as part of the Child Pedestrian Injury Prevention Project (CPIPP). SETTING: Three communities (local government areas) in the Perth metropolitan area, Western Australia. METHODS: A quasiexperimental community intervention trial was undertaken over three years (1995-97). Three communities were assigned to either: a community/environmental road safety intervention and a school based road/pedestrian safety education program (intervention group 1); a school based road/pedestrian safety education program only (intervention group 2); or to no road safety intervention (comparison group). Quantification of the various road safety community/environmental activities undertaken in each community during the trial was measured, and a cumulative community activity index developed. Estimates of the volume and speed of vehicular traffic were monitored over a two year period. RESULTS: Greater road safety activity was observed in intervention group 1 compared with the other groups. A significant reduction in the volume of traffic on local access roads was also observed over the period of the trial in intervention group 1, but not in the remaining groups. CONCLUSIONS: The findings indicate that the various community/environmental interventions initiated in collaboration with CPIPP in intervention group 1 contributed, in part, to the observed reduction in the volume of traffic. A combination of community/environmental interventions and education are likely to reduce the rate of childhood pedestrian injury.

Accidents, Traffic↗
PubMed1999

White matter hyperintensities and gray matter lesions in physically healthy depressed subjects.

OBJECTIVE: Previous studies reported that depressed subjects had more white matter hyperintensities on magnetic resonance imaging scans than control subjects, but the subjects had cerebrovascular disease risk factors. This study used subjects with a history of recurrent major depression and matched comparison subjects, screened to exclude cerebrovascular disease risk factors, to determine whether depressed subjects had more white matter hyperintensities and other lesions. METHOD: A semiautomated volumetric computer program was used to compare numbers and volumes of white matter hyperintensities, basal ganglia lesions, and total lesions in 24 women with a history of recurrent major depression and 24 comparison subjects case-matched on age and education and group-matched on height. In addition, images were measured with the use of a validated categorical scale. All subjects were screened to exclude cerebrovascular disease risk factors. RESULTS: There were no significant differences in the total volumes or total numbers of lesions. However, multiple linear regression showed a significant correlation of age and depression with number of lesions; this was accounted for by a greater number of small lesions (diameter < or = 0.4 cm). CONCLUSIONS: These findings suggest that cerebrovascular disease risk factors most likely mediated the relationship between depression and white matter hyperintensities seen in previous studies. However, the independent effect of depression, as well as an age-by-depression interaction, for small lesions suggests a causal role of depression in certain types of white matter pathology irrespective of other cerebrovascular disease risk factors. The volumetric method used in this study may be more sensitive than other methods in determining lesion characteristics and correlations with clinical variables.

Adult↗
PubMed1998

Assessment of the impact of a CD4+ T-cell testing laboratory improvement program.

OBJECTIVE: To evaluate the effectiveness of the Centers for Disease Control and Prevention's CD4+ T-cell laboratory testing improvement program and the influence of other laboratory improvement programs on CD4+ T-cell testing practices. DESIGN: Surveys asking for practice changes and factors that influenced the changes, a survey of clinicians' perceptions of laboratory quality in CD4 testing, and analysis of data from the Model Performance Evaluation Program. INTERVENTIONS: Centers for Disease Control and Prevention interventions included a series of 3-day workshops on flow cytometry, CD4+ T-cell testing guidelines published in the Morbidity and Mortality Weekly Report, the Clinical Laboratory Improvement Amendments of 1988, and the Model Performance Evaluation Program. PARTICIPANTS: All known laboratories in the United States that perform clinical CD4+ T-cell testing, workshop participants, and a sample of clinicians that treat patients infected with the human immunodeficiency virus. MAIN OUTCOME MEASURES: Changes in practices, factors most influential in effecting change, and performance on samples mailed to laboratories by the Model Performance Evaluation Program; knowledge before and after presentation of material in workshops; and practicing clinicians' observations of any effects of changes in laboratory practices. RESULTS: Many existing laboratories changed practices as a result of both governmental and nongovernmental CD4+ T-cell testing improvement programs. Sources of influence varied with each testing practice. Perceptions that test results were more reproducible seemed to offset presumed increases in the time and cost of testing. Clinicians who had ordered CD4+ T-cell testing for more than 10 years noted some improvements in results reported. CONCLUSIONS: As new complex testing methodologies are introduced into clinical and public health laboratories, the users seem to seek guidance in appropriate application of preanalytic, analytic, and postanalytic phases of the testing process. Testing improvement programs from a variety of sources were credited with changing practices and should continue to provide this guidance.

CD4 Lymphocyte Count↗
PubMed1997

NFE, a new transcriptional activator that facilitates p50 and c-Rel-dependent IgH 3' enhancer activity.

The induction of immunoglobulin heavy chain (IgH) 3' enhancer activity has been coupled to ligand/receptor-dependent activation of resting B cells. To search for transcriptional target sites that account for this induction, extracts from lipopolysaccharide (LPS)-stimulated B cells and cell lines were used. Here we describe, by gel-retardation analysis, the identification of an NF-kappaB site and an adjacent nuclear factor ets-like (NFE) site in the 3' enhancer. The NFE motif binds four protein complexes in resting B cell extracts, of which two are down-regulated upon LPS stimulation. Gel shift-shift experiments of the NF-kappaB complexes with specific antibodies identified p50 and c-Rel proteins to be the predominant factors in primary LPS-stimulated cell extracts. Site-directed mutagenesis of these motifs demonstrates that they contribute to part of the enhancer activity in plasma cells. One copy of the NFkappaB/NFE motifs, linked to a heterologous reporter construct, displays lymphoid-restricted reporter gene activity in transient transfection assays. Mutation of either site abrogates all promoter activity. Complementation experiments demonstrate that although p50 and c-Rel expression vectors reconstitute transcription of an intact NF-kappaB/NFE reporter construct in a dose-dependent manner, mutation of the NFE site or the NF-kappaB site abrogates essentially all transcriptional activity in both plasma cells and in COS cells. Taken together, we provide evidence for the existence of an activator, NFE, which in combination with the p50 and c-Rel proteins, are part of the transcription factor machinery that regulates 3' enhancer activity, and thus the control of the IgH locus in late B lymphocyte development.

Animals↗
PubMed1997

The PRECEDE-PROCEED model: application to planning a child pedestrian injury prevention program.

OBJECTIVES: The objectives were first, to modify the PRECEDE-PROCEED model and to use it is as a basis for planning a three year intervention trial that aims to reduce injury to child pedestrians. A second objective was to assess the suitability of this process for planning such a relatively complex program. SETTING: The project was carried out in 47 primary schools in three local government areas, in the Perth metropolitan area. METHODS: The program was developed, based on extensive needs assessment incorporating formative evaluations. Epidemiological, psychosocial, environmental, educational, and demographic information was gathered, organised, and prioritised. The PRECEDE-PROCEED model was used to identify the relevant behavioural and environmental risk factors associated with child pedestrian injuries in the target areas. Modifiable causes of those behavioural and environmental factors were delineated. A description of how the model facilitated the development of program objectives and subobjectives which were linked to strategy objectives, and strategies is provided. RESULTS: The process used to plan the child pedestrian injury prevention program ensured that a critical assessment was undertaken of all the relevant epidemiological, behavioural, and environmental information. The gathering, organising, and prioritising of the information was facilitated by the process. CONCLUSIONS: The use of a model such as PRECEDE-PROCEED can enhance the development of a child injury prevention program. In particular, the process can facilitate the identification of appropriate objectives which in turn facilitates the development of suitable interventions and evaluation methods.

Accident Prevention↗
PubMed1997

Localization of language cortices by functional MR imaging compared with intracarotid amobarbital hemispheric sedation.

OBJECTIVE: We undertook this study to investigate functional MR imaging as a new clinical method for determining hemispheric language dominance. Seven patients undergoing surgical evaluation for chronic intractable epilepsy were studied. Intracarotid amobarbital injection was also performed and the findings compared with the functional MR imaging results. CONCLUSION: Functional MR imaging studies enabled localization of the frontal and temporal lobe language cortices. The results of functional MR imaging and intracarotid amobarbital testing of hemispheric language dominance agreed in all seven patients, including two right-handed patients with right-hemisphere language dominance. These preliminary results show that functional MR imaging is an accurate noninvasive method of determining language dominance that may replace the amobarbital test for some purposes if confirmed by additional research.

Adult↗
PubMed1996

Tau-like proteins associated with centrosomes in cultured cells.

The subcellular association of tau-like proteins with centrosomes in cultured cell lines and its effects in nucleating microtubule assembly were analyzed using biochemical and immunocytochemical approaches. Tau proteins, major components of microtubules, appear to be tightly associated with actin filaments in a variety of cell lines, while in pathological conditions of neurons, they are part of paired helical filaments found in Alzheimer's disease. Different studies suggest that, in addition to tau interactions with the components of the cytoskeletal network, tau polypeptides appear to be associated with highly structured cellular elements, in both interphase and mitotic cells. An in-depth analysis of tau subcellular distribution us- ing different polyclonal and monoclonal antibodies showed colocalization of tau-like components with centrosomes in interphase cells of the human Huh-7 hepatoma, in SW-13 adenocarcinoma, and in normal human fibroblasts. Tau associated with centrosomes in mitotic Huh-7 cells was also identified. However, antibodies against the tau binding repeats did not stain centrosomes. A set of different tau isoforms was also identified by Western blot analysis on isolated centrosomal preparations from Huh-7 cells, obtained by differential centrifugation through sucrose gradients. Microtubule nucleation in vitro over isolated centrosomes was inhibited by both the polyclonal antibody against native tau and an antibody to the N-terminal tau sequence, as revealed by immunofluorescence analysis and assembly kinetics experiments. The antibody TRS1.2 against the fragment containing the first binding repeat on tau did not affect nucleation. These studies allowed us to characterize tau association with the isolated centrosomal preparation and its involvement in microtubule assembly nucleated over centrosomes, thus suggesting possible structural and functional roles for these interactions.

Cells, Cultured↗
PubMed1996

Antenatal screening for cystic fibrosis.

OBJECTIVE: To assess the practicality of implementing antenatal screening for cystic fibrosis in Yorkshire. DESIGN: Prospective study in which all pregnant women were offered testing for the delta F508 mutation which accounts for about 85% of carriers in Yorkshire. The reproductive partners of those found to be cystic fibrosis carriers were then tested and any carrier referred for genetic counselling. SETTING: Antenatal clinics in two hospitals and eight general practices. POPULATION: Six thousand and seventy-one pregnant women. RESULTS: A total of 3773 women (62%) accepted the screening offer. This was a lower uptake rate than in other published UK studies: Aberdeen (85-91%), Manchester (85%), Edinburgh (76-84%) and Oxford (67%). Nonetheless there were large and statistically significant differences in the uptake rate between centres within the study: 78% and 60% for the two hospitals and 67% for the general practices. One hundred and thirty women (3.4%) were found to be carriers and three carrier couples were identified. The median time interval for the laboratory to produce a result was five days and the cost was pounds 16 on average. CONCLUSIONS: Antenatal screening for cystic fibrosis does not pose any special practical difficulties. It would be feasible to introduce it into routine practice in Yorkshire.

Attitude to Health↗
PubMed1995

Subpopulations of tau interact with microtubules and actin filaments in various cell types.

It has been demonstrated that microtubule-associated proteins (MAPs) interact with tubulin in vitro and in vivo. However, there is no clear evidence on the possible roles of the interactions of MAPs in vivo with other cytoskeletal components in maintaining the integrity of the cell architecture. To address this question we extracted the neuronal cytoskeleton from brain cells and studied the selective dissociation of specific molecular isospecies of tau protein under various experimental conditions. Tau, and in some cases MPA-2, were analysed by the use of anti-idiotypic antibodies that recognize epitopes on their tubulin binding sites. Fractions of microtubule-bound tau isoforms were extracted with 0.35 M NaCl or after the addition of nocodazole to allow microtubule depolymerization. Protein eluted with this inhibitor contained most of the assembled tubulin dimer pool and part of the remaining tau and MAP-2. When the remaining cytoskeletal pellet was treated with cytochalasin D to allow depolymerization of actin filaments, only tau isoforms were extracted. Immunoprecipitation studies along with immunolocalization experiments in cell lines containing tau-like components supported the findings on the roles of tau isospecies as linkers between tubulin in the microtubular structure with actin filaments. Interestingly, in certain types of cells, antibody-reactive tau isospecies were detected by immunofluorescence with a discrete distribution pattern along actin filaments, which was affected by cytochalasin disruption of the actin filament network. These results suggest the possible in vivo roles of subsets of tau protein in modulating the interactions between microtubules and actin filaments.

Actins↗
PubMed1994

Carboxyl terminal sequences of beta-tubulin involved in the interaction of HMW-MAPs. Studies using site-specific antibodies.

After the finding of the involvement of the C-terminal moieties of tubulin subunits in the interaction of MAPs, different studies have focused on the substructure of the binding domains for the different MAPs. Current biochemical evidence point to the role of a low-homology sequence between alpha and beta-subunits within the conserved region of the C-terminal domain of tubulin, in the binding of MAP-2 and tau. Another line of studies indicates that a site for interaction of the high molecular weight MAPs is located in the variable region defined by the glutamic-rich C-terminus of beta-tubulin. Here, we report the usefulness of idiotypic site-directed antibodies, produced by immunization with peptides from different beta-tubulin isoforms, to study both MAP-1 and MAP-2 binding sites on tubulin. On the basis of these results with site-specific antibodies along with previous structural information (Cross et al., 1991, Biochemistry 30: 4362-4366), we propose the role of consensus sequences, from the invariant beta-tubulin C-terminal domain in the binding of MAP-2 and from the variable domain in the interactions of MAP-1 and MAP-2.

Amino Acid Sequence↗
PubMed1994

Thermostability of bacterial luciferase expressed in different microbes.

Bacterial luciferase was used to investigate the relationship between the thermostability of a cytoplasmic reporter molecule and cellular heat resistance. The luciferase activity of Vibrio fischeri was expressed in strains of Escherichia coli, Salmonella typhimurium, Listeria monocytogenes and Brochothrix thermosphacta following transformation with plasmid pSP13 carrying the luxAB genes. The thermostability of intracellular luciferase varied depending on the organism in which it was expressed, but was not related to the cellular heat resistance of the different organisms. Addition of xylitol to the heating medium protected against loss of viability and inactivation of intracellular luciferase. Glycerol also protected against loss of viability but was less effective at preventing thermal denaturation of luciferase.

Culture Media↗
PubMed1993

Abnormal cranial magnetic resonance imaging scans in sickle-cell disease. Neurological correlates and clinical implications.

OBJECTIVE: Eight asymptomatic patients with sickle-cell disease (SCD) with magnetic resonance imaging (MRI) abnormalities consistent with cerebral infarcts (group 1) and eight asymptomatic patients with SCD with normal MRI scans (group 2) were followed up to assess the neurological correlates and the clinical outcome. DESIGN: Patients in the two cohorts underwent clinical evaluations and xenon 133 regional cerebral blood flow (rCBF) studies within 1 month of the entry MRI. This study sequence was repeated up to 5 years later. Neuropsychological studies also were performed in six group 1 patients and eight group 2 patients at the end of the study. SETTING: The patients were recruited from the Comprehensive Sickle Cell Center at Columbia University, New York, NY. PATIENTS: All patients had SCD, hemoglobin SS, and normal findings on clinical evaluation at entry. The group 1 cohort had clinically silent MRI abnormalities consistent with cerebral infarction. The group 2 cohort was age matched to group 1 and had normal MRI studies. INTERVENTIONS: None. MAIN OUTCOME MEASURE: The natural history of MRI abnormalities and the neurological correlates were assessed to determine the predictive value of subclinical MRI lesions as a risk factor for clinically apparent stroke. RESULTS: The mean duration of MRI follow-up was 3.7 years. In group 1, four patients (50%) demonstrated progressive MRI abnormalities and three patients (38%) became clinically symptomatic. In group 2, findings for all patients remained normal on clinical and radiological examination. Both groups had markedly elevated rCBF values. Individual rCBF differences correlated with the specific MRI abnormalities. The psychometric study results were similar in the two cohorts. Eighty-three percent of group 1 and 88% of group 2 patients had defective scores in one or more areas of cognitive functioning. Three patients met cognitive criteria for dementia. CONCLUSIONS: Cranial MRI abnormalities have important prognostic implications even when detected in clinically asymptomatic patients. Cognitive abnormalities exist in patients with SCD even in the absence of MRI abnormalities or clinical stroke.

Adolescent↗
PubMed1993

Evaluation of a school-site cardiovascular risk factor screening intervention.

BACKGROUND: Though several published reports have demonstrated the feasibility of conducting school-site cardiovascular risk factor screening programs as well as the ability of such programs to detect high-risk children and parents, less is known about their cognitive and behavioral impact. METHODS: Four Michigan elementary schools received a cardiovascular risk factor screening intervention twice between spring 1989 and spring 1990 and four other area schools served as comparison sites. All eight schools received the Michigan Model Comprehensive School Health Education Program. RESULTS: Among participating students (n = 1,166) and their parents (n = 514), significant favorable changes in relevant health knowledge as well as attitudes regarding nutrition and early detection of disease relative to comparison student (n = 480) and parents (n = 158), were observed. There was also a significant decrease in students' self-reported intake of high-fat foods and parents of children who participated were themselves significantly more likely to report having had their cholesterol and blood pressure tested. CONCLUSIONS: This quasi-experimental study suggests that school-based risk factor screening programs can positively influence the knowledge, attitude, and behavior of schoolchildren and their parents and may, therefore, represent a potentially effective adjunct to traditional curricular approaches to disease prevention and health education as well as an alternative means of early detection.

Blood Pressure↗