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Biomedical subjects

I Evans

Publications and source records attributed to I Evans.

At least 19 recordsLinked to original sources
PubMed2001

The frequency of silencing in Arabidopsis thaliana varies highly between progeny of siblings and can be influenced by environmental factors.

In a collection of 111 transgenic Arabidopsis thaliana lines, silencing of the nptII gene was observed in 62 (56%) of the lines and three distinct nptII-silencing phenotypes were identified. Two T-DNA constructs were used, which differed in distance and orientation of the marker gene relative to the border sequences. Comparison of the sets of lines generated with each vector, indicate that the T-DNA construct configuration influence the incidence of lines displaying silencing, as well as the distribution of silencing phenotypes. Twenty lines were investigated more thoroughly. The frequency of silencing varied between siblings in 19 lines, including three lines containing a single T-DNA copy. The last line showed 100% silencing. The gus gene present in both constructs could be expressed in the presence of a silenced nptII gene. Investigation of methylation at a single site in the pnos promoter revealed partial methylation in multi-copy lines, but no methylation in single-copy lines. For 16 lines, the overall frequencies of silencing differed significantly between control plants and plants exposed to temperature stress; in 11 of these lines at the 0.1% level. In several cases, the frequency of silencing in progeny of stress-treated plants was higher than for the control group, while other lines showed higher frequencies of kanamycin-resistant progeny for the stress-treated sibling plants.

Amino Acid Oxidoreductases↗
PubMed2000

The Medical Research Council's approach to allegations of scientific misconduct.

The UK's Medical Research Council (MRC) introduced a specific policy and procedure for inquiring into allegations of scientific misconduct in December 1997; previously cases had been considered under normal disciplinary procedures. The policy formally covers staff employed in MRC units, but those in receipt of MRC grants in universities and elsewhere are expected to operate under similar policies. The MRC's approach is stepwise: preliminary action; assessment to establish prima facie evidence of misconduct; formal investigation; sanctions; and appeal. Strict time limits apply at all stages. The procedure will be evaluated after two years. The indications so far are that the procedure is robust, and its clarity and transparency have been an asset to all parties. The MRC is also convinced that it is equally important to achieve a working culture that fosters integrity. Thus education and training in good research practices are fundamental to the prevention of research misconduct.

Biomedical Research↗
PubMed2000

Thyroid hormone receptor gene expression in first trimester human fetal brain.

Maternal thyroid hormone is transferred to the fetus early in pregnancy and is postulated to regulate brain development. Thyroid hormone nuclear receptor (TR) proteins are present in fetal brain, but their isoformal composition is unknown. We therefore investigated the ontogeny of TR isoforms and related splice variants in first trimester human fetal brain (n = 9) by semi-quantitative reverse transcriptase-polymerase chain reaction analysis. Expression of the TRbeta1, TRalpha1 and c-erbAalpha2 isoforms was detected from 8.1 weeks gestation (wg). An additional truncated species was detected with the c-erbAalpha2 primer set, consistent with the c-erbAalpha3 splice variant previously described in the rat. All c-erbAalpha-derived transcripts were co-ordinately expressed and increased (ca. 8-fold) between 8.1 and 13.9 wg. A more complex ontogenic pattern was observed for TRbeta1, suggestive of a nadir between 8.4 and 12.0 wg. These findings point to an important role for the TRalpha1 isoform in mediating maternal thyroid hormone action during first trimester human fetal brain development.

Adult↗
PubMed1996

Amorous inclinations.

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Administration, Cutaneous↗
PubMed1996

Leading council.

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Health Planning Councils↗
PubMed1996

Treatment of children with stage IV favorable histology Wilms tumor: a report from the National Wilms Tumor Study Group.

The purpose of this study was to evaluate the effect of the sequential addition of doxorubicin and cyclophosphamide to the combination of vincristine and actinomycin D on the relapse-free survival of children with stage IV/favorable histology Wilms tumor. We reviewed the clinical courses of all randomized patients from National Wilms Tumor Study (NWTS)-2 and 3 with stage IV/favorable histology (FH) Wilms tumor. We determined the four-year relapse-free survival percentage for patients treated on NWTS-2 with the combination of vincristine (VCR) and actinomycin D (AMD) with (regimen D) or without (regimen C) doxorubicin (DOX), and for patients treated on NWTS-3 with the combination of VCR+AMD+DOX with (regimen J) or without (regimen DD-RT) cyclophosphamide (CTX). All children received whole lung radiation therapy. The four-year relapse-free survival percentage for children with stage IV/FH Wilms tumor treated with regimen C was 53.3%, compared to 57.7% for those treated with regimen D (P = 0.63). The four-year relapse-free survival percentage for children with stage IV/FH Wilms tumor treated with regimen DD-RT was 79.0%, compared to 80.9% for those treated on regimen J (P = 0.79). The four-year relapse-free survival for children with lung metastases only treated with regimen D on NWTS-2 was significantly lower than that of children treated with the related regimen DD-RT on NWTS-3 (P = 0.03). We conclude that the addition of doxorubicin to the combination of vincristine and actinomycin D and pulmonary irradiation did not clearly improve the four-year relapse-free survival percentage of children with stage IV/FH Wilms tumor, although the benefit may have been masked by the greater frequency of death due to toxicity in NWTS-2. There was no evidence that the addition of CTX to the three-drug treatment regimen improved the four-year relapse-free survival percentage of children with stage IV/FH Wilms tumor. The data with only two drugs derived from NWTS-2 suggest that there is a population of children with stage IV/FH Wilms tumor who can be successfully treated without an anthracycline. The goal of future research will be to identify this subgroup at the time of initial diagnosis.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1995

Relationship between dose schedule and charges for treatment on National Wilms' Tumor Study-4. A report from the National Wilms' Tumor Study Group.

National Wilms' Tumor Study-4 was designed to evaluate the efficacy, toxicity, and cost of administration of different regimens for the treatment of Wilms' tumor. The charges for treatment with dactinomycin and doxorubicin administered by two different schedules were calculated using current charges in Buffalo, N.Y. An annual savings of approximately $779,259 could be achieved by the use of the short, pulse-intensive (i.e., single-dose) treatment regimens for all children with Wilms' tumor of stages I-IV/favorable histology. The pulse-intensive administration schedule for the treatment of children with Wilms' tumor permits administration of chemotherapy at a substantially lower total treatment cost.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1994

The effect of chemotherapy dose intensity on the hematological toxicity of the treatment for Wilms' tumor. A report from the National Wilms' Tumor Study.

PURPOSE: To determine the relationship between hematological toxicity and actual dose intensity of treatment of patients randomized to therapy during the first 28 months of the National Wilms' Tumor Study-4. METHODS: The mean minimum white blood cell count (WBC), platelet count (PLT), hemoglobin, and absolute neutrophil count (ANC) during the first two courses of chemotherapy and the mean number of days of hospitalization for toxicity were compared between standard and "pulse-intensive" regimens for all randomized patients entered on National Wilms' Tumor Study-4 between August 6, 1986 and December 31, 1988. The mean dose intensity of dactinomycin, vincristine, and doxorubicin received during the first two courses and the entire course of treatment was compared between standard and "pulse-intensive" regimens. RESULTS: The mean minimum WBC, PLT, and ANC were all significantly lower during the first two courses of chemotherapy for stage I patients treated with the standard regimen, compared with the "pulse-intensive" regimen. The mean dose intensity of dactinomycin and doxorubicin was significantly higher for patients treated with the "pulse-intensive" regimens, compared with the appropriate standard regimen. CONCLUSIONS: The "pulse-intensive" administration schedule for the treatment of children with Wilms' tumor permits administration of chemotherapy at a higher dose intensity without an increase in hematological toxicity.

Adolescent↗
PubMed1993

NO CO-worker.

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Carbon Monoxide↗
PubMed1992

Outcomes in low-risk babies treated with half-dose chemotherapy according to the Third National Wilms' Tumor Study.

PURPOSE: To determine whether the 50% dose reduction of all chemotherapeutic agents recommended for babies (less than or equal to 12 months of age) by the Third National Wilms' Tumor Study (NWTS-3) produced acceptable toxicity without sacrificing any survival benefit. MATERIALS AND METHODS: The 365 babies enrolled in NWTS-3 had tumors of varying histologies and stages. The present analysis was restricted to the 256 infants who had tumors of favorable histology, were free of metastasis at diagnosis, and received treatment according to NWTS-3 guidelines. RESULTS: Despite the recommended attenuation of drug doses observed in 75% of the chemotherapy courses received, outcomes for these babies were comparable to those obtained in older children given full doses of chemotherapy. Four-year survival rates for 256 babies with stages I (n = 199), II (n = 38), and III (n = 19) favorable-histology tumors were 96%, 95%, and 90%, respectively. The figures for 498 stage I, 342 stage II, and 373 stage III older children with favorable-histology lesions were 92%, 94%, and 91% in that order. There were no deaths from hematologic toxicity or infection among babies who received half-dose chemotherapy. The death rates for their older NWTS-3 counterparts was 1%. CONCLUSION: Less aggressive therapies advocated for babies in NWTS-3 provide acceptable levels of morbidity without compromising the excellent results previously reported for low-risk patients of all ages.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Surgical complications after nephrectomy for Wilms' tumor.

We reviewed the charts of 1,910 children enrolled in the Third National Wilms' Tumor Study who underwent primary nephrectomy. Four hundred and ninety-five surgical complications occurred in 379 children (19.8 percent). Patients with inoperable tumors, bilateral renal tumors, peroperative therapy and those who refused treatment were excluded from this review. The most common complication was intestinal obstruction, which occurred in 132 patients (6.9 percent). This was followed by extensive intraoperative hemorrhage (112 patients), defined as blood loss exceeding 50 milliliters per kilogram of body weight. Intraoperative injuries to other visceral organs (including intestine, liver and spleen) occurred in 21 children and extensive vascular injuries were reported in 27 patients. There were nine deaths attributed to surgical complications (0.5 percent), only one of which was intraoperative. Survival of patients with complications was similar to patients without complications when stratified by histologic study and stage. Factors associated with the development of surgical complications included advanced local tumor stage at diagnosis, intravascular tumor extension and resection of other visceral organs at the time of nephrectomy. Complete removal of the tumor is important, but not at the expense of radical removal of adjacent structures, because of gross appearances at operation. They are often not invaded by the tumor, but rather are compressed, distorted or adherent without tumor infiltration. Identification of these groups will aid the surgeon in choosing the appropriate management for these patients at high risk. When initial exploration and precise surgical staging indicate that only a formidable operation will achieve total excision, shrinkage of the tumor with selective use of chemotherapy or radiotherapy, or both, may facilitate removal and decrease surgical morbidity. Preoperative therapy may also be the preferred approach for children with extensive intravascular tumor.

Actuarial Analysis↗