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Biomedical subjects

I Lewis

Publications and source records attributed to I Lewis.

At least 37 records · Page 2Linked to original sources
PubMed1997

Promiscuous translocations of chromosome arm 17q in human neuroblastomas.

Deletions of chromosome arm 1p and amplification of the MYCN oncogene are well-recognized genetic changes in neuroblastoma cells. Technical difficulties in cytogenetic analysis of this tumour have hampered the recognition of other recurring abnormalities, but recent use of molecular cytogenetic techniques has indicated significant involvement of chromosome arm 17q. In primary tumours and in cell lines, a recurrent unbalanced translocation t(1p;17q) has been identified by fluorescence in situ hybridization. We confirm the occurrence of this translocation in primary tumours and, in addition, we describe seven new structural rearrangements all of which result in gain of 17q in tumour cells. These rearrangements involved chromosome arms 9p, 10q, 11p, 14q, and 16q. Triplication of the 17q arm was seen in one case. The 17q breakpoint was most commonly q21. All these 17q changes were found in near-diploid tumours. We have also reviewed the literature for neuroblastoma karyotypes involving 17q abnormalities; taken in conjunction with our findings this indicates a remarkable promiscuity of translocation partners, with more than 20 different chromosome regions involved in 17q translocations.

Bone Marrow Neoplasms↗
PubMed1996

The rectus sheath block in paediatric anaesthesia: new indications for an old technique?

The rectus sheath block has been used with success for postoperative analgesia in adults. This paper reviews the anatomy of the rectus sheath, and presents our initial experience of using the block to provide intra- and postoperative analgesia in children having repair of umbilical and paraumbilical hernia. The rectus sheath block appears to be a useful technique in children, particularly for paediatric day-cases surgery.

Abdominal Muscles↗
PubMed1996

Centrifugation of bovine oocytes for nuclear micromanipulation and sperm microinjection.

The reproductive biotechnologies of intracytoplasmic sperm microinjection, nuclear transfer and DNA microinjection require the visualization of cytoplasmic components and nuclei of oocytes and early embryonic cells. Bovine oocytes were matured and fertilized in vitro, and then centrifuged at the germinal vesicle, metaphase II and pronuclear stages and at syngamy. These (n = 536) were examined using light and transmission electron microscopy. The organelles stratified in five distinct zones in a consistent pattern in both oocytes and zygotes, though relative fractions changed in organelle composition after fertilization. These comprised a centripetal lipid zone, below which was a vesicular zone, then a supra-equatorial band of smooth endoplasmic reticulum (SER), a clear zone and a centrifugal mitochondrial zone. Cortical granules were located peripherally, single or clumped together, in the clear and mitochondrial zones. The nuclei were usually found associated with the SER or Golgi membranes, and chromatin was clumped at one pole within the nucleus. The maturation spindles were often located beneath the oolemma in all zones, while the first mitotic spindle was usually located in the clear zone. Some of the oocytes were activated by centrifugation and completed maturation.

Animals↗
PubMed1994

Ifosfamide enantiomers: pharmacokinetics in children.

Ifosfamide, like other oxazaphosphorine drugs, is chiral and there is some evidence, mainly from animal studies, of stereo-selective differences in metabolism, excretion and cytotoxic activity between the two enantiomers. The pharmacokinetics of racemic ifosfamide (RAC-IFO), R-ifosfamide (R-IFO) and S-ifosfamide (S-IFO) were studied in five children who received intravenous therapy with racemic ifosfamide on 3 consecutive days. The clearance of S-IFO was greater than that of R-IFO. The clearance value at the end of the infusion was faster than the respective rate measured at the beginning of or during the ifosfamide regimens in four children and, therefore, suggests autoinduction of elimination of both enantiomers.

Adolescent↗
PubMed1994

Appropriateness of medication prescribing in ambulatory elderly patients.

OBJECTIVE: To assess the quality of medication prescribing in ambulatory elderly patients on multiple medications using the Medication Appropriateness Index (MAI). DESIGN: Cross-sectional study. SETTING: General Medical Clinic of the Durham VA Medical Center. PATIENTS: 208 elderly outpatients on five or more regularly scheduled medications. MEASUREMENTS: Medication prescribing appropriateness was measured with the MAI, a reliable method that employs 10 implicit criteria. A weighted MAI score (range 0-18 per drug) served as a summary measure of appropriateness. RESULTS: There were 1644 medications evaluated; 26% received no inappropriate ratings, 37% had one, 19% had two, and 18% had three or more. Of 16,440 ratings, 2295 (14%) were evaluated as inappropriate. The percentage of inappropriate ratings varied across prescribing dimensions: drug-drug interactions, 0%; drug-disease interactions, 1.4%; medication effectiveness, 4.7%; therapeutic duplication, 5.7%; indication, 11.5%; duration of treatment, 16.5%; dosage, 17.3%; practical directions, 20.3%; cost, 29.7%; and correct directions, 32.4%. The mean MAI score for all medications was 2.2 +/- 2.1 (range 0-10) and varied by therapeutic class. MAI scores were significantly lower for medications with a high potential for adverse effects compared with those with a low potential (MAI score of 1.8 vs 2.9, P < 0.001). Regression analysis revealed that no patient characteristics were associated with a higher likelihood of inappropriate prescribing. CONCLUSIONS: Medication prescribing for elderly outpatients taking multiple medications was substantially appropriate. Prescribing dimensions with the most room for improvement were more exact directions, less expensive drugs, and practical directions. Drugs at high risk for adverse effects were prescribed more appropriately than those at low risk.

Age Factors↗
PubMed1994

Doxorubicin and cisplatin with granulocyte colony-stimulating factor as adjuvant chemotherapy for osteosarcoma: phase II trial of the European Osteosarcoma Intergroup.

PURPOSE: This report describes the toxicity and feasibility of administering doxorubicin (DOX) and cisplatin (CDDP) at 2-week intervals with granulocyte colony-stimulating factor (G-CSF) to patients with osteosarcoma and the compatibility of this regimen with endoprosthetic surgery performed after three cycles. PATIENTS AND METHODS: Twenty-four patients with biopsy-proven osteosarcoma were treated with three preoperative cycles of DOX 25 mg/m2/d on days 1 to 3 and CDDP 100 mg/m2 on day 1 with G-CSF 5 micrograms/kg/d on days 4 to 14. Surgery was scheduled at week 6 to be followed by three further cycles of chemotherapy at 2-week intervals. RESULTS: Two-week chemotherapy was feasible, but delays and dose reductions only allowed 74% and 78% of the intended dose-intensity of DOX and CDDP to be administered. Thrombocytopenia accounted for 50% of delays. Significant toxicity included neutropenic sepsis, severe mucositis, prolonged nausea and vomiting, and electrolyte disturbances. Twenty-one limb-salvage procedures and one amputation were performed. There were eight episodes of excessive perioperative bleeding. CONCLUSION: Intensive 2-week chemotherapy with intercurrent surgery is feasible and allows a greater dose-intensity of chemotherapy to be administered compared with the same regimen administered at 3-week intervals without G-CSF. The toxicity is considerable, but manageable.

Adolescent↗
PubMed1993

21-day schedule oral etoposide in children--a feasibility study.

To determine the feasibility and toxicity of prolonged oral etoposide in children, 22 patients with relapsed or refractory disease were commenced on etoposide 50-100 mgs/m2 per day for 21 days. A second course was administered after full blood count recovery, followed by disease reassessment. In total, 72 courses were evaluable for toxicity, with 10% of completed courses complicated by febrile neutropenia. 15 patients were evaluable for response, with 1 partial response, 10 stable disease and 4 progressive disease. This schedule was well tolerated with acceptable toxicity when doses of less than 80 mg/m2/day were administered and warrants further evaluation.

Administration, Oral↗
PubMed1993

Childhood B cell lymphomas arising in the mediastinum.

AIMS: To report the clinical features and pathology of four childhood cases of primary mediastinal non-Hodgkin's lymphoma of non-lymphoblastic pathology. METHODS: Biopsy material was fixed in formol-saline and routinely processed and stained. Immunohistochemical staining was performed on paraffin wax embedded sections using the alkaline phosphatase anti-alkaline phosphatase method. RESULTS: The four patients presented with a large mediastinal mass and symptoms consistent with superior vena cava syndrome secondary to lymphoma. None of the patients had any clinically important disease outside the mediastinum. The four tumours had a histological appearance similar to diffuse large cell non-Hodgkin's lymphoma with sclerosis. Immunohistochemical staining showed that these tumours were of B cell origin. One patient died from infection during treatment and two patients died with progressive disease. The remaining patient remained well 43 months off all treatment. CONCLUSIONS: These four cases further illustrate the heterogeneity of paediatric large cell lymphomas. Clinically, they seem to be equivalent to the B cell lymphoma of the mediastinum, sclerosing type, that is seen in young (predominantly female) adults. The clinical and biological features of this type of tumour in childhood are largely unknown. Using standard treatment protocols, this tumour seems to have a poor prognosis and its optimal treatment therefore requires further clarification.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

Pilot study of high-dose vincristine, etoposide, carboplatin and melphalan with autologous bone marrow rescue in advanced neuroblastoma.

The efficacy and toxicity of a high-dose multiagent consolidation regimen, OMEC (vincristine, melphalan, etoposide and carboplatin), with autologous bone marrow rescue was studied in patients with poor-prognosis neuroblastoma, 20 patients were treated with OMEC, 18 after induction chemotherapy and 2 following relapse. All patients received, per m2, vincristine 4 mg, etoposide 1 g, carboplatin 1.0-1.75 g and melphalan 180 mg followed by bone marrow rescue. 4 patients (20%) died of treatment-related complications. Severe gastrointestinal toxicity occurred in all of these patients, and in 75% of patients overall. 1 of 5 patients with evaluable disease achieved complete remission. 13 patients (65%) have relapsed a median of 10 months (range 3-26) after receiving OMEC. Thus, OMEC was not more effective, yet more toxic, than high-dose melphalan given alone, and the use of similar multiagent regimens with overlapping toxicities in advanced neuroblastoma appears inadvisable.

Antineoplastic Combined Chemotherapy Protocols↗
PubMed1992

N-hydroxy-MeIQx is the major microsomal oxidation product of the dietary carcinogen MeIQx with human liver.

2-Amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), one of the most abundant of the heterocyclic aromatic amines formed during the cooking of meat, is genotoxic and carcinogenic in rodents. MeIQx requires metabolic activation by P450 before it can exert these effects. Whilst there is indirect evidence that the mutagenic product is N-hydroxy-MeIQx (N-OHMeIQx), we have now identified this unequivocally following incubation of the amine with human hepatic microsomal fraction. A mixture of unlabelled MeIQx, [13C,15N2]MeIQx and [14C]MeIQx was used as substrate and the products analysed by HPLC-thermospray mass spectrometry. Characteristic doublet ions, 3 mass units apart, were found at m/z 214/217 ([M+H]+) from the parent compound, MeIQx and at 230/233 ([M+H]+) from N-OHMeIQx. The presence of a doublet ion at m/z 214/217 with the doublet at 230/233 [M+H+] provided additional evidence that this was N-OHMeIQx, as facile loss of 'O' is characteristic of N-hydroxylamines. Further evidence for the identity of the major metabolite, which accounted for approximately 90% of all microsomal metabolism, was obtained by comparing the mutagenicity of the HPLC eluate using Salmonella typhimurium YG1024, which is particularly sensitive to N-hydroxylamines, and TA98/1,8-DNP6 which is resistant to most N-hydroxylamines. Ninety-five per cent of direct-acting mutagenicity present in the reaction mixture was associated with a single peak, which co-eluted with N-OHMeIQx, as indicated by mass spectrometry. In the presence of a metabolic activation system, only one additional mutagenic peak, corresponding to unchanged MeIQx, could be detected. MeIQx (5 microM) was N-hydroxylated at a rate of 77 +/- 11 pmol/mg/min (mean +/- SEM, n = 4) by human liver microsomes. The specific inhibitor of human CYP1A2, furafylline (5 microM) inhibited the N-hydroxylation of MeIQx by > 90%. These data show that N-OHMeIQx is both the major oxidation product and the major genotoxic product of MeIQx generated by microsomal fractions of human liver and that the reaction is catalysed almost exclusively by CYP1A2.

Carcinogens↗
PubMed1992

Childhood lymphoma in Yorkshire.

AIMS: A histopathological review of 43 cases of childhood non-Hodgkin's lymphoma (NHL) in an attempt to identify histological variables of prognostic importance. METHOD: Each case was reclassified according to the Working Formulation and an attempt made to allocate an immunophenotype using a panel of monoclonal antibodies. Results were correlated with clinical data on site and survival. RESULTS: Of the 43 cases, 30 were males and 13 females. There were 17 cases of lymphoblastic lymphoma, 15 cases of small non-cleaved cell lymphoma (SNCC), and four cases of large cell lymphoma. The SNCC group was subdivided into 10 cases of Burkitt's lymphoma and five cases of non-Burkitt's lymphoma. An immunophenotype was allocated in 65.1% of cases (23 B, 5 T). The SNCC cases were spread throughout the 0-16 year age range while the lymphoblastic lymphoma cases tended to occur in older children. Most mediastinal tumours were lymphoblastic lymphoma and most abdominal tumours were SNCC. Statistical analysis failed to show a significant difference in survival among histological subgroups or immunophenotypes. CONCLUSION: No histological variables of prognostic importance were identified partly due to the great variation in treatment regimens, standard of supportive care, and prognosis over the period of the study (1972 to 1988).

Adolescent↗
PubMed1992

Measurement of dopamine, HVA and HMMA in untimed urine samples: establishment of age-related reference data in children.

We describe assays for homovanillic acid, hydroxymethylmandelic acid and dopamine that have proven practical and reliable during 3 years of routine use. Homovanillic and hydroxymethylmandelic acids were measured as trimethyl silyl derivatives by capillary gas chromatography. Dilution of samples prior to extraction was found to be necessary to achieve consistent recoveries of these acidic metabolites. Dopamine was assayed by high pressure liquid chromatography with electrochemical detection using an optimized method of catecholamine isolation that involved both ion exchange and alumina extraction. Untimed urine samples were collected from 140 hospitalized children. Age related reference data for the excretion of all three metabolites are reported. We suggest certain precautions that should be observed when using untimed samples and relating the results to creatinine excretion.

Adolescent↗
PubMed1991

Dosimetry of iodine 131 metaiodobenzylguanidine for treatment of resistant neuroblastoma: results of a UK study.

In 1987, the United Kingdom Children's Cancer Study Group (UKCCSG) set up a multi-centre study to investigate the toxicity of iodine 131 metaiodobenzylguanidine (mIBG) in the treatment of resistant neuroblastoma. Since December 1987, 25 children suffering from neuroblastoma have been treated with 131I-mIBG at six UK centres. All centres followed standardised physics and clinical protocols to provide consistent toxicity and dosimetry data. These protocols describe the methods employed for both the tracer study using 131I-mIBG and the subsequent therapy. Whole-body dosimetry calculations were performed on data from the tracer study. The activity administered for therapy was the amount predicted to deliver a predefined whole-body dose. Estimates of doses delivered to various organs during treatment are given in Table 1.

3-Iodobenzylguanidine↗
PubMed1990

Interactive effects of alpha-interferon A/D and interleukin 2 on murine lymphokine-activated killer activity: analysis at the effector and precursor level.

Studies from our laboratory and others have demonstrated that alpha-interferon (IFN alpha) can regulate natural killer cells and lymphokine-activated killer (LAK) cell activation. In vitro experiments have shown that IFN alpha has differential effects on both natural killer cells and LAK activity when combined with interleukin 2 (IL2); IFN alpha synergized with IL2 to augment natural killer cells activity while it suppressed the IL2-induced LAK response. Here we demonstrated that IFN alpha A/D can also regulate IL2-induced LAK activity in vivo with enhanced or suppressed activity depending on the IFN alpha A/D dose. The enhanced response was observed with the combination when 80,000 units/day of IFN alpha A/D were used and was detectable in the spleen, lung, and peritoneum. When a high dose of IFN alpha A/D was combined with IL2, a moderate reduction in LAK activity was noted in the spleen and peritoneum. In contrast, a high dose IFN alpha A/D augmented IL2-induced LAK activity in the lung even though it reduced the level of cellular infiltration. We have also evaluated the effect that IL2, IFN alpha A/D, and IL2 plus IFN alpha A/D have on the frequency of LAK precursors in the spleen and lung using limiting dilution analysis. Treatment of normal mice with IL2 alone increased the frequency of LAK precursor (LAKp) in the lung. This increase was associated with an infiltration of Thy-1+, asialo-GM1+, Lyt-2- lymphocytes into the lungs. Moreover, treatment with IL2 plus IFN alpha A/D enhanced the frequency of LAKp over that observed with IL2 alone. Treatment with the combination did not change the phenotype of LAKp in the lung from that seen with IL2. The increase in LAKp frequency induced by the combined treatment may not be a direct effect of IFN alpha A/D on precursor cells since IFN alpha A/D alone did not increase the frequency of LAKp in vivo or in vitro when added to limiting dilution analysis cultures. In contrast to what occurred in the lung, a consistent increase in LAKp was not seen in the spleen after treatment with IL2 or with the combination, although LAK activity was observed. These results demonstrated that in addition to inducing lytic activity from LAK effectors in vivo, IL2 treatment increased the number of precursor cells within the lung. Moreover, IFN alpha A/D in combination with IL2 influenced the level of LAKp in situ.

Animals↗