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Biomedical subjects

A Yates

Publications and source records attributed to A Yates.

At least 19 recordsLinked to original sources
PubMed2000

Antibody responses to Yersinia pestis F1-antigen expressed in Salmonella typhimurium aroA from in vivo-inducible promoters.

Attenuated mutants of Salmonella typhimurium are being evaluated as delivery systems for a variety of heterologous vaccine antigens. Gene promoters which are induced in vivo can direct the stable expression of genes encoding these antigens. We have investigated the utility of the phoP, ompC, pagC and lacZ gene promoters for expression of the Y. pestis F1-antigen in S. typhimurium SL3261 (aroA). After i.g. (intragastric) dosing the highest level of spleen colonisation was found with recombinant Salmonella expressing F1-antigen from the phoP gene promoter, and this recombinant was most effective in inducing serum and mucosal antibody responses. The use of the pagC gene promoter to direct expression of F1-antigen resulted in the induction of serum and mucosal antibody responses even though the recombinant Salmonella were unable to colonise spleen tissues suggesting that colonisation of these tissues is not essential for the induction of antibody responses.

Animals↗
PubMed2000

Aberrant CpG-island methylation has non-random and tumour-type-specific patterns.

CpG islands frequently contain gene promoters or exons and are usually unmethylated in normal cells. Methylation of CpG islands is associated with delayed replication, condensed chromatin and inhibition of transcription initiation. The investigation of aberrant CpG-island methylation in human cancer has primarily taken a candidate gene approach, and has focused on less than 15 of the estimated 45,000 CpG islands in the genome. Here we report a global analysis of the methylation status of 1,184 unselected CpG islands in each of 98 primary human tumours using restriction landmark genomic scanning (RLGS). We estimate that an average of 600 CpG islands (range of 0 to 4,500) of the 45,000 in the genome were aberrantly methylated in the tumours, including early stage tumours. We identified patterns of CpG-island methylation that were shared within each tumour type, together with patterns and targets that displayed distinct tumour-type specificity. The expression of many of these genes was reactivated by experimental demethylation in cultured tumour cells. Thus, the methylation of particular subsets of CpG islands may have consequences for specific tumour types.

Adenocarcinoma↗
PubMed2000

Alterations of chromosome arms 1p and 19q as predictors of survival in oligodendrogliomas, astrocytomas, and mixed oligoastrocytomas.

PURPOSE: A recent report suggests that alterations of chromosome arms 1p and 19q are associated with chemotherapeutic response and overall survival in anaplastic oligodendroglioma patients treated with procarbazine, lomustine, and vincristine chemotherapy. We set out to further clarify the diagnostic and prognostic implications of these alterations in a broader set of diffuse gliomas, including astrocytic neoplasms and low-grade oligodendrogliomas. PATIENTS AND METHODS: Fluorescence in situ hybridization (FISH) signals from DNA probes mapping to 1p and 19q common deletion regions were enumerated in 162 diffuse gliomas (79 astrocytomas, 52 oligodendrogliomas, and 31 mixed oligoastrocytomas), collected as part of an ongoing prospective investigation of CNS tumors. RESULTS: The oligodendroglial phenotype was highly associated with loss of 1p (P =.0002), loss of 19q (P <.0001), and combined loss of 1p and 19q (P <.0001). Combined loss of 1p and 19q was identified as a univariate predictor of prolonged overall survival among patients with pure oligodendroglioma (log-rank, P =.03) and remained a significant predictor after adjusting for the effects of patient age and tumor grade (P <.01). This favorable association was not evident in patients with astrocytoma or mixed oligoastrocytoma. CONCLUSION: Combined loss of 1p and 19q is a statistically significant predictor of prolonged survival in patients with pure oligodendroglioma, independent of tumor grade. Given the lack of this association in patients with astrocytic neoplasms and the previously demonstrated chemosensitivity of oligodendrogliomas, a combined approach of histologic and genotypic assessment could potentially improve existing strategies for patient stratification and management.

Adolescent↗
PubMed2000

Phosphorylation of neurofilament heavy chain side-arms by stress activated protein kinase-1b/Jun N-terminal kinase-3.

Neurofilaments comprise three subunit proteins; neurofilament light, middle and heavy chains (NF-L, NF-M and NF-H). The carboxy-terminal domains of NF-M and NF-H form side-arms that project from the filament and that of NF-H contains multiple repeats of the motif lys-ser-pro, the serines of which are targets for phosphorylation. The level of phosphorylation on the lys-ser-pro repeats varies topographically within the cell; in cell bodies and proximal axons, the side-arms are largely non-phosphorylated whereas in more distal regions of axons, the side-arms are heavily phosphorylated. Here we show that stress activated protein kinase 1b (SAPK1b), a major SAPK in neurones will phosphorylate NF-H side-arms both in vitro and in transfected cells. These studies suggest that SAPK1b targets multiple phosphorylation sites within NF-H side-arms. Additionally, we show that glutamate treatment induces activation of SAPK1b in primary cortical neurones and increased phosphorylation of NF-H in cell bodies. This suggests that glutamate causes increased NF-H phosphorylation at least in part by activation of stress activated protein kinases.

Animals↗
PubMed1999

Localization of common deletion regions on 1p and 19q in human gliomas and their association with histological subtype.

Allelic alterations of chromosomes 1 and 19 are frequent events in human diffuse gliomas and have recently proven to be strong predictors of chemotherapeutic response and prolonged survival in oligodendrogliomas (Cairncross et al., 1998; Smith et al., submitted). Using 115 human diffuse gliomas, we localized regions of common allelic loss on chromosomes 1 and 19 and assessed the association of these deletion intervals with glioma histological subtypes. Further, we evaluated the capacity of multiple modalities to detect these alterations, including loss of heterozygosity (LOH), fluorescence in situ hybridization (FISH), and comparative genomic hybridization (CGH). The correlation coefficients for detection of 1p and 19q alterations, respectively, between modalities were: 0.98 and 0.87 for LOH and FISH, 0.79 and 0.60 for LOH and CGH, and 0.79 and 0.53 for FISH and CGH. Minimal deletion regions were defined on 19q13.3 (D19S412-D19S596) and 1p (D1S468-D1S1612). Loss of the 1p36 region was found in 18% of astrocytomas (10/55) and in 73% (24/33) of oligodendrogliomas (P < 0.0001), and loss of the 19q13.3 region was found in 38% (21/55) of astrocytomas and 73% (24/33) of oligodendrogliomas (P = 0.0017). Loss of both regions was found in 11% (6/55) of astrocytomas and in 64% (21/33) of oligodendrogliomas (P < 0.0001). All gliomas with LOH on either 1p or 19q demonstrated loss of the corresponding FISH probe, 1p36 or 19q13.3, suggesting not only locations of putative tumor suppressor genes, but also a simple assay for assessment of 1p and 19q alterations as diagnostic and prognostic markers.

Astrocytoma↗
PubMed1999

Presurgical serum albumin levels predict survival time from glioblastoma multiforme.

To determine whether serum albumin levels, before first surgery, predict time until death, 24 glioblastoma multiforme patients newly diagnosed at Ohio State University and Cleveland Clinic Foundation Hospitals between 1993 and 1995 were followed until 1996. Patients with presurgical serum albumin levels below 3.4 mg/dL survived an average (median) of 62 days (95% confidence interval (CI): 34, 135 days) after surgery. Those with serum albumin levels of at least 3.4 mg/dL survived an average of 494 days (95% CI: 241, 624 days). The association between serum albumin level and time until death persists when adjusted for demographic and treatment variables using Cox proportional hazards regression. Adjusted hazard ratios, by quartile of presurgical serum albumin level, are: 1.0, 1.2, 0.1, 0.1 (P-value for trend test = 0.007). In addition to providing a prognostic indicator, presurgical serum albumin levels can be used to evaluate the success of randomization of clinical trials for glioblastoma multiforme therapies. Our findings are consistent with results seen for tumors at other sites. We speculate that our results may be attributable to an association between low serum albumin levels and physiological events associated with angiogenesis.

Female↗
PubMed1998

High-dose carboplatin, thiotepa, and etoposide with autologous stem-cell rescue for patients with recurrent medulloblastoma. Children's Cancer Group.

PURPOSE: Medulloblastoma is a highly lethal disease when it recurs. Very few patients survive with conventional treatment. This study evaluated the use of high-dose carboplatin, thiotepa, and etoposide with autologous stem-cell rescue (ASCR) in patients with recurrent medulloblastoma. METHODS: Chemotherapy consisted of carboplatin 500 mg/m2 (or area under the curve = 7 mg/mL x min via Calvert formula) on days -8, -7, and -6; and thiotepa 300 mg/m2 and etoposide 250 mg/m2 on days -5, -4, and -3; followed by ASCR on day 0. In addition to the study-prescribed therapy, 21 patients received other treatment: neurosurgical resection in seven, conventional chemotherapy in 17, and external-beam irradiation in 11 cases. RESULTS: Twenty-three patients with recurrent medulloblastoma, aged two to 44 years (median, 13 years) at ASCR, were treated. Three patients died of treatment-related toxicities within 21 days of ASCR; multiorgan system failure in two, and Aspergillus infection with venoocclusive disease in one. Seven of 23 patients (30%) are event-free survivors at a median of 54 months post-ASCR (range, 24 to 78 months). Kaplan-Meier estimates of event-free (EFS) and overall survival are 34% +/- 10% and 46% +/- 11%, respectively, at 36 months post-ASCR. CONCLUSION: This strategy may provide long-term survival for some patients with recurrent medulloblastoma.

Adolescent↗
PubMed1998

Depressive symptoms among Filipino American adolescents.

Minority ethnic status has been found to be related to higher levels of depressive symptoms among adolescents and adults. The present study examined the rates of depressive symptoms (as measured by the Center for Epidemiologic Studies Depression Scale: CES-D Scale) of 270 Filipino American adolescents residing in rural and small-town areas of Hawaii. CES-D scores were compared with scores of a White group, and no ethnic differences were found. Compared with Filipino males, Filipino females were found to have higher CES-D scores, with higher mean scores on the majority of the CES-D items. The few Filipino students who reported attempting suicide had moderately high to very high levels of reported depressive symptoms. Lack of ethnic differences may be due to Hawaii's unique cultural mix, where there is no single "majority group" and a high rate of cultural interaction.

Adolescent↗
PubMed1997

Expression of oligodendrocytic mRNAs in glial tumors: changes associated with tumor grade and extent of neoplastic infiltration.

We examined the expression of glial- and neuronal-specific mRNAs within human gliomas using in situ hybridization. We found that low-grade astrocytomas contained a high number of proteolipid protein (PLP) mRNA-positive cells and that the number of PLP-stained cells decreased markedly with increasing tumor grade. Interestingly, the ratio of PLP mRNA-stained cells:myelin basic protein (MBP) mRNA-stained cells in normal white matter and low-grade astrocytoma was about 2:1 but approached 1:1 with increasing tumor grade. This parameter appeared to be a good indicator of tumor infiltration in astrocytomas, so we tested this in the analysis of other gliomas. Unlike astrocytomas, oligodendrogliomas were found consistently to contain few PLP mRNA- or MBP mRNA-expressing cells. In contrast, gemistocytic astrocytomas, typically highly invasive tumors, contained high numbers of PLP-positive cells and a ratio of PLP mRNA:MBP mRNA-stained cells of about 1.5:1, similar to low-grade astrocytomas. Nonradioactive in situ hybridization also enabled the morphological identification of specific cells. For example, gemistocytic astrocytes, which were found to be strongly vimentin mRNA positive, contained little glial fibrillary acidic protein mRNA and did not stain for PLP or MBP mRNAs. Neuronal mRNAs, such as neurofilament 68, were observed in small numbers of entrapped neurons within gliomas but were uninformative with respect to predicting tumor grade. Our results suggest that oligodendrocytes survive low-grade tumor infiltration and that glial tumor cells, unlike cell lines derived from them, do not express oligodendrocyte or neuronal mRNAs. In addition, the expression of mRNAs for the two major myelin protein genes, PLP and MBP, could be used to predict the grade and extent of tumor infiltration in astrocytomas.

Astrocytoma↗
PubMed1997

Psychiatric symptoms in offspring of within vs. across racial/ethnic marriages.

A large number of adolescents of interracial ancestry (parents comprising various combinations of African-American, American Indian/Alaska Native, European-American, Chinese, Filipino, Hispanic, Japanese, Korean, Puerto Rican, Samoan, and Tongan ancestry) were contrasted with a monoracial European-American sample in the degree to which they reported symptoms of depression, anxiety, conduct disorder/aggression, and substance abuse. The adolescents of interracial ancestry were subdivided into three groups in terms of parental ancestry: both parents of interracial ancestry, one parent of interracial and the other of monoracial ancestry, and both parents of monoracial but different ancestries. The interracial ancestry groups did not differ significantly from one another or from the European American sample in terms of symptom scores.

Adaptation, Psychological↗
PubMed1997

Stress-activated protein kinase/c-jun N-terminal kinase phosphorylates tau protein.

A proportion of the neuronal microtubule-associated protein (MAP) tau is highly phosphorylated in foetal and adult brain, whereas the majority of tau in the neurofibrillary tangles of Alzheimer's patients is hyperphosphorylated; many of the phosphorylation sites are serines or threonines followed by prolines. Several kinases phosphorylate tau at such sites in vitro. We have now shown that purified recombinant stress-activated protein kinase/c-Jun N-terminal kinase, a proline-directed kinase of the MAP kinase extended family, phosphorylates recombinant tau in vitro on threonine and serine residues. Western blots using antibodies to phosphorylation-dependent tau epitopes demonstrated that phosphorylation occurs in both of the main phosphorylated regions of tau protein. Unlike glycogen synthase kinase-3, the c-Jun N-terminal kinase readily phosphorylates Thr205 and Ser422, which are more highly phosphorylated in Alzheimer tau than in foetal or adult tau. Glycogen synthase kinase-3 may preferentially phosphorylate the sites found physiologically, in foetal and to a smaller extent in adult tau, whereas stress-activated/c-Jun N-terminal kinase and/or other members of the extended MAP kinase family may be responsible for pathological proline-directed phosphorylations. Inflammatory processes in Alzheimer brain might therefore contribute directly to the pathological formation of the hyperphosphorylated tau found in neurofibrillary tangles.

Antibody Specificity↗
PubMed1997

Ethics and the GMC core curriculum: a survey of resources in UK medical schools.

OBJECTIVES: To study the resources available and resources needed for ethics teaching to medical students in UK medical schools as required by the new GMC core curriculum. DESIGN: A structured questionnaire was piloted and then circulated to deans of medical schools. SETTING: All UK medical schools. RESULTS: Eighteen out of 28 schools completed the questionnaire, the remainder either indicating that their arrangements were "under review" (4) or not responding (6). Among those responding: 1) library resources, including video and information technology were found to be fairly well developed; 2) many schools had a good supply of handouts and sample cases for teaching; 3) most had a written syllabus, and 4) two-thirds examined in the subject. However, many schools indicated that there was an urgent need for: 1) full-time teachers (most ethics teaching is still by part-time and voluntary staff); funding for books and journals, and 3) additional teaching materials (including further case vignettes, handouts and sample exam questions). CONCLUSIONS: There has been a considerable overall improvement in resources for medical ethics teaching since the time of the last national survey (The Pond Report). However, provision varies widely from medical school to medical school. The particular needs identified were for full-time teachers, library resources and teaching materials. Wider use of existing organisations concerned with medical ethics could help to meet these needs.

Curriculum↗
PubMed1997

Subtrochanteric femoral fractures in children. Alignment after 90 degrees-90 degrees traction and cast application.

Fifteen children younger than 10 years of age with subtrochanteric fractures treated by a uniform method were evaluated. These patients had been treated with femoral skeletal traction, with the hip and knee flexed to 90 degrees until radiographic callus appeared, then with a hip spica cast. True neck to shaft and anteversion angles were calculated bilaterally using a biplanar method. Leg lengths were measured radiographically and clinically. Mean age at injury was 4.5 years, and mean followup was 6.5 years. Overgrowth averaged 10 mm after fracture. Anteversion at final followup differed only by a mean of 2 degrees from the contralateral side (range, -3 degrees to +4 degrees), and the mean neck shaft angle differed by only 1 degree. Remodeling of coronal angulation was 50% or more in all cases.

Adolescent↗
PubMed1996

When children witness domestic violence.

Children who grow up in violent homes do not necessarily become violent parents later on. Some children remain asymptomatic. However, the majority are behaviorally disordered and others suffer from PTSD, grief reactions and separation anxiety. Children who themselves are not abused are not likely to be identified and appropriately treated.

Adult↗
PubMed1995

Survival of infants with malignant astrocytomas. A Report from the Childrens Cancer Group.

BACKGROUND: Very young children with central nervous system malignant brain tumors have a poor prognosis. As compared with older children, survival is less likely, and those children who do survive frequently have severe impairment of growth and cognitive abilities, resulting partly from treatment with radiotherapy. Therefore, an intensive chemotherapeutic regimen was used to treat children younger than 2 years of age with a diagnosis of malignant astrocytomas. PATIENTS AND METHODS: Thirty-nine children younger than 24 months of age who were diagnosed with malignant astrocytoma were treated on a Childrens Cancer Group protocol with an eight-drug chemotherapeutic regimen (vincristine, carmustine, procarbazine, hydroxyurea, cisplatin, cytosine arabinoside, prednisone, and dimethyl-triazenoimidazole-carboxamide) after surgery and postoperative staging. Radiation therapy was to be deferred until the completion of chemotherapy. RESULTS: The objective response rate after two cycles of chemotherapy was 24%. Most patients did not receive radiotherapy. Progression-free survival (PFS) and survival at 3 years was 36% (standard error, 8%) and 51% (8%), respectively. The PFS of those children with anaplastic astrocytoma was 44% (11%), significantly better than that of glioblastoma multiforme (GBM) (0%). Extent of resection was not associated significantly with PFS, but tumors within the cerebral hemispheres were associated with a more favorable prognosis. Tumor progression occurred locally in almost all cases and early in treatment (median PFS, 8 months). CONCLUSION: Chemotherapy appears to be effective primary adjuvant treatment for some very young children with anaplastic astrocytomas. Overall, however, survival remains poor, especially for children with GBM. Strategies to improve outcome require early intervention, because tumor progression occurs soon after diagnosis in the majority of patients.

Antineoplastic Combined Chemotherapy Protocols↗