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J R Mann

Publications and source records attributed to J R Mann.

At least 73 records · Page 4Linked to original sources
PubMed1994

Quantitative RT-PCR assays show Xist RNA levels are low in mouse female adult tissue, embryos and embryoid bodies.

We have investigated expression of the Xist gene in mouse female adult kidney, embryos and embryonic stem (ES) cells undergoing in vitro differentiation as embryoid bodies. Using the quantitative RT-PCR single nucleotide primer extension (SNuPE) assay, we found that the amount of Xist RNA in adult kidney of three mouse strains was less than approximately 2000 transcripts per cell, with only modest differences between strains carrying different Xce alleles. Female embryos 7.5 days post coitum had the same number of Xist transcripts per cell as isogenic adult tissue. Using quantitative oligonucleotide hybridization assays after RT-PCR, we investigated Xist expression in ES lines heterozygous at the Pgk-1 and Xist loci. We found that, while in most (XX) ES lines Xist RNA levels increased during embryoid body formation, the levels seen were less than 10% those found in adult female kidney. In addition, we found that the allelic ratio of Xist transcripts from reciprocal (XX) ES cell lines differentiating in vitro was identical to that of isogenic 10.5 to 11.5 day female embryos. These latter results suggest that there is no pattern of preferential paternal imprinting during days 1 to 9 of in vitro differentiation of ES cells. However, the influence of the Xce locus on the randomness of X-inactivation in embryos seems to operate also in ES cell lines. Our overall conclusion is that the low levels of Xist RNA in female kidney, embryos and differentiating (XX) ES cells are compatible only with models that do not require Xist RNA to cover the entire inactive X chromosome.

Animals↗
PubMed1994

Expression and methylation of imprinted genes during in vitro differentiation of mouse parthenogenetic and androgenetic embryonic stem cell lines.

Messenger RNA and methylation levels of four imprinted genes, H19, Igf2r, Igf-2 and Snrpn were examined by northern and Southern blotting in mouse parthenogenetic, androgenetic and normal or wild-type embryonic stem cell lines during their differentiation in vitro as embryoid bodies. In most instances, mRNA levels in parthenogenetic and androgenetic embryoid bodies differed from wild type as expected from previously determined patterns of monoallelic expression in midgestation embryos and at later stages of development. These findings implicate aberrant mRNA levels of these genes in the abnormal development of parthenogenetic and androgenetic embryos and chimeras. Whereas complete silence of one of the parental alleles has previously been observed in vivo, we detected some mRNA in the corresponding embryonic stem cell line. This 'leakage' phenomenon could be explained by partial erasure, bypass or override of imprints, or could represent the actual activity status at very early stages of development. The mRNA levels of H19, Igf2r and Igf-2 and the degree of methylation at specific associated sequences were correlated according to previous studies in embryos, and thereby are consistent with suggestions that the methylation might play a role in controlling transcription of these genes. Paternal-specific methylation of the H19 promoter region is absent in sperm, yet we observed its presence in undifferentiated androgenetic embryonic stem cells, or before the potential expression phase of this gene in embryoid bodies. As such methylation is likely to invoke a repressive effect, this finding raises the possibility that it is part of the imprinting mechanism of H19, taking the form of a secondary imprint or postfertilization epigenetic modification necessary for repression of the paternal allele.

Animals↗
PubMed1993

Carcinoid tumours of the appendix in children 1957-1986: incidence, treatment and outcome.

Forty carcinoid tumours of the appendix were identified in children under 15 years of age between 1957 and 1986 from the records of the West Midlands Regional Children's Tumour Research Group. A significant excess of girls was observed (P = 0.02). All tumours were discovered incidentally and two patients underwent further surgery. Twenty-two of the 29 confirmed locations (76 per cent) were at the tip of the appendix and 34 of the 40 tumours (85 per cent) had invaded beyond the appendiceal submucosa. The reported incidence rate of 1.14 per million children per year remained constant throughout the study period. No recurrences, metastases or deaths from tumour were detected. Appendicectomy alone is confirmed as usually curative, although right hemicolectomy is occasionally necessary. Caution during routine appendicectomy is recommended to avoid possible tumour damage, as is consistent histological examination of all appendices in the paediatric age group. The importance of long-term follow-up is emphasized.

Adolescent↗
PubMed1993

Treatment of childhood acute myeloid leukaemia using the BFM-83 protocol.

Thirty children presenting with acute nonlymphoblastic leukaemia from June 1984 to December 1989 were treated at one UK centre using a West German protocol, AML-BFM-83. This consisted of Induction, an intensive outpatient-based Consolidation regimen with seven different drugs and cranial irradiation, and Continuation therapy with thioguanine and cytosine arabinoside for 2 years with additional Adriamycin in the first year. Twenty-five children achieved complete remission (83%). There were two early deaths from haemorrhage and infection and three from Induction failure. After a median follow-up time of 60 months, nine relapses have occurred, all in the bone marrow. Life table analysis revealed a probability for survival at 5 years of 47%, event-free survival 43%, and event-free interval 50%. Median bed occupancy for chemotherapy and toxicity was 41 days, with median hospital stays of 29 days for Induction, 11 days for Consolidation and less than 1 day for Continuation. This data suggests that long-term remissions can be achieved in just under half of children with acute nonlymphoblastic leukaemia while creating only modest demands on inpatient resources.

Acute Disease↗
PubMed1993

Thirty-year population-based review of childhood renal tumours with an assessment of prognostic features including tumour DNA characteristics.

We have reviewed all paediatric kidney tumours seen in the West Midlands Health Authority Region over a 30-year period. There were 205 cases confirmed after a review of the pathology by three paediatric pathologists. Seven were cases of bone metastasising renal tumour (clear cell sarcoma), 5 were rhabdoid tumours, 2 were renal cell carcinomas, and 13 were mesoblastic nephromas. In 3 cases, it was not possible to define further the histological diagnosis. The remaining 175 cases were considered to be Wilms' tumour (86%), which is equivalent to an incidence of 5.7/10(6)/year. In the cases of Wilms' tumour, there were 91 boys and 84 girls (1.1:1). The majority of patients were Caucasian with only 7% of non-Caucasian origin. At presentation, 78% of the patients were less than 5 years old. All of these patients except 9 had surgery as part of their treatment, 154 children had total nephrectomy, 3 had partial nephrectomy, and 9 had other surgical procedures. The majority also received chemotherapy and radiotherapy. Sex, chemotherapy, and stage all had prognostic significance in univariate analysis. The actuarial survival at 10 years increased from 17% for patients treated in the first decade of the study to 78% for patients treated in the third. DNA characteristics were investigated using flow cytometry in paraffin-embedded material and adequate information was obtained in 73 cases of Wilms' tumour. Only 7 had aneuploid tumours. Univariate survival analysis of these 73 results showed that stage, sex, the percentage of cells in the synthetic phase and the proliferative index from the DNA investigations had predictive value.

Actuarial Analysis↗
PubMed1993

Neuroblastoma: a 32-year population-based study--implications for screening.

This paper describes a retrospective population-based study of neuroblastoma in the West Midlands Health Authority Region--childhood population 1.12 million (OPCS, census 1981)--in which 239 cases were diagnosed between 1st January 1957 and 31st December 1988. The age standardised rate of tumour incidence has remained constant at 7.2 cases per million children per year. The median age at diagnosis was 2 years with 18% of children presenting before the age of 6 months. Fifty children (21%) presented before the age of one year, and for this group of children, the prognosis has improved significantly over the 32-year period (10 year survival increasing from 63% in 1957-67 to 87% in 1978-88), whereas for the 189 (79%) children who presented after one year of age, the prognosis has remained very poor during the study period (10 year survival 1957-67 = 9.5%, 1978-88 = 8.5%). This study supports the need for a prospective study of mass screening at several intervals rather than only at 6 months of age.

Abdominal Neoplasms↗
PubMed1993

Cancer associated haemolytic uraemic syndrome developing prior to treatment with cytotoxic agents.

The haemolytic uraemic syndrome has been reported in children and adults with neoplasias treated with mitomycin C and occasionally in adults prior to chemotherapeutic treatment, but it has not been reported in a child prior to the use of cytotoxic drugs. This case report concerns the development of the haemolytic uraemic syndrome in a 7-year-old male child with a metastatic hepatocellular carcinoma. The child had persisting haemolysis and renal impairment, and died three weeks after presentation. Though our experience with similar tumours suggested the outlook would be poor, we had hoped to provide palliative chemotherapy. This proved impossible as optimal chemotherapy could not be used because of the renal impairment.

Anemia, Hemolytic↗
PubMed1993

Malignant epithelial tumours in children: incidence and aetiology.

The purpose of this study was to establish the incidence of carcinomas in children, changes in incidence over a 30-year period, and to identify features of possible aetiological significance. A total of 173 cases were identified, but after review of the histopathology, 30 patients were excluded because they were considered to have benign epithelial tumours or malignant tumours of nonepithelial origin. Seven other cases were excluded because pathology material was not available. Overall, in 28% of cases, the diagnoses were changed by pathology review. Thus, 136 children in the West Midlands Region diagnosed 1957-1986 were included, with carcinoid tumours (44) and tumours of skin (22), nasopharynx (14), salivary gland (13), adrenal cortex (13), thyroid (9), large bowel (5), other (16). Excluding carcinoids, the age-standardised incidence rate was 2.4 x 10(6) per year. Male:female ratio was 0.7:1 and 66% were aged > 10 years. Incidence increased from 1.5 to 3.3 x 10(6) per year. Genetic factors predisposing to carcinoma included tyrosinosis, MEN II and III, congenital adrenal hyperplasia and basal cell naevus syndrome. There was a case of Li-Fraumeni syndrome and several other patients had relevant family histories. Probable "environmental" causes included antenatal exposure to stilboestrol or hydroxyprogesterone hexanoate, stilboestrol given for premature menarche, neonatal hepatitis and prior radiotherapy. The aetiology of carcinomas in children is multifactorial, both genetic and environmental factors being important. The incidence is increasing.

Adolescent↗
PubMed1993

Congenital abnormalities in children with cancer and their relatives: results from a case-control study (IRESCC).

Several studies have revealed an excess of malformations in children with certain malignancies. A few environmental causes have been identified which may damage the foetus and lead to malformation and cancer. However, most of the numerous recognised cancer/malformation syndromes are genetically determined. This report describes a case-control study of 555 newly diagnosed children with cancer and 1,110 matched controls, chosen from general practitioner lists (GP controls) and hospital admissions (H controls). Their parents were interviewed on topics of possible aetiological significance and medical records were checked to confirm reports at interview. The numbers of congenital malformations in the index and GP control children, and the relatives of the index children, the GP and H controls are described. There were more children with malformations among the cases (60/555) than among the GP controls (27/555), P < 0.001. The abnormalities in the cases included eight with specific chromosomal/genetic conditions (e.g. Down's syndrome, XY gonadal dysgenesis, Von Recklinghausen's neurofibromatosis, Goldenhar's syndrome) whereas only one GP control child had a chromosomal defect (P < 0.05). Five case children but no GP controls had neural tube defects; this is not statistically significant. No excess of malformations was found in the siblings of cases compared with GP and H control siblings. Case mothers had a small excess of malformations (22/555) compared with GP controls (8/555), P < 0.05. Among more distant relatives the results were difficult to interpret because of the relatively small numbers in the diagnostic subgroups and because of apparent under reporting in grandparents, but no striking differences were seen between case and control relatives. The excess of malformations found in children with cancer, compared with controls, without a similar excess of malformations in their close relatives may indicate that in some (perhaps very roughly one in 20) cases antenatal events may lead both to the malformation and the malignancy.

Case-Control Studies↗
PubMed1993

Retrospective study of prognostic value of DNA ploidy and proliferative activity in neuroblastoma.

AIM: To assess the prognostic value of age and stage at diagnosis, site of primary tumour, cell ploidy and N-myc copy number in children with neuroblastoma. METHODS: Flow cytometry was used to determine the cellular DNA content of paraffin wax embedded archival material from 69 cases of neuroblastoma and was successful in 52. RESULTS: The age, stage, and survival distribution of the sampled cases was not significantly different from that in a larger population based series. There were seven diploid ("non-aneuploid") and 45 aneuploid (including two tetraploid and four triploid) tumours. The 10 year survival was significantly better for cases of aneuploid rather than diploid tumours (p < 0.05). An important new finding was that 10 year survival was also significantly better for tumours with a low percentage of cells in S phase (p < 0.03). CONCLUSION: The percentage of cells in S phase, a measure of the proliferative activity of the tumour, correlated with prognosis in neuroblastoma. This should be measured with other biological features of the disease, such as N-myc copy number, when prognostic indicators are being assessed.

Adolescent↗
PubMed1992

Epstein-Barr virus (EBV) and Hodgkin's disease in children: incidence of EBV latent membrane protein in malignant cells.

Previous studies have detected EBV DNA by Southern blotting or in situ hybridization in biopsy material from up to 30 per cent of adult cases of Hodgkin's disease. Here we have used monoclonal antibodies specific for the EBV latent membrane protein LMP1 to examine archival material from children with Hodgkin's disease. Material from 74 cases (54 males and 20 females) was examined and 37 (30 males and 7 females) were classified as LMP1-positive in the malignant cells. LMP1 positivity was present in 4/13 (31 per cent) of lymphocyte predominant, 14/36 (39 per cent) of nodular sclerosis, 17/20 (85 per cent) of mixed cellularity, 1/2 (50 per cent) of lymphocyte depletion, and 1/3 (33 per cent) of unclassified subtypes. The positive cases by clinical stage were I 9/22 (41 per cent), II 9/20 (45 per cent), III 11/24 (46 per cent), and IV 8/8 (100 per cent). LMP1 positivity was present in 2/5 (40 per cent) children aged less than 5 years, 12/27 (44 per cent) aged 5-10 years, and 23/42 (48 per cent) aged between 10 and 15 years. The association between EBV and Hodgkin's disease in children thus appeared to be more frequent in patients with mixed cellularity and advanced disease, but examples of EBV-positive tumours were found in all histological subtypes, stages, and ages. Stepwise discriminant function analysis showed that clinical stage IV and mixed cellularity histology are independently associated with LMP1 positivity. These observations indicate that Hodgkin's disease in children is at least as strongly linked to EBV as is the disease in adults.

Adolescent↗
PubMed1992

Rapid production of diversity during the progression of a mixed lineage leukaemia.

A leukaemia presenting with two morphologically different blast populations failed to respond to either antimyeloid or antilymphoid treatment and showed a rapid clinical progression. Immunophenotyping provided good evidence for two blast populations, one lymphoid and the other lymphoid with granulocyte monocytic markers. Two different gene rearrangements within JH were also observed with band densities corresponding to the sizes of the two blast cell populations. A t(19; 22) translocation was observed in almost all cells at presentation one of which evolved into a subclone, becoming dominant in the terminal phase of the disease. We show here both the clonal evolution and clonal competition that occurred in this leukaemia and suggest that the potential of the tumour stem line for rapidly producing diversity was the reason for the resistance to treatment.

Bone Marrow↗
PubMed1992

Childhood cancer in the West Midlands: incidence and survival, 1980-1984, in a multi-ethnic population.

The purpose of this study is to describe the incidence and survival of childhood cancer in the West Midlands for the period 1980-1984. Proportional breakdown by Asian subgroup is also considered. A total of 587 patients were registered, 49 of them of Asian origin. Breakdown to Asian versus non-Asian subgroups by diagnosis revealed comparatively high rates for Hodgkin's disease, retinoblastoma and neuroblastoma in the Asian patients. However, a deficit of cases was seen for CNS tumours. Comparison of overall age-standardized rates (ASR) for all cancers revealed a substantially lower value compared to that reported for the USA white population but a similar value to the USA black and UK white populations. Diagnostic breakdown revealed that the major difference between the West Midlands Regional Children's Tumour Research Group (WMRCTRG) and the USA white ASR was in the leukaemia and lymphoma group. Overall survival for the series was 56% at 5 years. The poorest prognosis was found in acute myeloid leukaemia, with only 23% of patients surviving at 5 years, against 62% in acute lymphoblastic leukaemia. CNS tumours also had a poor outcome, with an overall survival rate of 47%, although certain individual diagnoses were more favourable. We observed a 100% survival rate in Hodgkin's disease up to 5 years from diagnosis, and both Wilms' tumour and retinoblastoma had 90% survival rates.

Adolescent↗
PubMed1992

Urinary protein/creatinine index in follow up of patients with Wilms' tumour after nephrectomy.

The protein/creatinine index (p/c) was determined in early morning urine (EMU) samples from available patients with Wilms' tumour who had had a nephrectomy and whose diagnosis had been made between January 1970 and December 1989. Clinical details were obtained by case note review. Results were obtained from 36 boys and 40 girls. The mean interval between nephrectomy and measurement of the EMUp/c was 9.0 years (2-23). Eleven patients had a EMUp/c greater than 20 mg/mmol (normal range less than 20). Of the 11 patients with proteinuria, there were in addition to nephrectomy other adverse features including bilateral tumours, treatment with nephrotoxic drugs, and dysplastic kidneys. Renal dysfunction seems most likely to occur where there are adverse factors in addition to unilateral nephrectomy. There was a significant correlation between the glomerular filtration rate and the EMUp/c, and it is thought that this is a simple tool which can be used for the regular monitoring of renal function in these patients.

Adolescent↗
PubMed1992

A geostatistical approach to the analysis of pattern in rare disease.

The incidences of human disease vary from place to place, and some show distinct patterns. Patterns in rare diseases, such as childhood cancer, are not readily discernible, however, and this makes it difficult to relate their distribution to factors in the environment in seeking possible causes of the disease. Provided cases are geographically indexed, data on a disease can be analysed geostatistically. Variograms can be computed to determine the strength and spatial scale of any pattern, and to summarize the variation, and then the risk of developing the disease can be estimated by kriging. This has been done for the incidence rates of childhood cancer from 1980 to 1984 in the West Midlands Health Authority Region of England. A novel modification was made to compute the variogram of the risk from that of the frequencies, taking into account the binomial nature of the data. The incidence of the disease appears patchy. The results show that this patchiness is spatially correlated and not purely random. The risk appears greatest in the rural south west of the Region and in some of the suburbs around the conurbation. This approach using geostatistics seems very promising and will be developed further as more data for this and other diseases become available.

Child↗