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Biomedical subjects

C Peterson

Publications and source records attributed to C Peterson.

At least 325 records · Page 18Linked to original sources
PubMed1982

Prednimustine and vincristine compared with cytosine arabinoside and thioguanine for treatment of elderly patients with acute nonlymphoblastic leukemia.

Sixty-seven patients with acute nonlymphoblastic leukemia (ANLL) and above the age of 60 years were randomly allocated to treatment with either prednimustine + vincristine or cycles with cytosine arabinoside and thioguanine. Of the 67 patients, 13 (19%) entered a complete remission and four a partial remission. Of 33 patients randomized to prednimustine and vincristine (15 adequately treated), three entered a complete remission and one a partial remission. Four further patients went into complete remission after a switch to other treatment modalities. Of 34 patients randomized to cycles of ARA-C and thioguanine (22 adequately treated), four entered a complete remission and three a partial remission with the correct program. One patient entered a remission with intermittent cytosine arabinoside + thioguanine (wrong program) and one further patient entered a complete remission after a switch to prednimustine and vincristine. Prednimustine + vincristine did not appear to be superior to treatment with cytosine arabinoside thioguanine cycles for elderly patients with ANLL.

Acute Disease↗
PubMed1982

Patient behavior in hospitals: helplessness, reactance, or both?

Forty-eight inpatients hospitalized for 1, 3, or 9 weeks and 24 outpatients were tested on cognitive tasks: poor performance and depressive symptoms increased with length of hospitalization, even as illness resolved. Further, increased hospitalization made patients more susceptible to the debilitating effect of uncontrollable events. Taken together, these results imply that the passive, compliant, and inanimate behavior of the "good patient" may be the result of learned helplessness engendered by hospitalization.

Adult↗
PubMed1982

Attributional styles and life events in the classroom: vulnerability and invulnerability to depressive mood reactions.

A core prediction of the reformulated model of learned helplessness and depression (Abramson, Seligman, & Teasdale, 1978) is that when confronted with the same negative life event, people who display a generalized tendency to attribute negative outcomes to internal, stable, or global factors should be more likely to experience a depressive mood reaction than people who typically attribute negative outcomes to external, unstable, or specific factors. We tested this prediction with a prospective design in a naturalistic setting by determining whether the content of college students' attributional styles at one point in time predicted the severity of their depressive mood response to receiving a low grade on a midterm exam at a subsequent point in time. Consistent with the prediction, students with an internal or global attributional style for negative outcomes at Time 1 experienced a depressive mood response when confronted with a subsequent low midterm grade, whereas students with an external or specific attributional style for negative outcomes were invulnerable to this depressive mood response. In contrast to the results for the internality and globality dimensions, students' scores along the stability attribution dimension were not correlated with the severity of their depressive mood response to the low midterm grade. In the absence of a negative life event (i.e., receipt of a high midterm grade), students' generalized tendencies to make internal or global attributions for negative outcomes at Time 1 were not significantly correlated with their subsequent changes in depressive mood although there was a nonsignificant positive correlation between severity of depressive mood response and the tendency to make global attributions for negative outcomes at Time 1.

Achievement↗
PubMed1982

Toxic effects of free and DNA-linked daunorubicin on isolated rat cardiac myocytes.

Isolated cardiac myocytes from adult rats were used as a model to study the cardiotoxicity of free and DNA-linked daunorubicin. The toxic effects on the myocytes were evaluated by studying morphological changes, trypan blue exclusion and cell membrane permeability to NADH, as determined by LDH-activity. At a concentration of 100 microM daunorubicin caused an increased plasma membrane permeability within 30 min. Using light microscopy, the myocytic injury induced by daunorubicin could be distinguished from that induced by anoxia or elevated pH. In contrast to the effect of the free drug, no toxic effects could be demonstrated after incubation with DNA-linked daunorubicin (100 microM) for 5 hours. The higher toxicity of the free drug was related to a much higher intracellular accumulation of daunorubicin. No fluorescent metabolites of daunorubicin could be detected in the myocardial cells. Daunorubicin did not induce lipid peroxidation, as judged by the absence of malondialdehyde production and evolution of ethane. It is concluded that daunorubicin exerts toxic effects on rat cardiac myocytes by mechanisms that do not involve lipid peroxidation. Isolated cardiac cells from adult rats seem to be a useful model for the further study of such mechanisms.

Animals↗
PubMed1982

3,4-diaminopyridine alters acetylcholine metabolism and behavior during hypoxia.

Low oxygen (hypoxia) decreases the release and synthesis of acetylcholine (ACh) as well as behavioral performance (i.e., tight rope test scores). These hypoxic-induced impairments are partially reversed by 3,4-diaminopyridine (3,4-DAP). With mouse brain slices, the Ca++-dependent-K+-stimulated synthesis of ACh from [U-14C]glucose decreased 45% under 2.5% oxygen and 80% under 0% oxygen. During hypoxia, 3,4-DAP (10 nM) increased in vitro ACh synthesis 67% (2.5% oxygen) and 63% (0% oxygen). The Ca++-dependent-K+-stimulated release of ACh declined by 55 or 67% under 2.5 or 0% oxygen, respectively.3,4-DAP partially reversed this hypoxic impaired release of ACh under 2.5 (+69%) or 0% (+226%) oxygen. In vivo, chemical hypoxia (i.e., NaNO2-induced methemoglobinemia) reduced ACh synthesis from [U-14C]glucose in striatum (-82%), cortex (-68%) and hippocampus (-55%). During hypoxia, 3,4-DAP (10 pmol/kg) increased [U-14C]glucose incorporation into ACh in the hippocampus (+62%) and striatum (+36%). Tight rope test performance decreased 89% during hypoxia and 3,4-DAP diminished this decline to only 55%. These findings demonstrate that the hypoxic-induced deficits in ACh metabolism and behavior can be partially reversed by interaction with Ca++ homeostasis. The therapeutic usefulness of 3,4-DAP in the treatment of human metabolic encephalopathies remains to be evaluated.

4-Aminopyridine↗
PubMed1982

Significance of cellular pharmacokinetics for the cytotoxic effects of daunorubicin.

The effect of free and DNA-linked daunorubicin on the colony-forming ability of granulocyte-macrophage committed stem cells and spleen colony-forming cells (i.e., multipotent stem cells) from normal mice has been studied in vitro and in vivo. After incubation of bone marrow cells in short-term suspension cultures, both committed and multipotent stem cells were more sensitive to the free drug than to the DNA complex, whereas the reverse was found in vivo after i.v. injection. However, when the in vitro cell-killing effect was related to the cellular retention of daunorubicin, no difference in activity was found between free and DNA-linked drug. Incubation of the bone marrow cells with a higher drug concentration for a shorter time resulted in a considerably lower cell survival than incubation with a lower concentration for a longer time, the intracellular exposure dose being the same. When the in vivo cell survival was related to the cellular retention of daunorubicin, the DNA complex was slightly more toxic than free drug, which can be explained by the higher peak concentration obtained. The results obtained with committed granulocytic stem cells and multipotent stem cells were comparable. Thus, the observed discrepancy between the in vitro and in vivo toxicity of free and DNA-linked daunorubicin can be explained by the differences in cellular retention of daunorubicin under these two conditions; i.e., the DNA complex probably acts as a slow-release preparation of daunorubicin. The results also demonstrated for the first time the importance of the peak concentration of daunorubicin in the target cells and indicate an important role of dose scheduling for the cytostatic effect of the drug.

Animals↗
PubMed1981

Reducing the cardiotoxicity of anthracyclines by complex-binding to DNA: report of three cases.

Three patients with acute myeloblastic leukemia received high doses of daunorubicin, first in the free form and later as complex with DNA. Two of the patients also received doxorubicin-DNA. Two patients showed symptoms of cardiotoxicity with signs of congestive heart failure after cumulative doses of 910 and 250 mg of noncomplexed daunorubicin/m2 body surface area, respectively. Thereafter they tolerated daunorubicin-DNA complex up to total doses of 1430 mg and 1200 mg daunorubicin/m2, respectively, with no further signs of cardiotoxicity. One of them entered another complete remission after therapy with the complex. The third patient had received 820 mg daunorubicin/m2 and was in his second relapse when he was switched to daunorubicin-DNA complex. A new remission was induced and the patient received a total daunorubicin dose of 1480 mg/m2 with no clinical signs of cardiotoxicity. However, a cardiac biopsy showed minor myocardial changes, which could have been due to daunorubicin. During a third relapse the patient received 270 mg/m2 doxorubicin-DNA. At autopsy still only minor signs of cardiomyopathy were seen. Thus, complex-binding of anthracyclines with the DNA appears to enhance the usefulness of these drugs in the treatment of patients with leukemia.

Adult↗
PubMed1981

Brain acetylcholine synthesis declines with senescence.

The synthesis of whole brain acetylcholine is reduced in two strains (C57BL and BALB/c) of senescent mice. The incorporation of [U-14C]glucose into acetylcholine decreased in both strains by 40 +/- 4 per cent in 10-month-old mice and by 58 +/- 9 percent in 30-month-old mice compared with mice 3 months old. The incorporation of [2H4]choline into acetylcholine declined 60 and 73 percent in 10- and 30-month-old mice, respectively. Deficits in the cholinergic system may contribute to brain dysfunctions that complicate senescence.

Acetylcholine↗
PubMed1981

Intracellular localization of estramustine in rat ventral prostate in vitro.

With the aim of studying the mechanism behind the effect of estramustine in the treatment of prostatic carcinoma, the intracellular fate of the drug has been investigated in rat ventral prostate in vitro. Minced tissue was incubated with [3H] estramustine under different conditions, homogenized, and submitted to isopycnic centrifugation on a sucrose gradient using the recently introduced vertical tube rotor. The subcellular localization of the drug was determined by comparison between the distribution of radioactivity in the gradient fractions and the activities of a number of marker enzymes. No metabolism of estramustine occurred as judged by thin-layer chromatography. After incubation of the minced prostate tissue for 1 hour at 30 degrees C with 0.15 microM of [3H] estramustine, most of the drug was recovered in the cytosol fractions which also contained the highest concentrations of the estramustine-binding protein. However, after incubation with 220 microM of estramustine, most drug equilibrated in heavier fractions with high concentrations of N-acetyl-beta-glucosaminidase and cathepsin B, marker enzymes for the lysosomes as well as NADPH:cytochrome c reductase, marker enzyme for the endoplasmic reticulum. Extending the incubation time and increasing the temperature reduced the amount of estramustine equilibrating in the heavy fractions and concomitantly increased the portion localized in the cytosol. During all incubation conditions, very little drug seemed to accumulate in the nuclei since the drug distribution was completely different from that of DNA. This suggests that effects other than interaction with nuclear DNA might be of importance for the cytotoxic effect of estramustine.

Acetylglucosaminidase↗
PubMed1981

Comparison of daunorubicin and daunorubicin-DNA complex in the treatment of acute nonlymphoblastic leukemia.

Sixty consecutive patients, 15-60 years old, with ANLL were divided randomly into three groups for induction treatment with one of the following regimens: R1, daunorubicin (DNR) 1.5 mg/kg on day 1 + ARA-C 2 mg/kg body weight on days 1-5; R2, DNR 1.5 mg/kg on days 1 and 2 + ARA-C 2 mg/kg on days 4-8; R3, DNR-DNA complex 1.5 mg/kg on days 1 and 2 + ARA-C 2 mg/kg on days 4-8. Maintenance treatment consisted of monthly courses of DNR 1.5 mg/kg (R1, R2) or DNR-DNA 1.5 mg/kg (R3) combined with ARA-C 1 mg/kg on days 1-5, alternating with thioguanine 2 mg/kg PO on days 1-5 combined with ARA-C 1 mg/kg IV on days 1-5. Fourteen patients of 20 went into complete remission with R1, 13 or 18 with R2, and 15 of 22 with R3. The overall remission frequency was 70% and there was no significant difference between the different groups. The median time in first remission and the median survival time were 300 and 510 days, respectively, with R1; 335 and 495 days with R2; and 295 and 677 days with R3. There was no statistically significant difference between the groups treated according to the different regimens concerning the time in first remission. Survival was slightly better with R3 than with R1. Treatment with the DNR-DNA complex caused less pronounced thrombocytopenia and fewer 'minor' cardiac abnormalities than treatment with free DNR in the same dosage schedule.

Acute Disease↗