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Biomedical subjects

D Cross

Publications and source records attributed to D Cross.

At least 19 recordsLinked to original sources
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

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↗
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↗
PubMed1993

Prognostic value of p53 overexpression and c-Ki-ras gene mutations in colorectal cancer.

BACKGROUND: Mutations in Ki-ras codon 12 and the p53 gene are common abnormalities in colorectal cancer. The occurrence of p53 overexpression and/or Ki-ras codon 12 mutations were analyzed in 100 colorectal adenomas to determine if they were related to patient survival. METHODS: p53 overexpression was identified by immunohistochemistry, and Ki-ras codon 12 mutations were detected using the polymerase chain reaction and a restriction enzyme digestion method. RESULTS: p53 overexpression was identified in 45% of tumors, with a higher frequency identified in DNA aneuploid and left-sided tumors than in DNA diploid and right-sided tumors. Mutations in Ki-ras codon 12 were identified in 24% of carcinomas. Individually, mutations in Ki-ras codon 12 or p53 overexpression were not prognostic indicators of survival. However, a statistically significant difference in survival was identified when these two oncogenic abnormalities were analyzed together. The median survival of patients whose tumors contained both oncogenic abnormalities was less than half of that of patients with either alteration alone or without either abnormality. CONCLUSIONS: Screening for multiple genetic abnormalities in colorectal cancers excised at surgery may prove to be a useful tool in determining prognosis.

Adenocarcinoma↗
PubMed1993

Flow cytometry and AgNORs in benign, borderline, and malignant mucinous and serous tumours of the ovary.

We performed flow cytometry and AgNOR counts on 117 serous and mucinous ovarian tumours, comprising 56 cystadenomas, 21 borderline tumours, and 40 cystadenocarcinomas. DNA aneuploidy was present in one cystadenoma and in 11% of mucinous and 46% of serous cystadenocarcinomas. All borderline tumours were DNA diploid. Major and minor FIGO stages and flow cytometrically determined DNA ploidy and DNA index were prognostically significant. Age, histological type (serous versus mucinous), flow cytometric proliferative index, and AgNOR counts were not predictive of survival. Cystadenomas and borderline tumours had lower rates of proliferation than cystadenocarcinomas. AgNORs correlated with DNA ploidy and proliferative index. Borderline tumours showed elevated AgNOR numbers despite low proliferative indices and universal DNA diploidy, suggesting that AgNOR numbers may be related to nuclear events other than proliferation and DNA ploidy.

Adult↗
PubMed1993

Repeat thrombolysis.

Since 20% of patients with myocardial infarction (MI) have had a previous infarction, and reinfarction within one year after infarction occurs in 9% of cases, it is important to clarify the role of repeat thrombolysis. After streptokinase (SK) administration, IgG antibodies rise to a peak at two weeks and slowly fall over the next 12 months, but 50% of patients still have antibody levels sufficient to neutralise a standard dose of SK up to four years after initial SK administration. On this evidence, SK or anistreplase should not be readministered, except perhaps in the first two to three days after initial treatment. The efficacy of tissue plasminogen activator (t-PA) and urokinase is not affected by prior treatment with SK.

Antibodies↗
PubMed1993

Ten unanswered questions regarding comprehensive school health promotion.

The past two decades witnessed dramatic growth in support for comprehensive school health promotion. Yet, many questions about its effectiveness and feasibility remain unanswered. This article poses several research and policy questions, the answers to which may help to shape the future of school health programs in this country.

Adolescent↗
PubMed1993

A tau-like protein interacts with stress fibers and microtubules in human and rodent cultured cell lines.

The cytoskeletal integrity of human and rodent cell lines was analyzed using site-directed monoclonal antibodies prepared from hybridomas. Secreting hybridomas were produced by immunizing mice with synthetic peptides from the C-terminal domain of the beta II-tubulin isotype, beta II(422-434), YQQYQDATADEQG, and the first imperfect repeat from brain tau, Tau-I(187-204), VRSKIGSTENLKHQPGGG. Two hybridomas were selected for this work: MTB6.22, an anti-idiotypic monoclonal antibody, which was obtained from a mouse immunized with the beta II-peptide and recognizes specific tubulin-binding domains on MAP-2 and tau; and Tau-I/1, which recognizes the repetitive binding sequences on tau and MAP-2. Immunoblots of cytoskeletal protein preparations from the five different tumor cell lines studied, showed the interaction of the site-directed antibodies MTB6.22 and Tau-I/1 with a group of proteins that co-migrate with brain tau. Immunoreactive tau components were also identified using an anti-tau monoclonal antibody (clone Tau-2), and several polyclonal anti-tau antibodies that interact with tau epitopes, other than those of the tubulin-binding domains. These tau-like proteins bound to a calmodulin-Sepharose affinity column and were eluted using 2 mM EGTA. Interestingly, washing the extracted cytoskeleton pellet with 5 x 10(-3) M Ca2+ for short periods of time selectively released the tau-like protein components, whilst most of the other cytoskeletal proteins remained in the pellet. On the other hand, immunofluorescence microscopy of detergent-extracted cells showed immunostaining of MAP components that appear to be co-localized in a discrete dot-like distribution along the stress fibers, which were revealed using rhodamine-phallacidin. Further support for the specificity of tau interaction with sites on tubulin and actin polymers was obtained with double-immunofluorescence, using the MAP-reactive monoclonal antibody MTB6.22 and a polyclonal antibody to a tubulin peptide containing part of the tau-binding domain on tubulin. Considering the anti-idiotypic nature of the MTB6.22 monoclonal antibody, our studies indicate that, in all the cell lines analyzed, a tau-like protein component is involved in mediating the interaction of both actin and tubulin polymers.

Actins↗
PubMed1993

The Know Your Body program: a review of evaluation studies.

Know Your Body is a comprehensive school health promotion program for kindergarten through six grades, initially developed in the 1970s by the American Health Foundation. The impact of the KYB program has been evaluated in three field trials, the results of which have been reviewed in this article. Across the three studies, at 3-year follow-up, consistent positive intervention effects were reported for systolic blood pressure, diastolic blood pressure, smoking, HDL-cholesterol, and health knowledge. Results for total blood cholesterol, fitness score, heart-healthy snacks, fruit/vegetable intake, whole milk intake, and health attitudes were mixed. For body mass index, triceps skinfold, all remaining dietary variables, self-esteem/self-efficacy, and locus of control no significant effects were observed. Overall, significant treatment effects were reported for 19 of the 40 variables assessed at 3-year follow-up, an effects ratio of 48%. Consistent positive results at 5-year follow-up were reported for smoking and health knowledge. Mixed results were obtained for total blood cholesterol, diastolic blood pressure, and percent kilocalories from saturated fat. Consistent null results were reported for HDL-cholesterol, systolic blood pressure, body mass index, triceps skinfold, fitness score, percentage kilocalories from fat, cholesterol intake, and fiber intake. Overall, significant treatment effects were reported for 7 of 36 variables at 5-year follow-up, an effects ratio of 19%. Although reported program effects were largely mixed, they seem consistent with other health education evaluations. Null results may have been related to insufficient teacher implementation as well as weaknesses in design and assessment. Additional research is needed to determine the effect of the program on a broader range of outcomes, to what degree increasing the "dose" produces larger and more enduring treatment effects, and the relative impact of the various components that comprise the program.

Child↗
PubMed1993

Are parents' self-reported total cholesterol levels useful in identifying children with hyperlipidemia? An examination of current guidelines.

OBJECTIVE: Recently, the American Academy of Pediatrics (AAP) Committee on Nutrition adopted the recommendation of the Expert Panel on Blood Cholesterol Levels in Children and Adolescents (NCEP) that children and adolescents with a family history of premature cardiovascular disease or parental hypercholesterolemia (> or = 240 mg/dL) be screened for hyperlipidemia. The rationale for using parental hypercholesterolemia as a screening trigger is based on sensitivity estimates using parents' actual lipid values. However, in clinical practice pediatricians may often have to rely on parents' self-reported cholesterol levels to determine a child's family risk history. This study examines the feasibility and utility of parental self-reported cholesterol levels as a means of identifying children with elevated total cholesterol levels. METHODS: As part of a school-based risk factor screening program that included total cholesterol measurement, conducted in nine elementary schools between 1989 and 1991, parents of participating children were asked if they had their cholesterol tested in the past year and if they had, to provide their total cholesterol values. RESULTS: If only the children who had one parent with a self-reported total cholesterol value > or = 240 mg/dL would have been screened, between 90% and 93% of children with elevated total cholesterol values, either > or = 170 mg/dL or > or = 200 mg/dL, would have been missed. CONCLUSIONS: These data suggest that parents' self-reported cholesterol values are an ineffective means of identifying children with elevated total cholesterol and modification of the current AAP, and NCEP guidelines for selective cholesterol screening in children may be warranted.

Adult↗
PubMed1992

The right-hemisphere bias in conditional reasoning: a short report on multiple failures to replicate previous findings.

The present set of studies attempted to replicate Gellatly's (1985) findings that were supportive of Evan's (1982) hypothesis that the right hemisphere produces a selective bias towards the incorrect solution of a complex reasoning task. Subjects solved problems of the form "if p then q." In four studies, participants simultaneously performed a bottle--balancing task on each hand to interfere with processing of the reasoning task in the right hemisphere. In the fifth study, the bottle--balancing task was replaced by a finger--sequencing task. The results of the five studies did not show that the interference with right-hemisphere activity resulted in better performance on the conditional-reasoning task. It is concluded that the hypothesis of a right-hemisphere bias in conditional reasoning is still in need of reliable findings.

Attention↗