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Biomedical subjects

C Peterson

Publications and source records attributed to C Peterson.

At least 289 records · Page 16Linked to original sources
PubMed1985

Decreased retention of vinca alkaloids in chronic lymphatic leukemia cells from refractory patients.

Uptake and retention of vincristine (VCR), vinblastine (VB), and vindesine (VD) in isolated mononuclear cells from six healthy donors and in leukemic cells from 12 patients with chronic lymphatic leukemia (CLL) were studied: Three patients responded to VCR-containing regimens, whereas 4 patients were or became refractory and five patients did not receive VCR. Incubation of leukemic or normal cells with 1 microgram/ml vinca alkaloid for 1-24 h showed a steady state level after 1-2 h. Normal cells both took up and retained significantly more drug than those from patients, both responding and refractory. Cells from VCR-refractory patients had a significantly (P less than 0.01) lower drug retention than those from patients responding to or not receiving VCR. In contrast, the difference in uptake was not statistically significant.

Aged↗
PubMed1985

Hypocholesterolemia in cancer patients may be caused by elevated LDL receptor activities in malignant cells.

Several epidemiological studies indicate an inverse relation between plasma cholesterol and the occurrence of cancer. Since we in previous studies have found that certain malignant cell types have an elevated LDL receptor activity, the aim of the present study was to further explore the possibility that an elevated LDL consumption by tumor cells causes hypocholesterolemia. The plasma cholesterol concentrations in patients with acute leukemia were inversely correlated with the rate of receptor-mediated degradation of 125I-LDL by the leukemic cells. During chemotherapy, the total plasma and the LDL cholesterol levels increased concomitantly with the reduction in the leukemic cell count in a patient whose leukemic cells exhibited a high rate at receptor-mediated degradation of 125I-LDL. In certain patients with inoperable urinary bladder carcinoma, the plasma cholesterol concentration fell as the disease progressed. Studies in breast cancer patients indicate that the number of LDL receptors in the tumor tissue may have prognostic significance. The results are in agreement with the hypothesis that an elevated LDL receptor activity in malignant cells may lead to hypocholesterolemia.

Blood Donors↗
PubMed1985

Subsynaptosomal distribution of calcium during aging and 3,4-diaminopyridine treatment.

Since previous studies showed that calcium uptake by synaptosomes from rodents declines with aging, the subsynaptosomal distribution of calcium was determined with the disruption method of Scott et al. Calcium uptake by the mitochondrial (digitonin-resistant) and non-mitochondrial (digitonin-labile) compartments, as well as total uptake, were determined at 2, 5 and 10 min. After a 10 min incubation under resting conditions (5 mM-KCl), total calcium uptake decreased at 10 months (-14.6%) and 30 months (-33.0%) of age; mitochondrial calcium uptake increased by 10 months (+ 11.2%) but declined by 30 months (-17.5%); the non-mitochondrial calcium compartment declined at 10 (-34.7%) and 30 (-43.4%) months when compared to the 3 month old control. With potassium depolarization (31 mM-KCl), total calcium uptake declined from 100% (3 months) to 73.8% (10 months) or 53.0% (30 months); mitochondrial calcium uptake declined from 100% (3 months) to 85.6% (10 months) or 68.4% (30 months); non-mitochondrial calcium uptake decreased at 10 (-34.3%) and 30 (-57.7%) months of age when compared to 3 months (100%). The deficits in calcium homeostasis are not due to changes in synaptosomal volumes or to diminished membrane potentials, as assessed by tetraphenylphosphonium ion accumulation. 3,4-Diaminopyridine partially reversed the alterations in total, mitochondrial and non-mitochondrial calcium uptake by synaptosomes from aged mice.

4-Aminopyridine↗
PubMed1985

Gigantic malignant melanoma in a thermal burn scar.

Carcinoma developing in burn scars is overwhelmingly of the squamous cell type; in fact, almost 2% of all squamous cell carcinomas develop in old burn scars. We report a case of malignant melanoma that developed in a burn scar and review eight other reported cases of malignant melanoma that developed similarly. We also compare the group having malignant melanomas in burn scars with those having the more common type of squamous cell carcinoma in burn scars.

Aged↗
PubMed1985

Low density lipoprotein receptor activity in human leukemic cells--relation to chromosome aberrations.

Chromosome analysis and low density lipoprotein (LDL) receptor activity of leukemic cells from 38 patients with acute non-lymphocytic leukemia were correlated. Clonal chromosome aberrations were found in 22 patients, and an extra chromosome 8 was found in 7 of them. LDL receptor activity was significantly higher in patients with an extra chromosome 8 than in patients with other abnormalities or a normal karyotype. Chromosome 8 may harbor genes of importance for the expression of the LDL receptor.

Adolescent↗
PubMed1985

Subsynaptosomal calcium distribution during hypoxia and 3,4-diaminopyridine treatment.

Previous results demonstrate that hypoxia (low oxygen) diminishes calcium uptake by synaptosomes. The present studies examined the effects of low oxygen on calcium homeostasis in the digitonin-resistant (mitochondrial) and the digitonin-labile (nonmitochondrial) compartments of intact synaptosomes and their relation to altered membrane potentials. A 10-min hypoxic incubation in low-potassium media reduced total (-38.3%), mitochondrial (-43.3%), and nonmitochondrial (-27.8%) calcium uptake. In high-potassium media, low oxygen reduced mitochondrial (-41.2%) and total (-34.4%) uptake whereas nonmitochondrial (+ 6%) calcium uptake was essentially unaffected. A temporal analysis of nonmitochondrial calcium uptake revealed an initial depression (0-5 min) followed by a stimulation (5-10 min). Hypoxic-induced alterations in the subsynaptosomal distribution of calcium resembled those produced by uncouplers [FCCP (carbonylcyanide-p-trifluoromethoxyphenylhydrazone) or rotenone plus oligomycin]. 3,4-Diaminopyridine partially ameliorated the hypoxic- and FCCP-induced decreases in synaptosomal calcium uptake. Low oxygen reduced the total synaptosomal membrane potential (i.e., plasma plus mitochondrial membrane potential) as measured by an increased efflux of tetraphenylphosphonium ion. This hypoxic-induced efflux of tetraphenylphosphonium was slowed by pretreatment with 3,4-diaminopyridine. Thus, both drug and membrane potential studies suggest that hypoxic-induced alterations in the subcellular distribution of calcium may be due to an uncoupling mechanism and a collapse of the synaptosomal mitochondrial membrane potential.

4-Aminopyridine↗
PubMed1984

The pyruvate dehydrogenase complex during aging.

Acetylcholine synthesis and pyruvate oxidation decline with age. To determine the role of the pyruvate dehydrogenase complex in these age-related deficits, its activity and activation state were measured in vivo and in vitro in the brains of 3-, 10- and 30-month-old mice. Aging did not alter the active form of pyruvate dehydrogenase complex in vivo, although the total complex was 17% lower at 30 than at 3 months of age. In vitro, total or active forms of pyruvate dehydrogenase complex did not change with age. The results suggest that neither changes in total activity nor in the activation state of the pyruvate dehydrogenase complex account for the age-related deficits in oxidative or acetylcholine metabolism.

Acetylcholine↗
PubMed1984

Growth and development of plants flown on the STS-3 Space Shuttle mission.

Pre-germinated pine seedlings and germinating oat and mung bean seeds were flown on the STS-3 Space Shuttle mission. Overall, the seedlings grew and developed well in space. Some oat and mung bean roots, however, grew upward. Lignin content was slightly lower in flight tissues and protein content was higher.

Avena↗
PubMed1984

Antibody to poliovirus genome-linked protein (VPg) precipitates in vitro synthesized RNA attached to VPg-precursor polypeptide(s).

Antibody to poliovirus genome-linked protein VPg, specifically precipitated RNA synthesized in vitro by the poliovirus replicase and host factor in response to poliovirion RNA. A significant amount of the immunoprecipitated RNA was RNAase T1 resistant, sedimented at approximately 2-4 S and was shown to be largely polyuridylic acid. RNAase A digestion or alkali hydrolysis of the immunoprecipitated RNA left [32P]UMP-labeled material which comigrated on SDS-polyacrylamide gels with known VPg-precursor polypeptides. The results presented in this paper suggested that VPg was involved in the host factor-dependent, poliovirus replicase-catalyzed in vitro RNA synthesis, most probably in the form of a larger precursor protein.

Antibodies, Viral↗