Search PubMed⌕ Search

Biomedical subjects

V A Levin

Publications and source records attributed to V A Levin.

At least 163 records · Page 9Linked to original sources
PubMed1983

Primary cerebral neuroblastoma. Long-term follow-up review and therapeutic guidelines.

Primary cerebral neuroblastoma is a distinct pathological and clinical entity that differs from other primitive neuroectodermal tumors. To characterize the clinical course of this lesion, the authors performed a retrospective analysis in 11 patients who ranged in age from 17 months to 26 years. The tumor had no predilection for either sex. Signs and symptoms were mostly those associated with increased intracranial pressure. The lesions commonly involved the parietal and occipital lobes. Computerized tomography scans of nine patients showed five solid and four cystic lesions; calcifications were found more commonly in the solid lesions. Contrast enhancement was seen in all tumors, yet angiograms typically showed an avascular mass. Total removal of tumor was possible in only two patients, both with cystic tumors. The remaining nine underwent subtotal resection of a solid lesion (in five) or a cystic lesion (in four). All 11 patients underwent postoperative irradiation that included the spinal axis in two cases; only one received adjuvant chemotherapy (solid tumor). Four patients, all with solid tumors that initially were subtotally resected, had evidence of tumor recurrence. The only patient with a subtotally resected solid lesion who did not have recurrence received adjuvant chemotherapy. The six patients who had cystic lesions are free of recurrent tumor at 26 to 109 months after surgery. Based on follow-up analysis of the 11 patients, recommendations are proposed for the treatment of primary cerebral neuroblastomas.

Adolescent↗
PubMed1982

Age-related chemosensitivity of stem cells from human malignant brain tumours.

After radiation therapy and chemotherapy for malignant glioma, patients aged 50 or under survive longer than patients over 50. Data from Brain Tumor Study Group trials show that, without treatment, these age groups have similar survival; therefore unperturbed tumour growth does not account for the difference. Sixteen consecutive patients with malignant glioma were studied, half of whom were less than or equal to 50 years of age; none had been treated before initial surgery, and all were subsequently treated with radiation and chemotherapeutic agents (in all but two patients, with nitrosoureas). Median survival of those aged greater than 50 was less than or equal to 50 years was 54 + weeks whereas that of those aged greater than 50 was 37 weeks. The longer survival for younger patients could not be attributed to tumour type, size, or location, pretreatment Karnofsky status, or mode of treatment. In-vitro sensitivity testing of clonogenic cells obtained from biopsy specimens showed that tumour cells from seven of eight patients aged less than or equal to 50 years were sensitive to 1,3-bis (2-chloroethyl)-1-nitrosourea (greater than 40% cell kill at clinically achievable concentrations) compared with only one patient with sensitive cells out of eight older patients. Patient age was inversely correlated with in-vitro cell kill, and patients with sensitive cells were significantly younger than those with resistant cells. Therefore influence of age on survival after treatment of malignant gliomas is probably due to inherent differences in the sensitivity of clonogenic cells to radiation and/or chemotherapeutic agents.

Age Factors↗
PubMed1982

Chemotherapeutic approaches to brain tumors. Experimental observations with dianhydrogalactitol and dibromodulcitol.

Dianhydrogalactitol (DAG) or its active cell-killing moiety has a relatively long biological half-life in 9L cells cultured in vitro. The shape of the DAG dose-response curves was similar to that of those observed for most oncolytic agents. The prominent shoulder on the 24-h dose-response curve indicates that 9L cells can accumulate a reasonable amount of DAG-induced sublethal damage before they are killed. The appearance of 9L colonies in petri dishes was delayed 3-5 days after a DAG treatment that killed more than 99% of the cells, an observation not previously made with radiation, hyperthermia, the nitrosoureas, or other chemotherapeutic agents. Comparison of the in vitro exposure integral and the in vivo tumor tissue integral indicated that DAG would have to be administered at a dose in excess of its LD10 to achieve an in vivo 2 log cell kill. The lack of a significant increase in lifespan after a LD10 dose confirmed this prediction. While DAG alone is active against IC ependymoblastoma, it had very limited activity against IC glioma 26; however, the combination of DAG with BCNU was curative in 85%-100% of animals at 120 days. BCNU alone achieved no more than 4%-16% survival at 120 days. The combination of DBD and BCNU was not consistently better than BCNU alone against IC glioma 26. It appears that DAG may have a limited place in CNS chemotherapy for specific kinds of tumors. BCNU-DAG combination studies suggest that we may, under the right conditions, enhance the antitumor activity of the hexitol epoxides by drug combination therapies, although the mechanism for this enhanced antitumor activity is presently unknown.

Animals↗
PubMed1982

Evaluation of misonidazole peripheral neurotoxicity in rats by analysis of nerve trains evoked response.

The clinical use of misonidazole and other nitroimidazole radiosensitizing agents is limited by the peripheral and central neurotoxicity that is produced in animals and humans. In a blinded study, rats treated with misonidazole at either 100 mg/kg or 300 mg/kg, 5 days/week for 3 weeks, were evaluated for peripheral neurotoxicity using nerve trains evoked responses. Only one rat treated at a dose of 100 mg/kg developed symptoms and signs of neurotoxicity, while all rats treated at 300 mg/kg developed these signs and symptoms. Nerve trains analysis made possible a diagnosis of neurotoxicity before overt clinical signs appeared. This test is non-invasive and may be useful for evaluating patients receiving nitroimidazole radiosensitizers as part of a radiation therapy regimen.

Animals↗
PubMed1981

Final report on the United States Phase I Clinical Trial of the hypoxic cell radiosensitizer, misonidazole (Ro-07-0582; NSC #261037).

The hypoxic cell sensitizer misonidazole began phase I evaluation in the United States in July 1977. One hundred two patients received 104 individual courses of drug. Drug was administered from once to five times per week over time spans from one to six weeks. The individual doses ranged 1-5 g/m2, and 411 mean 4-6 hour serum levels were determined. The mean 4-6 hour serum level ranged from 30 micrograms/ml at 1 g/m2 to 183 micrograms/ml at 5 g/m2. The major toxicity noted was neurologic; 49% of evaluable courses showed peripheral neuropathy, and 9% of evaluable courses showed central nervous system effects and/or ototoxicity. In addition, 48 of 102 patients exhibited some degree of nausea and vomiting. The concomitant administration of dexamethasone and phenytoin sodium appeared to lower the incidence of neuropathy. Observations of efficacy were made comparatively in five patients who had multiple lesions treated with and without misonidazole. All five showed increased response in the lesions treated with misonidazole. It is concluded that misonidazole is a reasonably safe and potentially effective hypoxic cell sensitizer whose dose-limiting toxicity is neurologic.

Adolescent↗
PubMed1981

CSF polyamines: a new and important means of monitoring patients with medulloblastoma.

An earlier study that showed the importance of cerebrospinal fluid polyamine levels for monitoring patients harboring medulloblastomas was expanded to 210 determinations evaluated in 32 patients. The results and conclusions of our earlier study have been confirmed in this expanded patient group. Patient status, with regard to either progression or regression of tumor, was determined by correlating polyamine levels with neurologic examination, computerized tomography, radionuclide scan, cerebrospinal fluid cytology, and myelography. The polyamine assay was predictive of recurrence in 15 patients; three false negatives and no false positives were found. We feel that cerebrospinal fluid polyamine determinations should be a routine diagnostic procedure in the long-term monitoring of patients harboring medulloblastoma.

Chromatography, Ion Exchange↗
PubMed1981

Complete myelographic evaluation of spinal metastases from medulloblastoma.

Twenty-six patients with medulloblastoma had complete myelography and spinal fluid cytology and tests for polyamine levels in the evaluation for spinal metastases. The nature and location of abnormalities are presented in this report. Metrizamide was demonstrated to be safe and effective for complete myelography in children. The usefulness of myelography in detecting spinal metastases at the time of initial diagnosis (11%) and at the time of first intracranial recurrence (33%) is discussed.

Adolescent↗
PubMed1981

Intrathecal chemotherapy for leptomeningeal dissemination of medulloblastoma.

Cerebrospinal fluid dissemination of medulloblastoma occurs despite adequate systemic chemotherapy, and unless it is present at the time of initial diagnosis, occurs late in the course of the disease. Intrathecal chemotherapy with an implanted Ommaya reservoir can produce short-term benefit. We report here our protocol for and the results of intrathecal chemotherapy for leptomeningeal dissemination of medulloblastoma.

Adolescent↗
PubMed1981

Chemotherapy of pediatric brain-stem tumors.

Forty-five children harboring brain-stem tumors were treated at the University of California, San Francisco, between 1969 and 1979. Pathological diagnoses were made in 19 patients. All patients received radiation therapy (RT). Thirteen patients received chemotherapy before, during, or immediately after RT. Twenty-four patients were treated with chemotherapy at the time of tumor progression, after initial treatment with RT alone. No statistically significant difference in time to tumor progression or survival was found for treatment with chemotherapy as an adjuvant to RT compared to treatment with RT alone followed by chemotherapy administered at the time of tumor progression. There were, however, more long-term survivors in the group that was first treated with chemotherapy at the time of tumor progression. There was no statistically significant correlation between survival and tumor pathology or location, although there were more long-term survivors among patients harboring low-grade gliomas and among patients with tumors confined to the midbrain. The authors documented the response of some brain-stem tumors to chemotherapy; however, cooperative controlled studies will be required to determine the optimum treatment for this disease.

Adolescent↗
PubMed1981

Potentiation of the antitumor therapeutic effects of 1,3-bis(2-chloroethyl)-1-nitrosourea by alpha-difluoromethylornithine, an ornithine decarboxylase inhibitor.

alpha-Difluoromethylornithine (DFMO), an enzyme-activated irreversible inhibitor of ornithine decarboxylase, was used alone and in combination with various single doses of 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) to treat animals bearing murine glioma 26 and rat 9L gliosarcoma intracerebral tumors. Used as a single agent, DFMO has little or no effect against these tumors. However, in both intracerebral tumor models, pretreatment with DFMO p.o. before i.p. administration of BCNU potentiates the effect of BCNU without increasing toxicity. The effects of DFMO administered p.o. after BCNU or before and after various doses of BCNU indicate that DFMO may also effectively slow the repopulation of these tumors after BCNU therapy.

Animals↗
PubMed1981

Comparative pharmacokinetics of 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)-1-nitrosourea in rats and patients and extrapolation to clinical trials.

The plasma pharmacokinetics of 1-(2-chloroethyl)-3-(2,6-dioxo-1-piperidyl)1-nitrosourea (PCNU) were determined in ambulatory rats and in patients receiving PCNU chemotherapy in Phase 1 and II studies. After derivativization to the methyl carbamate, both rat and human PCNU plasma levels were measured by gas chromatography-mass spectrometry. Comparison of the tolerated dose levels and pharmacokinetics of PCNU to the values determined for 1,3-bis(2-chloroethyl)-1-nitrosourea in humans indicated that PCNU has a lower plasma drug area under the curve at equitoxic doses. We conclude that PCNU may show less clinical efficacy than 1,3-bis(2-chloroethyl)-1-nitrosourea in the treatment of solid tumors.

Animals↗