Biomedical subjects

I J Lewis

Publications and source records attributed to I J Lewis.

At least 37 records · Page 2Linked to original sources

PubMed1999

Improved methods using the reverse transcriptase polymerase chain reaction to detect tumour cells.

Reverse transcriptase polymerase chain reaction (RT-PCR) is increasingly used to detect small numbers of circulating tumour cells, though the clinical benefit remains controversial. The largest single contributing factor to the controversy of its value is the different approaches to sample processing. The aim of this study was to compare the sensitivity and reproducibility of RT-PCR for the detection of tumour cells after four commonly used different methods of sample processing. Using RT-PCR, one tumour cell spiked in 2 ml of whole blood was detected after analysis of separated mononuclear cell RNA, whole blood total or poly-A+ RNA. No false positives were identified with any method. However, the reproducibility of tumour cell detection was reduced after isolation of the mononuclear cell fraction. Only analysis of poly-A+ RNA had a sensitivity of 100% in all the cell spiking experiments. In patient blood samples, analysis of poly-A+ RNA increased the number of blood samples positive for tyrosine hydroxylase (TH) mRNA compared with those positive after analysis of total RNA. This may reflect high levels of cDNA reducing the efficiency of the PCR. Isolation of poly-A+ RNA increases the sensitivity and reproducibility of tumour cell detection in peripheral blood.

DNA↗

PubMed1999

Ifosfamide/etoposide alternating with high-dose methotrexate: evaluation of a chemotherapy regimen for poor-risk osteosarcoma.

Fifteen patients with relapsed osteosarcoma were treated with an intensive combination chemotherapy schedule. Ifosfamide 2.5 g m(-2) daily and etoposide 150 mg m(-2) daily coincidentally for 3 days and high-dose methotrexate 8 g m(-2) (with folinic acid rescue) on days 10-14 in a planned 21 -day cycle. Feasibility, toxicity and response to this alternative combination for the treatment of relapsed osteosarcoma was assessed. There were 98 evaluable cycles for toxicity and tolerability. The majority of cycles were well tolerated. Haematological toxicity of grade 3/4 (common toxicity criteria) was seen in all courses. Renal tubular loss of electrolytes, particularly magnesium, occurred in 71% of cycles. Thirteen per cent of cycles were repeated within 21 days and 61% within 28 days. In the thirteen patients evaluable for response, a partial response rate of 31% was seen after two cycles. However, patients with stable disease continued on therapy, and an overall consequent response rate of 62% was observed. Four patients were alive with no evidence of disease at 8-74 months. Three are alive with disease (at 8-19 months). There were six deaths, all disease related. This regimen exhibits an encouraging response rate in a group of children with poor prognosis disease, with a tolerable toxicity profile.

Adolescent↗

PubMed1998

Contrasting levels of p21ras activation and expression of neurofibromin in peripheral primitive neuroectodermal tumour and neuroblastoma cells, and their response to retinoic acid.

Ras protooncogenes encode small guanine nucleotide binding proteins (p21ras) activated by phosphorylation. Phosphorylation of p21ras is predominantly regulated by the GTPase activating proteins type 1 GAP120 and neurofibromin. Increased levels of p21ras-GTP (active) have been associated with increased cell growth and malignant transformation. In this study the relationship between p21ras, type 1 GAP120 and neurofibromin with growth and differentiation has been examined in neuroblastoma and peripheral primitive neuroectodermal tumour (pPNET) cell lines. The level of p21ras protein in neuroblastoma and pPNET cells was the same. However, the amount of p21ras-GTP bound was higher in pPNET than in neuroblastoma cells. This most likely reflects the absence of neurofibromin. Retinoic acid (RA)-induced differentiation and growth inhibition of neuroblastoma cells was associated with an increase in type 1 GAP120 and neurofibromin mRNA, and a decrease in p21ras-GTP. In pPNET cells levels of type 1 GAP120 but not neurofibromin mRNA were increased to similar levels to those in neuroblastoma cells. This was not associated with decreased p21ras-GTP, modulation of growth or change in morphology. In summary, constitutive activation of p21ras may have a role in the biology of pPNET cells. This may reflect abnormalities in neurofibromin expression, and could inpart explain why RA did not induce morphological differentiation and growth inhibition in pPNETs.

Cell Differentiation↗

PubMed1998

Phase I study of temozolomide in paediatric patients with advanced cancer. United Kingdom Children's Cancer Study Group.

A phase I study of temozolomide administered orally once a day, on 5 consecutive days, between 500 and 1200 mg m(-2) per 28-day cycle was performed. Children were stratified according to prior craniospinal irradiation or nitrosourea therapy. Sixteen of 20 patients who had not received prior craniospinal irradiation or nitrosourea therapy were evaluable. Myelosuppression was dose limiting, with Common Toxicity Criteria (CTC) grade 4 thrombocytopenia occurring in one of six patients receiving 1000 mg m(-2) per cycle, and two of four patients treated at 1200 mg m(-2) per cycle. Therefore, the maximum-tolerated dose (MTD) was 1000 mg m(-2) per cycle. The MTD was not defined for children with prior craniospinal irradiation because of poor recruitment. Plasma pharmacokinetic analyses showed temozolomide to be rapidly absorbed and eliminated, with linear increases in peak plasma concentrations and systemic exposure with increasing dose. Responses (CR and PR) were seen in two out of five patients with high-grade astrocytomas, and one patient had stable disease. One of ten patients with diffuse intrinsic brain stem glioma achieved a long-term partial response, and a further two patients had stable disease. Therefore, the dose recommended for phase II studies in patients who have not received prior craniospinal irradiation or nitrosoureas is 1000 mg m(-2) per cycle. Further evaluation in diffuse intrinsic brain stem gliomas and other high-grade astrocytomas is warranted.

Adolescent↗

PubMed1998

An activity week for children with cancer: who wants to go and why?

Many children now live with cancer rather than die from it, and such children need both to continue their social, emotional and cognitive development and to make long-term psychological adjustments. This paper presents the findings of a research project set up to explore issues pertinent to the current provision of an activity week experience for a group of British paediatric cancer patients. The aims of the study included finding out which factors discriminate between families who apply for a place to attend the week for their child and families who do not, and to develop a knowledge of what factors are considered by parents and children. The findings suggest that the week appeals to children who are confident, active and able to separate from parents and whose parents are keen to encourage independence and new experiences. Children diagnosed and treated at a younger age and further away from treatment were more likely to express concerns about being homesick and safety and to not apply for the week. Issues of protection, independence and disability are discussed with reference to the importance of parental attitude on children's psychological accommodation to disease and treatment and to the experiences of adult survivors of childhood cancer.

Adaptation, Psychological↗

PubMed1998

Conduct of phase I trials in children with cancer.

PURPOSE AND METHODS: Future progress in the care of children with cancer requires appropriate evaluations of promising new agents for pediatric indications, beginning with well-conducted phase I trials. This report summarizes current guidelines for the conduct of pediatric phase I trials and represents a consensus between American and European investigators. The primary objective of pediatric phase I trials is to define safe and appropriate doses and schedules of new agents that can subsequently be used in phase II trials to test for activity against specific childhood malignancies. Prioritization of agents for evaluation in children is critical, since many more investigational agents are evaluated in adult patients than can be systematically evaluated in children. Considerations used in prioritizing agents include activity in xenograft models, novel mechanism of action, favorable drug-resistance profile, and activity observed in adult trials of the agent. RESULTS AND CONCLUSION: Distinctive characteristics of pediatric phase I trials, in comparison to adult phase I trials, include the necessity for multiinstitutional participation and their higher starting dose (typically 80% of the adult maximum-tolerated dose [MTD]), both of which reflect the relative unavailability of appropriate patients. The application of uniform eligibility criteria and standard definitions for MTD and dose-limiting toxicity (DLT) help to assure that pediatric phase I trials are safely conducted and reliably identify appropriate doses and schedules of agents for phase II evaluation. Where possible, pediatric phase I trials also define the pharmacokinetic behavior of new agents in children.

Antineoplastic Agents↗

PubMed1997

Thiopurine methyltransferase deficiency in childhood lymphoblastic leukaemia: 6-mercaptopurine dosage strategies.

Daily 6-mercaptopurine (6MP) forms the backbone of continuing chemotherapy for childhood lymphoblastic leukaemia (ALL). A major metabolic route is catalysed by thiopurine methyltransferase (TPMT). TPMT deficiency occurs in 1 in 300 individuals and results in high concentrations of thioguanine nucleotides (TGNs), cytotoxic 6MP metabolites. A leukaemic child taking 6MP repeatedly developed profound pancytopenias. TPMT deficiency was confirmed. TGN formation was then studied on attenuated 6MP dosages. Four weekly oral doses of 75 mg/m2 6MP produced TGNs of 2348 pmol/8 x 10(8) red cells, nearly double the maximum TGNs recorded in ALL children with TPMT activity taking long term daily 75 mg/m2 6MP. Grossly elevated TGN concentrations were also produced at 10% standard 6MP dosage (7.5 mg/m2 daily), accompanied by unacceptable 6MP toxicity (neutropenia, diarrhoea, vomiting). The child was eventually stabilised on 10% alternate day therapy and after 15 weeks TGNs were 1670 pmol, just above the upper end of the TGN range for ALL children with TPMT activity.

Antimetabolites, Antineoplastic↗

PubMed1997

EWS-FLI1 fusion transcripts identified in patients with typical neuroblastoma.

The t(11.22)(q24.q12) results in expression of a chimeric RNA product, EWS-FLI1. This RNA product is expressed in over 85% of tumours belonging to the Ewing's family, and is increasingly used as a definitive characteristic of these tumours. In this study, we evaluated reverse transcriptase-polymerase chain (RT-PCR) for EWS-FLI1 fusion transcripts in 18 neurally derived small round cell tumours. These included six Ewing's family tumours and 12 neuroblastomas. EWS-FLI1 fusion transcripts were identified in all six Ewing's tumours, but also in two of the 12 neuroblastomas. One neuroblastoma contained the classic type 1 fusion transcript, and the second a type 1 transcript containing a 66 bp (base pair) insert that was not derived from the EWS or FLI1 gene. The presence of EWS-FLI1 fusion products in RNA extracted from primary neuroblastoma suggests the identification of EWS-FLI1 fusion transcripts is not pathognomonic for tumours of the Ewing's family. The clinical significance of these fusion transcripts in neuroblastoma is not known.

Adolescent↗

PubMed1997

Dental parameters in the long-term survivors of childhood cancer compared with siblings.

There have been a number of reports on the dental health of long-term survivors (LTS) of childhood malignancy as compared with normal controls. However, it is usually difficult to identify a meaningful control population as most of these patients are from widely differing geographical areas and socio-economic status. The aim of this investigation was, therefore, to study the dental health of LTS compared with siblings. 46 LTS who had siblings of a similar age were identified for the study. Both groups were examined for dental caries, gingivitis and enamel defects. There was no statistically significant difference in the mean DMFS of the test and control groups. However, the LTS had a significantly (P = 0.006) higher number of decayed surfaces (1.50 +/- 0.30) as compared with their siblings (0.50 +/- 0.20). The LTS also had a significantly higher prevalence of severe gingivitis (1.11 +/- 0.33) compared with controls (0.02 +/- 0.02). There was a significantly higher prevalence of all types of enamel defects in the LTS and fewer teeth with no enamel defect as compared with their siblings, with the mean values being 15.7 +/- 0.9 and 25.3 +/- 0.3, respectively. It was concluded that there was a higher prevalence of untreated dental disease and developmental defects in long-term survivors.

Adolescent↗

PubMed1997

Positive MIBG scanning at the time of relapse in neuroblastoma which was MIBG negative at diagnosis.

Metaiodobenzylguanidine (MIBG) labelled with iodine-123 (123I) or 131I has become a well established tool with high sensitivity and specificity in the diagnosis and staging of neuroblastoma in children. However, some neuroblastomas do not take up MIBG at the time of diagnosis. The reasons for this are unclear but may be related to uptake mechanisms. Follow-up MIBG scans have not been reported in these patients. We present a case where an initial 123I-MIBG-scan was negative at diagnosis but became positive when the patient relapsed. This unusual occurrence may have implications for patients with a negative MIBG-scan at presentation. These patients should be re-evaluated by MIBG-scan at the time of relapse as a positive scan then offers the possibility of additional treatment with MIBG therapy.

3-Iodobenzylguanidine↗

PubMed1996

Progressive glomerular toxicity of ifosfamide in children.

Glomerular toxicity following ifosfamide (IFO) is not as well recognized as renal tubular damage. Following a case of ifosfamide-induced renal failure with histological evidence of glomerular changes, we undertook a retrospective study of all IFO-treated children to assess the extent and severity of its glomerular toxicity and to identify possible predisposing factors. Thirty-seven children with a follow-up of 6 months or more from the end of chemotherapy were studied. They were a median of 10.8 years old (range 3.25-18.5), had received a median of 54 g/m2 (range 9-135) of IFO, and had a median follow-up of 29 months (range 6-68). The criteria to identify glomerular dysfunction were raised plasma creatinine (Pc) values on two occasions or a low glomerular filtration rate (GFR) measured by Tc-99-DTPA clearance. Detailed assessment was carried out to identify other nephrotoxic influences in these children. Subjects in whom glomerular dysfunction could be causally linked to IFO were compared with the rest of the group for a variety of predisposing factors. Of eight children with glomerular dysfunction, two had other nephrotoxic influences and were excluded from further analysis. In six (17.1%) children, glomerular dysfunction appeared to be causally linked to IFO. Their median GFR was 61.9 ml/min/1.73 m2(range 33-85) and Pc was 123 mumol/l (range 85-216). Five of the six had normal glomerular function at the end of therapy and the raised Pc values were first noted 19, 21, 26, 29, and 36 months later. Children with glomerular toxicity had a significantly longer median follow-up (41.5 vs. 19 months; P = 0.04) than the rest of the group, suggesting late onset of this problem. They were older at the time of the study and had received nearly twice the dose of IFO, though the differences in age and dose did not reach statistical significance. The earliest signs of renal toxicity were seen in the index case, who had had prior nephrectomy. All affected children had coexistent and preceding tubular toxicity. The inadequacies of tests commonly used to assess glomerular function and the possibility of underestimation of dysfunction are discussed. Glomerular dysfunction following IFO is poorly recognized and evidence from this study of its later onset and progressive nature is a cause for concern. The index case is described with histological findings.

Adolescent↗

PubMed1996

Phase I trials in paediatric oncology--the European perspective. The New Agents Group of the United Kingdom Childrens Cancer Study Group.

The current recommendations for Phase I trials should allow more confident interpretation of the toxicity and efficacy of new agents by providing a framework for multicentre and international co-operation. An overview of the aims and designs of Phase I trials is presented, along with a summary of current and recently published United Kingdom Childrens Cancer Study Group Phase I trials, and a discussion of some of the difficulties faced in the methodology and evaluation of Phase I studies in children.

Antineoplastic Agents↗

PubMed1996

Cancer in adolescence.

Adolescence is a flexible concept reflecting specific developmental tasks but broadly encompassing individuals in their teens and early twenties. Comparison of published data from cancer registries demonstrates that the incidence of cancer (rate/10(6)/year) increases through the 5 year age bands 10-14 (range 100-130.1 for males, 80-115.3 for females), 15-19 (range 154.3-220.7 for males, 127-206.7 for females) and 20-24 (229 for males, 313 for females). Leukaemia and central nervous system tumours predominate in the 10-14 year group but during mid and late adolescence lymphomas become the main single tumour group and epithelial cancers become increasingly common. Arguments are presented for the formation of specialised adolescent cancer units based on the premise that centralisation of care would lead to improved treatment and survival. The physical, psychological, social and educational needs of adolescents are best served by the expertise of a single multidisciplinary team.

Adolescent↗

PubMed1995

Activation of p21ras by nerve growth factor in neuroblastoma cells.

Nerve growth factor (NGF) is essential for the differentiation and survival of sympathetic and sensory neurones and is thought to play a role in the differentiation of neuroblastoma. In this study we have shown NGF decreased the mRNA level of the two GTPase activating proteins neurofibromin (containing the NF1-GRD) and type 1 GAP120 in two neuroblastoma cell lines, IMR-32 and SK-N-SH. This effect was seen within 15 min exposure to NGF and was maintained up to 2 h after the addition of NGF. Treatment with NGF increased the amount of GTP bound p21ras 3-fold, within 20 min exposure. Western blot analysis showed SK-N-SH and IMR-32 cells to contain equal amounts of p21ras protein and these levels were unchanged by NGF treatment. However, NGF induced an increase in the level of neurofilament L protein, which was accompanied by an increase in neurite extension. These effects of NGF occurred in the absence of growth inhibition. In conclusion, our results demonstrate a decrease in GTPase activating proteins and activation of p21ras by NGF in IMR-32 and SK-N-SH cells, thus implicating p21ras in NGF signal transduction in neuroblastoma.

Base Sequence↗

PubMed1995

Early clinical evaluation of neuroblastoma cell detection by reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosine hydroxylase mRNA.

Disseminating disease in neuroblastoma is of considerable clinical importance. Detection of circulating neuroblastoma cells using tyrosine hydroxylase (TH) as a tissue-specific target for reverse transcriptase-polymerase chain reaction has proved to be a sensitive and specific method for the detection of contaminating tumour cells in peripheral blood. The aim of this study was to report the early clinical observations made using this technology in neuroblastoma patient blood samples. A strong association was found between the detection of neuroblastoma cells in circulation with the detection of neuroblastoma in bone marrow. This method may be of use to monitor disease status and identify early signs of relapse in clinically disease-free patients. These results show that RT-PCR detection of TH mRNA is a relatively noninvasive, sensitive method for the detection of circulating tumour cells in neuroblastoma patients.

Child↗

PubMed1995

Effect of retinoic acid on p21ras and regulators of its activity in neuroblastoma.

p21ras is a membrane-associated guanine nucleotide-binding protein with intrinsic GTPase activity. This protein is important in the regulation of cell growth and differentiation in a number of different cell types. Therefore, the aim of the present study was to examine the role of p21ras and regulators of its activity in the differentiation of neuroblastoma cells induced by retinoic acid (RA). Phosphorylation of p21ras is regulated by the GTPase activity of type I GAP120 and neurofibromin. RA-induced differentiation of the two neuroblastoma cell lines SK-N-SH and IMR-32 was closely related to growth inhibition. Differentiation induced by RA resulted in an increase in both type I GAP120 and neurofibromin mRNAs. This increase was accompanied by a decrease in the activation of p21ras. These results suggest that, in neuroblastoma, activation of p21ras is not associated with RA-induced differentiation. However, the GTPase activating proteins type I GAP120 and neurofibromin may have effector functions in RA-induced differentiation of neuroblastoma.

Base Sequence↗

PubMed1995

Molecular epidemiology of ceftazidime resistant Enterobacteriaceae from patients on a paediatric oncology ward.

Between the autumn of 1989 and January 1990, 21 of the 44 children on the paediatric oncology ward of St. James's University Hospital, Leeds, UK were infected or colonised with Enterobacteriaceae producing extended-spectrum beta-lactamases. This represents 48% of the patients on the ward. Only six patients (14%) had microbiologically proven septicaemia caused by such bacteria during this period. Eighty-one isolates of Enterobacteriaceae producing extended-spectrum beta-lactamases derived from blood culture (7 isolates from 6 patients) or faecal samples (74 isolates) were available for examination. These comprised 28 Escherichia coli, 28 Klebsiella oxytoca, 11 Klebsiella pneumoniae, 10 Citrobacter freundii, 3 Enterobacter spp. and 1 Serratia marcescens. Clinical isolates were resistant to penicillins and to ceftazidime. Strains isolated in this study also showed multiple resistance to a range of antimicrobial agents. Transfer to a nalidixic acid resistant laboratory strain of E. coli UB5201 was attempted, but transfer of the ceftazidime resistance determinant was only successful in 25 isolates (31%). Examination of plasmid DNA revealed sequences in each isolate that hybridised with the TEM beta-lactamase gene probe used on a variety of plasmids ranging in size from 2.5- > 150 kb, sometimes found on several replicons in a single isolate. The TEM gene probe also hybridised with chromosomal DNA in a large number of isolates. Nucleotide sequence analysis demonstrated the presence of three extended-spectrum beta-lactamases: TEM-10B produced by two isolates, TEM-12B produced by 37 isolates and TEM-26B produced by 40 isolates. In two cases, isolates produced two beta-lactamases, and it proved impossible to identify these enzymes unequivocally. The genes encoding TEM-10B and TEM-26B both differ from TEM-12B by single nucleotide substitutions. Analysis of the ribotype patterns derived from the clinical isolates provided evidence for cross-colonisation between patients, and this was confirmed by analysis of the plasmid profiles. Four years after discontinuing ceftazidime and other extended-spectrum cephalosporins on this ward, patients were still colonised with bacteria that produced extended-spectrum beta-lactamases.

Base Sequence↗

PubMed1994

Neuroblastoma cell detection by reverse transcriptase-polymerase chain reaction (RT-PCR) for tyrosine hydroxylase mRNA.

The presence of tumour cells in peripheral blood of neuroblastoma patients is of considerable clinical importance. Nucleic acid amplification offers an opportunity to detect very small numbers of such cells, but in neuroblastoma a frequent specific abnormality in the tumour DNA suitable for this purpose has yet to be identified. To facilitate the detection of such cells we have developed RT-PCR using tyrosine hydroxylase (TH) as a tissue-specific target gene. TH mRNA was detected in 3 neuroblastoma cell lines and in all neuroblastoma tumours examined, but was undetectable in peripheral blood from children without neuroblastoma. The method was highly sensitive, detecting 1-10 neuroblastoma cells per 10(7) blood cells. Thirty blood samples from 24 patients were analysed and results were compared with known disease status. At diagnosis 4/7 patient blood specimens were positive; the four positive samples were from stage-4 patients. In blood samples from these patients 6-8 weeks after the initiation of treatment, TH mRNA was undetectable. Of 7 samples taken at the time of clinical relapse, 5 were positive; 4 of these were from patients with evidence of disseminating disease. Of 16 blood samples from disease-free patients, 14 were negative and 2 were positive. One positive patient in this group subsequently had a clinical relapse. These results show that this technique is of value for detecting neuroblastoma cells in peripheral blood. The significance of these cells at diagnosis, during treatment or on follow-up requires further evaluation.

Base Sequence↗