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Biomedical subjects

A T Meadows

Publications and source records attributed to A T Meadows.

At least 145 records · Page 8Linked to original sources
PubMed1978

Acute and long-term cytogenetic effects of childhood cancer chemotherapy and radiotherapy.

Approximately 30 banded karyotypes per subject from the lymphocytes of 66 childhood cancer patients and 14 noncancer control subjects have been analyzed in an attempt to gauge the late effects of anticancer chemotherapy and chemotherapy plus radiotherapy on the genetic material, i.e., the chromosomes. The frequencies (f) of aberrant cells were: f = 1/306 among cells from noncancer controls; f = 1/377 from cancer patients prior to therapy, f = 1/15 from patients currently on chemotherapy; and f = 1/32 from posttherapy patients (range, 3 months to 22 years poattherapy). The frequency of chromosomally aberrant cells did not appear to change with time among posttherapy patients, and the majority of aberrations detected in subjects from this group were balanced rearrangements. This was not the case for the on-therapy group where unbalanced rearrangements and unstable aberrations predominated.

Antineoplastic Agents↗
PubMed1977

The value of maintenance therapy following treatment of central nervous system leukemia.

The efficacy of intrathecal (IT) maintenance chemotherapy following central nervous system (CNS) leukemia was demonstrated in a retrospective study of 77 such episodes. The median durations of CNS and bone marrow (BM) remissions were significantly longer for the 41 maintained episodes (10+ and 9.5 months, respectively) compared with the 36 unmaintained episodes (4 and 2 months, respectively). Patients were comparable in each of these two groups. For those patients receiving maintenance therapy, there appeared to be an advantage in using four or more doses of IT medications for treatment of CNS leukemia, regardless of the number of doses necessary to clear the cerebrospinal fluid (CSF).

Antineoplastic Agents↗
PubMed1977

Patterns of second malignant neoplasms in children.

A search of the records of 10 pediatric oncology centers revealed 102 children with more than one malignant neoplasm. In this group of 102 patients, all pediatric cancers were seen as initial lesions, but Wilms' tumor and retinoblastoma were over-represented and leukemia and brain tumors underrepresented. Survival variation as well as tumor susceptibility may be responsible for this disproportion. Osteosarcomas and chondrosarcomas were the most frequent second malignant neoplasms (SMN). Embryonal tumors were rare as SMN and adult-type tumors (carcinomas) appeared at earlier than expected ages, whether arising after irradiation or not related to that form of therapy. Radiation was associated with 69 SMN, genetic disease accounted for 27 SMN and both conditions were noted in 15 SMN. In the group of 21 patients for whom neither radiation nor a known genetic disorder could be implicated, there were three with colon carcinoma and glioma and five with leukemia or lymphoma and glioma. These combinations may reflect new tissue-specific hereditary cancer syndromes.

Adolescent↗
PubMed1976

Effects of chemotherapy on the central nervous system. A study of parenteral methotrexate in long-term survivors of leukemia and lymphoma in childhood.

Twenty-three children surviving more than 5 years from the diagnosis of leukemia, lymphoma, or malignant histiocytosis were evaluated for clinical evidence of central nervous system disease. Severe impairment, consisting of seizures, paraplegia, and dementia was present in 4, all of whom received methotrexate (MTX) and other agents for 2 to 7 years. Brain biopsies in 3 of these children showed white-matter gliosis and no evidence of viral or other infections or leukemic infiltrates. Of the remaining children 10/19 were found to have mild clinical or EEG abnormalities. All had received i.v. MTX with other drugs for 2-6 years; 5 did not receive cranial irradiation. Common to all impaired patients was the administration of intravenous methotrexate in relatively high doses over a prolonged period of time. Impairment in nervous system function may present as a spectrum of deficiencies, with the most severe resulting in death, or as in the 4 patients described here, profound dementia and dependence. Less dramatic changes in functioning, may, however, result from various combinations of chemotherapy and radiation therapy. Methods of assessing their etiology and impact on survivors need now to be devised.

Adolescent↗
PubMed1976

Pulmonary function in survivors of Wilm's tumor. Patterns of impairment.

Whole-lung irradiation in Wilms' Tumor patients has been given prophylactically and for treatment of metastasis. Thirty-three children with Wilm's tumor who have survived for 4 to 20 years from the time of diagnosis were avaiable for study. Whole-lung irradiation was given in doses from 1163 to 1370 rads (orthovoltage). Eighteen patients (Group N) received no irradiation to the lungs. The remaining 15 patients were divided according to whether pulmonary irradiation was given for metastatic disease (Group M--10 patients) or for prophylactic treatment (Group P--five patients). All but five patients in Group N received at least one course of actinomycin D. A routine set of pulmonary function tests was done to assess possible abnormalities of lung volume and the mechanics of breathing. Group N was normal. The findings in Group M suggested moderately reduced lung volumes and may have also reflected obstruction of the large airways and/or a limited expiratory effort. Group P had essentially normal lung volumes but also appeared to have obstruction of the larger airways. Abnormalities were generally not severe; only two patients, in Group M, were symptomatic. Excess irradiation, presence of metastatsis, additional lung irradiation, and pneumonitis may have contributed to morbidity.

Child↗
PubMed1976

Developmental genetics of neuroblastoma.

Case reports of neuroblastoma revealed that some individuals are genetically predisposed and that this genetic predisposition may have other consequences. According to a mutation model, two classes of individuals could acquire neuroblastoma. One (prezygotic) was a rare class that carried a dominant gene imparting high risk of the tumor. The other (postzygotic) comprised all other individuals, each at low risk. The model related tumor incidence to germinal and somatic mutation rates and thereby carried implications for environmental modification of tumorigenesis and demographic variation in incidence. Case reports also revealed associations of neuroblastoma with congenital defects and a susceptibility to second tumors. Analogy with retinoblastoma and Wilms' tumor of the kidney suggested that these associations could result from action of a neuroblastoma gene or from chromosomal aberration. One known dominantly inherited condition, von Recklinghausen's disease, could dispose to neuroblastoma and create some associations. According to the two-mutation model, neuroblastoma may have been a single recessive gene disorder at the level of the cell. The phenomena of aganglionosis, neuroblastoma in situ, maturation of neuroblastoma to ganglioneuroma, and spontaneous regression suggested that such a neuroblastoma gene interfered with normal developmental processes. The specificities of this gene and of those for von Recklinghausen's disease and pheochromocytoma suggested that the functiof a membrane macromolecule.

Carcinoma in Situ↗
PubMed1975

Oncogenesis and other late effects of cancer treatment in children.

Review of hospital charts of 168 patients surviving two or more years following the diagnosis of cancer and subsequent-examinations of 40 of these patients yielded these observations: (a) Hospital charts were adequate to ascertain the number of second primary neoplasms. Three malignant and eight benign tumors were found, an incidence of 6.5%. (b) The three patients with second malignant neoplasms did not receive chemotherapy and two of three were treated with radiation. (c) Abnormalities other than second neoplasms, which may have been delayed consequences of treatment, were infrequently noted in hospital records, but were subsequently detected on specific examinations.

Antineoplastic Agents↗