Electron correlation effects on the femtosecond dephasing dynamics of E22 excitons in (6,5) carbon nanotubes.

Highly nonlinear pump fluence dependence was observed in the ultrafast one-color pump-probe responses excited by 38 fs pulses resonant with the E(22) transition in a room-temperature solution of (6,5) carbon nanotubes. The differential probe transmission (ΔT/T) at the peak of the pump-probe response (τ = 20 fs) was measured for pump fluences from ∼10(13) to 10(17) photons/pulse cm(2). The onset of saturation is observed at ∼2 × 10(15) photons/pulse cm(2) (∼8 × 10(5) excitons/cm). At pump fluences >4 × 10(16) photons/pulse cm(2) (∼1.6 × 10(6) excitons/cm), ΔT/T decreases as the pump fluence increases. Analogous signal saturation behavior was observed for all measured probe delays. Despite the high exciton density at saturation, no change in the E(22) population decay rate was observed at short times (<300 fs). The pump probe signal was modeled by a third-order perturbation theory treatment that includes the effects of inhomogeneous broadening. The observed ΔT/T signal is well-fit by a pump-fluence-dependent dephasing rate linearly dependent on the number of excitons created by the pump pulse. Therefore, the observed nonlinear pump intensity dependence is attributed to the effects of quasi-elastic exciton-exciton interactions on the dephasing rates of single carbon nanotubes. The low fluence total dephasing time is 36 fs, corresponding to a homogeneous width of 36 meV (290 cm(-1)), and the derived E(22) inhomogeneous width is 68 meV (545 cm(-1)). These results are contrasted with photon-echo-derived parameters for the E(11) transition.

Phonon-assisted electroluminescence from metallic carbon nanotubes and graphene.

We report on light emission from biased metallic single-wall carbon nanotube (SWNT), multiwall carbon nanotube (MWNT) and few-layer graphene (FLG) devices. SWNT devices were assembled from tubes with different diameters in the range 0.7-1.5 nm. They emit light in the visible spectrum with peaks at 1.4 and 1.8 eV. Similar peaks are observed for MWNT and FLG devices. We propose that this light emission is due to phonon-assisted radiative decay from populated pi* band states at the M point to the Fermi level at the K point. Since for most carbon nanotubes as well as for graphene the energy of unoccupied states at the M point is close to 1.6 eV, the observation of two emission peaks at approximately 1.6 +/- approximately 0.2 eV could indicate radiative decay under emission or absorption of optical phonons, respectively.

t(11;22) and other chromosomal rearrangements in Ewing's sarcoma.

Abnormal karyotypes from 13 human cases of Ewing's sarcoma are reported in this paper. The t(11;22) was seen in 9 cases, with 2 additional cases containing only a del(22). Other abnormalities included trisomy of 1q, translocations to 19p13, deletions of 3p and 6q, and homogeneously staining regions.

Chromosome 1 abnormalities: a common feature of pediatric solid tumors.

Abnormalities of chromosome 1 were found in 32 of 46 pediatric solid tumors including Ewing's sarcoma, Wilms' tumor, rhabdomyosarcoma, primitive neuroectodermal tumor, and hepatoblastoma. Trisomy of 1q was the most common abnormality, and breakpoints were most frequent in the region 1cen to 1p22. Abnormalities of chromosome 1 are not specific to any type of tumor. However, their frequent occurrence indicates that they may endow a clonal advantage in the development of cancer.

Determination of cell surface membrane antigens common to both human neuroblastoma and leukemia-lymphoma cell lines by a panel of 38 monoclonal antibodies.

The surface membrane antigens of 7 neuroblastoma and 91 leukemia-lymphoma cell lines were studied with the use of a total of 36 murine monoclonal antibodies (MoAb) primarily developed against hematopoietic cells and 2 MoAb developed against human fetal brain. Five of the MoAb against hematopoietic cells (BA-1, BA-2, DU-ALL-1, J-5, and BA-3) consistently bound to common acute lymphoblastic leukemia cell lines, and 2 others (MCS-2 and OKM-1) reacted uniformly with acute myeloblastic-acute monoblastic leukemia cell lines. However, these 7 MoAb also reacted with 1-7 neuroblastoma cell lines. All the human neuroblastoma cell lines bound MoAb BA-2 and DU-ALL-1. Six of the 7 lines reacted with BA-1. Only 1 neuroblastoma cell line (SJ-N-CG) gave positive staining with J-5 and BA-3, and another line (SK-N-AS) bound MoAb MCS-2 and OKM-1. Anti-fetal brain MoAb (UJ-13A and UJ-127-11) were highly positive for all the neuroblastoma cell lines. By contrast, 4 of 43 leukemia-lymphoma cell lines tested bound these anti-fetal brain antibodies. Both B3/25 and OKT-9, anti-transferrin receptor antibodies, reacted with all of the hematopoietic and neuroblastoma cell lines. These results demonstrate that neuroblastoma and hematopoietic cell lines possess common antigenic determinants despite their different embryologic origins. The neuroblastoma cell lines may be classified into subgroups on the basis of phenotype profiles determined by the MoAb. MoAb may be useful in characterization and classification of neuroblastoma cells, as has already proved to be the case for cells of the hematopoietic lineages.

Chemotherapy of childhood rhabdomyosarcomas growing as xenografts in immune-deprived mice.

Xenografts derived from the neoplastic tissues of children with rhabdomyosarcoma have been used in immune-deprived mice to examine the efficacy of agents known to be active against this disease, and in others that received either limited or no clinical evaluation. Two models were derived; xenografts were established from tumors obtained from either (a) untreated patients or (b) from patients who had become refractory to conventional therapy. Model a identified as being effective each of these clinically used agents: vincristine, dactinomycin, cyclophosphamide, and doxorubicin; mitomycin C and 5-(3,3-dimethyl-1-triazeno)-2-methylimidazole-4-carboxamide also showed activity, as did busulfan in one tumor line. Tumors derived from refractory patients were significantly less responsive to all agents examined.

Correlation of cell kinetic and clinical response to chemotherapy in disseminated neuroblastoma.

Mitotic and labeling indices of bone marrow tumor cells were determined from patients with disseminated neuroblastoma. Although pretreatment values were variable, the median indices indicated that only a small proportion of tumor cells were proliferating. The pretreatment indices could not be correlated with presenting clinical features or with the response to chemotherapy. Studies were repeated after 7 daily doses of cyclophosphamide (150 mg/sq m) and serially after Adriamycin (35 mg/sq m) given on Day 8. Changes in the mitotic and labeling indices during the first course of therapy could be directly correlated with the clinical response as evaluated after 4 months of induction chemotherapy. In all patients who attained a complete or partial remission, an increase in these indices was observed after 7 days of cyclophosphamide. If this increase was associated with an observed kinetic effect of Adriamycin in the G1, S, and G2 phases of the cell cycle, a complete remission was attained. If, following Adriamycin, kinetic evidence of an effect was not present in all three phases of the cell cycle, only partial remission was attained. No clinical response to therapy was observed in those patients in whom the mitotic index and labeling index did not increase after 7 days of cyclophosphamide.

Distribution and properties of type I and type II binding proteins in the cyclic adenosine 3':5'-monophosphate-dependent protein kinase system in Wilms' tumor.

We compared the relative amounts and properties of cyclic adenosine 3':5'-monophosphate (cAMP)-binding proteins in surgical specimens of Wilms' tumor and normal kidney. Cytosolic fractions of both tissues contained type I and type II isozymes of cAMP-dependent protein kinase (adenosine triphosphate: protein phosphotransferase, EC 2.7.1.37). Among tumor samples, the mean ratio of type I to type II cAMP-binding activity was 2.76 +/- 0.52 (S.D.) contrasted with 1.36 +/- 0.23 for normal kidney (p less than 0.001). The total soluble cAMP-binding activities in normal and malignant tissues differed only slightly. Photoaffinity labeling of cytosol from either tissue, using cyclic adenosine 3':5'-[8-azido-32P]monophosphate, disclosed three cAMP-binding proteins (Mr 47,000, 51,000, and 55,000) that were identified as regulatory subunits of the holoenzyme. Three lower-molecular-weight proteins with unknown function were considered to be proteolytic products of the larger proteins. The Mr 47,000 protein, a monomeric regulatory subunit of type I kinase, was clearly the dominant protein in tumor specimens, but it was much less abundant in normal kidney. The temperature sensitivities of the cAMP-binding proteins and their dissociation constants for cyclic adenosine 3':5'-[8-azido-32P]monophosphate incorporation did not differ appreciably between tumor and normal tissues. Wilms' tumor appears to have a full complement of regulatory subunits of cAMP-dependent protein kinase that are capable of normal cellular function.

Consistent N-myc copy number in simultaneous or consecutive neuroblastoma samples from sixty individual patients.

Amplification of the N-myc oncogene is detected in about 30% of untreated neuroblastomas. Amplification is associated with advanced stages of disease and rapid tumor progression. However, it was not known if the N-myc copy number was homogeneous in tumor tissue of an individual patient, or if it changed with time in vivo. Therefore, we have made 66 observations on multiple simultaneous or consecutive tumor samples from 60 patients with neuroblastoma. (a) Simultaneous samples were obtained from different areas of 31 tumor masses from 30 patients: a similar N-myc copy number (1-2, 3-10, or greater than 10) was found in all samples from each patient. (b) Simultaneous samples were obtained from different anatomical sites in ten patients. No difference in N-myc copy number was seen. (c) Finally, 25 patients had two or more tumor samples obtained over time. Thirteen patients had a single copy of N-myc in all samples, and 12 had consistent levels of amplification in all samples. Two of the latter cases had single copy of N-myc in a second-look surgery sample, but no tumor was evident histologically. This study demonstrates that the N-myc copy number in human neuroblastomas is usually consistent within a tumor, not only at different tumor sites, but also at different times in vivo. Overall, these findings suggest that N-myc amplification is an intrinsic biological property of a subset of neuroblastomas, and if amplification is going to occur, it is generally present at the time of diagnosis.

Cytogenetic features of human neuroblastomas and cell lines.

We reviewed the banded karyotypes of 24 human neuroblastomas and cell lines to identify any consistent chromosomal abnormalities. Six of the 10 primary tumors and one of the 14 cell lines were studied at this institution. Of the 24 neuroblastomas karyotyped, 20 were near-diploid, one was near-triploid, and 3 were near-tetraploid. One primary tumor had a diploid karyotype without numerical or structural rearrangements. The 20 cases with a karyotype in the diploid range were statistically analyzed for gain or loss of while chromosomes and for structural abnormalities of each chromosome arm. The short arm of chromosome 1 was preferentially involved in structural rearrangements, occurring in 14 cases (p less than 0.01). In 11 of these cases, the abnormality of chromosome 1 included deletion of bands 1p32 leads to 1pter, rendering the cells monosomic for this genetic material. Of the remaining three cases, one involved a reciprocal translocation of chromosomes 1p and 12q, another had insertion of genetic material at band 1p13, and the third had an extra dark band at 1p36. No other numerical or structural abnormalities occurred with sufficient frequency to reach statistical significance (p greater than 0.20). Six of the primary tumors or cell lines in the diploid range had double minute chromatin bodies, four cell lines had homogeneously staining regions, and two cell lines had either double minute chromatin bodies or homogeneously staining regions in subpopulations of cells. Hence, partial monosomy for the short arm of chromosome 1 was the most consistent cytogenetic abnormality in the human neuroblastomas studied.

Malignant melanoma in childhood: clinical course and response to chemotherapy.

Malignant melanoma is uncommon in patients less than 20 years of age, and little is known about the response to chemotherapy in this age group. We report here a series of 18 children, of whom ten with metastatic disease were treated with cyclophosphamide, vincristine, and dactinomycin. Only two of nine evaluable patients failed to show an objective response to therapy. Five of ten patients treated are alive and free of tumor 12 to 80 months from the start of chemotherapy. Three have been in remission for more than five years. Results suggest that melanoma in this age group may be more responsive to chemotherapy than melanoma in adult patients and that a trial of this therapy in a larger number of children with evaluable disease is warranted.

Phase II testing of melphalan in children with newly diagnosed rhabdomyosarcoma: a model for anticancer drug development.

We describe events that led to successful testing of melphalan, one of the nitrogen mustard compounds, in children with newly diagnosed, poor-risk rhabdomyosarcoma (RMS). Preclinical studies with xenografts of human RMS, growing in the flanks of immune-deprived mice, had indicated superior oncolytic activity by melphalan compared with other agents commonly used to treat this tumor. However, in a conventional phase II trial, melphalan failed to produce partial responses in 12 of 13 heavily pretreated patients with recurrent tumors. Subsequent comparison of the drug's pharmacokinetics in mice and patients indicated that its poor clinical performance was not the result of interspecies differences in drug disposition. Therefore, we elected to retest melphalan in untreated patients, before they were enrolled in a phase III study. Of 13 children who received the drug for 6 weeks, ten had partial responses, confirming the significant antitumor activity seen in the xenograft system. These findings illustrate the inherent limitations of phase II drug trials in previously treated patients and suggest a useful paradigm for the development of antineoplastic drugs.

Hyperdiploidy and chromosomal rearrangements define the anaplastic variant of Wilms' tumor.

Flow cytometric measurement of the DNA content of Wilms' tumor cells revealed a striking correspondence with the histologic subtype and treatment outcome. In the 48 cases studied, a hyperdiploid DNA content ranging from 1.7 to 3.2 times the result for normal diploid cells distinguished all but one of the ten anaplastic tumors. Lower values, from 1.0 to 1.4 times the diploid DNA content, characterized the nonanaplastic specimens. By Kaplan-Meier analysis, the probability of achieving 3 years of relapse-free survival was significantly lower in the group with higher DNA content (0.42 v 0.87, P less than .01). Analysis of banded chromosomes for a subset of 22 patients contributed important information beyond the flow cytometric study. Cases of anaplasia associated with poorer responses to therapy showed numerous complex translocations, whereas all others lacked such changes. By combining flow cytometric techniques and conventional methods of chromosome analysis, it should be possible to identify those patients with Wilms' tumor who are most likely to fail therapy. The biologic implication of these findings is that the development of clinical drug resistance in Wilms' tumor is a result of the genetic instability of the malignant clone.

Central nervous system toxicity following the treatment of pediatric patients with ifosfamide/mesna.

Ifosfamide/mesna treatment of 50 patients with pediatric malignant solid tumors was associated with the development of neurotoxic signs and symptoms in 11 of these individuals who received 29 courses of treatment. Neurologic toxicity included changes in mental status, cerebellar function, cranial nerve, and cerebellar and motor system function, including seizures. All symptoms, signs, and EEG abnormalities were transient. Some of the affected individuals failed to develop acute neurotoxic signs of symptoms when retreated with ifosfamide. A grading system for scoring these neurologic abnormalities is presented for comparison of acute neurotoxic effects of other agents. Recommendations are made regarding early termination or delay of ifosfamide/mesna treatments in the presence of significant neurotoxicity.

Hearing loss in children and young adults receiving cisplatin with or without prior cranial irradiation.

One hundred seventy-seven children and young adults with various malignant neoplasms were prospectively tested for hearing loss after they had received cisplatin (n = 146), cranial irradiation (n = 18), or both (n = 13). Adequate renal function, no history of treatment with ototoxic drugs other than cisplatin, and availability for repeated audiometric testing were requirements for enrollment. Substantial hearing loss, defined as a hearing threshold of 50 dB or greater, was noted in only 11% of the cohort on tests conducted at the common speech frequencies (500 to 3,000 Hz). About half the patients had substantial deficits at higher frequencies (4,000 to 8,000 Hz). The probability of substantial hearing loss was directly related to the cumulative dose of cisplatin. In nonirradiated patients tested at the speech frequencies, there was a negligible risk of substantial deficits over the dose range of 90 to 360 mg/m2. As the dose increased to 720 mg/m2, the risk increased to 22%. In irradiated patients who later received cisplatin, cumulative drug doses as low as 270 mg/m2 were associated with a high probability of substantial hearing loss, suggesting potentiation of ototoxicity when these therapies are used together. Hearing acuity was either not affected or only minimally decreased in the irradiation-only group. Younger age, prior irradiation, and the presence of a CNS tumor each contributed significantly to the severity of hearing deficits at given cisplatin dose levels. We conclude that early increases in hearing threshold at a stimulus frequency of 4,000 Hz indicate probable subsequent deficits at lower frequencies, especially in young children with CNS tumors who have received cranial irradiation. The probability charts derived from this analysis should provide a useful tool for predicting hearing loss in the speech frequencies.

The effect of prior cisplatin therapy on the pharmacokinetics of high-dose methotrexate.

The pharmacokinetics of high-dose methotrexate (MTX, 5-15 g/m2) were evaluated in 11 children and adolescents who had previously received two to eight doses of cisplatin (90 mg/m2) in the treatment of malignant solid tumors. The half-life for disappearance of MTX from serum during the first 24 hours after infusion was determined from serum samples obtained at the end of a six-hour infusion and six, 12, and 24 hours after infusion. These values were compared to a mean half-life of 2.83 (+/- 0.34) hours following 489 courses administered to 71 patients who had not received cisplatin. Stepwise multiple linear regression analysis of patient variables revealed cumulative cisplatin dosage and time from last cisplatin dose as the best predictors of MTX half-life (r2 = 65.4%, p less than 0.001). The best predictors of 24-hour serum concentration were cumulative cisplatin dosage and MTX dosage (r2 = 54.2%, p less than 0.001) in the multiple linear regression model. Patients with delayed MTX clearance received additional leucovorin and experienced no severe toxicity. Patients receiving up to 270 mg/m2 of cisplatin appear to have minimal increases in MTX half-life, while the likelihood of delayed clearance increases in patients who have received 360 mg/m2 or more of cisplatin. All patients who have previously received cisplatin should be treated cautiously with high-dose MTX and prospective pharmacokinetic monitoring should be routinely performed.

Phase II investigational window using carboplatin, iproplatin, ifosfamide, and epirubicin in children with untreated disseminated neuroblastoma: a Pediatric Oncology Group study.

PURPOSE: Children less than 1 year of age with metastatic neuroblastoma NB are at high risk of death. The need to identify new and effective chemotherapy agents is clear. A study was conducted by the Pediatric Oncology Group (POG) to determine the efficacy and safety of administering two courses of a single phase II agent before conventional treatment as a means to evaluate new agents in this setting. PATIENTS AND METHODS: One hundred seventy-three eligible patients more than 1 year of age with disseminated neuroblastoma received two courses of one of the following: ifosfamide (IFOS) 2 g/m2/d for 4 days intravenously (IV) plus mesna; carboplatin (CARB) 560 mg/m2 i.v. over 1 hour; iproplatin (CHIP) 325 mg/m2 IV over 2 hours; or epirubicin (EPIR) 90 mg/m2 i.v. push. Following evaluation for response and toxicity, eligible patients were randomized to receive either cisplatin 90 mg/m2 i.v. on day 1, etoposide 200 mg/m2 i.v. on day 3, cyclophosphamide 150 mg/m2/d orally on days 7 to 13, doxorubicin 35 mg/m2 i.v. on day 14 (CECA), or cisplatin 40 mg/m2 IV on days 1 to 5 and etoposide 200 mg/m2 i.v. on days 2 to 4 alternating at 3-week intervals with cyclophosphamide 150 mg/m2/d orally on days 1 to 7 and doxorubicin 35 mg/m2 IV on day 8 (HDP/VP/CA). An additional 86 patients were randomized to receive either CECA or HDP/VP/CA without initial phase II therapy. RESULTS: After phase II therapy, only 20% of patients experienced grade 3/4 hematopoietic toxicity. No toxic deaths occurred. Objective response rates (partial responses [PRs] plus minor responses [MRs]) following IFOS, CARB, CHIP, and EPIR were 70%, 77%, 67%, and 26%, respectively. Following phase III treatment, there was no statistically significant difference in rates of complete response (CR)/PR or progressive disease (PD), or in time to PD of patients who participated in the phase II window versus those who received only CECA or HDP/VP/CA. CONCLUSION: IFOS, CARB, and CHIP are efficacious in neuroblastoma, are well tolerated, and should be incorporated into primary treatment regimens. Combination regimens using these agents may be possible, since most repeat courses were given within 2 weeks. Administering phase II therapy to untreated patients with high-risk tumors provides a unique and sensitive method to assess new agents without compromising patient outcome.

Impact of intensified therapy on clinical outcome in infants and children with neuroblastoma: the St Jude Children's Research Hospital experience, 1962 to 1988.

To gauge the impact of intensified therapy on the survival of infants (younger than 1 year, n = 129) and children (greater than or equal to 1 year of age, n = 275) with neuroblastoma, we analyzed the results of eight successive clinical trials comparing various combinations of antineoplastic drugs, surgery, and radiotherapy. Changes in treatment did not affect the survival of children with involved noncontiguous lymph nodes or distant metastatic disease until the combination of cisplatin and teniposide (CDDP/VM26) was added to a basic regimen of cyclophosphamide and doxorubicin (CTX/DOX). The resulting 4-year survival was 28% +/- 5% (SE) compared with 7% +/- 2% for previous treatments (P less than .001 by the log-rank test). The 4-year survival of infants with metastatic disease was improved by administering CTX/DOX to all patients, reserving CDDP/VM26 for those whose disease was resistant to the former combination: 82% +/- 6% versus 45% +/- 8% in earlier studies; P less than .001. In the subset of infants whose tumors had disseminated to bone or bone marrow at diagnosis, this therapeutic approach increased the probability of long-term survival from 48% +/- 10% to 85% +/- 9% (P = .01). The small group of children over 1 year of age with localized unresectable tumors also fared significantly better with the switch to CTX/DOX chemotherapy (4-year survival, 93% +/- 7% v 42% +/- 13%; P = .02). Multivariate analysis indicated that young age, limited-disease stage, nonadrenal primary site, and intensified treatment were independent predictors of a more favorable outcome. We conclude that substantial advances in the treatment of neuroblastoma have occurred over the past 25 years at this institution. The current overall 4-year survival probability of 57% +/- 4% compares favorably with estimates for most other common solid tumors of childhood.

Therapy for childhood soft-tissue sarcomas other than rhabdomyosarcoma: a review of 62 cases treated at a single institution.

The rarity and diverse characteristics of the nonrhabdomyosarcomatous soft-tissue sarcomas (NRSTS) in children have hindered study of their clinical presentations and response to therapy. Here we describe the findings of a retrospective analysis of 62 cases of NRSTS seen in a single institution from 1962 through 1983. The most common histopathologic diagnosis was synovial sarcoma, occurring in 18 patients, followed by malignant schwannoma in 12. The median age at diagnosis was 11 years (range, 2 months to 20 years). Anatomic sites of primary tumors were the trunk (28), extremity (24), and head and neck (10). Of the 31 patients whose tumors were completely resected, 26 (84%) survive with no evidence of disease. Postoperative chemotherapy, administered to nearly one half of this group, did not produce any demonstrable gains in survival. Only one of the 26 patients with local or metastatic gross tumor after resection survives. We conclude that an aggressive surgical approach is imperative in patients with NRSTS and that the contribution of other treatment modalities needs to be defined in a collaborative group trial.

Clinical studies of ifosfamide/mesna at St Jude Children's Research Hospital, 1983-1988.

A phase-II study of ifosfamide with mesna, given intravenously daily for five days by bolus injection, has demonstrated the activity of ifosfamide against a spectrum of childhood malignant solid tumors. Ifosfamide presently is being investigated in alternative phase-I schedules, daily times three or every other day times three with the aim of delivering comparable amounts of ifosfamide without increasing toxicity--specifically, neurotoxicity. Additionally, response following ifosfamide treatment is being evaluated for previously untreated children with osteosarcoma and rhabdomyosarcoma after 6 weeks of treatment, and for previously untreated patients with Ewing's sarcoma after 9 weeks of treatment with ifosfamide/VP-16 (etoposide) given in combination.